intestinal morphology

The use of antibiotics in poultry feed has been banned or severely restricted in many countries due to the development of antibiotic resistance and threats to human health. Therefore, there has been a significant focus on alternative feed additives, such as probiotics, prebiotics, synbiotics, organic acids, and herbal products. Prebiotics are specific dietary fibers that cannot be directly digested by the bird's digestive system but serve as food for beneficial gut bacteria, promoting their growth and proliferation. By increasing the population of these beneficial bacteria, the gut environment is altered in a way that inhibits the growth of harmful bacteria and strengthens the bird's immune system. Consequently, the use of prebiotics in poultry feed leads to improved digestion and nutrient absorption, increased growth, a strengthened immune system, reduced disease incidence, and ultimately increased production and improved product quality. Probiotics are live microorganisms that, when added to poultry feed, alter the microbial balance of the gut in favor of beneficial bacteria. These beneficial bacteria produce short-chain fatty acids, strengthen the immune system, improve digestion and nutrient absorption, and reduce the growth of pathogenic bacteria, contributing to gut health and overall bird performance. As a result, the use of probiotics in poultry feed leads to increased growth, improved feed conversion ratio (FCR), reduced mortality, and improved carcass quality. In this context, inulin and yeasts such as Saccharomyces cerevisiae, which are classified as prebiotics and probiotics, respectively, have shown beneficial effects on improving poultry performance.

This experiment was performed as a 2 × 2 factorial arrangement, using a total of 240 Japanese laying quails (Coturnix japonica) at 45 days of age in a completely randomized design with four treatments, six replicates per treatment, and 10 birds per replicate. The factors were inulin (0 and 15 g/kg) and yeast autolysate (S. cerevisiae) (0 and 1.5 g/kg). The birds were placed in the experimental cages for one week prior to the start of the experiment for adaptation and fed a commercial diet. The experimental period lasted 7 weeks, and the birds had ad libitum access to feed and water during the entire experimental period. The experimental diets were formulated to have similar AMEN and crude protein. Egg production (number and weight) was recorded daily, and feed intake was calculated weekly. At the end of the experiment, the FCR was calculated by dividing the feed consumed (in grams) by the produced egg mass (in grams). The eggs collected in the last 4 days of the experiment were used to determine the quantitative and qualitative characteristics of the eggs. One bird per replicate was randomly selected, bled, and then slaughtered on the final day of the experimental period. Samples were collected from the jejunum tissue for histological examination and from the ileum content for microbial population analysis.

The results of this experiment demonstrated that supplementation with autolyzed yeast led to a decrease in feed intake (p < 0.05). The addition of inulin and autolyzed yeast to the diet resulted in an increase in egg production and mass, as well as an improvement in FCR (p < 0.05). A significant interaction was observed between inulin and autolyzed yeast on egg production(p < 0.05). This interaction indicated that adding yeast to diets without inulin resulted in a significant increase in egg production (p < 0.05). Additionally, adding inulin to diets without yeast resulted in a significant increase in egg production (p < 0.05). Autolyzed yeast significantly increased egg weight and shell thickness (p < 0.05). No significant main effects of inulin or interaction effects between the two supplements were observed on egg quantitative and qualitative traits (P > 0.05). Histological findings showed that autolyzed yeast significantly increased villus length and the ratio of villus length to crypt depth (p < 0.05). No significant main effects of inulin or interaction effects were observed between the two supplements on jejunal morphology(p > 0.05). The results showed that supplementation with inulin and autolyzed yeast increased the population of lactobacillus and decreased the population of Clostridium perfringens, coliforms, and total anaerobic bacteria in the ileum (p < 0.05). The interaction between inulin and yeast showed that adding yeast to diets containing inulin resulted in a significant decrease in the coliform population in the ileum (p < 0.05). Analysis of blood parameters showed that supplementation with autolyzed yeast significantly reduced serum cholesterol levels (p < 0.05).

Overall, the results of this experiment demonstrated that both inulin and autolyzed yeast supplements, at levels of 15 and 1.5 grams per kilogram of diet, respectively, either individually or in combination, had a positive impact on the production performance of quails. The improvement in the gut structure by autolyzed yeast and the alteration of gut microbiota toward an increase in beneficial bacteria by both supplements indicate their synergistic effects. These findings suggest that the combined use of these two supplements can be an effective nutritional approach to enhance the health and production performance of quails.

Various factors have been reported to influence broiler chicken performance, including environmental conditions, nutrition, management practices, and genetics. One of the priorities in poultry production is the availability of effective alternatives to antibiotics, and the native strains of this type of alternative have various advantages. Probiotics as live microbial supplements in feed improve the microbial balance of the gastrointestinal tract and then improve animal health. Probiotics can enhance growth performance, support the immune system, aid nutrient digestion, and positively influence the microbial population of the gastrointestinal tract. Commercial probiotics are the most commonly used; however, screening the natural flora of the gastrointestinal tract has become a valuable approach in identifying effective probiotic strains. Selecting the optimal species for use in probiotic supplements is largely experimental and depends on their proven impact on the performance of living organisms. This project aimed to investigate the effects of indigenous probiotics on broiler chickens. The probiotics included strains of Lactobacillus reuteri isolated from native chickens in Oshnavieh, Shush, Shaft, and Masal, as well as Lactobacillus salivarius isolated from native ducks in Mazandaran. The study aimed to assess the impact of these probiotics on the performance, immune response, morphology, and gut lactobacillus population in broiler chickens. The single strain (Plr2) and combination strains (Plr9, Plr10, Plr11, and Plr12) were evaluated in a completely randomized design. There were seven treatments, each with four replicates, and 16 one-day-old Ross 308 broiler chickens per replicate. Treatments include 1) control: basic diet without any additive, 2) Positive control 2: basic diet + commercial probiotic, 3) Basic ration + 1.36×109 CFU/g L. Reuteri isolated from Oshnavieh native hen (Plr2), 4) Basic ration + 1.36×109 CFU/g L. Reuteri isolated from Oshnavieh native hen and L. salivarius isolated from Mazandaran native duck (Plr9), 5) Basic ration + 1.36×109 CFU/g L. Reuteri isolated from Oshnavieh native hen and L. salivarius isolated from Mazandaran native duck and L. Reuteri isolated from Shush native hen (Plr10), 6) Basic ration + 1.36×109 CFU/g L. Reuteri isolated from Oshnavieh native hen and L. salivarius isolated from Mazandaran native duck and L. Reuteri isolated from Shush native hen and L. Reuteri isolated from Shaft native hen (Plr11) and 7) Basic ration + 1.36×109 CFU/g L. Reuteri isolated from Oshnavieh native hen and L. salivarius isolated from Mazandaran native duck and L. Reuteri isolated from Shush native hen and L. Reuteri isolated from Shaft native hen and L. Reuteri isolated from Masal native hen (Plr12). There were no significant differences in feed intake, daily weight gain, or feed conversion ratio among the probiotic treatment groups. However, evaluation of antibody production against sheep red blood cells (SRBC) injected during the first 30 days of rearing showed that the Plr12 probiotic combination significantly increased IgG levels compared to the control group (without additives). The secondary immune response, measured 42 days after SRBC injection, showed an even greater increase in antibody levels. Additionally, all probiotic combinations significantly enhanced antibody levels compared to the control. It appears that as the chicks mature, their immune system continues to develop, and the memory cells generated during the initial immune response led to an increased production of antibodies during the subsequent response. Results derived from the broilers jejunum morphology study in the first experiment showed that the addition of the native probiotic combination Plr9, Plr11, and Plr12 to the diet resulted in a significant increase in the length of the intestinal villi of jejunum in chickens from the experimental groups when compared to chickens from the control group. Also, investigation of villus length/crypt depth and surface villus area indicated a significant increase in these traits in all probiotic treatments used compared to control treatments and commercial probiotic. The examination of the lactobacillus population in the cecal contents of broiler chickens showed that the combination of strains Plr9, Plr11, and Plr12 significantly increased the population of these beneficial bacteria compared to the control and commercial probiotic treatments. Each strain had specific probiotic properties. When these strains were combined and administered to broiler chickens, there was a significant increase in beneficial bacteria and a reduction in harmful bacteria. This study demonstrates that probiotic bacteria, isolated from the microbial population of the digestive system of native birds, have the potential to serve as valuable dietary supplements in poultry nutrition. Each probiotic strain confers varying levels of optimal efficacy; as a result, these probiotics can be used individually or in combination, and they can replace antibiotics and commercial probiotics.

