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Growing-finishing pigs, Ideal Protein concept, Phase feeding, Split sex feeding.


For every stage of growth, pigs have a requirement for essential amino acids provided in a specific ratio and for additional nitrogen provided as amino acids or other nitrogen sources to allow synthesis of nonessential amino acids. The typical manner of balancing swin diets has involved supplying several traditional feed ingredients in a ratio in the diet that meets the required level of the most limiting amino acid leaving excesses of most other amino acids. With this method, considerable nitrogen above that needed for nonessential amino acid synthesis is provided and excess nitrogen is excreted in the urine as urea. The Ideal Protein concept is based upon the idea that total amino acid levels and nitrogen levels in the diet are reduced by placing all essential amino acids in the proper ratio and at the proper level with just enough additional nitrogen in the diet to allow nonessential amino acid synthesis. Nitrogen excreted as urea is minimized. This is possible because crystalline amino acids are available for all essential amino acids. However, because of the high cost of some crystalline amino acids, formulation on a complete Ideal Protein basis is not pratical. Because crystallin lysine and methionine are affordable and crystalline threonine and tryptophan prices have been reduced, it is practical to formulate to the first limiting amino acid beyond those four amino acids. For pigs in growth stages 22 to 114 kg that fifth limiting amino acid is isoleucine when using corn and soybean meal as the main dietary ingredients It is possible, therefore, to exactly meet the amino acid ratio and levels of lysine, methionine, tryptophan, threonine, and isoleucine, leaving excesses for only the last five essential amino acids. The research reported herein was designed to evaluate the effect on pig performance throughout the four growth phases of the growing and finishing periods when nitrogen levels in the diet are reduced by systematically balancing for the first through the fifth limiting amino acids utilizing crystalline amino acids to maintain the Ideal Protein ratios for the most limiting amino acids.

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South Dakota State University


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