Factors Affecting the Effectiveness of Litter Management Practices: An Overview

In terms of selection, pig farmers have aimed to maximize profitability for decades by increasing litter sizes through choosing gilts with seven or more pairs of teats. This has resulted in sows with numerically large litters, an increase in within-litter birth weight variation, and more piglets with a low birth weight. For newborns, the amount of colostrum consumed within the first 24 h after birth is particularly important for thermoregulation, passive immunity and adequate growth during lactation. The colostrum must be consumed early, for at least the first 6 h after birth. Only after consuming the mother’s colostrum, i.e., within 24 to 48 h after birth, is performing cross-fostering (CF) recommended, whereby light piglets are placed with another sow. Alternatively, farmers can choose a one- or two-step CF technique with nurse sows. If there are surplus piglets and substitute mothers are not available, the option of artificially rearing the piglets with liquid (milk replacer) and, later, solid feed remains, which is nevertheless a suboptimal method compared to CF. One way or another, all breeder interventions and different management strategies for large litters are associated with reduced piglet welfare.