Effects of the Mean Weight of Uniform Litters on Sows and Offspring Performance

SIMPLE SUMMARY: Piglet survival and performance until weaning are key features of sow productivity and, therefore, swine production efficiency. The genetic improvement of the last decades has led to larger litters but also to more heterogenous ones, with an increased number of low birthweight piglets that are more prone to die before weaning due to their lower capacity to ingest colostrum and milk in the competitive environment with their littermates. Some studies show that more uniform litter can be beneficial to piglet survival; however, selection for litter uniformity can lead to smaller litter or birth weight reduction. In this study, we aimed to check the influence of different mean weights of uniform litters on piglet survival and performance. As main conclusions we observed lower pre-weaning mortality in uniform than in heterogenous litters, the colostrum yield (CY) of sows is dependent on the total weight of the litter and litter weight gain in the first day after farrowing is a good marker for CY. The mean weight of piglets of uniform litter influences their colostrum intake and the weaning weight but not their survival. According to the present results, selection for litter uniformity is advisable due to its beneficial effects on sow productivity. ABSTRACT: This study aimed to determine the effects of uniform litters of different mean birth weights on colostrum production of sows and piglets performance. The study involved 98 multiparous sows from a commercial lean genotype and their piglets. Simultaneous farrowing were supervised and the piglets were divided into experimental litters of 12 piglets each of heterogenous litters (HET, CV = 23.8%, n = 20), uniform light litters (ULL, CV = 9.8%, n = 27), uniform average litters (UAL, CV = 8.2%, n = 23) or uniform heavy litters (UHL, CV = 8.6%, n = 28) piglets and allowed to suckle. Piglets were re-weighed at 24 h and 21 d of life and deaths registered. Colostrum intake (CI) of the piglets and sow’s colostrum yield (CY) was estimated using two prediction equations. Significant differences (p < 0.001) were observed in the CY of sows being higher in UHL, lower in ULL and intermediary in HET and UAL litters. CY was positively related to litter total weight at birth and litter weight gain in the first 24 h (p < 0.001). The CI differ between litter type being higher in UHL litters and lower in ULL litters. The coefficient of variation of CI in HET litters was higher than in uniform litters, regardless of their type. The mortality rate of piglets until 21 d was globally 9.6% and it was significantly higher in HET than in UAL (p = 0.033) and tended to be higher than in UHL litters (p = 0.052). No differences in piglet survival were observed between uniform litters. Results show the beneficial effect of uniformity in piglet survival and that the mean weight of uniform litter influences colostrum intake and piglet performance.