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Reducing Protein in Swine Diets Three experiments were conducted at the University of Nebraska
to determine the limiting amino acids in an 11% crude protein corn-soybean
meal diets for growing pigs. In each experiment, 36 gilts were individually
fed diets containing 16, 12 or 11% crude protein diets. The 12 and 11%
crude protein diets were supplemented with lysine, methionine, tryptophan
and threonine to provide the same levels as was in the 16% crude diet.
The treatments consisted of various combinations of supplement histidine,
valine, and isoleucine. In all three experiments, average daily gain
and feed efficiency were reduced (P<0.07) as the protein was reduced.
Supplementation of isoleucine further reduced (P<0.05) average daily
gain, daily feed intake, gain/feed and fat-free lean gain. Supplementing
valine alone increased average daily gain and feed intake in two of
the experiments, however, the increases were not significant. Supplementing
with histidine and valine together resulted in growth performance equal
to, or greater than, that of the pigs fed the 12% crude protein diet,
but less than the performance of the pigs fed the 16% crude protein
diet. Supplementation of isoleucine and valine together resulted in
performance better than supplementing either amino acid alone. In two
experiments, supplementing the 11% crude protein diet with isoleucine
and valine together resulted in average daily gains that were not significantly
different (P<0.05) from the pigs fed the 16% crude protein diet.
Supplementing with all three amino acids did not improve performance
over supplementing with histidine and valine. These results indicate
that valine is the fifth most-limiting amino acid for pigs and either
histidine or isoleucine is the sixth-limiting amino acid in an 11% crude
diet for growing pigs. |
