Effect of fish oil in Iberian sow diets on fatty acid, oxylipins and immune traits of colostrum and milk, and suckling piglets' growth performance.

Iberian sow productivity is characterised by a low number of weaned piglets with higher within-litter variation in piglet birth BW compared with conventional breeds. To overcome this, nutritional strategies, such as the dietary addition of n-3 fatty acids (FAs), are being studied to improve sow performance, as well as colostrum and milk composition. In addition, n-3 FAs and their derived oxylipins could also be beneficial for the offspring due to their anti-inflammatory roles. The present study was conducted in an outdoor production system where sows were group-fed during the mating and gestation periods, while feed intake was provided individually during lactation. The study aimed to evaluate the effects of including fish oil rich in eicosapentaenoic and docosahexaenoic acids (EPA and DHA, respectively) in Iberian sow diets on litter size, piglet growth during lactation, and the concentrations of anti-inflammatory molecules in colostrum and milk. Forty sows were randomly assigned to either a control or fish oil diet during pregnancy and lactation. Sow performance and litter traits were monitored until weaning. Colostrum and milk were collected after the birth of the first piglet and at weaning, respectively. Their FA composition, oxylipin profile, and immune indicators were analysed. Despite the piglets from the control group having greater average birth BW than those from the fish oil litters (P = 0.016), the fish oil piglets were heavier at weaning (P < 0.028). Total n-3 FA concentration was increased in the colostrum and milk of fish oil-fed sows (all P < 0.001), mainly due to increases in EPA and DHA concentrations (all P < 0.001). In the same way, most of their oxygenated derivatives were also increased in both colostrum and milk (P ≤ 0.045). The colostrum from fish oil-fed sows also presented higher concentrations of immunoglobulins (Ig) G and A than that from control sows (P = 0.025 and P = 0.026, respectively). In conclusion, the inclusion of fish oil in sow diets increased the levels of IgG and IgA in colostrum, n-3 FAs and their derived oxylipins in colostrum and milk, and piglet BW at weaning.