 Probiotics are live microbial feed supplements that exert beneficial effects on host animals by enhancing the balance of intestinal microbes (Fesseha, 2019). In poultry production, probiotics are increasingly viewed as alternatives to oral antibiotics due to growing concerns regarding antimicrobial resistance (Ogbuewu et al., 2022). Bacillus probiotics, in particular, have shown significant promise thanks to their spore-forming capabilities and resistance to feed processing (Ogbuewu et al., 2022). The stability of Bacillus spores in various stressful conditions, along with their ability to produce a range of enzymes such as protease, amylase, and lipase, makes them suitable food additives (Lei et al., 2013). Research indicates that probiotic supplementation can enhance growth performance, feed conversion efficiency, and antioxidant status in broilers (Jadhav et al., 2015; Ogbuewu et al., 2022). Additionally, probiotics contribute to improved intestinal health by promoting beneficial microflora and enhancing intestinal morphology (Ogbuewu et al., 2022). Likewise, probiotics can boost various performance and health parameters in poultry, including body weight gain, feed conversion ratio, and overall intestinal health (Alhefny et al., 2022; Aziz et al., 2022; Hassan et al.,2023; Prentza et al., 2022; Smolovskaya et al., 2023).The administration of synbiotics has been associated with positive effects on gut health, survival rates, and the composition of gut microbiota in broiler hens, suggesting potential benefits for reproductive performance and overall health in later life (Prentza et al., 2022). Furthermore, the use of probiotics does not lead to antibiotic resistance in intestinal bacteria, nor does it cause the accumulation of antibiotics in bird tissues (Angelakis, 2017; Blajman et al., 2015). Common probiotic strains utilized in poultry include species of Lactobacillus, Enterococcus, and Bacillus (Fesseha, 2019). Although probiotics demonstrate potential as growth promoters, their effects can vary depending on the specific strains used and their dosages (Ahmad,2006). The characteristics of an effective probiotic include the following:1. It is non-pathogenic.2. It exerts a positive effect on the host animal.3. It can survive in the intestinal environment.4. It remains viable under storage conditions.5. It has a high shelf life during processing.6. It competes effectively with harmful bacteria (Smirnov et al., 2005).

This experiment aimed to investigate the effects of commercial probiotics on sperm traits, intestinal morphology, gut microflora, and antioxidant status in 65-week-old Ross 308 male broiler breeders. A completely randomized design was used with 5 treatments, 10 replications, and one male per unit, totaling 50 males. Sperm characteristics were assessed by collecting samples using the abdominal rub method every ten days. The eosin and nigrosine staining method determined the percentage of live and dead sperm. Antioxidant capacity and glutathione peroxidase activity were also measured. At the experiment's conclusion, all roosters were slaughtered to evaluate intestinal morphology and quantify E. coli and Lactobacillus populations.

The effects of varying levels of commercial probiotics on sperm parameters—such as volume, motility, live sperm percentage, sperm count, and abnormal sperm percentage—in 65-week-old Ross 308 broiler breeders are detailed in Table 3. The study found that the experimental treatments did not significantly affect sperm volume, motility, or live sperm percentage. However, during the first and second months, sperm counts in groups receiving 100, 150, and 200 mg/kg of probiotics were significantly higher than in the control group (P<0.05). Bacillus supplementation notably increased live sperm counts (Mazanko et al., 2018). Additionally, the percentage of abnormal sperm was significantly lower (P<0.01) in the 100, 150, and 200 mg/kg probiotic groups compared to controls. Consistent with our findings, vitamin E has been reported to enhance semen volume, sperm motility, and egg fertility, while vitamin C reduces dead sperm percentages (Khan et al., 2012; Khan et al., 2013). In the first month, supplementation with 150 and 200 mg/kg of probiotics, and in the second month with 50, 150, and 200 mg/kg, significantly increased total antioxidant capacity (P<0.05). Probiotics also significantly increased villi length, with the highest jejunum villi length observed in the 150 mg/kg group (1231 micrometers) compared to the control (1156 micrometers). The villus-to-crypt depth ratio was highest in the 150 mg/kg group, showing significant improvement over controls. Probiotic addition significantly increased Lactobacillus numbers in the jejunum and ileum (P<0.05), while E. coli counts in the jejunum were significantly reduced compared to the control group.

The study demonstrated that probiotics in poultry nutrition enhance the immune system by settling in the digestive tract, preventing pathogens from adhering to intestinal villi, creating acidic conditions, and producing bactericides. This, in turn, improves nutrient digestion. Additionally, roosters fed with 100, 150, and 200 mg/kg probiotics showed a significantly higher number of live sperm compared to the control group. Overall, based on sperm characteristics, intestinal morphology, gut microflora, and antioxidant status, 100 mg/kg of probiotics is recommended as the optimal dosage.

Bee pollen is used in human and animal nutrition and is rich in bioactive compounds, such as flavonoids and polyphenols. It has a wide range of therapeutic properties and plays an important role in preventing diseases related to free radicals. The use of unprocessed bee pollen in human nutrition can be harmful due to the presence of allergenic compounds and contamination of the product. Bee pollen is a natural product and fungal contamination is possible during collection by insects or improper storage. Gamma irradiation can remove microbial contamination, increase protein bioavailability, change their function, and be used for bee pollen processing by changing the structure of allergenic compounds. This research aimed to study the effects of gamma irradiation on the properties of bioactive compounds, including protective effects against tissue damage, digestive system health, and anti-inflammatory and anti-allergenic effects of gamma-irradiated bee pollen.

Raw and gamma-irradiated bee pollen with a dose of 25 kGy of gamma rays in 2% of the basic diet was fed to 96 adult male Wistar rats. Experimental diets included no use of pollen, using raw bee pollen, and using gamma-irradiated bee pollen with a dose of 25 kGy. Sodium fluoride (1 g/kg of diet) was used to cause poisoning and tissue damage. After 42 days, the effects of pollen nutrition in preventing sodium fluoride toxicity were studied using histological studies and liver enzymes. The effects of pollen feeding on the microbial flora of the digestive tract, intestinal morphology, and villus growth were studied by sampling intestinal tissue and contents. Interleukin-4 was measured to study the antiallergic effects of pollen by the ELISA method. Experimental data were analyzed in a completely randomized experimental design using SAS statistical software.  Means were compared with Duncan's test at the level of 5%.

The total protein and malondialdehyde contents in the irradiated samples were not different from the control sample (p > 0.05), but using bee pollen caused a decrease in serum alanine transferase (p < 0.05). There was a significant difference in the amount of blood cations in the sodium fluoride group. The use of bee pollen improved the increase of sodium and potassium levels and the decrease of phosphorus in the sodium fluoride group (p < 0.05). No significant difference was observed in serum interleukin-4 concentration in different treatments of raw and radiation-processed pollen with a dose of 25 kGy (p > 0.05). The results of measuring the antimicrobial properties of gamma-irradiated pollen showed that irradiation did not affect the antimicrobial properties of bee pollen (p < 0.05). The antimicrobial properties of bee pollen on Gram-positive bacteria are more than Gram-negative bacteria. Bee pollen has more antimicrobial activity against Gram-positive bacteria than Gram-negative bacteria and fungi. Bee pollen destroys Gram-positive and Gram-negative bacteria, but the sensitivity of Gram-positive bacteria is higher than that of Gram-negative bacteria due to the nature of the cell membrane layer. The use of pollen decreased the population of Gram-positive and Gram-negative bacteria in the intestine (p < 0.05). The decrease in the population of intestinal bacteria can be due to the antimicrobial effects of pollen or changes in the morphology of the intestinal wall, which plays a role in bacterial attachment and establishment and prevents the destruction and damage of the intestinal epithelial cells. The histological results showed that the diet containing raw and irradiated bee pollen reduced sodium fluoride damage, including bleeding of  the testicles and digestive tract, hyperemia, and swelling of hepatocytes, and kidney damage. The morphological characteristics of the intestines of rats fed with pollen were significantly different from those fed with a pollen-free diet (p < 0.05). In the experimental group of raw and processed pollen, the ratio of villus height to crypt depth and villus height increased in the duodenum, jejunum, and ileum (p < 0.05). Diets containing sodium fluoride caused a decrease in villus length and crypt depth along the intestine, but the reduction percentage was lower in pollen-containing diets. There was a significant difference in the intestinal morphological characteristics of rats fed with both raw and processed pollens (p < 0.05). The effect of raw pollen was greater in the duodenum and jejunum, but processed pollen increased the length of the villi in the ileum, though the depth of the ileal crypt was not different (p > 0.05). The use of pollen caused an increase in the relative volume of the epithelium and a decrease in the connective tissue of the jejunum, along with increases in the villi length and the jejunum crypt depth. These results show the growth-stimulating effect of pollen on intestinal villi. The use of pollen increased the height of the villi and the depth of the intestinal crypt of the tested rats. Bee pollen gamma irradiation did not change this property of pollen, and it caused better functioning of the digestive system in cases such as the length of ileal villi.

