Energy, protein, and amino acid levels in the rations of weanling pigs /

Abstract

Experiments were designed to study fat, lysine, and methionine additions to rations containing three levels of crude protein for weanling pigs from 3 to 9 weeks of age.The experiments were 3 x 5 x 2 x 2 factor¬ ials in which the factors were fat level, protein treatment, breed group, and sex. The levels of supplemental fat were 0, 4, and 8 per cent. The five protein treatments were based on rations containing 12, 16, or 20% protein and 12 or 16% protein supplemented with lysine and methionine so that the level of these amino acids was calculated to be the same as in the 20%,-protein ration. The two breed groups were Lacombe x Yorkshireand Hampshire x Lacombe-Yorkshire .Increasing protein from 12 to 16% resulted in doubling the rate of gain (from 0.11 to 0.22 kg/day) while increasing protein from 16 to 20%, resulted in a smaller but significant increase (from 0.22 to 0.28 kg/day).Increasing the lysine and methionine in the 12 and 16%, rations resulted in a 27 and 36% increase in rate of gain, respectively. Average daily feed intake was increased when the protein level was increased from 12 to 16%,, but the increase in feed consumption was not significant when protein was raised from 16 to 20 per cent. Supplemental lysine and methionine added to the 12 and 16%,-protein rations resulted in a 13%, increase in daily feed intake. Efficiency of feed utilization was improved (P <0.05) as protein was increased from 12 to 16%, (2.97 and 2.14 kg feed/kg gain, respectively) and supplementing these rations with lysine and methionine resulted in a further improvement of 15 and 17%, in the efficiency of feed utilization.Apparent digestible energy for 6-week-old pigs was not significantly influenced by any of the treatment factors. Apparent nitrogen digestibility and nitrogen retention were significantly (P <T 0.05) increased by supple-ACKNOWLEDGMENTS