Poultry Science Journal
Volume:10 Issue: 1, Winter-Spring 2022

Given the escalating environmental temperature and a considerable progress in meat production capacity, broiler chickens are more sensitive to heat stress than before. The detrimental influences of heat stress include diminished feed intake and reduced average daily gain, low feed efficiency, impaired immune response, deterioration of meat quality, and disturbed gastrointestinal microflora. Generation of free radicals, reactive oxygen species, and their combined action on cell membrane leads to damage in the cell membrane integrity and alters the metabolic function of the body resulting in various physiological abnormalities. There have been numerous studies on cost-effective strategies to mitigate the harmful effect of heat stress. The use of various dietary antioxidants, vitamins, minerals, flavonoids, and probiotics, alone or in combination, has led to promising results on the growth performance of broiler chickens, thereby decreasing the unexpected losses incurred due to heat stress. This article aims to review the scientific evidence concerning the various harmful consequences of heat stress in broiler chicken, with emphasis on meat quality, carcass traits, and growth performance. We also discuss some mitigation strategies in the next section.

Salmonella Infantis (S. Infantis) is one of the most important zoonotic bacteria, which has become one of the leading public health problems in the world, especially in developing countries. The prevalence of multi-drug resistant (MDR) S. Infantis strains has increased worldwide and can be prevented by controlling the use of antibiotics in poultry. The purpose of this review article is to discuss the status of S. Infantis antibiotic resistance, especially, its prevalence, detection methods and resistance mechanisms in isolates from poultry samples using search engines such as Web of Science, Scopus, and PubMed. Based on our review, S. Infantis was the most prevalent serovar in poultry accompanied by an enhancing number of resistance genes in these strains. The use of different genotypic and genetic methods can rapidly detect the presence of Salmonella in suspicious specimens to prevent disease and epidemics. Genes such as invA, hilA and fliC were most commonly used genes in the detection of Salmonella, and other genes were viaB, spv, flijB, rfbJ and 16Sr RNA. The results of studies emphasize that poultry could act as reservoirs of MDR with a high tendency for dissemination. Resistance to the beta-lactam family is an important issue, because antibiotics such as beta-lactams are the best candidates for the treatment of salmonellosis, and this has raised concerns in the treatment of invasive Salmonella.  These findings highlight the need to find ways to manage and reduce the impact of antibiotic use in poultry and prevent the transmission of antibiotic-resistant S. Infantis to the human food chain and to find potential alternatives to antibiotics.

In this study, a meta-analysis was employed to evaluate the effects of dietary flavonoids on laying hens. A database of flavonoids was developed from published journal papers in which flavonoids were supplemented to laying hens at various doses and then monitored for production performance, egg quality, liver condition, and antioxidant enzyme profile. A total of 22 journal papers were included in the database, and statistically analyzed using a mixed-model methodology in which random effects consisted of the different studies and fixed effects were the dosages of flavonoids. The model statistics were p-value and Akaike information criterion. The significance of an effect was assumed at P < 0.05. The results showed that dietary addition of flavonoids linearly decreased (P < 0.001) feed intake. The laying rate was not affected by the addition of flavonoids, while the FCR tended to linearly decrease (P < 0.1). The addition of flavonoids linearly reduced egg and yolk cholesterol (both at P < 0.001), and linearly increased egg mass (P < 0.001), egg strength (P < 0.05) and yolk color (P < 0.001). Further, a linear decreasing response was observed in the liver triglyceride, and cholesterol concentrations (both at P < 0.001) after flavonoid supplementation. Superoxide dismutase showed a quadratic response (P < 0.01) following the addition of flavonoids. In conclusion, dietary supplementation of flavonoids is able to favourably modulate production performance and egg quality of laying hens.