According to the results of this research, a dose of 25 kGy of gamma radiation without negative effects on the properties of the bioactive compounds of bee pollen can be used for the radiation processing of bee pollen.

Antibiotics have been used for many years in animal production to treat infectious diseases and as growth promoters. However, the misuse of antibiotics causes problems such as bacterial antibiotic resistance. Also, the possible accumulation of antibiotic residues in livestock products is risky for consumers. After the ban on the use of antibiotic growth promoters in 2006, there was a need to use substitutes in animal feed to replace antibiotics. These alternatives include prebiotics, probiotics, phytobiotics and synbiotics. Probiotics are live microorganisms that, when consumed in sufficient amounts, have beneficial effects on the host by creating a microbial balance in the gut. The purpose of probiotics is to create a competition between the species that are naturally present in the intestinal flora of broilers. The most important advantage of probiotics is that they do not remain in animal products. Prebiotics are feed compounds that are not digested by the host when consumed but can support beneficial bacteria. These compounds are short-chain carbohydrates such as non-digestible oligosaccharides that cannot be digested by animal enzymes. Compounds containing prebiotics and probiotics used in nutrition are called synbiotics. Phytobiotics include a wide range of plant-derived products with bioactive compounds. Plant feed additives (PFAs) are widely effective in improving gut health, increasing digestibility and thus growth performance. These bioactive compounds include secondary metabolites (phenolic and flavonoid). In recent years, various marine organisms have been considered as valuable biological compounds for livestock. Marine algae, due to a wide range of bioactive components such as flavonoid, carotenoid, phenolic compounds, tocopherol, peptide and various sulfated and carboxylated polysaccharides such as alginate and fucoidan with antibacterial, antifungal and antiviruses have beneficial effects on health. Brown macroalgae such as Sargassum angustifolium have beneficial effects on health due to a wide range of bioactive components such as fucoidan, fucose sulfate and polysaccharides. Also, this group of algae is a rich source of sodium alginate oligosaccharides.

The present study was conducted in the form of a completely randomized design, lasted for 42 days at the Ali Abad Kamin research farm of the Fars Agricultural and Natural Resources Research and Education Center, Shiraz, Iran. A total of 240 Ross 308 broilers were distributed in five treatments, four replications and 12 birds per replication. The dietary treatments included: 1 basal diet, without additives, 2 basal diet + 0.05% Oxytetracycline, 3 basal diet + 0.2% brown algae Sargassum and treatments 4 and 5 the basal diet was + 1% and 1.5% of synbiotics Limax, respectively. Ingredients and chemical composition of the ration are presented in (Table 1). At the end of each period, chickens in each group were weighed and the average body weight gain (g/b) in each period was calculated. Feed intake in each period was calculated and expressed as g/b/d. Based on weight gain and feed intake in each period, the FCR values of each group were calculated. Tow representative chickens from each group were selected for carcass analysis representing the average weight and variability of each group. The data obtained on various parameters studied during this experimental trial were analyzed statistically with SAS software.

The results showed that the treatments had no significant effect on the feed conversion ratio of the birds. In the finisher period (25-42 days) and total period (1-42 days), oxytetracycline and Limax 1% treatments had the highest and lowest average daily weight gain, respectively. There wasn't any significant difference between average daily weight gain of the oxytetracycline treatment and other experimental treatments. In the finisher period, the highest amount of feed intake was for the control treatment and the lowest for the Limax 1% treatment (P<0.05). The highest value of production index was belonged to oxytetracycline and Limax treatments was 1.5% (295 and 272, respectively). The highest abdominal fat percentage in the day 42 was related to Oxytetracycline treatment and the lowest was related to Limax treatment of 1.5% (P<0.05). The highest villus width in the day 42 was belonged to Limax treatment of 1 and 1.5% and the lowest was belonged to Oxytetracycline, control and Sargassum treatments (P<0.05). The treatments did not show a significant difference in the feed conversion ratio. The highest value of production index was observed in oxytetracycline and Limex 1.5% treatments (295.25 and 271.71, respectively).

The final result is that the two oxytetracycline and 1.5% of synbiotics Limax treatments shown the highest average daily weight gain and the production index among the experimental treatments. Also, the maximum width of villi and its absorption surface of villus was related to Limax treatment of 1.5%. Therefore, despite the problems of using antibiotics in the diet of birds, Limax synbiotic supplement can be a suitable substitute for oxytetracycline antibiotic.

This study was conducted to evaluate the effects of acid hydrolyzed processing on the nutritional value of soybean meal (SBM) and its influence on the growth performance, intestinal morphology, microbial population, digestive enzymes activity, and nutrient digestibility in broiler chickens fed with diets containing different levels of crude protein. A total of 300 one-day-old male broiler chickens were used in a design with 6 treatments and 5 replicates per each during 1 to 42 days of age. This experiment was conducted as a completely randomized design with a 2 × 3 factorial arrangement of treatments including two types of SBM (raw and treated with 0.50% citric acid) and three inclusion rates of crude protein (90, 95 and 100 % of  requirements). The results showed that acid-treated SBM improved feed conversion ratio in broilers compared to raw-SBM group (P < 0.05). The decrease of protein requirements up to 90% declined growth performance of broilers compared to 95 and 100 % of requirements (P < 0.05). The villus length was greater in broiler chickens fed with acid-treated SBM compared with raw-SBM group (P < 0.05). Meanwhile, reduction of protein requirements decreased the villus length, the ration of villus length to crypt depth and villus surface in broilers (P < 0.05). Acid processing of SBM increased digestibility coefficient of crude protein and protease and amylase activity in broiler chickens (P < 0.05). In addition, a decrease in protein digestibility and enzyme activity was observed in broilers fed low protein (90 % of the requirements) diet (P < 0.05). Based on the results of this study, it can be concluded that acid processing of SBM improved its nutritional quality. Also, use of acid-treated SBM increased growth performance, intestinal morphometric indices, digestive enzymes activity and nutrient utilization in broiler chickens. In addition, reducing of crude protein requirements up to 95% in diets containing citric acid-treated SBM had not negative impact on growth performance in broiler chickens.

