جستجوی مقالات مرتبط با کلیدواژه « جوجه های گوشتی » در نشریات گروه « دامپزشکی »

The purpose of this research is to identify and isolate antibiotic-resistant Escherichia coli strains and determine the antibiotic resistance pattern in 30 Escherichia coli isolates isolated from broiler chickens with colibacillosis in Behbahan city. The antibiotic resistance pattern of all isolates was determined against 15 important and common antibiotics in Iran's poultry industry using the disk diffusion method. The percentage of resistance to difloxacin, enrofloxacin, trimethoprim, chlortetracycline, erythromycin, tylosin, tiamulin, doxycycline, florfenicol, lincomycin, danofloxacin, neomycin, colistin, amikacin and gentamicin is 100, 100, 100, 96/6, 96/6, respectively. 96/6, 90, 76/66, 66/6, 63/33, 60, 53/33, 26/66, 10 and 0 were observed. 17 drug resistance patterns were identified among 30 Escherichia coli isolates to 15 commonly used antibiotics in the poultry industry, of which 26 isolates (86.67%) belonged to more than one pattern, while the other 4 isolates (13.33%) each They belonged to only one pattern. The results of this study showed that the resistance of the isolates to the majority of commonly used drugs in Iran's poultry industry is high, which makes it necessary to implement a strong national monitoring plan for antimicrobial resistance and the principled use of antibiotics.

This study aimed to evaluate the effects of bile acids (BAs) on performance, digestibility of nutrients, and intestinal morphology in broiler chickens. A total of 300 one-day-old male broiler chicken (Ross 308) were distributed into five treatments, six replications with 10 chicks each in a completely randomized design. experimental diets included: 1) control diet (CON; based on corn and soybean meal), 2) basal diet containing a commercial emulsifier, 3) basal diet containing 0.05 % BAs, 4) basal diet containing 0.1 % BAs, and 5) basal diet containing 0.2 % BAs. Intestinal morphological specifications, including villus height index, crypt depth, and villus height to crypt depth ratio were determined in duodenum, jejunum, and ileum. The results showed that consumption of 0.1 % BAs improved daily weight gain and feed conversion ratio during the starter period (p< 0.05). Broiler chickens fed a diet containing 0.1 % BAs had higher fat and energy digestibility compared to chicks of other treatments (p<0.05). Birds fed 0.1 % BAs had a higher villus height in the jejunum compared to the birds in control group (p<0.05). Dietary BAs supplementation of 0.1% significantly increased the villus height to crypt depth ratio in all three portions of the small intestine compared to the control treatment. In conclusion, dietary BAs supplementation may probably promote performance to some extent by improving the intestinal morphology and utilization of fat and energy in the broiler diet.

Reducing the protein and amino acid content of diet or altering the dietary electrolyte balance were suggested as the effective strategies to prevent the harmful effects of the heat stress in poultry.

This study surveyed the effects of various levels of threonine and dietary cation-anion balance on the broiler chickens under the heat stress conditions.

700 one-day-old male broilers (Ross 308) were used for 6 weeks under high- temperature conditions. This experiment was conducted using a 2 × 3 + 1 factorial experiment based on a completely randomized design, with 7 treatments (5 replicates per treatment and 20 birds per replicate). Experimental factors included two threonine concentrations (recommended level and 10 % above recommended level) and three dietary electrolyte balances (175, 250, and 325 mEq/kg). The control group considered the treatment with a normal threonine concentration (recommended level) and a dietary electrolyte balance of 250 mEq/kg under optimal temperature conditions.

Although there was no interaction between threonine level and electrolyte balance, the electrolyte balance of 175 meq/kg increased the performance index compared to the electrolyte balance of 250 or 325 mEq/kg (P<0.05). The villus height to crypt depth ratio and villus surface area in the jejunum improved with an electrolyte balance of 175 or 250 mEq/kg (P<0.05). A decrease in the dietary electrolyte balance increased in the nitrogen-corrected apparent metabolizable energy (P<0.05). Besides, an increase in the population of lactobacilli and bifidobacteria in the cecum, as well as an increase in protein digestibility, were observed by increasing levels of threonine in the diet (P<0.05).

Based on these results, a high level of threonine or a low electrolyte balance in diet (175 mEq/kg) may improve the performance, metabolizable energy, and intestinal microbial flora of broilers reared under heat stress.

