Influence of butyric acid supplemented diets on growth response, precaecal nutrient digestibility, gut morphology and histopathological measurements in broiler chickens

Abstract

In recent time, there has been call for antibiotics substitute in animal feed due to concerns over its residual effects and the development of antibiotic-resistant bacteria in humans consuming the meat. Short chain fatty acids are often used as viable alternatives to antibiotics. However, there has conflicting reports on the efficacy of the organic acids. This study was therefore aimed at assessing the effects of butyric acid supplemented diets on growth performance, ileal nutrient digestibility, gut morphology and histopathology of broiler chickens in a 21-day feeding trial. Three hundred and thirty-six, one-day old Arbor Acre plus broiler chicks were randomly assigned to seven dietary treatments with six replicate groups of eight chickens each. Diet 1 was the Corn-SBM diet {basal diet (negative control NC)}; Diet 2 (positive control) was basal diet+105g of oxytetracyclene/tonne of feed; Diet 3 comprised NC+0.1% butyric acid); Diet 4 consisted of NC+ 0.2% butyric acid, Diet 5 contained NC+ 0.3% butyric acid, Diet 6 had NC+ 0.4% butyric acid and Diet 7 consisted of NC+ 0.5% butyric acid. Titanium dioxide was added at the rate of 5g/kg as indigestible dietary marker. Performance indices were calculated. On day 21, two chickens per replicate were slaughtered, excised and digesta samples collected at two-thirds to ileo-caeco-colonic junction for digestibility assay. After flushing out the digesta samples, sections of the ileum (5cm posterior to Meckel's diverticulum) were removed for ileal morphological measurements while ileal sections and liver were harvested for histopathological examinations. There were no significant (P>0.05) differences in the performance indices across the treatments. Digestibility of crude protein, ash and nitrogen free extract in broiler chickens fed diets containing antibiotic and 0.2, 0.3, 0.4 and 0.5% butyric acid supplemented diets were significantly (P<0.05) higher than those fed basal diet and diet supplemented with 0.1% butyric acid. Ether extract digestibility of those fed basal diet was similar (P>0.05) to chickens on other dietary treatments. Similar crude fibre digestibility was recorded for basal diet and 0.1% butyric acid supplemented diet. Diets had no significant influence on the villus length, villus height, crypt depth, epithelial thickness and villus height to crypt depth ratio. Histopathological observation of chickens on the control diet showed clinical symptoms of villi and hepatocellular atrophy. No lesions were observed in the ilea of chickens on the antibiotics supplemented diets. Clinical symptoms ranging from villi atrophy, necrosis of the villi, clubbing of the villi, loss of enterocyte, hepatocellular atrophy and necrosis, hyperplasia of bile ductular epithelium, accentuation of sinusoids, and focus of lymphoid aggregate in parenchyma of liver were observed for chickens on butyric acid supplemented diets. Due to the equal level of performance recorded across treatments, it may therefore be concluded that using butyric acid up to 0.5% in diet can replace antibiotic usage but had no comparative beneficial effect on broiler productivity at 21 days.