Application of suitable feed additives can increase feed utilization, improve production and improve health. Years ago, growth-promoting antibiotics were used at high levels in diets to increase poultry performance (Ronquillo & Hernandez, 2017). However, its remnants remain in the animal's body and create microbial resistance in the animal, and humans also develop microbial resistance by consuming it. Therefore, there is a need to find substances that can replace antibiotic growth stimulants in the diet. The aim of these alternatives is to increase performance while protecting the environment and animal health (Ogbuewu, koro, Mbajiorgu, & Mbajiorgu, 2019). Therefore, probiotics such as Saccharomyces cerevisiae yeast have been investigated as a feed additive to improve the performance and health of animals (Al-Khalaifah, 2018). It is thought that probiotics improve performance by affecting the natural microbial community and improving the absorption process in the intestine (Sohail et al., 2011). Also, symbiotic are able to work both in the small intestine and in the large intestine and have the effect of probiotics and prebiotics at the same time (Ai et al., 2011; Bengmark, 2002). Gut cognition can affect the amount of nutrient absorption (Miles, Butcher, Henry, & Littell, 2006; Rahimi, Grimes, Fletcher, Oviedo, & Sheldon, 2009) and as a barrier against disease agents (Brown, 2011). Saccharomyces cerevisiae, also known as baker's yeast, is a type of yeast that is added to food formulas in poultry diets (Elghandour et al., 2020). Saccharomyces cerevisiae contains significant levels of digestible proteins, vitamins, magnesium and zinc, whose wall has many features such as polysaccharide α-D-mannan, chitin and β-D-glucan (Alizadeh et al. ., 2016) which plays an important role in beneficial microbial balance in the gut, tissue proliferation in the gut and lymphocytes (Council, 1994). In most studies, no reliable results were obtained with diets supplemented with yeast. Beneficial effects on animal health and performance may be due to the use of detectable yeast strains and levels, diet compositions, animal species and their age (Bolacali & İrak, 2017). Therefore, in order to investigate the potential effects of using commercial yeast Saccharomyces cerevisiae in Japanese quail diet as a feed additive on growth performance, some serum parameters, intestinal morphology and the number of Clostridium perfringens and E-coli bacteria. It was done in the waste.Materials and Methods This experiment was conducted in order to investigate the effect of different levels of Chitacell commercial yeast on performance, carcass characteristics, intestinal morphology and blood parameters in the form of a completely randomized design with 7 treatments, 6 replications and 12 chicken in each experimental unit and a total of 504 chicken. One day Japanese quail mixed of two sexes was performed. At the end of the experiment (d 35), 2 Japanese quails from each replicate were weighed and slaughtered. Visceral and lymphoid organs were also weighed and recorded. About 8g of the contents from duodenum, jejunum and ileum were collected in 80 mL physiological saline for pH value measurement. Blood samples were collected from the same Japanese quails used for carcass traits and were centrifuged at 3000 rpm for 10 min, then stored for later analysis at -20°C. In order to measure E. coli and C. Perfringens bacteria in feces, standard plate counting method was used. And also Duodenum specimens were collected and fixed in 10% neutral buffered formalin solution for 24 h, then embedded in paraffin and sectioned at 4 μm. The following parameters were measured: (i) villous height (VH), (ii) depth of crypt (CD) and (iii) ratios of VH/CD. The effects of different levels of commercial yeast Saccharomyces cerevisiae on the growth performance of Japanese quail chicks are reported in Table 2. The results of this study show that the experimental treatments had no significant effect on feed consumption. The group fed with 0.75, 1.1, 1.25 and 1.5 percent of yeast could significantly increase weight compared to the control group (P<0.05). Also, the food conversion ratio in the groups receiving 0.75 and 1 g/kg of Saccharomyces cerevisiae yeast feed compared to the control groups and 0.25 and 0.5 g/kg of yeast in the diet decreased significantly (<0.05). P). According to the results of this experiment, it has been reported that live yeast has a favorable effect on feed conversion ratio and final weight gain in broiler chickens (Borda-Molina, Seifert, & Camarinha-Silva, 2018). Abdominal fat and thymus size were significantly affected by experimental treatments (P<0.05). Thus, adding yeast levels higher than 0.75 g/kg reduced the fat in the ventricular area, while the size of the thymus increased compared to the control group. It has also been shown that the percentage of carcass, liver, stone, heart, spleen and bursa of Fabricius were not affected by experimental treatments (P<0.05). It has been reported that live yeast reduces abdominal fat and increases thymus size. In fact, yeast stimulates the intestinal immune system by acting as a non-pathogenic microbial antigen and creates an effect similar to adjuvants. By adding the level of commercial yeast Saccharomyces cerevisiae, the amount of total protein and albumin in the blood increased significantly (P<0.05). On the other hand, cholesterol and triglyceride in the blood decreased significantly by adding different levels of commercial Saccharomyces cerevisiae yeast (P<0.05). Superoxide dismutase and catalase in serum increased significantly with increasing yeast consumption (P<0.05). On the other hand, interleukin 1 and 6, as well astumor necrosis factor alpha decreased significantly (P<0.05) with the increase in the level of yeast in the diet. Results of this research showed that the use of commercial yeast Saccharomyces cerevisiae has favorable effects and it can also be said that the best level used is 0.75 grams per kilogram of feed.

During the last two decades, the use of antibiotics in poultry diets as animal growth promotors and growth inhibitors of harmful microorganisms has been stopped in different parts of the world (Roth et al., 2019), which led to a decrease in poultry performance and an increase in the prevalence of diseases (Jha et al 2019; Adhikari et al 2020). Researchers have proposed various ways to improve production efficiency, including the use of probiotics, prebiotics, symbiotic, plant extracts, enzymes and organic acids (Gadde et al 2017; Yadav et al 2019). As the age of laying hens increases, the quality of the egg shell decreases, which is due to the increases in weight and size of eggs, the direct effect of age on the structure of the shell, decreased bone calcium uptake and etc (Curtis et al 2005; Curtis 2008). Heat stress has negative effects on the human health and animal performance and product quality. High ambient temperatures cause reduced egg production, egg weight, egg quality (especially egg shell thickness and strength), impaired immunity and poor poultry welfare (Elnagar et al 2010, Ebied et al 2012). The impaired performances of poultry subjected to heat stress (HS) have been associated with a number of factors, including poor appetite and reduced feed intake (due to activation of the hypothalamic-pituitary-adrenal axis), impaired digestion and metabolism, altered endocrine status (increased corticosterone concentration and reduced thyroid hormones concentrations), metabolic shifts at the systemic and cellular levels and changes in body composition (Elnagar et al 2010, Azad et al 2010, Ebied et al 2012, Safdari-Rostamabad et al 2017). Therefore, it is important to design the strategies or ways of minimizing the negative effect of heat stress as part of methods to maintaining egg production, egg quality and poultry welfare. There are several strategies to reduce the effects of heat stress in the laying hens, including use of feed additive, vitamins, organic minerals and antioxidants. In this study, researchers evaluated the effects of MultiAct-L® (Contains probiotics, prebiotics, organic acids, enzymes, organic form of Zn, Mn, Cu, Fe, Co, Cr and antioxidants) on production performance, egg quality, Newcastle disease antibody titer, antioxidant capacity and gut morphology of laying hens subjected to HS in late laying cycle.

Two hundred and sixteen LSL-Lite laying hens (90 weeks of age) were randomly assigned to three dietary treatments with six replicates and twelve birds in each replicate. Dietary treatments were: 1) basal diet based on a corn-soybean meal 2) basal diet with 0.3 % MultiAct-L® and 3) basal diet with 0.5% MultiAct-L®. The birds were exposed to 36±1°C for 6 hours per day. Egg production, egg weight, feed intake, egg mass and feed conversion ratio were recorded weekly and mortality was recorded daily. Egg mass was calculated by multiplying the total number of eggs laid per hens by the average egg weight. At the end of experimental period, one bird from each replicate (close to cage average weight) was slaughtered, and blood samples were taken for analysis. Blood samples were collected from the jugular vein and then serum samples were separated at 3000 ×g for 10 min. Total antioxidant capacity, malondialdehyde, glutathione peroxidase, superoxide dismutase, glucose, cholesterol, triglycerides, uric acid, albumin, calcium and phosphorus were measured using analytical kits. Serum titer to Newcastle disease virus was determined by hemagglutination inhibition test. Villus height, villus width, crypt depth, villus surface area and villus height/crypt depth were measured in the jejunum section of the small intestine. The data were analyzed using the general linear model procedure of the SAS (2003). The Duncan multiple range test was used to determine the significant differences between treatment means.