Marek's disease (MD) is a highly contagious neoplastic disease in poultry. The causative virus is an alphaherpesvirus that causes immunosuppression and predisposes poultry to other pathogens.  Although the MD is more common in laying, the incidence of the disease is also increasing in broilers. Due to the increasing rate of infection with the marker virus in broiler chickens, this study aimed to investigate the occurrence of MD in broiler poultry farms in Semnan, Iran. The feather follicle epithelium and spleen tissues were collected randomly from 15 broilers flocks at 6-10 weeks old in Semnan slaughterhouse and were subjected to polymerase chain reaction by amplifying the meq gene. The results of this study showed of 15 flocks, two (13.6%) had a positive reaction. There was no evidence of macroscopic lesions among the studied flocks. Considering the infection of 13.6% of the studied flocks, without any macroscopic complications, it seems the MD virus is circulating in broilers and could transmit to the other birds. It is indicated that the current national vaccination has not stopped the disease in commercial chickens. Due to the immunosuppressive properties of the virus, it is considered that the MD virus, along with other immunosuppressive agents such as adenoviruses, has an essential role in the development of immunosuppression syndrome in broilers in Iran, and to reduce the economic losses caused by this disease, effective prophylactic measures should be considered by the country's health officials.

Methylamine exists as an endogenous amine in the brains of birds and mammals, and on the other hand, it acts as a neuromodulator in the release of some neurotransmitters such as serotonin. The effects of methylamine have been well established in mice, but there is no evidence about the effect of methylamine on feeding behavior in poultry. So, the present study was designed to evaluate the effect of intracerebroventricular (ICV) injection of methylamine and involvement of central methylamine/serotonergic systems on feeding behavior in FD3 neonatal meat type chicks. In experiment 1, chicks were ICV injected with different doses of methylamine (15, 30, 45, 60 and 75 μg). In experiment 2, chicks received a dose of either the control solution, 75 μg methylamine, 1/5 μg PCPA (serotonin synthesis inhibitor) or a combination of methylamine plus PCPA. Experiments 3 was similar to experiment 2 except that 1/5 μg SB242084 (antagonist of HT2C receptor) was used instead of 1/5 μg PCPA, respectively. Cumulative food intake was determined until 30, 60, 120 minutes post-injection. The volume of injections in each group was 10 μl. According to the results, methylamine significantly decreased food intake in a dose dependent manner. Therefore, the effective dose of methylamine was considered to be a continuation of the 75 μg test. It was also found that the hypophagic effect of methylamine by PCPA (inhibitor of serotonin synthesis, 1.5 μg) and SB242084 (antagonist of 5-HT2C receptor, 1.5 μg) was significantly attenuated. These results suggest that methylamine has a hypophagic effect on food intake in broiler chickens, and that this reduction in methylamine-induced food intake is mediated by serotonin (a 5-HT2C receptor).

This study was performed to compare the sensitivity of seven plate methods and commercial kits for the detection of antibiotics in vitro and in poultry carcasses. In the first step, different concentrations of five commonly used antibiotics in poultry breeding were prepared and the sensitivity of both methods in antibiotic residue detection was evaluated. Subsequently, 20 days old broilers were divided into 5 groups. After an adaptation period and feeding non-antibiotic diet, groups were treated with therapeutic doses of Oxytetracycline, Enrofloxacin, Florfenicol, and Fosfomycin through drinking water. One group was considered as a control. At antibiotic discontinuation day (day 0) and days 1, 2, 3, 4, 5, and 6 thereafter, 3 chicks from each group were slaughtered and thigh muscle, liver and kidney were sampled and residual antibiotics were evaluated by both methods. The results showed that sensitivity of commercial kits was higher in in-vitro condition than that of poultry carcass. In the seven plate method, the residuals were more detectable in the liver and kidney. The commercial kit was able to detect antibiotics only up to 24 hours, after which almost all specimens were negative. The seven plate method was positive for most of the specimens up to three days after discontinuation.  This study showed that the efficacy of the seven-plate method was more than commercial kits, and in order to increase the efficiency of detection methods, it is recommended to perform it on the liver and kidney of four carcasses from each herd (total of 8 samples). If at least four samples are positive, the herd is considered as infected and the HPLC method is used to confirm the specimens.

Optimal levels of minerals in the diet are crucial for improving performance and immune response against the environmental stresses.

This study was conducted to evaluate the effects of water supplementation of chelated trace mineral (CTM) on growth performance, hematology, blood biochemistry, antioxidant status, and antibody response in broilers reared under heat stress condition.

