Problems in the Formulation of a Semi-Synthetic Diet for Amino Acid Studies with the Pig

Open Access
Publisher Website
Google Scholar
Abstract
A diet formulated with dextrose, dried skim milk, zein, corn starch, woodflock, corn oil, methionine, histidine, isoleucine, ammonium citrate, minerals, vitamins and an antibiotic was designed to be low in lysine and tryptophan. Weanling pigs weighing about 20 lb. were individually fed. With 18 percent dried skim milk and 5.0 percent zein (1.99 percent nitrogen) in the diet pigs gained at a satisfactory rate and efficiency and did not differ in growth response to L-lysine levels as low as 0.54 percent of the diet. With 12.0 percent dried skim milk and 7.5 percent zein (2.17 percent nitrogen) in the diet the pigs gained at a sub-optimum rate and efficiency, and failed to exhibit differences in growth rate to levels of L-lysine as low as 0.37 percent of the diet. However, pigs fed 0.10 percent or more L-tryptophan exhibited faster gains and a significantly greater feed intake than pigs fed 0.06 percent L-tryptophan. A digestion trial revealed that the apparent digestion coefficient of the zein was 44.8 percent so that the latter diet, particularly, was low in digestible protein. Also pigs occasionally exhibited a sudden lack of locomotor coordination, although they were otherwise normal. Usually the pigs showed a quick recovery, but several pigs died suddenly while on test. Autopsy immediately after death revealed a severe distention of the stomach and intestines with gas. Contents of the stomach and intestines were frothy and possessed an odor of alcoholic fermentation. No pathogenic organisms were isolated, although, yeast organisms were present and active in the stomach and cecum. Chronic or acute symptoms were noted consistently in pigs fed the diet modified to contain 50 percent dextrose.