The study was designed to evaluate the growth performance of exotic dual-purpose chicken breed of Koekoek (K) and Kuroiler (Ku) crosses with an improved Horro (H) chicken under reciprocal mating to select potential crosses for development of a synthetic breed in Ethiopia. The experiment was carried out on seven genotypes, including three pure lines (i.e., Horro, Koekoek, Kuroiler) and their direct (K × H, Ku × H) and reciprocal crosses (H × K and H × Ku). A total of 446one-day-old chicks from the seven genotypes were randomly distributed between pens using a completely randomized design with three replications (experiment period?). Data on body weight at hatch (DO), 4, 8, 12, 16 and 20 weeks of age, body weight gain, feed conversion rate (FCR) and mortality rate were calculated during the experiment. The crossbreeding effects were estimated to select the best genotype as a dam or a sire line in the synthetic breed for the next generation. The result showed that the highest mean body weight (P < 0.05) and body weight gain were related to Horro×Kuroiler crossbred chicken that followed by Ku×H, and pure Ku at most of studied ages. Average feed intake was comparable among genotypes. Additive (Ae), maternal and heterosis effects for body weight were significantly (P < 0.05) positive at most ages for both crosses. Additive effects range from 1.79 to 10.1% for Horro-Koekoek crosses, whereas it ranges from 1.6 to 44% for Horro-Kuroiler crosses. In Horro-Koekoek crosses, the highest positive contribution of maternal effect was observed for body weight at eight weeks (8.22 %). Estimates of heterosis effects (He) were positive and ranged from 6.54 to 13.79%. In the Horro-Kuroiler crosses, estimates of maternal additive (Me) and the heterosis effects on body weight were positive and significant (P < 0.05) at 8- and 12-weeks of age. Generally, the positive and significant additive effects suggest merits of the sire line in the growth performance which favors use of Kuroiler and Koekoek as sire lines to improve the body. Positive values and significant contribution of heterosis indicate the substantial effect of crossbreeding on body weight at most of the studied ages. From this study it can be recommended that crossbred hens sired by improved Horro (H × Ku) can be used for growth performance potential in the forthcoming synthetic breed development program.

This study was conducted to determine the effects of Nutrition Bio-Shield Superfood® (NBS) supplementation in diets varying in energy (ME) and crude protein (CP) levels on the performance of Hy-line W-36 laying hens. The experiment was performed in a 5 × 2 factorial arrangement in a completely randomized design with five dietary levels of NBS (0, 0.5, 1.0, 1.5, 2.0 g/kg of diet) and two dietary nutrient levels (standard and 5% reduced ME and CP). The experiment was conducted during 63-74 weeks of age using 420 laying hens in 10 treatments and 6 replicates of 7 birds each. The egg production was not significantly affected by diet dilution, NBS levels, and their interactions. The diet dilution, NBS powder, and their interaction did not significantly affect egg mass. Except that, it was significantly decreased (P < 0.05) by the diluted diet during 66-68 weeks of age. Feed intake (FI) was not significantly affected by diet dilution, NBS levels, and their interactions. Except that, the diluted diet significantly (P < 0.05) decreased during 66-68 weeks. Feed conversion ratio (FCR) was not significantly different between standard and 5% diluted diet, among the NBS levels and the interaction means. Diluting the diet and NBS supplementation did not significantly affect blood parameters; however, diluted diet significantly increased (P = 0.05) blood LDL-c concentration compared to the standard diet. Anti-SRBC titers were not significantly affected by the diet dilution, dietary levels of NBS powder, or their interactions. The treatments did not affect eggshell strength and the eggshell Ca and P percentages. In conclusion, reducing dietary ME and CP by 5%,  adding NBS to the diet and their interaction had no significant effect on the layers' performance, immune response, blood parameters but diluting the diet increased blood LDL-c concentration.

This study aimed to evaluate the effects of dietary supplementation of Nutrition Bio-Shield Superfood® (NBS) on the growth performance, intestinal morphology, immune response and blood metabolites in broiler chickens fed with low metabolizable energy (ME) and crude protein (CP) diets. A total of 360 one-day-old Ross 308 broilers were used in a 42-d experiment. The birds were allotted to 6 dietary treatments with 5 floor pen replicates of 12 birds each; based on a completely randomized design. Dietary treatments included a positive control diet (PC, standard diet), a negative control diet (NC, 3% reduction in ME and CP without NBS supplementation), and dietary supplementation of NBS at 0.5, 1, 1.5, and 2 g/kg to negative control diet (NBS0.5, NBS1, NBS1.5, NBS2, respectively). Body weight on d 10 and body weight gain during d 1-10 were lower (P < 0.05) in birds fed with NC and NBS diets compared to the positive control group. During later phases and d 1-42, no significant differences were observed in body weight, body weight gain, feed intake, and feed conversion ratio of broilers among the treatments. Supplementation of NBS or lowering the nutrients by 3% had no significant effect on immune response (total Ig, IgG and IgM concentrations) compared to positive control group. NBS supplementation decreased muscle layer thickness (MLT) in the jejunum (P < 0.01). Villus width (WV) and MLT showed a linear response to the treatments (P = 0.02 and P = 0.02, respectively), in this case, VW increased with the supplementation of NBS at 0.5 to 2 g/kg, and MLT decreased with these levels of dietary NBS. In general, dilution of nutrients by 3% of the standard diet and dietary supplementation of NBS had no significant effect on growth performance, immune response, blood metabolites and carcass traits in broiler chickens.

