Effect of Varying Protein and Energy Intakes on Growth and Carcass Quality of Swine

Abstract

During two seasons corn-soybean oil meal type rations were self-fed to crossbred weanling pigs at three different protein levels, 12%, 16%, and 20% at each of three energy levels, 950, 1050, and 1200 Calories (Fraps Productive Energy values) per pound. Ground rice hulls and stabilized animal fat were used to adjust the energy to the desired levels. There was a highly significant seasonal effect on rate of gain, summer gains being the faster. All of the ration differences revealed by statistical analysis were during the period from weaning to 75 lb. During this period the linear component of the protein effect was highly significant. Analysis of the gains from both tests revealed no statistically significant difference between the gains of pigs fed the 950- and 1050-Calorie rations. During the period from 40 to 75 lb. there was a significant (P<.01) protein x energy interaction. Rations with Calorie:protein ratios of from 49 to 75 produced the fastest gains during the early part of the feeding trials (40–125 lb.). Later a Calorie:protein ratio of 100 resulted in the most rapid gains. Increasing levels of energy intake resulted in more efficient gains and lower daily feed intake. Carcasses from pigs fed the 1200-Calorie rations were fatter than those from pigs fed the 950- or 1050-Calorie rations. Pigs fed the 16 or 20% protein rations produced longer carcasses (P<.01) with a greater yield of primal cuts as compared to pigs fed the 12% protein ration. Copyright © . .