Effects of flavomycin and probiotic supplementation to diets containing different sources of fat on growth performance, intestinal morphology, apparent metabolizable energy, and fat digestibility in broiler chickens

This study was conducted with broilers to evaluate the effects of growth-promoting antibiotic (flavomycin) and probiotic (7 bacterial species) supplementation in diets containing soybean oil or free fatty acids (FFA) on performance, morphological parameters of the small intestine, apparent digestibility of gross energy (GE) in the ileum, and apparent digestibility of fat in the ileum and total intestinal tract. Eight-hundred and sixty 4-d-old Ross 308 broiler chicks were used in a 3 x 3 factorial arrangement of dietary treatments that comprised 3 additives (without additive, flavomycin, and probiotic) and 3 fat sources (without fat, 30 g/kg of FFA, and 30 g/kg of soybean oil) with 4 pen replicates per treatment. All diets contained chromic oxide (3 g/kg) as an indigestible marker. Body weight and feed intake were recorded weekly over 40 d. Flavomycin interacted positively with soybean oil and FFA causing improvements (P < 0.05) in BW gain. Among the different fat sources, soybean oil significantly increased (P < 0.05) BW gain and jejunal villi height, whereas flavomycin improved (P < 0.05) BW gain and feed conversion when compared with the remaining dietary additives. However, the probiotic negatively affected (P < 0.05) BW gain and feed conversion despite increased (P < 0.05) villi heights of the duodenum, jejunum, and ileum. At 21 and 38 d of age, fat and GE digestibility were higher (P < 0.05) in the ileum and total intestinal tract of birds fed diets containing soybean oil than those of birds fed FFA. Fat and GE digestibility were highest (P < 0.05) among birds fed flavomycin but lowest (P < 0.05) among probiotic-fed birds. Flavomycin addition to soybean oil or FFA diets significantly increased (P < 0.05) fat and GE digestibility when compared with the same diets containing the probiotic. Therefore, soybean oil is a better energy source than FFA, as indicated by increased growth, nutrient digestibility, and jejunal villi height. However, probiotic supplementation to fat-rich diets caused detrimental effects on nutrient digestibility and growth.