Developmental expression of fatty acid binding protein and its regulation in the fetal, neonatal, and weanling pig

This dissertation examined the regulation of fatty acid binding protein (FABP) expression in the pig. Physiological and nutritional regulation of FABP activity, by factors such as age, weaning, dietary lipid, and cortisol in porcine adipose tissue, liver and small intestine were examined in this dissertation. Firstly, FABP development in the fetus was examined. FABP activity on a per gram basis in the liver was four to five times greater than that in the small intestine; however, activity per mg of tissue protein exhibited no difference from that in the small intestine, indicating that FABP development in the fetal liver and small intestine were proportional to cell development, but liver developed earlier than small intestine. FABP activity in the small intestine increased rapidly prior to birth, implying that it is essential for dietary lipid absorption. Secondly, we demonstrated that intestinal-FABP activity was weaning independent, but age related. Development of FABP in the small intestine displayed a bimodal response with age with two peaks at 2 and 5 wk of age; its activity was lowest at 4 wk of age regardless of weaning. In this regard, more concern is needed when feeding early weaned pigs long chain triglyceride. Thirdly, when pigs were fed ad libitum a corn-soybean meal-dried whey diet with the addition of different lipid sources, results demonstrated no positive effect of an adding 10% lipid to the basal diet. FABP activity in the liver was significantly higher in pigs fed tallow and medium chain triglyceride compared to pigs fed corn oil. Pigs fed coconut oil and medium chain triglyceride had greater FABP activity compared to pigs fed corn oil and tallow in the small intestine. Lastly, we demonstrated that intestinal-FABP activity was regulated by cortisol. FABP activity in the small intestine was high in the 1 mg cortisol injection group. No difference was apparent among treatments when comparing total FABP activity in the small intestine, implying that compensation of lipid absorption occurred in the body.