ABSTRACT This experiment was conducted to investigate the effects of leucine (Leu) supplementation on performance and carcass traits of broilers along with the re-evaluation of standardized ileal digestible (SID) Leu requirement of broiler chicks on days 0-14. Birds were fed seven experimental diets with SID Leu levels of 16.3 (basal), 17.3, 18.3, 19.3, 20.3, 21.3, and 22.3 g/kg. Some 280 male broiler chicks were randomly assigned to the seven dietary treatments in a completely randomized design with five replicates. Dietary SID Leu levels had significant effects on body weight gain(BWG), feed conversion ratio(FCR), carcass, and breast percentages. BWG increased (p<0.05) when the broilers fed diets with 18.3 to 21.3 g/kg SID Leu compared to the basal diet. FCR decreased (p<0.05) by dietary SID Leu levels of 18.3 to 21.3 g/kg in comparison with the basal diet. Carcass yield increased (p<0.05) by SID Leu levels of 19.3 to 21.3 g/kg. Breast percentage increased (p<0.01) when the broilers received diets with 18.3 to 22.3 g/kg SID Leu and the highest value obtained by the SID Leu level of 21.3 g/kg. Abdominal fat decreased linearly by Leu supplementation (p<0.01). Regression analysis indicated the SID Leu requirement of 18.67, 18.88, and 19.85 g/kg for BWG, FCR, and breast meat yield, respectively. It can be concluded that broiler performance characteristics, especially breast yield, improve by Leu supplementation. Based on the results, the Leu requirement of modern broilers has increased dramatically due to genetic selection for a higher growth rate.

ABSTRACT This study was conducted using Analytic Hierarchy Process (AHP) in order to rank broiler breeding farms in Zanjan province, Iran, regarding buildings, installations, and equipment to determine their effects on production factors. Data on 108 farms were collected using designed forms. This data was analyzed based on the effectiveness of each parameter in the production and management category according to experts’ opinion. The results indicated that ventilation systems (fans, inlets, and damper) as well as wall and roof insulation in poultry houses, constituted 66% of the technology coefficient. The stocking density increased through improvement of the mechanization coefficient. Most of these farms used longitudinal or tunnel ventilation and a combination of small and large fans. Roof insulation was mostly done using glass wool, and corrugated plastic while installing the heaters outside the poultry house. In these farms, the use of nipple drinkers and plate feeders was more prevalent. Moreover, the results showed that feed conversion and production indices have a significant correlation with mechanization coefficient so that farms with better mechanization coefficients had lower conversion ratio (p=0.04) and higher production indices (p=0.015). In general, the results indicated that ventilation and air inlet systems, as well as wall and roof building technologies have the greatest influence on the mechanization coefficient, while better mechanization coefficients translated into improvements in production efficiency and economic performance of poultry farms.

ABSTRACT We hypothesized that the supplementation of vitamin C (Vit. C) and coenzyme Q10 (CoQ10) alone or in combination could reduce the negative effects of cold stress in broilers. Four hundred male chicks were exposed for 24 h to cold stress (15 ºC) starting from 15d of age, while a positive control group (PC, 100 birds) was kept under normal temperature condition. The experimental groups under cold stress (four treatments in 5 replicates of 20 birds) were: negative control (NC, basal diet), Vit. C (basal diet + 300 mg/kg Vit. C), CoQ10 (basal diet + 40 mg/kg CoQ10) and Vit. C plus CoQ10 (basal diet + Vit. C+ CoQ10at above mentioned doses). Vit. C or CoQ10 supplementation were restored (p<0.01) performance and lowered (p<0.01) ascites mortality. Blood hematocrit and hemoglobin concentration were decreased (p<0.01) to the level comparable to PC by Vit. C supplementation. Lower plasma concentrations of thyroxin (T4) and higher triiodothyronine (T3) were observed in NC birds (p<0.01) and were not affected by Vit. C or CoQ10. In conclusion, supplementation of Vit. C or CoQ10 in diet of broilers under cold stress conditions resulted improved performance parameters (body weight and feed conversion ratio) and ascites related traits (low red blood cell count, hematocrit, T3, and heart weights and high T4). No additional benefit was observed by combination of Vit. C and CoQ10.

A 2 × 2 × 2 factorial arrangement was conducted to evaluate the effects of cereal type (corn vs. wheat), enzyme supplementation (0 or 0.4 g/kg diet), and sodium butyrate addition (0 or 2 g/kg diet) on growth performance, carcass traits and intestinal morphology of male broilers from 10 to 42 d. A total of 600 male Arbor Acres chickens were assigned to eight dietary treatments in a completely randomized design, providing five replicate pens per treatment. Diets were formulated to meet or exceed NRC nutrient recommendations. When compared with birds fed corn-based diets, chickens fed wheat-based diets had inferior weight gain (1978 vs. 1807 g, p < 0.01) and feed per gain ratio (1.81 vs. 1.93; p < 0.01). Both weight gain (1870 vs. 1915 g; p < 0.01) and feed intake (3511 vs. 3556 g; p < 0.01) were increased by enzyme addition to experimental diets. Feed intake significantly (p < 0.01) increased by sodium butyrate addition to experimental diets; however, no significant differences were observed in weight gain or feed per gain ratio when sodium butyrate added to experimental diets. The birds fed wheat-based diet had higher relative weights of the proventriculus (p < 0.01), gizzard (p < 0.05), liver (p < 0.05), duodenum (p < 0.05), and ceca (p < 0.01) when compared with those fed corn-based diet. Enzyme and sodium butyrate addition had no significant effects (p > 0.05) on the relative weights of the proventriculus, gizzard, pancreas, liver and heart. Cereal type had a significant (p < 0.05) effect on intestinal morphology, including villus height and crypt depth. Jejunal villus height (p < 0.05) and crypt depth (p < 0.01) were improved by sodium butyrate addition. In conclusion, the results of this experiment showed that enzyme and sodium butyrate addition, especially to the wheat based diet, improve growth performance.