Dietary antibiotic growth promoters enhance the bioavailability of alpha-tocopheryl acetate in broilers by altering lipid absorption.

The influence of intestinal microbial bile salt deconjugation on absorption of fatty acids and alpha- and gamma-tocopherol was investigated in a trial with Ross 208 broilers. Birds (n = 1600) were assigned to 4 dietary treatments: no supplementation or supplementation of antibiotics (salinomycin, 40 mg/kg feed and avilamycin, 10 mg/kg feed), and inclusion of either animal fat (10 g/100 g feed) or soybean oil (10 g/100 g feed) in the diet. At d 7, 14, 21, and 35 of age, the intestinal number of the bile salt hydrolase-active bacteria Clostridium perfringens, the concentration of conjugated and unconjugated bile salts, the ileal absorption of fatty acids and tocopherols, and the blood plasma concentrations of tocopherols were measured.

Pancreatic lipase activity as influenced by unconjugated bile acids and pH, measured in vitro and in vivo.

The relation between pancreatic lipase activity, unconjugated bile acids and pH was studied in vitro and in vivo. Lipase activity was assayed in vitro using automatic titration, where the fatty acids liberated from the hydrolysis of glycerol tributyrate (GTB) were measured. The lipase activity was determined at different ratios of conjugated to unconjugated bile acids (100:0, 75:25, 50:50, 25:75, 0:100) in response to pH 6.

Quantitative determination of bile salt hydrolase activity in bacteria isolated from the small intestine of chickens.

A quantitative assay based on high-performance liquid chromatography analysis of bile salts and bacterial protein determination was established for investigating bile salt hydrolase (BSH) activity in bacteria isolated from the small intestine of chickens. Bacteria were isolated using various media and were subsequently grouped according to cell morphology, fermentation profile, and 16S ribosomal DNA sequence. Representative isolates from each bacterial group were assayed for BSH activity.

Effects of dietary fat source and subtherapeutic levels of antibiotic on the bacterial community in the ileum of broiler chickens at various ages.

The effect of dietary fat source (soy oil or a mixture of lard and tallow) and dietary supplementation with antibiotics (a combination of avilamycin at 10 mg kg of feed(-1) and salinomycin at 40 mg kg of feed(-1)) on the bacterial community in the ileum of broiler chickens at different ages (7, 14, 21, and 35 days) was studied using PCR with denaturing gradient gel electrophoresis (DGGE) analysis and bacteriological culture. The bacterial origin of fragments in DGGE profiles was identified by sequencing. Bacterial enumeration results, together with PCR-DGGE profiles, showed that the composition of the microflora was age dependent and influenced by dietary fat source and antibiotic supplementation.