MultiAct-L® did not affect the body weight gain of laying hens (P>0.05). The results also showed that feeding MultiAct-L® enhanced the feed intake, egg production, egg weight and egg mass (P<0.05). Feed conversion ratio was improved and mortality was lower in the treatments receiving 0.3 or 0.5% MultiAct-L® than the control group (P<0.05). In agreement with our findings, Deng et al. (2012) and Zhang et al. (2017) reported the significant increase of egg production, feed intake and egg weight by dietary supplementation of probiotic in laying hens subjected to HS. Supplementation of 0.3% MultiAct-L® to diet decreased the abnormal eggs (P>0.05). Shape index, Haugh unit, yolk weight, albumen weight, shell weight, shell thickness and egg specific gravity were not affected by dietary treatments (P>0.05). Similarly, Bozkurt et al. (2012) showed that egg quality parameters weren’t affected by dietary supplementation of essential oil or mannan oligosaccharide in laying hens subjected to heat stress. MultiAct-L® supplement did not significantly affect the titer of antibody against Newcastle disease virus at days 10 and 30 post-vaccination (P>0.05). There was no significant difference in the total antioxidant capacity and glutathione peroxidase among experimental treatments (P>0.05); however, dietary MultiAct-L® supplementation had increased the superoxide dismutase levels and decreased malondialdehyde levels in serum (P<0.05). Blood glucose, cholesterol, triglycerides, uric acid, albumin, calcium and phosphorus in experimental treatments were not significantly different between the control group and the MultiAct-L®-treated groups (P>0.05). No significant changes in villus height, villus width, villus surface area, crypt depth and villus height to crypt depth ratio were observed between three groups at the end of the 8 weeks experimental period (P>0.05). Similarly, Deng et al. (2012) showed that villus height, villus width, crypt depth in the ileum weren’t affected by dietary supplementation of probiotic in laying hens subjected to HS.

As for the results of this study, Multiact-L® could improve laying performance and antioxidant status in laying hens subjected to heat stress during the late laying period.

The use of medicinal plants and their derivatives can stimulate feed consumption, increase daily weight, feed conversion ratio, increase shelf life, improve the health and function of the digestive system. It seems that the use of an optimal mixture of several medicinal plants in the diet has positive effects on performance and carcass quality of broiler chickens in comparison to each one. Nowadays, with the popularization of ready-made feed in raising broiler chickens, many breeders tend to add food additives in drinking water. Therefore, it is a question that adding these compounds in feed or drinking water makes a difference. Three commercial plant additives that are used today are Coxan, O.X. Plant, and Entex. Coxan contains oregano (with the active ingredient of menthol) and garlic (with the active ingredients of allin and allicin), O.X. Plant contains savory (with the active ingredients of carvacrol and thymol), thyme (with the active ingredients of thymol and carvacrol) and red pepper oleoresin (with the active ingredient of capsaicin), Entex contains cinnamon (with the active ingredient of cinnamaldehyde), and garlic and eucalyptus (with the active ingredient of cineol). The aim of this research was to compare the effects of using these commercial plant additives (in water and feed) on growth performance, intestinal microflora and morphology and immune response of broilers.
A total of 336 Ross 308 broilers were examined in a completely randomized design with seven treatments, four replications, and 12 chickens per replication. Experimental treatments included: control (without phytogenic in feed or water), Coxan in feed (300 mg/kg) and in water (200 mL/1000 L), O.X. Plant in feed (200 mg/kg) and in water (135 mL/1000 L) and Entex in feed (500 mg/kg) and water (350 mL/1000 L). Daily weight gain, daily feed intake, daily water intake and feed conversion ratio were measured. At 42 days of age, two birds were selected from each experimental unit and after slaughter, the length of the intestinal components was measured separately (duodenum, jejunum, and ileum). To determine the microbial population, samples were taken from the ileum of chickens. EMB culture medium was used to determine Escherichia coli population and MRS culture medium was used for Lactobacillus bacteria. To check the humoral immune response, 0.1 mL of 25% sheep red blood cell solution in PBS was injected into the breast muscle of chickens on the 12th and 29th days of rearing. Blood was taken from the chickens on the 28th, 35th and 42nd days of breeding and the levels of Anti-SRBC, and immunoglobulins G and M were calculated. Antibody titer against Newcastle disease was measured by HI method.
The effect of additives in water and feed on average daily feed consumption, daily weight gain, feed conversion ratio and daily water consumption was not significant in the whole period. Since the amount of water consumed by the chickens did not change, it can be concluded that the additives added to the water in the examined amounts do not have a spicy or unpleasant taste that would cause the birds to refuse to drink water. The relative length of duodenum, jejunum, cecum and colon was not affected by experimental treatments. However, the relative length of the ileum was lower in the chickens that received Entex in the feed compared to the control group. No significant difference was observed in the relative length of different parts of the intestine in the treatments that received herbal additives either in feed or water. The relative length of duodenum, jejunum, cecum, and colon, villus length, villus area, crypt depth, thickness of lamina propria, thickness of muscular layer, and thickness of advantis layer were not affected by experimental treatments. The chickens that consumed 500 mg/kg of Entex herbal additive of feed had a lower villus width in the ileum region compared to the control group chickens. The population of Escherichia coli bacteria in the ileum of chickens that had received the addition of O.X. Plant and Entex in the feed decreased compared to the control group. The population of Escherichia coli bacteria in the Entex treatment in the feed was also reduced compared to the Coxan treatment in the feed. The population of Lactobacillus bacteria in the ileum of chickens that received Coxan in water, O.X. Plant in feed and water, and Entex in feed increased compared to the control group. There was no significant difference in the population of Escherichia coli and Lactobacillus bacteria in the treatments that received herbal additives either in feed or in water. The use of plant essential oils in poultry feed, while improving the microbial population by increasing the number of lactobacilli, by improving the morphological characteristics of the intestine, probably improves the ability of digestion and absorption in the digestive system and improves the growth efficiency of broiler chickens. Antibody levels against SRBC were higher at 28, 35, and 42 days in all chickens consuming herbal additives in water. The performance of animals is significantly influenced by the state of health and safety of the animal. A weak or stressed immune system causes weight loss when dealing with infectious diseases, so the use of immune system stimulating substances can increase performance by improving the immune status. In raising poultry, it is important to strengthen the immune system to prevent the occurrence of diseases.
The results of this research showed that the commercial plant additives of Coxan, O.X. Plant, and Entex had no significant effect on growth performance, relative length and intestinal morphology. The population of opportunistic bacteria Escherichia coli was significantly reduced compared to the control group with the addition of O.X. Plant and Entex in the diet. In general, it can be concluded that adding tested herbal additives not only did not have a negative effect on the drinking water consumption of broiler chickens, but also using them in water improved the immune responses of broilers more than adding them in feed. A total of 336 Ross 308 broilers were examined in a completely randomized design with 7 treatments, 4 replications, and 12 chickens per replication. Experimental treatments included: control (without phytogenic in feed or water), Coxan in feed (300 mg/kg) and in water (200 mL/1000 L), O.X. Plant in feed (200 mg/kg) and in water (135 mL/1000 L) and Entex in feed (500 mg/kg) and water (350 mL/1000 L). Daily weight gain, daily feed intake, daily water intake and feed conversion ratio were measured. At 42 days of age, 2 birds were selected from each experimental unit and after slaughter, the length of the intestinal components was measured separately (duodenum, jejunum, ileum). In order to determine the microbial population, samples were taken from the ileum of chickens. EMB culture medium was used to determine Escherichia coli population and MRS culture medium was used for Lactobacillus bacteria. To check the humoral immune response, 0.1 ml of 25% sheep red blood cell solution in PBS was injected into the breast muscle of chickens on the 12th and 29th days of rearing. Blood was taken from the chickens on the 28th, 35th and 42nd days of breeding and the levels of Anti-SRBC, immunoglobulin G and M were calculated. Antibody titer against Newcastle disease was measured by HI method. The effect of additives in water and feed on average daily feed consumption, daily weight gain, feed conversion ratio and daily water consumption was not significant in the whole period. Since the amount of water consumed by the chickens did not change, it can be concluded that the additives added to the water in the examined amounts do not have a spicy or unpleasant taste that would cause the birds to refuse to drink water. The relative length of duodenum, jejunum, cecum and colon was not affected by experimental treatments. However, the relative length of the ileum was lower in the chickens that received Entex in the feed compared to the control group. No significant difference was observed in the relative length of different parts of the intestine in the treatments that received herbal additives either in feed or water. The relative length of duodenum, jejunum, cecum, and colon, villus length, villus area, crypt depth, thickness of lamina propria, thickness of muscular layer, thickness of advantis layer were not affected by the experimental treatments. The chickens that consumed 500 mg/kg of Entex herbal additive of feed had a lower villus width in the ileum region compared to the control group chickens. The population of Escherichia coli bacteria in the ileum of chickens that had received the addition of O.X. Plant and Entex in the feed decreased compared to the control group. The population of Escherichia coli bacteria in the Entex treatment in the feed was also reduced compared to the Coxan treatment in the feed. The population of Lactobacillus bacteria in the ileum of chickens that received Coxan in water, O.X. Plant in feed and water and Entex in feed increased compared to the control group. There was no significant difference in the population of Escherichia coli and Lactobacillus bacteria in the treatments that received herbal additives either in feed or in water. The use of plant essential oils in poultry feed, while improving the microbial population by increasing the number of lactobacilli, by improving the morphological characteristics of the intestine, probably improves the ability of digestion and absorption in the digestive system and improves the growth efficiency of broiler chickens. Antibody levels against SRBC were higher at 28, 35 and 42 days in all chickens consuming herbal additives in water. The performance of animals is significantly influenced by the state of health and safety of the animal. A weak or stressed immune system causes weight loss when dealing with infectious diseases, so the use of immune system stimulating substances can increase performance by improving the immune status. In raising poultry, it is important to strengthen the immune system to prevent the occurrence of diseases. The results of this research showed that the commercial plant additives Coxan, O.X. Plant and Entex had no significant effect on growth performance, relative length and intestinal morphology. The population of opportunistic bacteria Escherichia coli was significantly reduced compared to the control group with the addition of O.X. Plant and Entex in the diet. In general, it can be concluded that adding tested herbal additives not only does not have a negative effect on the drinking water consumption of broiler chickens, but using them in water improves the immune responses of broilers more than adding them in feed.