A total of 240 male Ross 308 broiler chickens were randomly allocated into one of the following five treatments (each consisting of four replicates): (1) positive control (PC; thermoneutral condition), (2) negative control (NC; heat stress condition), (3) low-CTM (NC + low CTM level in tap water), (4) medium-CTM (NC + medium CTM level in tap water),  and (4) high-CTM (NC + high CTM level in tap water). The CTM levels in the tap water for the low-CTM treatment were 0.1, 0.15, 0.3, 0.4, and 0.45 mg/bird/day on days 1-10, 11-20, 21-30, 31-40, and 41-50, respectively. The respective values were 1.0, 1.5, 3.0, 4.0, and 4.5 for the medium-CTM, and 10, 15, 30, 40, and 45 mg/bird/day for the high-CTM water.

The average weight gain during the whole experimental period in the medium-CTM treatment was higher compared to that in the negative control treatment, but lower than that in the positive control treatment (P<0.05). The heterophil/lymphocyte ratio and total antibody titers against Newcastle disease in the medium-CTM and high-CTM groups were similar to those of the broilers in the PC group, yet better (P<0.05) those of the NC group. The serum superoxide dismutase activity was also higher (P<0.05) in the high-CTM group compared to that of the NC group.

The results suggested that the water supplementation of CTM at a moderate level (1.0, 1.5, 3.0, 4.0, and 4.5 mg/bird/day during different rearing periods) could be a strategy to ameliorate the detrimental effects of heat stress in broilers.

On account of the importance of iodine in the synthesis of thyroid hormones, different levels of dietary iodine can affect the occurrence of ascites syndrome in broilers.

The current research aimed to investigate the effects of different sources and levels of iodine on performance, carcass traits, ascites mortality, thyroid hormones, and serum biochemical parameters of broiler chickens under cold stress condition.

This experiment was performed using 375 one-day-old male broiler chickens in a completely randomized design with five treatments, five replications, and 15 birds per replication. To induce ascites, the room temperature was reduced to 15 °C from 14 days and this temperature was maintained until the end of the period. The experimental treatments included: control treatment (basal diet with iodine at the recommended level, 1.25 ppm), basal diet + potassium iodide (KI) with iodine levels (6.25 and 3.75 ppm), and basal diet + calcium iodate [Ca(IO3)2. H2O] with iodine levels (6.25 and 3.75 ppm).

The effect of the treatments on the performance indices was not significant throughout the experiment. The lowest percentage of ascites mortality, heart weight, and triiodothyronine (T3) were observed in the treatment (6.25 ppm), which was significantly different from the control treatment (P<0.05). The lowest ratio of right ventricle to total ventricles (RV/TV) was related to potassium iodide treatment (6.25 ppm), which indicated tendency (P<0.10). Chickens receiving higher levels of iodine (6.25 ppm) had higher thyroxine than those receiving lower levels (3.75 ppm) (P<0.05) and showed a lower ratio of triiodothyronine to thyroxine compared to those (P<0.05).

The results of this experiment implied that the use of higher levels of dietary iodine (6.25 ppm), especially as potassium iodide, reduces broiler’s ascites mortality under cold stress conditions.

During the modification of several races, which has been done on chickens, there have been several changes in the function of neural pathways and receptor density involved in the control of food intake and appetite. Melanocortin system and its receptors are involved in the central regulation of nutritional behaviour and energy balance. Therefore, this study was designed to investigate the role of this system in the central control of food and water intake in birds.

The present study aimed to evaluate the role of MCR3 and MCR4 receptors in controlling the food and water intake in birds.

This work was performed on 48 Ross 308 broiler chicks through two experiments (each experiment in four groups). Primarily, stereotaxic surgical guide cannula was implanted in the chickens. Subsequently, in the first experiment, the chickens were divided into the four following groups: the control solution, 0.2, 2, and 10 nmol/5µl of SHU9119 (Non-selective antagonist of MCR3 and MCR4 receptors) In the second experiment, the chickens were also divided in four groups: the received control solution, 0.2, 2, and 10 nmol/5µl of MCL0020 (Selective MCR4 receptor antagonist) via intracerebroventricular (ICV) injection. Afterwards, cumulative food and water intake were measured at 30, 60, 90, 120, 150, and 180 minutes after the injection.

