Hereditary and Environmental Factors Affecting Growth Rate in Swine1

Publisher Website
Google Scholar
Abstract
Analyses of variance and offspring-dam regression techniques were used to analyze data on 2,396 pigs and 312 dam-litter pairs, respectively, in order to investigate factors of heredity and environment affecting the growth curve of swine. The data included weights and gains in intervals from birth to 168 days, as well as average daily rates of gain from birth to 200 pounds (R1) and weaning to 200 pounds (R2). Pigs farrowed from sows were about four pounds heavier at weaning than pigs from gilts. This advantage was maintained at least to 168 days of age. The variance arising from age differences of dams accounted for 22 percent of the total intra-line and year variance in weaning weight. These age differences appeared to have no influence on gains after weaning while their influence on weight after weaning declined only gradually. Environmental variance common to each litter was greatest at 21 days and accounted for 37 percent of the total variance. On gains after weaning it decreased from 24 percent, 28 days post-weaning, to 7 percent, 112 days post-weaning. Environmental effects peculiar to individual pigs accounted for approximately one-half of the total variance in the periods of gain and weights studied. The heritabilities of gains 28, 56, 84, and 112 days post-weaning were estimated as 18, 28, 39, and 45 percent, respectively, from analyses of variance. Those for R1 and R2 were estimated as 21 and 40 percent, respectively. The heritability of R1 and R2 as estimated from regression of offspring on dam was 3 and 21 percent, respectively. It is concluded that the differences reported between estimates of heritability containing and not containing pre-weaning growth are over-estimated. However, the results furnish evidence that heritability of post-weaning gains is greater than of post-weaning weights. Copyright © . .

This publication has 0 references indexed in Scilit: