Consumption of high energy maize diets is associated with increased soluble collagen in muscle of Holstein bulls

The aim was to investigate whether energy supplementation of gazing bulls can influence collagen concentration and solubility in three different muscles: longissimus dorsi (LD), semitendinosus (ST) and supraspinatus (SS). Thirty three Holstein bulls aged 15 months and reared on grass, were randomly assigned to three treatment groups for 85 days: fed grass ad libitum (G1-control); fed grass ad libitum and supplemented with 4 kg day− 1 of ground maize (G2); fed grass ad libitum and supplemented with 8 kg day− 1 of ground maize (G3). Total collagen content did not differ (P > 0.05) among treatments, however, soluble (heat-labile) collagen was significantly (P < 0.001) higher in meat from G3 (34%, 23% and 25% for LD, ST and SS, respectively), compared with G1-control (24%, 18% and 17% in LD, ST and SS, respectively). Overall, these results suggest that meat tenderness of grazing bulls may be improved by supplementing with ground maize (8 kg day− 1).