Title: Growth of Baby Pigs Fed Infant Soybean Formulas
Abstract: Newborn pigs were used to compare the nutritional quality of a recently developed soybean protein isolate (supplemented with methionine) with that of milk protein in 31-day studies. The pigs were fed liquid formulas which contained lactose as the sole carbohydrate and either 15% soybean protein calories or 10, 15, and 19% milk protein calories. Data from the pigs fed the milk formulas showed that weight gain and caloric efficiency, and levels of hemoglobin, plasma protein, liver protein, and carcass protein were directly related to protein content of the formulas; liver glycogen was inversely related to the level of protein in the diet. Weight gain, caloric efficiency and other data indicated that the protein quality of the soybean isolate plus methionine was approximately 85% that of milk protein. Young baby pigs were used to compare the overall nutritional quality of an infant formula made from the soybean protein isolate with hitherto available infant soybean formulas made from soybean flour. During a 2-week pretest period, newborn pigs were fed milk formulas, either high or low in protein; they were then fed the soybean formulas for 4 weeks. In pigs fed a low protein pretest formula, marked differences in overall nutritional quality of the soybean formulas were found. The soybean isolate formula was far superior to the others. The pigs fed the high protein milk formula during the pretest period apparently had good protein reserves and little difference in growth performance was found on the soybean formulas. The latter studies show the importance of protein status of the test animal in short-term nutritional studies.