High canola meal in sow diets: effects on reproduction, piglet growth, milk composition, serum metabolites, and nutrient digestibility over two reproductive cycles

Feed costs and global demand for soybean meal are increasing, reducing profitability in pig industry. Canola meal is the second most used protein source in swine diets, but evidence on its long-term effects across successive sow parities is limited. This study investigated the effects of canola meal inclusion as the main protein source in sow diets on sow and litter performance over two reproductive cycles. Sixty-eight sows from two batches were randomly allotted one of two diets on d 80 of pregnancy. The control diet (CON) consisted of corn, barley and soybean meal, and the treatment diet (CSCM) consisted of corn, barley and canola meal, included at 14.50% for gestating and 24.50% for lactating sows. The BW and backfat thickness of sows were measured on d 1, d 35, d 80, and d 111 of pregnancy, and on d 1 and d 21 post-farrowing. On d 1 and d 19 post-farrowing, piglets were weighed and milk and blood samples from sows were collected to determine milk composition and serum metabolites. Fecal samples from sows were collected on d 110 of gestation and d 19 of lactation to determine apparent total digestibility (ATTD) determination. Data were analyzed using a randomized complete block design with repeated measures. Results showed that sow BW and backfat thickness were unaffected by diet. Sows fed the CSCM diet exhibited lower (P < 0.05) BW gain than CON sows during late gestation in the first cycle but not in the second cycle. Litter performance, including weight and size, was unaffected by dietary treatment, though litter weight at birth was higher (P < 0.05) in the second cycle than in the first cycle. The composition of colostrum and milk was generally unaffected by diet or cycle, except for colostrum fat, which showed a significant interaction (P < 0.05) between diet and cycle. Serum metabolites revealed tendencies (P < 0.10) for increased creatinine and gamma-glutamyl transferase (GGT) with the CSCM diet, while reproductive cycle effects were observed for GGT, cholesterol, calcium, protein, and albumin levels. Apparent total tract digestibility of nutrients was not significantly influenced by diet or reproductive cycle, though the CSCM diet tended to reduce (P = 0.06) the ATTD of CP. In conclusion, sow diets containing 14.50% canola meal during gestation and 24.50% during lactation maintained similar sow reproductive and litter performance comparable with soybean meal-based diets across two reproductive cycles.