EFFECTS OF VARYING DIETARY ENERGY, PROTEIN AND AMINO ACID LEVELS ON GROWTH, NUTRIENT DIGESTIBILITY, AND SERUM PROTEIN LEVELS OF EARLY WEANED PIGS

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Abstract
Fifteen rations formulated by a factorial arrangement of 3 fat and 5 protein treatments were fed to non-castrate crossbred pigs from 3 to 9 weeks of age. Levels of 0, 4, and 8% fat and 12, 16, and 20% crude protein, and 12 and 16% crude protein with supplemental lysine and methionine to equal that present in the 20% protein diet were fed. Each increment of protein resulted in increased rate of gain. The amino acid supplemented 16% protein ration supported as rapid gain and as efficient utilization of feed as did the 20% ration. Feed intake and efficiency of feed utilization were improved as protein was raised from 12 to 16% and when lysine and methionine were added to the rations. Fat levels were not found to affect rate of gain, feed intake or efficiency of feed utilization. Apparent digestibility of nitrogen was higher in the 20% protein ration than the 12 or 16% protein rations and was also found to increase when amino acids were added to the low protein rations. More of the apparent digestible nitrogen was retained from the amino acid-supplemented rations. Increasing fat levels were found to reduce: the total serum protein levels in gilts but not in boars.