The effect of litter size and littermate weight on pre-weaning performance of low-birth-weight piglets that have been cross-fostered

Abstract To evaluate the effect of litter size and littermate weight on low-birth-weight (< 1 kg) piglets that have been cross-fostered, piglets' pre-weaning performance in the following groups were compared. Group A (no. = 10), low-birth-weight piglets raised with equal number of heavy-birth-weight piglets in small (eight piglets) litters; group B (no. = 10), low-birth-weight piglets raised with equal number of heavy-birth-weight piglets in large (12 piglets) litters; group C (no. = 10), low-birth-weight piglets raised with equal number of average-birth-weight piglets in small (eight piglets) litters; D (no. = 10), low-birth-weight piglets raised with equal number of average-birth-weight piglets in large (12 piglets) litters; E (no. = 10), small (eight piglets) low-birth-weight litters; F (no. = 10), large (12 piglets) low-birth-weight litters. Mortality of low-birth-weight piglets in large litters was greater (P < 0.001) with heavy littermates, but in small litters was no different. Weight gain of piglets until day 3 post partum was not significantly (P > 0.05) affected by littermate weight and litter size, or their interaction. Weight at 21 days post partum was significantly affected by littermate weight, litter size, and their interaction. Low-birth-weight piglets in small litters had significantly higher 21-day weights in large litters (P < 0.01, P < 0.05 and P < 0.05 with littermates of low, average and heavy birth weight respectively). In large but not small litters, low-birth-weight piglets missed more nursing episodes and spent more time in teat disputes than their heavier littermates whether in heavy-birth-weight (P < 0.01), or average-birth-weight (P < 0.05) litters. Littermate weight may affect the performance of low-birth-weight piglets due to direct competition for access to a functional teat.