Poultry researchers have used mathematical models to explain some laying bird responses. There are many equations of the egg characteristics, but their validity has not yet been confirmed. Therefore, the aim of the current study was to assess the accuracy of the equations proposed to predict egg characteristics in laying hens. A total of one hundred forty-eight prediction equations of egg characteristics were collected from different studies. A total of 781 eggs from 75-week-old Hy-Line laying hens were gathered to measure egg quality characteristics, and other egg characteristics were calculated using these measurements. The residuals of the difference of observed and predicted values were used to calculate accuracy measurements like mean absolute deviation (MAD), mean squared error of prediction (MSEP), mean absolute percentage error (MAPE) and root mean squared error of prediction (RMSEP). RMSEP was used to estimate the error of the model (EM) with a 12% as the maximum level of validation of the egg characteristics prediction equation and 1.2% only for specific gravity. Nine egg characteristic prediction equations were validated with great accuracy because validated equations showed a value of MAD, MSEP, MAPE and RMSEP very low and EM less than 12%. Equations validated for external egg characteristic used easy-to-measure traits (i.e., egg weight, egg length, and egg width) as predictor variables. Fifteen egg characteristic prediction equations were validated with considerable accuracy. These equations might shorten the process of egg quality determination, reduce the waste of eggs, and thereby saving time and money.

The aim of the experiment was to investigate the effect of microbial enzyme supplements on egg production and the nutrient digestibility of laying hens. A total of 360 twenty-one-week-old Hisex Brown laying hens were assigned to three treatments with four replicates of 30 birds each using a completely randomized design and reared for 30 days. The treatments consisted of 1) A basal diet provided according to the recommended feeding standards (as the control group), 2) a basal diet supplemented with proteinase enzyme at a concentration of 10 U/kg, and 3) a basal diet supplemented with phytase enzyme at a concentration of 1000 FTU/kg. Supplementation of proteinase enzyme increased (P < 0.05) the retention percentage of dry matter and crude protein in laiyng hens compared to the control treatment. and phosphorus retention increased in laying hens by using of the enzymes. The addition of proteinase enzyme to the diet increased body weight gain of laying hens compared to other treatments. Feed convertion ratio improved in laying hens recieved enzyme supplements (P < 0.05). The dietary enzymes supplementation increased the egg weight and egg mass than those fed with the enzyme-free diet (P < 0.05). The Thickness of eggshell increased by using of phytase enzyme than other treatments. Also, ash content of eggshell increased in treatments supplemented by both of the enzymes. According to the results of the experiment, the addition of proteinase and phytase to the diet could be effective in improving the performance of laying hens and the quality characteristics of eggshell.

The present study was conducted to evaluate the effects of basil (Ocimum basilicum) leaf extract (BLE) in drinking water on growth performance, hepatic and serum-antioxidant related parameters, enzyme activity and biochemical parameters of serum,  and breast muscle lipid peroxidation of (after storage at 2-3°C,  for 1, 7 and 14 d).  A total of 450 one-day-old male broiler chickens of Ross 308 were randomly divided to three groups, with five replicates of 30 birds and allocated to the following treatments including control (only drinking water), or drinking water supplemented with either 300 or 600 ppm of BLE. At the end of the experiment (day 42), Two birds were randomly selected from each cage and decapitated. There were no significant effects of dietary treatments on body weight gain, feed intake and feed conversion ratio of the broilers. Basil leaf extract significantly increased the hepatic catalase, superoxide dismutase, and glutathione peroxidase activities and decreased lipid peroxidation in the liver and serum. Serum-enzyme activity (aspartate aminotransferase and lactate dehydrogenase) and biochemical parameters (low density lipoprotein and cholesterol) were significantly decreased by basil leaf extract. Moreover, BLE significantly reduced the malondialdehyde formation in breast muscle during storage period.  In conclusion, supplementation of basil leaf extract significantly increased the antioxidant capacity of broilers and consequently increased the oxidative stability of frozen meat.

