1. This experiment was conducted to evaluate the effects of replacing dietary cottonseed meal (CSM) or fermented cottonseed meal (FCSM) for soya bean meal (SBM) on growth performance, carcass characteristics, gastrointestinal microbial populations, and intestinal morphology of broiler chickens. 2. CSM was fermented with Bacillus subtilis, Aspergillus niger and A. oryzae for 7 d. A total of 300 one-d-old male Ross 308 broiler chickens were used in a 42-d experiment in which the birds were randomly allotted to one of 5 dietary treatments (containing 0%, 10% and 20% CSM or FCSM) in a completely randomised design. Birds were reared on litter floor and had free access to feed and water during the experiment. 3. Results indicated that the fermentation process significantly reduced crude fibre and free gossypol, while it increased crude protein content and lactic acid bacteria (LAB) count in CSM. 4. The use of FCSM instead of CSM significantly improved growth performance of broilers. The abdominal fat yield in treatments containing FCSM was significantly lower than in the other treatments. The increase in the population of LAB in the crop and decrease in the population of coliforms in the ileum of birds fed on diets containing FCSM were more significant than in other birds. Villi in the duodenum and jejunum of the birds fed on diets containing FCSM were significantly higher than for the other experimental groups. 5. The positive effects of diets containing FCSM on growth performance and intestinal health of broiler chickens showed that this processed source of protein can serve as an appropriate alternative for SBM in diets for broiler chickens.

A broiler chick bioassay was used to measure the effect of two inert digestibility markers on the determination of dietary AME. Diets contained 80% of either wheat or barley (with or without enzyme) and either chromic oxide at 0.5% or one of three levels of insoluble ash (0.5, 1.0, or 1.5%) as markers. The various cereal and marker diet combinations were consumed ad libitum (0 to 21 d) by two groups of 10 male broilers in each of two trials. The AME of each diet was determined by measuring the respective marker ratios between diet and excreta (collected for 24 h at 7 or 21 d) or ileal digesta collected at 21 d. Growth and feed conversion were measured on each group of birds between 0 and 21 d. There was no effect of marker on growth or feed efficiency. However, determination of AME of wheat- or barley-based diets with or without enzymes were affected by choice of marker and whether markers were measured in excreta (7 or 21 d) or ileal digesta. Chromic oxide was viewed as the least accurate method for determining AME, based on chronic oxide's inability to define AME differences between barley-based diets with and without enzymes, whereas insoluble ash clearly demonstrated improved AME of wheat- and barley-based diets with an enzyme. The optimum levels of insoluble ash for accuracy and repeatability were between 0.5 and 1.0%. The AME of the diets were, on average, 5% lower when determined with 7 vs 21 d excreta and 2.5% lower for ileal digesta than excreta collected at 21 d. It was concluded that identification of components that result in variability in AME levels of diets will be improved if a bioassay uses insoluble ash as a marker.

The aim of this study was to evaluate the effect of different durations of flaxseed oil consumption on broiler performance, fatty acid content of meat and expression of FADS2 gene in the liver of chicken. A total of 336 unsexed day old chicks were randomly assigned to 7 dietary treatments with 4 replicates of 12 chickens in each. Body weight, weight gain, feed intake and feed conversion ratio were not affected by dietary treatments. Longer consumption of flaxseed oil resulted in higher deposition of long chain n‐3 fatty acids in broiler breast and thigh (P < 0.05). Regression analysis showed that feeding broilers with diet enriched with flaxseed oil 17 and 7 days prior to slaughter for breast and thigh respectively, is enough for producing n‐3 labeled meat. Weekly replacement of oil source of diet (soybean oil) with flaxseed oil increased expression of FADS2 gene. To incorporate enough n‐3 fatty acids into chicken meat through addition of flaxseed oil to broiler diet and to maximize de novo long chain n‐3 fatty acid synthesis in broiler body, we recommend adding flaxseed oil to broiler diets 17 days prior to slaughter. Practical applications: Omega‐3 enrichment of broiler chickens depends on both nutrition and gene expression. Flaxseed oil is an omega‐3 oil source that can be supplemented to broiler diet to enrich chicken meat with the beneficial n‐3 fatty acids. However, adding such oil sources to broiler rations is restricted because of their negative effects on broiler performance and meat quality. Therefore, shorter period of such oil sources consumption is preferred. Flaxseed oil consumption can affect gene expression too. Thus, it is necessary to determine the optimum duration of flaxseed oil supplementation to broiler diets to produce omega‐3 labeled chicken using both nutrition and gene expression. Flaxseed oil consumption can affect fatty acid profile of chicken meat through manipulation of fatty acid deposition, de novo fatty acid synthesis, fatty acid oxidation and expression of genes involved in fatty acid metabolism. To incorporate enough n‐3 fatty acids into chicken, providing at least 3 g n‐3 fatty acid per kilogram of meat, by adding flaxseed oil to broiler diet, we recommend adding flaxseed oil to broiler diets 17 days prior to slaughter.

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