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

Background: There is a linear correlation between piglet weaning weight and average daily gain during the post-nursery period. A key factor that influences piglet weight gain during lactation is milk intake. Thus, the variation in piglet weaning weight is hypothesized to be, to some extent, a result of differences in milk production among individual mammary glands. Objective: The objective of this study was to evaluate the impact of piglet nursing location throughout lactation on piglet weaning weight, with a secondary objective of determining the impact of piglet birth weight on nursing location selection. Methods: Teat pairs were labeled from anterior to posterior (1–7). A total of 1,078 individual piglets from 108 litters were observed; nursing observations were recorded at three time points, typically within the same day, to verify each piglet’s nursing location during the lactation period. All data were analyzed using the individual piglet as the experimental unit. Results: The teat pair on which piglets nursed during lactation impacted their overall weaning weight (P < 0.001). Numerically heavier piglets were weaned from the anterior teats (teat pairs 1–4: 5.906–6.121 kg), with the heaviest piglets weaned from teat pair 4 (6.1219 kg), and the lightest weaned piglets located at teat pair 7 (5.171 kg; teat pairs 5–7: 5.745–5.171 kg). Piglet weight gain and, thus, subsequent weaning weight was ultimately impacted by their chosen nursing location along the udder line. While the first four pairs of anterior teats produced the heaviest weaning weights, after accounting for piglet birth weight to examine actual weight gain, the first four pairs of teats remained the most productive, but the magnitude of the advantage for teat pair 4 was reduced. Additionally, piglets nursing at teat pair 7 represented the lowest birth weight and had overall lower weight gain. Conclusion: Piglet weaning weight differs according to the suckling position along the udder line, and it is partially a function of both the birth weight of the pigs nursing at a particular location and, presumably, the milk production and composition at that location.