Beef production from dairy bulls under two different production systems and its effect on the fatty acid profile and beef quality

Bulls in dairy production are usually slaughtered at an early age to avoid production problems and unnecessary costs. However, the animals could be a source of additional income and better quality meat. The objective of this work was to determine the characteristic and quantity of fatty acids of the Longissimus thoracis muscle of dairy bulls finished at pasture and in an intensive feeding system. Sixteen 14-mo old Holstein Friesian dairy bulls with initial live weights (LW) of 340 ± 20 kg were randomly assigned to bulls with daily pasture silage and kale ( Brassica oleracea L.) supplements and 1.0% concentrate at pasture (T1) and bulls with pasture silage supplements and 2% concentrate in confinement (T2). No differences (P > 0.05) were found between treatments for dressing percentage, rib eye area, and fat cover when animals were slaughtered at 21-mo, with LW 550 kg. However, kidney fat for T1 and T2 of 4.44 and 2.61 kg an-1, respectively, were different (P < 0.05) as was pH, where T2 had a higher value (5.72) than T1 (5.46). Significant differences (P < 0.05) between treatments were found for all polyunsaturated fatty acids (PUFA), conjugated linoleic acid (CLA) c-9, t-11, C18:2 n-6 trans, C18:3 n-3, C22:5 n-3, C22:6 n-3, with higher levels for T1. Beef from the forage-fed bulls (T1) had an n-6: n-3 ratio below 4.0.