Results of a so-called « hyperprolific line » used in pure and cross-breeding

Abstract

born — and on their granddaughters (sired by H. boars). In experiment 1, ovulation rate was higher for H X LW than for LW X LW females (16.3 against 14.5, p < 0.01), but no significant difference was found for the number of embryos at one month of gestation. Conversely, H X FL showed no superiority over crossbred LW X FL in ovulation rate (15.4 against 15.2) but a higher number of embryos (11.2 against 10.4, p < 0.10). In experiment 2 the progeny of hyperprolific sows did not significantly differ from the controls in the first litter but showed an advantage of 2.4 piglets born (p < 0.01) in the second litter. Altogether the results suggest that there is an antagonism between ovulation rate and embryo survival in gilts but less in sows. Thus, by increasing the ovulation rate, a gain in litter size may only be obtained in sows.