Effects of dietary total non-structural carbohydrates and folic acid and vitamin B-12 supplement on growth and meat quality of yearling steers in a forage-based beef production system

摘要

Thirty-two spring calving cows [760 +/- 91 kg body weight (BW)] and calves (44 +/- 4.5 kg BW) were assigned to eight blocks of four cows and their calves each according to parity and calving date. Within each block, two cows were fed a low total non-structural carbohydrate (TNC) diet, while the two others were fed a high TNC diet. Within each diet, cows were administered either no vitamins or weekly intramuscular injections of 160 mg of folic acid plus 10 mg of vitamin B-12. Calves were slaughtered at 305 +/- 9 d. Neither TNC concentration nor vitamin supplementation affected (P > 0.10) milk yield but the vitamin supplementation increased (P = 0.002) milk concentrations of vitamin B-12. There was no treatment effect on calf performance, or carcass and meat characteristics (P > 0.10) except for collagen concentrations and shear force measurements in the longissimus lumborum muscle, which had a tendency to be decreased (P = 0.06) by the vitamin supplement. In the present study, differences in forage TNC concentrations did not influence cow and calf performance. Moreover, folic acid and vitamin B-12 supplements were shown to have little impact in this study on growth of beef cattle.