Effects of partial replacement of soybean meal by flaxseed cake on growth performance, rumen function and meat quality of Simmental cows.

Soybean meal faces challenges of price fluctuations and limited supply, making it imperative to research cost-effective alternative protein feed ingredients in animal husbandry. This study investigated the effects of partially replacing soybean meal with flaxseed cake (FSC) in diets on growth performance, nutrient digestibility, rumen fermentation, serum biochemical parameters, and meat quality of adult Simmental cows. A total of 16 Simmental cows, weighing 650.67 ± 7.75 kg, were randomly divided into two groups: CON (fed a diet with 3.8% soybean meal) and FSC (fed a diet containing 2.28% soybean meal + 1.52% flaxseed cake, which replaced 40% of the soybean meal with FSC). The formal trial period lasted for 60 days, with a 15-day pretrial phase. The results showed that replacing soybean meal with FSC improved the average daily gain (ADG) (P < 0.05) and reduced the feed-to-gain (F/G) ratio (P < 0.05). CP apparent digestibility was enhanced in the FSC group (P < 0.05). Rumen fermentation analysis indicated increased acetate (P < 0.05) and decreased valerate concentrations (P < 0.05) in the FSC group. Serum biochemical analysis revealed the cows in the CON group had a higher albumin (ALB) content (P < 0.05). The cows in the FSC group showed significantly higher serum immunoglobulin A (IgA, P < 0.05) and IgM (P < 0.01) concentrations than those in the CON group. Regarding antioxidant indexes, the serum total antioxidant capacity (T-AOC) activity in the FSC group was higher than in the CON group (P < 0.05). Meat quality and nutritional ingredients remained similar between the two groups, while the meat's a* (redness) was significantly higher in the FSC group (P < 0.05). C15:1 content in beef was higher in the FSC group than in the CON group (P < 0.01). In conclusion, replacing 40% of soybean meal in the diet with FSC could improve the growth performance, crude protein digestibility, immunity and antioxidant status, without negatively affecting the meat quality in beef cows, suggesting flaxseed cake as a viable partial replacement for soybean meal in beef production.