This experiment was conducted to determine the influence of different concentration of calcium (Ca) and non-phytate phosphorus (NPP), with a constant ratio of 2:1(Ca:NPP), on young broiler chickens. A total of 900 Ross 308 d-old male broiler chickens were randomly allocated to 60 pens (15 birds per pen). Four dietary treatments including high concentration of Ca and NPP (H), moderate concentration of Ca and NPP (M), low concentration of Ca and NPP (L), and very low concentration of Ca and NPP (VL) were given to the birds. The concentration of Ca was 9.6, 7.6, 5.6, and 3.6 g/kg of diet, respectively. In starter period, broiler chickens fed the M diet showed the lowest feed conversion ratio (FCR) in comparison to those received the H, L and VL diets. In grower periods, broiler chickens fed the H diet had the highest average daily feed intake (ADFI); M and L diets showed the highest average daily weight gain (ADG) compared to H and VL diets. In whole period, broiler chickens fed the H and M diets showed the highest ADFI in comparison to those received the L and VL diets and FCR was higher in broiler chickens received H diet in comparison to those fed M, L and VL diets. Decreasing the dietary Ca and NPP level elicited linear reductions in tibia Ca. The count of lactic acid bacteria in the duodenum improved with increasing levels of Ca and NPP. In conclusion, M treatment could support maximal ADG and body weight, while lowest FCR was obtained from birds received L diets. The use of L treatment resulted in comparable Ca and phosphorus content of tibia bone compared to those of M treatment.

This experiment was conducted to evaluate the effects of changing feed form in commercial laying pullets at their 9-14 weeks of age. In the first eight weeks of rearing, the birds were fed four basal diets, including two feed forms (mash;M vs. pellet;P) and two levels of sunflower hulls (SH)  inclusion (0 vs. 4%); then, they were assigned to 11 treatments with eight replicates of 9 birds each. The experimental groups consisted of the mash diet during 0-8 and 9-14 weeks (control); mash from 0-8 week and pellet +SH from 9-14 weeks (M-PSH); and so on MSH-MSH; MSH-PSH; P-P; P-M; P-MSH; P-PSH; PSH-PSH; PSH-MSH; and M-MSH. During the whole period, average daily feed intake (ADFI) in the birds fed with pellet or mash and then fed with the pellet containing SH (P-PSH and M-PSH) was higher than with the other treatments (P < 0.05). Average daily weight gain (ADG) was affected by dietary fiber and feed form, whereas it was found lower in the PSH–MSH treatment birds and greater for the birds in MSH-PSH treatment than others (P < 0.05). Further, FCR improved in the birds fed the mash diet with and without fiber from  during 1-14 weeks (P < 0.05). Feeding pellet diet without fiber during 1-14 weeks resulted in lower gizzard weight and deeper crypt than the other groups (P < 0.05). In addition, the greater and lower villus surface area belonged to the birds fed MSH-MSHP-P diets during 1-14 weeks, respectively. The greatest tibiotarsal index was related to the group fed the pellet or mash without fiber during 0-14 weeks (P < 0.05). In conclusion, considering the costs for pellet production, it seems that feeding pellets just during the first eight weeks of age could lead to better performance in commercial situations. Moreover, dietary  inclusion of SH improved the function of gizzard.

The objective of this study was to investigate the effect of whey protein concentrate (WPC) and selenium (Se) supplementation on sperm quality, antioxidant enzymes activity and lipid peroxidation in seminal plasma, liver and testis of roosters. Forty-five Ross-308 broiler breeder roosters aged 60 weeks were used for an eight-week period in a 3 × 3 factorial arrangement of dietary treatments. Three levels of WPC (0.0, 1.5 and 3.0% of diet) and selenium supplementation (0.0, 0.2 and 0.4 mg/kg of diet) with five replications were tested. Total and progressive sperm motility, sperm concentration, plasma membrane integrity, and sperm viability were significantly lower in birds treated with Se supplementation-free diet (P < 0.05). Also, abnormal sperms were significantly higher in Se supplementation-free diets when compared to the diets supplemented with 0.4 mg/kg Se (P < 0.05). The use of 1.5% of WPC resulted in significantly increased total and progressive sperm motility compared to the WPC-free diet (P < 0.05). Selenium at the level of 0.4 mg/kg along with 3.0% WPC were associated with significantly increased Glutathione peroxidase and superoxide dismutase activity in seminal plasma as compared to other levels (P < 0.05). The highest level of total antioxidant capacity (TAC) in seminal plasma was observed at the level of 0.2 mg Se (P < 0.05). Further, 3.0% WPC resulted in significantly increased TAC concentration in seminal plasma compared to the WPC-free diet (P < 0.05). Moreover, the Malondialdehyde (MDA) level of seminal plasma in selenium supplementation-free diets was significantly higher than those of other levels (P < 0.05). Glutathione peroxidase activity, TAC, and MDA levels in the testis and liver were not affected by the WPC and Se levels. It can be concluded that dietary inclusion of WPC and Se improved the semen quality, increased antioxidant enzymes activity and decreased lipid peroxidation in seminal plasma of  broiler breeder roosters.