The importance of a high feed intake during lactation of primiparous sows nursing large litters

The objective of this study was to investigate whether nursing a large number of piglets has negative effects on lactation and postweaning performance of primiparous sows and whether a greater lactation feed intake can prevent possible negative effects. Data were recorded on 268 ad libitum-fed sows of three genotypes (G1, G2, and G3) in an experiment where litter size was standardized to 8, 11, or 14 piglets during a 4-wk lactation. Compared to G1 and G2, G3 sows were heavier (P 9.8 piglets (P <0.01). Body weight loss of the sow and litter weight gain increased linearly with litter size (P <0.001). Per extra piglet nursed, sows had a 23% (P <0.01) higher probability of a prolonged weaning-to-estrus interval. A higher daily feed intake during lactation reduced tissue loss of the sow, increased litter weight gain (P <0.01), and reduced the probability of a prolonged weaning-to-estrus interval (by 42% per extra kilogram; P <0.01). Sows with a lower daily body weight loss during first lactation had a larger second litter (1.28 piglets/kg; P <0.01), and their probability of a prolonged weaning-to-estrus interval was reduced by 61% per kilogram (P