The continuous effort of breeders towards producing high-quality broiler strains demands continuous evaluation of broiler strains in terms of traits beyond performance. Increase in leg disorders in commercial broiler chickens resulted in considerable attention being given to the characteristics of leg bones. Furthermore, digestive tract characteristics have been considered to have a critical role in the poultry growth. Therefore, in this study, feedlot performance, intestinal morphology and tibial bone characteristics were compared and investigated in two strains of broiler chickens (Ross 308 and Arian) in Iran.

One-day-old chicks from Ross308 and Arian strains were separately allocated to two treatment groups. The initial number of each strain was 48, divided into 12 replicate cages, each with four chicks. The body weight and feed intake were recorded in weekly intervals for six consecutive weeks. The randomly selected broilers were slaughtered at 32 days of age, to make measurements of the morphometric characteristics in the different segments of small intestine, and also tibial morphology, breaking strength and composition. Feet relative weight and carcass percentage were determined at the end of the rearing period.

The whole feed intake of the Arian broilers was significantly higher throughout the experimental period, but overall body weight and feed conversion ratio (FCR) were not statistically different between the two strains. In accordance with the present results, in most of the studies conducted in Iran, Ross and Arian strains were not superior to each other in terms of body weight gain and feed conversion ratio during the breeding period of 1 to 42 days. Carcass yield in both slaughter ages was lower in Arian than in Ross. This may be due to the lower relative weight of the feet, visceral fat, or internal organs in the Ross308 broiler chickens in comparison with the Arian broilers. The villus thickness and the jejunal and the ileal surface area were significantly greater in the Arian broilers than in the Ross308. However, ileal goblet cell densities were lower in the Arian broilers than in Ross308. A decrease in the acidic goblet cells may be considered relevant to increased susceptibility of the small intestine to bacterial translocation, which theoretically may lead to inflammatory responses in the broiler body. Among the tibial characteristics, only the diameter of the diaphysis and the medullary canal were significantly wider in the Arian broilers than in the Ross308.

Ross308 strain had lower feed intake (in the entire period of trial), the better feed conversion ratio (up to 28 days of age), and higher carcass yield in comparison with those in Arian. It is possible that the gut microbial flora of the Arian strain has a role in higher feed consumption and lower density of acidic goblet cells in the intestinal villi of this strain. However, the Arian chickens had a tibial bones with higher diameters and intestinal villi with greater absorptive surfaces than those in Ross308; the features which may lead to the reduction of leg disorders (especially in the cage breeding system) and better absorption of nutrients in the broiler chickens, respectively. In general, according to the experimental conditiond and economic considerations, Ross308 strain is recommended for broiler farms.

[1]Selenium is an essential mineral for many metabolic functions of the body, including the activation of enzymes and the optimal biochemical and physiological function of birds (Antongiovanni et al., 2007). Selenium protects cell membranes from oxidative damage and can therefore improve nutrient efficiency (Arner et al., 2012). The small intestine is the most important part in the digestion and absorption of nutrients, while the large intestine and intestinal tract are very important areas for the accumulation of microbes (Chitra et al., 2013). Gastrointestinal health is one of the most important and effective factors in bird function. Gastrointestinal microbial population affects the nutrition and health of various animal species, including poultry. These microorganisms need trace elements such as selenium to perform their normal metabolic functions. Selenium may affect bacterial cells by disrupting the respiratory chain (Pappas et al., 2005). In addition to improving the quality and composition of intestinal microflora, selenium can have a positive effect on the morphology of the intestine as an antioxidant (Haghighi-khoshkhoo et al., 2010). Despite these benefits, the effect of selenium on intestinal microbial population is largely unknown, so the aim of this study was to investigate the effect of different levels of organic and inorganic selenium in the diet on microbial population, intestinal morphology and intestinal acidity in laying hens.

The experiment was conducted in a completely randomized design with 300 laying hens of high-line strains from 23 to 35 weeks of age with 5 treatments, 6 replications and 10 hens per replication. Experimental treatments include 1- Base diet (without selenium), 2- Base diet + 0.5 mg/kg sodium-selenite, 3- Base diet + mg/kg 1 selenite-sodium, 4- Base diet + mg/kg 0.5 selenium-methionine, 5-base diet + 1 mg/kg selenium-methionine. At the end of the experiment, two birds were randomly selected from each replicate; To evaluate the microbial population, a sample of the contents of the cecum on the culture medium was used (1). Tissue samples were prepared and then measured using a microscope, villi length, villi width, crypt depth, and number of goblet cells (9). To measure acidity, samples were taken from the contents of the cecum, and acidity was measured by a pH meter.

The results indicate that consuming 1 mg/kg of selenium-methionine increased the villi area compared to the control treatment. The experimental treatments did not affect villi length, villi width, crypt depth, number of goblet cells, and the ratio of villus length to crypt depth. The consumption of 1 mg/kg of selenium-methionine significantly decreased the population of Salmonella and increased the population of Lactobacillus in the cecal compared to other experimental treatments. The consumption of 0.5 and 1 mg/kg of selenium-methionine caused a significant decrease in the population of aerobic bacteria compared to the control treatment. The acidity of cecal contents in the treatment containing 1 mg/kg of selenium-methionine was significantly reduced compared to the control treatment. Several studies (Langhout et al., 1999, Lukaszewicz et al., 2011, Pappas et al., 2005) have reported that using organic sources of selenium reduces the coliform population. In mice, dogs, and laying hens, selenium intake has been shown to increase the number of Lactobacillus and decrease Escherichia coli and Staphylococcus aureus in the cecum (Langhout et al., 1999, Lukaszewicz et al., 2011, Pappas et al., 2005). Increasing the population of beneficial bacteria due to the provision of sufficient selenium for their synthesis is also an antioxidant property of selenium in preserving the life of these bacteria. It appears that beneficial bacteria, such as Lactobacillus, can competitively eliminate harmful bacteria such as Escherichia coli in the gut (Lukaszewicz et al., 2011). An increase in the number of pathogenic bacteria in the intestine causes the villi to shorten and the lining to shrink (Attia et al., 2010).Numerous studies demonstrate that the consumption of diets containing selenium compounds has destructive effects on harmful intestinal bacteria (Chantiratikul et al., 2008, Hashemi et al., 2012, Heindl et al., 2010, Horn et al., 2009, Langhout et al., 1999). Adding organic selenium to the diet of broilers increases the weight of the intestines due to the growth of villi and intestinal lamina propria (Haghighi-khoshkhoo et al., 2010, Heindl et al., 2010). The lack of selenium consumption on morphology can be attributed to the levels of selenium used, as well as the bird's lack of stress. Selenium can exert its effect more effectively under stress conditions. Most harmful bacteria grow in an environment with acidity close to 7 or slightly higher, while beneficial bacteria multiply in an acidic environment and compete with pathogenic bacteria (Cooke et al. 1973). An increase in acidity leads to a decrease in Escherichia coli and Salmonella in the gastrointestinal tract. Therefore, the consumption of organic sources of selenium reduces the population of pathogenic microorganisms (aerobic bacteria, Escherichia coli, and Salmonella) and increases the population of Lactobacillus competitively, followed by an increase in gastrointestinal acidity. This improvement may lead to an increase in digestion, absorption, and performance (Kasaikina et al., 2011).

