Primiparous and Multiparous Sows Have Largely Similar Colostrum and Milk Composition Profiles Throughout Lactation

SIMPLE SUMMARY: Progeny born to primiparous sows (gilt progeny) are born lighter, grow slower, and have higher rates of mortality than piglets born to multiparous sows. An understanding of why this might be the case is necessary to implement management strategies that improve the health and welfare of first-litter piglets and increase their production efficiency. Differences in the composition of colostrum and milk between primiparous and multiparous sows might be a contributing factor. Results from this study suggest that primiparous and multiparous sows (parities 3 and 4) have similar levels of immunoglobulin G and energetic components (net energy, fat, protein, and lactose) in colostrum and milk throughout the course of lactation. However, lower lactose levels from day 14 onwards in milk from primiparous sows compared to milk from multiparous sows may indicate that there is a reduction of lactose uptake into the mammary gland in primiparous sows during late lactation, which may reduce milk volume. Lower growth rates and higher rates of mortality in gilt progeny are therefore likely to be as a result of lower colostrum and milk production in primiparous sows and (or) an inability of their piglets to digest these nutritional components effectively. ABSTRACT: It is important to understand the biological factors influencing the poorer lifetime performance of gilt progeny in comparison to sow progeny and determine whether this may be partially due to differences in lactation performance between primiparous and multiparous sows. It was hypothesized that primiparous sows would have lower levels of immunoglobulin G (IgG) in colostrum and milk compared to multiparous sows, and lower levels of other energetic components. Differences in colostrum and milk composition between ten primiparous and ten multiparous sows (parities 3 and 4) from a commercial herd were examined throughout lactation (day 0, 1, 2, 3, 7, 14, and 21). Overall, there were no (p ≥ 0.05) parity differences in total IgG, fat, protein, lactose, and net energy (NE) concentrations. Primiparous sows had higher lactose levels at day 2 (parity by timepoint interaction; p = 0.036) and lower NE at day 3 (p = 0.091), and multiparous sows had higher lactose levels at days 14 and 21. Results suggest that shortcomings of gilt progeny are unlikely due to insufficient nutrient levels in colostrum and milk, and more likely to reduced colostrum and milk intake and their capacity to digest and absorb each component.