Department of Animal Science


Date of this Version



Published in JOURNAL OF ANIMAL SCIENCE, Vol. 56, No. 4, 1983. Copyright American Society of Animal Science. Used by permission.


Individual plus maternal heterotic effects on swine production were simulated with a bioeconomic model by changing performance levels of eight traits: -8 d in age at puberty, +3% in conception rate, +.94 in pigs born/litter, +.035 kg in pig birth weight, +2.05 Mcal•sow-1•d -1 in maximum milk output, +8% in preweaning survival, +10.8% in protein growth rate and +17.3% in fat growth rate. Associated heterosis simulated for other traits, such as weaning weights and postweaning gain/feed, was similar to experimental results. Effects of heterosis on biological (feed Mcal/kg) and economic ($/kg) costs were evaluated by simulating two- and three-breed crosses and purebred production. Pig heterosis reduced $/kg lean or $/kg live weight by 4% for marketing at 100 kg, and by 6% for $/kg of lean and 8% for $/kg of live weight for marketing at average 185-d weight. Sow heterosis reduced $/kg lean or $/kg live weight about 4%. Pig heterosis reduced feed Mcal/kg by only 1% and Mcal/kg live weight by 3%, and both were reduced only 1% by maternal heterosis. Traits that reduced litter costs/kg of output by increasing output/litter were responsible for most effects of heterosis on $/kg. However, heterosis in growth rate was important for feed Mcal/kg of lean marketed at 100 kg, and for feed Mcal/kg of live weight marketed at either 100 kg or at 185-d weight. Nonfeed costs/kg lean or live weight marketed at 100 kg were reduced more than feed costs by pig heterosis (-5 or -6 vs -2 or -3%) and by sow heterosis (-8 vs -1 or -2%). Effects of pig heterosis on nonfeed costs were increased to -12 or -14% by marketing at mean 185-d weight. Percentage reductions in total costs from heterosis were about one-third as large as corresponding increases in output/litter at market age.