effects of dietary conjugated linoleic acid and n-3 fatty acids on the performance, carcass traits and small intestinal morphology of broiler chickens

an experiment was conducted on broiler chickens to study the effects of conjugated linoleic acid (cla), fish oil, both at 7% of the diet, or their mixtures at 3.5% of the diet, on the performance, carcass traits and intestinal morphology of broiler chickens. the chicks fed with 7% fish oil or 7% cla diets, were found to have an inferior weight gain in grower and finisher phases, respectively. a significant reduction in feed intake was observed with the diets containing 7% fish oil. however, adding cla to the diets, did not affect birds feed intake. the dietary fish oil and cla supplementation adversely affected the feed conversion ratio as well as carcass yield. cla at the 7% level increased liver weight. there were no differences in the carcass, thigh or abdominal fat pad percentages between the experimental treatments; however the birds fed the diet containing 7% fish oil had the lowest breast and the highest liver percentages. histological examination of small intestine revealed that, the diet containing 3.5% fish oil + 3.5% cla resulted in higher villus height than the diets with 7% fish oil or cla. such an increase was observed in the crypt depth of the duodenum and jejunum, but no difference was detected in the crypt depth of the ileum. the small intestinal wall thickness and goblet cell numbers in the chickens fed the diet containing the mixture of fish oil and cla were lower than those of the other treatments. the results of this study showed that a high dose of fish oil or cla can reduce broiler chickens performance, but their combination can moderate this adverse effect.