Examining Factors That Influence Pig Quality Measured By Weaning Weight

Maintaining pig quality with increasing litter sizes is an issue currently facing the swine industry. One management practice that has been implemented to manage large litter sizes is cross-fostering, where some pigs are placed on nurse sows when the birth sow may be unable to nurse her pigs. How this protocol and other management practices are executed may impact wean pig quality. Weaning weight is an indicator trait for pig quality. Understanding the factors that affect pig weaning weight can aid producers in enhancing pig quality. The objective of this study was to examine factors that influence pig weaning weight. The data used for this study were recorded on 40,616 purebred Landrace and Yorkshire pigs from four sow farms with similar management protocols. Pig weaning weight was analyzed using a model with fixed effects of nurse sow parity, number of foster events for the pig, and sex, covariates of birth weight and wean age, and random effects of nurse litter, birth dam, and wean week within site. An increase in birth weight of 0.1 kg was related to an increase in weaning weight of 0.28 and 0.25 kg for the Yorkshire and Landrace pigs, respectively (P < 0.05). In both breeds, females weighed less than males at weaning by 0.1 kg (P < 0.05). Each day increase in weaning age was related to 0.2 kg (P < 0.05) increase in weaning weight for both breeds. Yorkshire and Landrace pigs that were not fostered from their birth dam weighed 0.2 and 0.1 kg more (P < 0.05) than pigs that were cross-fostered, respectively. The effect was magnified to -0.5 and -0.4 kg for Yorkshire and Landrace pigs that were fostered to multiple nurse sows prior to weaning (P < 0.05). All factors were related to weaning weight in a similar manner for both breeds, except nurse sow parity. Interestingly, higher parity nurse sows weaned significantly lighter (P < 0.05) Yorkshire pigs; however higher parity nurse sows weaned significantly heavier (P < 0.05) Landrace pigs. When examining pigs that were cross-fostered to one nurse sow, each day after birth before the pig was fostered resulted in 0.07 and 0.03 kg (P < 0.05) lighter weaning weights for Yorkshire and Landrace pigs, respectively. Knowing how certain management practices can influence pig quality as measured by weaning weight can aid producers in recognizing the impact on quality associated with management decisions and system limitations.