 According to the results of this study, it can be said that consuming organic sources of selenium (levels of one and 0.5 mg of selenium-methionine per kg of feed) significantly reduces the population of harmful aerobic bacteria, bacteria. Salmonella and Escherichia coli and cause a competitive increase in the beneficial population of Lactobacillus; The consequence of this operation is to increase the acidity of the cecum and reduce the damage and microbial destruction to the intestinal tissue, and therefore with positive changes in the morphology of the small intestine will lead to improved bird function.

Antibiotics reduce the microbial population of the gastrointestinal tract, increase the available nutrients, and improve the feed conversion ratio (FCR) and body weight gain (BWG) of broilers. Due to the persistence of antibiotics in manufactured products and their transmission to humans, and the emergence of resistance, their use has been banned in many countries. Therefore, the use of antibiotic alternatives in the livestock and poultry industry has been considered, including organic acids. Organic acids modulate the intestinal microbial and improve animal performance by destroying harmful bacteria and providing nutritional conditions for beneficial bacteria. This study was performed to compare the effects of citric acid-based acidifiers with the commercial samples in drinking water on performance, serum biochemical parameters, pH, and intestinal morphology of broilers.

In this experiment, 400 one-day-old Ross 308 male broiler chicks were allotted to 5 treatments with 4 replicates in a completely randomized design. Experimental treatments included control treatment receiving drinking water without an acidifier and groups receiving drinking water with 0.025, 0.05, and 0.075% of produced acidifier and 0.2% of commercial acidifier.

The results indicated that feed intake (FI) and FCR decreased during the growth period by adding 0.05% of produced acidifier to drinking water compared to the control group (p<0.05). The BWG of broiler chickens increased at the level of 0.075% of the produced acidifier at the stater period and in the groups treated with the commercial sample in the total period compared to the control group (p<0.05). A numerically and significantly decrease in serum triglyceride was observed at treatments containing 0.05 and levels of 0.025 and 0.075% acidifiers respectively. The serum HDL was increased at treatments containing commercial acidifier than the control group (p<0.05). Groups receiving acidifiers had lower serum alkaline phosphatase compared to the control group (p<0.05). A decrease in the pH of the duodenum and jejunum in 42 days, as well as a decrease in the crypt depth and an increase in the villus height were observed in treatments containing 0.2 and 0.05% of commercial and produced acidifiers respectively (p<0.05).

According to the results, the level of 0.05% of produced acidifier in drinking water is recommended to improve the performance, intestinal morphology, and reduce the pH of the gastrointestinal tract in broilers.

Today, the poultry industry tends to increase production per unit area, at the same time, the increase in flock density is faced with management and health restrictions and obstacles. Consuming medicinal plants can be an effective nutritional solution to overcome the challenge of high density. Therefore, an experiment was designed and conducted in order to investigate the effects of the essential oils of medicinal plants in two un-capsulated and microencapsulated forms in the diet on the performance, intestinal morphology and acidity of the digestive system of broiler chickens.

In this research, out of 250 broiler chickens of the Ross 308 strain in the form of a completely randomized design with a factorial arrangement of 2x2, with 4 treatments and 5 repetitions, and in each repetition, normal density of 10 chickens and high density of 15 chickens with a similar weighted average was used. Microcapsules containing essential medicinal plants containing effective compounds of thyme leaf, savory leaf, peppermint leaf and black pepper seeds developed in the Agricultural Biotechnology Research Institute of East and North-East region of Iran. The tested treatments were; The first treatment: normal density (10 chickens per square meter) + no plant essential oil (control), the second treatment: high density (15 chickens per square meter) + no plant essential oil, the third treatment: normal density (10 chickens per square meter) + 500 mg/kg of un-capsulated essential oil mixture, fourth treatment: high density (15 chicks per square meter) + 500 mg/kg of encapsulated essential oil mixture. The number of casualties, the weight of the casualties and the weight of the eliminated chickens were recorded separately. The amount of feed consumed and weight gain were measured weekly and the food conversion ratio was calculated. At the end of the experiment, 2 birds were randomly selected from each repetition and slaughtered after blood sampling. To study the structure of small intestine villi, samples were obtained from duodenum, jejunum and ileum. A microscope with 40 times magnification was used to measure the height and width of the villus, and a 100 times magnification was used to measure the depth of the crypt. The acidity of the caecum was measured by a pH meter.

The results showed that the addition of microcapsules led to a decrease in the percentage of losses, an increase in weight at high density compared to the absence of microcapsules. The use of microcapsules in conditions of high concentration led to a decrease in the oral conversion factor. Treatments using microcapsules in normal and high density conditions had significantly higher gastrointestinal acidity compared to treatments that did not receive microcapsules. Consumption of microcapsules in normal and high concentrations led to an increase in the length of intestinal villi.

It can be concluded that the addition of encapsulated essential oil improved the weight gain, feed conversion ratio, intestinal morphostructural characteristics.

A total of 500 one-day old broiler chicks (as hatched) were assigned to 4 treatments with 5 replicates and 25 chickens in each replicate. Experimental design was a completely randomized block design in a 2×2 factorial arrangements with 2 levels of citric acid (0 and 0.4 % of diet; A0 and A1, respectively) and 2 levels of phytase (0 and 2000 FTU/kg diet; P0 and P1, respectively) in three phases including starter (1-10d), grower (11-24d) and finisher (25-42d). During grower, finisher and overall period of experiment feed intake and body weight gain was increased by dietary citric acid addition. Dietary phytase supplementation increased feed intake at finisher and overall period of experiment (P>0.05) and increased body weight gain during grower and overall period of experiment (P>0.05). The interaction effect of phytase and citric acid was significant for feed intake and body weight gain through the experimental period (P<0.01). Serum phosphorous was increased by phytase supplementation and alkaline phosphatase decreased by inclusion of citric acid to the diet (P>0.05). The interaction effect of phytase and citric acid significantly increased serum calcium, alkalin phosphatase and phosphorous in A0P0, A1P0 and A1P1 treatments, respectively (P>0.05). Crypt depth and villi length were significantly higher in A1P1 and A1P0 treatments, respectively (P<0.05). it was concluded that dietary addition of phytase improves broiler performance and intestinal morphology and the effect was more pronounced by supplementation of citric acid.

This experiment was designed to investigate the effects of sunflower seed meal fermented with Aspergillus niger and the probiotic Saccharomyces cerevisiae on the morphology and microbial population of different parts of the intestine and some digestive parameters.

This experiment conducted as a completely randomized design with 200 one-day-old Ross 308 male commercial broiler chicks, in five treatments five replications and eight chickens per replication. Experimental treatments including: 1- Diet containing sunflower meal fermented with Aspergillus niger 2. Diet containing sunflower meal fermented with Saccharomyces cerevisiae 3- Diet containing sunflower meal fermented by both Aspergillus niger and Saccharomyces cerevisiae 4. Diet containing unprocessed sunflower meal 5- Control diet based on corn and soybean. The effect of treatments at the end of the 39-day raising period was investigated on the morphology of ileum, viscosity, microbial population and pH contents of broiler chick’s intestine.

