NUTRITIONAL RELATIONSHIP OF LYSINE AND MONOVALENT CATIONS IN RATS AND SWINE
Abstract
Four experiments were conducted with rats fed corn-soybean meal diets to test dietary lysine (lys) levels from 0.36 to 1.00% in combination with K levels from 0.36 to 1.00% or Na levels from 0.13 to 1.00%. In another trial, five K sources were tested in combination with two dietary levels of lys (0.36 and 0.68%); two control diets, without supplemental K, were included. Based on performance, the estimated lys requirement was 0.79 to 0.89%. The lys requirement was increased at the higher Na levels. Na showed a detrimental effect on performance, which was accentuated in rats fed low lys diets. Supplemental K tended to depress the performance of rats. In terms of weight gain, potassium carbonate and citrate were less detrimental than K phosphate, but all other K sources were statistically equivalent. The increase in liver weight in lys supplemented rats may be due to an increase in protein synthesis. The increase in kidney weight, by adding lys to the diet, may be due to a reduction in urea excretion. In two trials with swine, supplementation of a corn-soybean meal diet (0.75% lys) with lys up to 0.95% improved performance of 4-week-old weaned pigs. It appears that the lys requirement of baby pigs is 0.95% of the diet or higher. Results obtained with supplemental K up to 1.00% were variable. In one trial, supplemental K improved and in another, it depressed performance of pigs. K level of the basal diet (0.58%) appeared to be adequate. Serum or plasma lys increased in both species by adding lys to the diet. Supplemental lys increased hematocrit and decreased lys in red blood cells of swine. In rats, serum lys, arginine, K and Na were not affected by K sources, and in pigs, they were not affected by supplemental K. In some cases, these parameters had variable responses to the addition of one nutrient at different levels of the other nutrients in the diet, suggesting some interrelationship. In general, for both species, K and/or Na did not alleviate a lys deficiency in corn-soybean meal diets and, in most cases, supplementation of either appeared depressive.
Degree
Ph.D.
Subject Area
Livestock
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