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Objective: To assess the influence of reduction of crude protein (CP) by 5% and 10% with supplementation of crystalline synthetic essential amino acids (EAAs) on performance and carcass traits of broilers. Design: Randomized controlled study Animals: A total of 320 one-day-old broiler chicks, (Cobb 500) reared up to 35 days of age were randomly allocated into eight experimental groups with four replicates (10 each). Procedures: The treatments as follow; the first group of chicks were fed on control protein to meet the CP requirement and total AAs according to Cobb 500 recommendation; the second group were fed idle EAAs (Id EAAs) to meet the recommended CP and the digestible EAAs. The third, fourth, and fifth groups were fed on diet 5% reduction of CP with EAAs supplementation exceed the digestible EAAs requirement of Cobb by 110, 120, and 130% (LCP3+110EAAs, LCP4+120EAAs, LCP5+130EAAs). However, the sixth, seventh, eighth groups of chicks were fed on diet 10% reduction of CP with AAs supplementation exceed the digestible EAAs requirement of Cobb by 110, 120, and 130% (LCP6+110EAAs, LCP7+120EAAs, LCP8+130EAAs). Results: Broilers of group four, five, six, seven and eight showed a significant decrease final body weight (BW), body weight gain (BWG) and feed intake at 21 and 35 days of age. However, the same variables were significantly enhanced in broilers of group one, two, and three (p <0.05). Additionally, there was a significant decrease of relative weight of abdominal fat pad of broilers in groups three, four, five compared to other treatment groups. Serum uric acid and cholesterol were linearly decreased with reduction of CP and supplementation with synthetic essential amino acids. Conclusion and clinical relevance: The present results indicate that reduction of CP by 5% or 10% with crystalline EAAs supplementation by 110, 120 and 130% more than the digestible EAAs of broiler recommendation did not support the growth performance.

The present study was carried out to evaluate the effect of dietary supplementation of soybean oil (SBO) to increase neutral detergent fiber (NDF) contents on growth performance (GP), nutritive values (NV) and carcass quality of growing New Zealand White (NZW) rabbits. A total sixty, 5 weeks old male weaned rabbits of mixed breeds with a mean body weight of 774.42g were randomly allocated to four dietary groups of 15 rabbits each. Experimental groups were fed diets supplemented with 0, 1, 2 &3% fat. The feeding trial lasted for 6 weeks. Growth performance parameters as body weight (BW), feed intake (FI) and feed conversion ratio (FCR) were determined every week. At the end of the experiment (8 weeks), 6 rabbits from each group were randomly taken, weighted and slaughtered to complete bleeding. The rabbits from each treatment were dressed, eviscerated samples taken for determination of moisture, CP, EE and ash contents.The obtained results revealed that supplementation of SBO in diets NZW rabbits up to 2% improve BW and FCR and didn't significantly affect the feed intake. However, supplementation of 3% SBO in diets of NZW rabbits did not significantly increased the BW and weight gain (BWG), FI and FCR. Fat supplementation didn't affect the dressing carcass percent & internal organs weight. The present study concluded that supplementation of SBO in diets NZW rabbits up to 2% significantly improve the growth performance and body composition.

The present work was conducted to study the effects of feeding low crude protein diets (LCP-diets) with supplementation of threonine (Thr) on growth performance and immunocompetence in broiler chickens. One day old 264 Cobb chicks were divided into 6 equal groups (each of 4 replicates and each replicate was of 11 chicks). The 1 st group is considered the control one and fed normal basal control starter, grower and finisher diets containing the recommended levels of CP, threonine, methionine, lysine, tryptophan, valine, arginine and metabolizable energy as specified for Cobb500 broiler performance. The 2nd experimental group was fed ideal protein diets which were formulated to contain the minimum nutrient specifications based upon supplementing digestible essential amino acids (lysine, methionine, tryptophan, threonine, arginine, and valine). The other experimental chick groups (3 rd , 4 th , 5 th and 6 th groups) were fed isocaloric diets containing low levels of total dietary CP% (1 and 2% less than the minmum recommended CP%) with supplementation of Thr to 120 or 140% of the minimum recommended levels. The diets were isocaloric (3035, 3108 and 3180 Kcal/kg for starter, grower and finisher diets respectively). All chicks were vaccinated against Newcastle disease virus (NDV) at day 14 of age through eye drops. Growth performance indices (body weight, feed intake, feed conversion ratio and protein efficiency ratio) were measured. Blood samples were collected from the broilers at 14, 21, 28 and 35 days of age to determine the serum titre of antibodies against NDV using haemagglutination inhibition test (HI). At 42 days of age, blood samples were collected for determination of serum metabolites and 12 chickens from each group were slaughtered to obtain some of the carcass traits.The results revealed that BW and FCR of the broilers fed 2% LCP-diets with 120 or 140% Thr supplementation were significantly lowered than those fed control or ideal protein diets, as well as those fed 1% LCP-diets with Thr supplementation. There were no differences between the groups in dressed carcass percentages. The abdominal fat % in the carcass of the broiler chickens was not significantly affected by decreasing the dietary CP or supplementation of threonine. Liver weight% significantly increased with feeding the 2% LCP-diets. Feeding 2% LCP-diets also resulted in significant increase in serum uric acid and decreased serum total protein, albumin and globulin. The highest HI titer values and lowest serum levels of uric acid were observed in chickens fed ideal protein diets. While, chickens fed LCP-diets (-2%) had reduced HI titer values.From the present study, it could be concluded that the dietary protein level could be decreased by 1% of the recommended levels with threonine supplementation to 120 % of requirements with no adverse effects on body weight development, FCR, serum metabolites and immune competence in broiler chickens. Formulating broiler diets based upon digestible essential amino acids achieved optimal growth performanc...