The results of this study showed that ICV injection of SHU9119 and MCL0020 increased cumulative food intake (P>0.05), but did not affect cumulative water intake (P<0.05).

According to the findings herein, central melanocortin system is one of the systems involved in central control of food intake in birds.

Leucine is one of the subgroups of amino acids, which play an important role in the anabolism of muscles, adipose tissue, and the liver by stimulating insulin secretion.

Effects of different levels of leucine were investigated on carcass yield, characteristics, and quality, and expression of insulin-like growth factor (IGF-1) and insulin genes in male broilers.

Five levels of L-leucine (100, 110, 120, 130, and 140 % of Ross strain requirements) were tested with 250 male one-day-old chicks in a completely randomized design with five treatments and five replicates (containing 10 chicks each). On day 42 of their age, the blood samples of two birds from each replicate (10 birds per treatment) were taken to determine serum IGF-1 gene expression. Subsequently, these birds were slaughtered for analysis of carcass characteristics and quality, and collecting the samples of liver and breast for expression of IGF-1 and insulin genes.

Body weight increased by consumption of 140 % of leucine as compared to 100 %. Reduction in feed conversion ratio was observed by feeding 140 % of leucine level. The IGF-1 gene expression of breast and liver increased by 110 % of leucine level. Moreover, feeding 110 % of leucine level caused a higher expression of insulin gene in breast and liver. Consumption of 130 % of leucine improved the meat protein, fat, and ash contents. Furthermore, consumption of 110 % of leucine increased the serum IGF-1 concentration.

Consumption of leucine in broiler diets was found to increase the expression of IGF-1 and insulin genes and consequently, improve the performance and carcass quality. It also decreased the abdominal fat in broiler chickens.

The present study was performed to evaluate the effects of different levels of tarragon powder on growth performance, carcass traits, immune system and microbial population of broiler ileum using 432 Ross 308 strains in a completely randomized design. During the test, the broiler herd became infected with the flu. Experimental treatments were: diet without additives (control), and experimental diets containing 0.5, 1 or 1.5% percent of dried tarragon powder.  The performance of chickens was recorded in different stages and at the end of the experimental stages. On day 34 of the experiment, blood samples were taken from a vein to measure antibody titer against Newcastle and influenza. On day 38, two birds from each replicate were injected with diluted 0.5% SRBC solution at a rate of 2.5 cc. One week later, a blood sample was taken through a wing vein and then antibody titer levels against SRBC and serum IgM and IgG levels were determined. At the end of the experiment, 2 birds (male and female) were killed from each replication and ileal contents were collected. The weight of parts such as chest, thighs, abdominal fat, liver, heart, spleen and bursa of Fabricius was also determined. The results showed that the use of tarragon powder at all levels, without a significant effect on feed consumption, significantly improved the feed conversion ratio of birds in the final stage of rearing (p <0.05). Heart weight in birds fed diets containing tarragon powder decreased compared to the control diet (p <0.05). Diet containing 1.5% tarragon powder significantly increased serum IgM antibody production. Supplementing the diet with any of the tarragon powder levels in comparison with the control treatment significantly reduced the population of Escherichia coli in chickens and also the diet containing 0.5% of tarragon powder reduced the lactobacillus population in comparison with the control treatment. The present results indicate that the use of tarragon powder in the diet of broilers improved their growth performance. According to the findings of this study, the optimal level of tarragon powder consumption is 0.5 to 1%..

This study was conducted to assess the gene expression of antioxidant enzymes (superoxide dismutase and catalase) in broiler chickens under heat stress. For this purpose, 200 Ross 308 broiler chicks in a completely randomized design with 5 treatments, 4 replicates and 10 chicks were used in each replicate. The treatments included: 1- control diet (base diet without any additives), 2- basal diet plus 200 mg / kg vitamin E, 3- basal diet plus 100 mg / kg of wild pistachio extract, 4- basal diet with 100 mg / kg of Common Purslane extract, 5- basal diet plus 100 mg / kg of wild pistachio extract and 100 mg / kg of Common Purslane extract. After 42 days, at the end of testing two chickens each replicate were slaughtered and their livers were excised quickly and transported with liquid nitrogen to the laboratory. The expression of the enzymes catalase and superoxide dismutase were evaluated by Real-time qPCR. In this way as beta-actin gene as housekeeping gene is used to normalize the data. The results indicate that the expression of antioxidant enzymes superoxide dismutase and catalase, included the highest level in the 5 treatments. Moreover, the expression of these genes showed a significant increase compared to the control in other treatments (treatments 2, 3 and 4). Therefore, the results indicated that the combination of extracts of wild pistachio and purslane can be together to be great impact on gene expression of antioxidant enzyme than the other groups under heat stress condition.

