Fat absorption from the small intestine of gnotobiotic chicks.

The small intestine of 3-week-old gnotobiotic chicks was divided into five equal segments for analysis. Since it has been found that most fat absorption occurs in the third and fourth segments, they were selected for study. The major fatty acids in the diet and the feces of chicks were palmitic, stearic, oleic, and linoleic acids. Consequently, these fatty acids were selected for quantitative analyses in the absorption studies. Germ-free chicks were contaminated at 7 days of age with bacteria isolated from the third and fourth intestinal segments, except for the Escherichia coli contaminant, which had been previously isolated from a chicken with air sac disease. There were two different degrees of response by chicks to the bacterial contaminants in this study. For this reason, the chicks were placed retrospectively into two categories according to their response to environmental conditions. The first category (A) contained germ-free chicks and chicks monocontaminated with E. coli, Staphylococcus, or Lactobacillus. The second category (B) was composed of conventional chicks and chicks monocontaminated with Streptococcus faecalis or Clostridium welchii, dicontaminated with S. faecalis and C. welchii, and accidentally polycontaminated with coliforms and anaerobic gram-positive bacilli. Chicks in category A demonstrated increased absorption of palmitic and stearic acids and total fat as compared to category B chicks. Conversely, category B chicks showed slightly increased absorption of oleic and linoleic acids. Thin-layer chromatographic analyses demonstrated that cholesterol esters were affected similarly to fatty acids. The site of absorption of fatty acids, cholesterol esters, and total fat was unchanged, regardless of the environment.