Intestinal morphological results showed that the highest villus height and the ratio of villus height to crypt depth in ileum were related to birds fed fermented treatment with Aspergillus niger (p<0.05). The amount of viscosity in the jejunum and ileum of the small intestine in all three treatments contained fermented sunflower meal was higher than the treatment contained unprocessed sunflower meal (p<0.05). The treatment contained sunflower meal fermented with Aspergillus niger was the closest to the control treatment based on corn and soybean (p<0.05). The population of duodenum coliform increased significantly in the treatment contained sunflower meal fermented by Aspergillus niger (5.41) and also the treatment contained sunflower meal fermented by both fungi and yeast (5.35) compared to the control treatment (5.57). The highest population of aerobic bacteria in this section was related to the treatment contained sunflower meal fermented by Saccharomyces cerevisiae (5.45): (p<0.05). The highest populations of Lactobacillus and aerobic bacteria in the jejunum were related to the treatment contained sunflower meal fermented with Aspergillus niger (5.16) and the control treatment based on corn and soybean (6.49): (p<0.05). The highest population of Lactobacillus bacteria in the ileum was related to treatment contained sunflower meal fermented with Aspergillus niger (5.92) and treatment contained unprocessed sunflower meal (5.95): (p<0.05). Also, the highest population of coliform (5.43) and aerobic bacteria (7.61) in this part was related to the treatment containing sunflower meal fermented with Aspergillus niger (p<0.05). The population of coliform, lactobacillus and aerobic bacteria in cecum was higher in all treatments than the control treatment based on corn and soybean (p <0.05). The highest pH of duodenum and jejunum was related to control treatment based on corn and soybean (p<0.05).

The results of this experiment indicated that fermented sunflower meal with Aspergillus niger and Saccharomyces cerevisiae decreases the pH of the gastrointestinal tract contents, increases the total microbial population, decreases coliform and increases Lactobacillus and improves the intestinal morphology of broiler chicks.

 The increase in the cost of the diet, especially the protein part, has caused the desire of producer and researchers to use by-products. The use of animal waste not only reduces the cost of feed but also reduces the entry of contaminants into the environment. Hydrolyzed feathers, meat meal, bone meal, poultry by-product meal (PBM) and fish oil are some of the by-products used in poultry, dairy cattle and other livestock diet. Also, the use of pelleted feed in broiler chicken is increasing, because it produces less dust, improves digestibility, reduces transportation costs, and improves performance indicators such as feed consumption and decrease feed conversion ratio. Sodium bentonite (SB) is one of the substances that has been used as pellet binder in feed. Several studies have evaluated the effects of the addition of SB and had beneficial results on pelleting physical properties such as pellet durability index (PDI) and pellet hardness. Addition of active SB as a pellet binder in wheat-soybean meal-based diets has increased the relative electrical energy usage (REEU) and decreased the feed conversion ratio. However, studies on the use of different levels of PBM and SB as a pellet binder in broiler chicken diets are very limited, the aim of the present study was to investigate the effects of pellet binder levels of SB in diets containing different amounts of PBM on performance, carcass traits and blood metabolites of Ross 308 broiler chickens in finisher period.

Treatments were assigned in a completely randomized design based on a factorial arrangement of 3 levels of SB conditioning time (0, 1.5 and 3%) × 3 levels of PBM (0, 5 and 10%). Experimental diets were balanced based on Ross 308 recommendations for finisher period (24-42 d) by using UFFDA software. In the present experiment PBM and pellet binder of SB samples were prepared from MegaFaravar Co., Iran. Ingredients of diets were ground through a 2-mm screen size in a hammer mill. All diets mixed in a double-shaft mixer and transferred to super conditioner with 82◦C for 10s, and then pelleted through a 3-mm die. After pelleting of feed produced, 3 replications of each treatment with 3-minute intervals were sampled from the cooler part of the pellet machine. The PDI, hardness test and REEU related to experimental diets was measured. Also, a total of 360 24-day-old male chicks were individually weighted and allocated to 9 treatments of 4 replicates (10 birds in each replication). Feed intake (FI), average daily gain (ADG) and feed conversion ratio (FCR) were recorded. On 42 day, 2 birds per pen were randomly euthanized by cervical dislocation. Carcass characteristics and relative weight of small intestinal segments were measured. Total protein, glucose, albumin, lipoproteins (HDL, LDL) were determined by using autoanalyzer device and commercial kits.

Addition of 1.5% SB improved and the use of PBM due to its high fat content reduced the quality characteristics of the pellet that due to their strong colloidal properties and giving rise to a thixotropic gelatinous substance. Likewise, different levels of SB as a pellet binder and PBM did not change the ADG and FCR (P <0.05). However, the use of different levels of PBM with and without SB reduced FI (P<0.05). Also, the relative weight of carcass, breast and thigh was not affected by experimental treatments (P <0.05). Abdominal fat increased significantly in the groups receiving PBM (P <0.05). Amino acid imbalances in PBM probably increase deamination and conversion of amino acids to fat. Significant reduction in duodenum and ileum length was observed in the group containing 3% SB and 10% PBM (P <0.05). Also, the level of 10% PBM with and without SB increased the concentration of blood lipids. Blood lipids concentration have a positive correlation with weight and feed as an environmental factor affects its amount.

In general, the results of this experiment showed that application of PBM as a source of protein with adequate nutritional value up to 5% without negative effects on performance for use in pelleted diet of broilers at high levels when soybean meal is expensive and or not available, it is possible and useable. Also, commercial sodium bentonite can be used as a pellet binder to increase the quality of pellets up to 1.5%. The need for further studies on the simultaneous use of sodium bentonite as a pellet binder and PBM are recommended to ensure the results obtained in other broiler chicken breeding periods.

Organic acids are one of the alternatives to antibiotics growth promotor which have beneficial effects on animal performance and gastrointestinal microbial population. In general, addition of organic acids into the feed lowers pH of the feed and gastrointestinal tract, stimulates growth, helps beneficial bacteria to overcome pathogenic bacteria, and reduces toxic metabolites produced by harmful bacteria.

A total of 240 day-old Ross 308 male broiler chicks were divided into 4 treatments, 4 replicates, and 15 broiler chickens per replicate in a completely randomized design. Experimental treatments were included 0, 200, 300 and 500 mL of acidifier in 1000 L drinking water.

Feed conversion ratio in broilers that received two levels of 200 and 500 mL of acidifier per 1000 liters in drinking water decreased compared to the control treatment (p<0.01). European efficiency index was higher in the whole acidifier levels than the control and a linear increasing trend was observed (p<0.05). Broilers received 500 mL of acidifier in water had the lowest FCR (1.64 vs. 1.80; p<0.01) and the highest EEF (394 vs. 332; p<0.01) compared with the control. The weight of bursa of Fabricius, spleen and pancreas in broilers received graded levels of acidifier was higher than the control (p<0.05). The pH of the proventriculus, duodenum and jejunum of broilers that received 500 mL of acidifier decreased compared to the control (p<0.05). Administration of graded levels of acidifier in drinking water had no effect on Lactobacillus, coliforms and Escherichia coli count in ileum (p>0.05). The thickness of the lamina propria layer increased in broilers received 300 mL of acidifier (p<0.05). Administration of acidifier in drinking water had no effect on antibody titer against SRBC and Newcastle.

The results indicate that adding 500 mL of acidifier in 1000 L drinking water improves growth performance by increasing the weight of digestive organs such as pancreas and acidifying the initial areas of the digestive tract.

In this experiment, nano DL-methionine was synthesized from commercial DL-methionine and used in broiler diets to evaluate the effects on growth performance, carcass characteristics, blood parameters and small intestine morphology. A total of 200 one-day-old broilers (Arian) were used in a completely randomized design with five treatments and four 4 replicates of 10 birds for a period of 40 days. Experimental treatments included: 1) a control diet consisted of DL-methionine, 2) a diet included 75% of DLM of the control+2.5% nano-methionine, 3) a diet included 50% of DLM of the control+5% nano-methionine, 4- a diet included 25% of DLM of the control+7.5% nano-methionine, and 5- a diet included 10% nano-methionine. The results showed that replacing DLM with NM caused no significant difference between treatments for live responses, carcass characteristics and activities of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase. There was no significant difference between treatments for serum uric acid, height and width of villi in duodenum and jejunum. However, groups with 7.5% and 10% NM manifested a significant increase (P < 0.05) in breast weight and villus height and width and its absorptive surface area compared to the control. In conclusion, the use of NM could save up to 90% of DLM requirements.