Some Amino Acid Needs of the Young Pig Fed a Semisynthetic Diet

Abstract

Nitrogen balance experiments were conducted to determine some amino acid needs of pigs weighing about 10 kg. and fed a semi-synthetic diet. Maximum nitrogen retention was the major criterion of response to graded amino acid levels. The pigs were equally fed for a 7-day pre-test period, and urine and feces were collected for the following 5 days. The needs for various amino acids, expressed as percent of the diet, were as follows: isoleucine, 0.67; threonine, 0.60; tryptophan, 0.15; valine, 0.55; and total sulfur-bearing amino acids, 0.74. Further, cystine can replace at least 70% of the need for total sulfur-bearing amino acids. The young pig utilized dietary nitrogen most efficiently when the essential and non-essential amino acids each furnished about 50% of the total dietary nitrogen. A crystalline amino acid diet containing 10.7% protein equivalent and glutamic acid as the sole source of non-essential nitrogen supported nitrogen retention equal to a diet with the same essential amino acid distribution but with 1% casein. Substitution of 10% casein into the amino acid diet and a diet containing 17% casein plus 0.24% methionine supported a greater nitrogen retention by pigs than the amino acid diets. During a 9-day feeding trial young pigs fed the amino acid diet gained 0.34 kg. per day and those fed 17% casein gained 0.42 kg. daily. Copyright © 1968. American Society of Animal Science. Copyright 1968 by American Society of Animal Science