This experiment was performed to evaluate the effect of different levels of valine in low protein diets on the immune response of broilers. This study was conducted using 200 one-day old male broilers (Ross 308 strain) in a completely randomized design with 5 replications and 10 birds per replication from the age of 8-21 days. Experimental treatments included the control diet, recommended levels of valine (1.359), 10% higher than the recommended level of valine, 20% higher than the recommended level of valine in a diet containing 2% protein diluted. The results show that different levels of valine had no effect on liver, spleen and bursa of Fabricius weight (p < 0.05). Moreover, blood lymphocytes, heterophils, lymphocyte to heterophil ratio, monocytes, basophils and eosinophils did not affected by valine (p < 0.05). Diets containing 20% valine increased the HI antibody and humoral immunity responses (p < 0.05). Inclusion of 10% valine increased the IgM as compared to the other levels (p < 0.05). The secondary response of total antibody was affected by experimental treatments, so that the level of 20% valine increased the total secondary response and IgM secondary response to SRBC (p < 0.05). Moreover the addition of valine had a significant effect on the injection reaction of PHA-P (p < 0.05), and level of 20% valine, increased the cellular immunity of broiler in compared to the control treatment and lower valine levels. The addition of high levels of the valine in low-protein diets improved the cellular and humoral immune systems of broiler chickens.

In poultry farms, the stresses are inevitable, therefore, it is very necessary to achieve an efficient and practical way to control and reduce its negatives effects. Thus, this study was conducted to evaluate the effects of different sources of chromium on thyroid hormones and some blood parameters of broiler chicks under physiological stress conditions. A total of 216 one day old Ross broiler chicks (male) were used in a 3 × 2 factorial arrangement with two stress conditions (no stress, stress) and three levels of additive (no Additive, 2000ppb chromium-methionine, and 2000ppb chrome-methionine mill) in a completely randomized design with 6 treatments, 3 replicates and 12 bird per each. Dexamethasone was added to the diet (1.5 mg/kg diet) during 24-18 days of age to induce physiological stress. The birds were fed with chromium diets from 18 d until the end of the experiment. Blood samples were taken at 24 and 46 days of age via brachial vein and then analyzed for blood glucose, lipids, cortisol, thyroxine (T4) and thyroid iodothyronine (T3). Physiological stress reduced the concentration of thyroid hormones, glucose, serum lipids and cortisol hormones. In stressed birds, the use of chrome methionine diet significantly reduced cholesterol of serum. Chromium supplementing diet increased thyroxine (T4) concentration. Dietary chromium methionine significantly decreased cortisol concentrations of serum. Based on the results, adding chromium ppb 2000 from various sources reduces the effects of physiological stress on thyroid hormones and cholesterol concentrations in the serum of birds under physiological stress.

This experiment was conducted with the aim of the effects of pellet and mash feed on the production index, intestinal morphology characteristics, index of ascites, quality and microbial count of litter in broiler chickens using three diets of pellet, mash, mash+pellet on broiler performance. This experiment was conducted in a completely randomized design with three treatments and four replicates during 42 days. The measured traits included production index, intestinal morphology traits, ascites, hematocrit percentage, litter moisture and nitrogen content and microbial count of litter. In the whole of the total period, the results showed that the highest production indexes were pellet and pellet+mash treatments. The results of the morphological traits of the intestine showed that pellet and pellet+mash treatments had the highest ratio of villus height to the crypt depth in jejunum and the lowest level of mash treatment was observed. The results showed that the high ratio of villus height to the crypt depth in jejunum resulting from the use of pellet and pellet+mash ration due to production index was improved. The consumption of mash and pellet+mash treatments in the first three weeks reduced ascites significantly and increased with the prolonged feeding period of the pellet diet. The pellet+mash and all-flour treatments had the lowest amount of moisture content and nitrogen content, and as a result, the microbial count of litter was lower than that of pellet treatment. The pellet+mash treatment had the lowest index of ascites (32.62%) and less hematocrit (36%). The final result was that the use of pellet+mash treatment had the highest production index and the most suitable litter quality and the lowest ascites and microbial count compared to the full pellet diet in broiler chickens.