An experiment was conducted to study the effects of different dietary levels of desiccated ox bile on the performance, fat digestibility, gut morphology and blood variables of broiler chickens fed tallow diet. One hundred and fifty one-day-old male broilers (Ross 308) were equally distributed into three treatments (with five replicates each) in a completely randomised design. Desiccated ox bile was added to the experimental diets during starter (7–21 day) and grower (22–42 day) periods (0.00, 0.25 and 0.50% of diet). During the experiment, the measured parameters were average body weight gain, average feed intake, average feed conversion ratio, gut morphology, serum cholesterol (Chol), triglyceride, high density lipoprotein and low density lipoprotein. During the grower and overall periods, ABWG and AFCR were significantly improved (p<0.05). Dietary supplementation of desiccated ox bile in the diet resulted in significant (p<0.05) linear increase in fat digestibility ranged from 51% (0.00% desiccated ox bile in the diet) to 84% (0.50% desiccated ox bile in the diet). Dietary desiccated ox bile supplementation increased (p<0.05) villus height, crypt depth, villus width and villus apparent surface area in the jejunum and ileum. The results of this study indicated that dietary desiccated ox bile can be used as a natural non-nutrient additive to improve broiler performance and tallow digestibility in broiler chickens at least by stimulation of morphological maturation of gastrointestinal tract.

The effects of three plant extracts, i.e. lemon peel extract (LPE), orange peel extract (OPE) and Curcuma xanthorrhiza essential oil (CXEO), on the performance and gut health parameters of broilers exposed to high temperature was investigated. A total of 336 unsexed Ross 308 broilers were distributed to seven dietary treatments, a control diet and six diets containing 200 or 400 mg kg-1 feed of one of the three products between d 25-38 (12 chicks per pen, four replicates). To induce chronic heat stress, the temperature was increased to 34°C with 50% relative humidity for 5 h daily starting from d 28 until d 38. At d 38, four animals per pen were sampled for morphological characteristics (duodenum, jejunum and ileum) and microbial counts (ileo-cecal contents). Plant extracts did not affect the bird performance. The bursa weight of the control birds was lower (p<0.05) comparing to those fed 400 mg kg-1 OPE and 200 and 400 mg kg-1 CXEO diets. Feeding 400 mg kg-1 of LPE decreased the duodenal villus:crypt ratio compared to control and 200 mg kg-1 OPE fed birds. Plant extracts did not have effect on ileal histo-morphology. Feeding with 400 mg kg-1 of LPE and CXEO caused a decrease in coliform counts in ileum and feeding of 400 mg kg-1 CXEO diet decreased coliform counts in caecum compared to control birds (p<0.05). These results elucidate that CXEO, OPE and LPE might modify some microbial and intestinal traits, but without beneficial effect on performance of broilers under heat stress.

Threonine needs based on Ross manuals might be 14% of the National Research Council (NRC) recommendation, thus the effect of threonine on mucin2 gene expression, histological characteristics and performance were evaluated in Ross male broilers fed diets containing 0.8% (NRC requirement), 0.87% (average of NRC and Ross requirement), 0.94% (Ross requirement) and 1.01% (more than Ross requirement) total threonine. The dietary treatments consisted of an isonitrogenous corn-soybean meal-based diet with incremental levels of threonine. At the first day of chicken age, 24 pens were equalized to 12 birds per pen, in a completely randomized design and dietary treatments were randomly distributed for the 14-d period. Live performance measurements improved (Pmucin2 gene expression and goblet cells density. According to these results, threonine needs in starter period in Ross (308) broilers is more than NRC recommendation

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