Piglet nursing location along the sow udder line affects piglet weight gain and subsequent weaning weight

Background: There is a linear correlation between piglet weaning weight and average daily gain in the post nursery period. A key factor that influences piglet weight gain during lactation is milk intake, and the variation that results in piglet weaning weight is hypothesized to be to some degree a result of differences in milk production by individual mammary glands. Objective: The objective was to evaluate the impact of piglet nursing location throughout lactation and its impact on piglet weaning weight, with a secondary objective determining the impact of piglet birthweight on nursing location selection. Methods: Teat pairs were labeled from anterior to posterior (1-7). A total of 1,078 individual piglets were observed; nursing observations were recorded at three timepoints, typically within the same day to verify each piglet’s nursing location during the lactation period. All data was analyzed with the individual piglet as the experimental unit. Results: The teat pair that piglets nursed during lactation impacted their overall weaning weight (P < 0.01). Numerically heavier piglets were weaned from the anterior teats (teat pairs 1-4: 5.915-6.129 kg), with the heaviest piglets weaned from teat pair 4 (6.129 kg), and the lightest weaned pigs located at teat pair 7 (5.131 kg; teat pairs 5-7: 5.764-5.131 kg). Piglet gain and, thus, subsequent weaning weight was ultimately impacted by their chosen nursing location along the udder line. Within this study, it appears that the first four pairs of anterior teats produced the heaviest weaning weight, but when piglet birthweight is accounted for, the output and nutritional value of milk may be similar, as the average gain was not different across the first four pairs of teats. In contrast, the piglets nursing the posterior pairs five through seven had overall reduced growth characteristics, which may indicate that piglets lighter at birth are pushed to the more posterior teats. Conclusion: An understanding of how milk quantity and quality may differ along the udder line will be necessary for large litters in providing teat access that provides the best opportunity for piglet growth.