Heritability of Gain in Different Growth Periods in Swine

Abstract

Data from 2176 pigs produced at North Platte and 572 pigs produced at Lincoln were used to determine the heritability of gain in three growth periods. The growth periods studied were (1) birth to weaning (56 days), (2) 56 to 112 days, and (3) 112 to 154 days. Heritability of gain was based on paternal half-sib relationships. Heritability estimates of gain in the three periods were for North Platte .22, .51 and .25 respectively and for Lincoln .02, .35 and .34 respectively. These estimates agree quite well with those found by Hazel et al. (1943) based on earlier North Platte stock considering the large sampling errors to which estimates of this kind are subject. The three sets of estimates show that gain in the period 56 to 112 days is determined more by the pig's own genes than is gain in either the preceding or following period. Based on the intra-sire regression of offspring on dam heritability estimates of gain were .11, .28, and .08 for the three periods respectively. The multiple regression based on growth in each period was .754 for North Platte and .690 for Lincoln. With respect to selecting boars for use in a breeding program the increased accuracy of the multiple regression is offset by the added time which must elapse before the selection can be made. The present data substantiate the findings and statements of Hazel et al. (1943) concerning the selection of boars. If growth rate is one of the criteria upon which selections are based, gain from 56 to 112 days of age can be used satisfactorily. It has the advantage of being available relatively early and it is based more upon growth in bone and muscle and less on fatness than is gain at a later period. Copyright © . .