Researchers: Mark Knauer, Jeff Wiegert and Garrett See, North Carolina State University
It is well known that colostrum is vital to newborn piglets. Insufficient consumption of colostrum greatly increases the risk of preweaning mortality and reduces piglet quality. Yet few studies have investigated strategies to increase piglet colostrum intake.
Researchers at North Carolina State University evaluated the impact of divergent genetic selection for age at puberty on piglet colostrum intake and piglet quality. Genetic lines were formed at the Tidewater Research Station at Plymouth, N.C., by selecting gilts for young age at puberty (Young) or old age at puberty (Old). The current study utilized 120 second parity females from generations three and four of the divergent selection experiment. Females were housed in modern, environmentally controlled facilities with ad libitum access to water.
Sows were fed in gestation based on body condition and to appetite in lactation. At birth, piglets were weighed prior to first suckle and individually identified. Piglets were individually weighed again at 24 hours of age and at weaning. Colostrum production was estimated using a published equation (Theil et al., 2014) incorporating the values of weight at first suckling, 24-hour age weight and duration of suckling. From generation four sows, a colostrum sample was collected during farrowing and analyzed for protein, lactose, fat, total solids and energy at a DHIA laboratory (no differences between genetic lines detected). Reproductive variables included total number born, number born alive, average piglet birth weight, total litter birth weight, number weaned, average 21 day piglet weight, total 21 day litter weight and piglet survival. Piglet survival was calculated as litter size at weaning divided by total number born. Variables were analyzed in SAS (SAS Inst. Inc., Cary, N.C.) with fixed effects of genetic line and generation. Average piglet birth weight, total litter birth weight, average 21 day piglet weight, total 21 day litter weight and piglet survival were adjusted in the statistical model for litter size.
Results showing the impact of puberty selection line on litter size, colostrum intake and piglet quality are shown in Table 1. Litter size and piglet birth weights did not differ between genetic lines at birth. Yet piglets from young puberty sows consumed statistically greater amounts of colostrum when compared to old puberty sows. Piglet survival was significantly greater for young puberty sows when compared to old (84.7 versus 79.3%, respectively). Hence total 21 day litter weaning weight was statistically greater for young puberty sows in comparison to old puberty sows (139 versus 129 pounds, respectively).
Researchers say producers could see a potential cost benefit, as the difference in the number of pigs weaned between genetic lines was about 0.5 pigs. Assuming a weaned pig price of $35 per pig, the difference between genetic lines (just due to preweaning mortality) would be about $17.50.
While these results are promising, further large scale studies are needed to evaluate these genetic lines across multiple parities.
Given the industry’s challenges with preweaning mortality, the difference in piglet survival between genetic lines is thought-provoking. Is the difference in piglet survival driven by differences in colostrum intake, differences in fetal development or some combination of these factors? We are hoping subsequent studies help us understand the underlying biology causing differences in piglet survival between young and old puberty lines.
For more information, contact Mark Knauer. Researchers thank the North Carolina Department of Agriculture’s Tidewater Research Station for their collaboration on this project and the North Carolina Pork Council for funding.