Effects of prenatal energy supplementation and prenatal ans prebreeding trace mineral/vitamin E supplementation on calf health and reproductive performance on beef cows

Abstract

Forty-two d prior to the start of the experiment, 67 multiparous cross-bred beef cows were assigned to one of two supplement groups based on body condition score (BCS). Moderate condition cows (BCS = 5.5 ± .10) received .82 kg/d of a cottonseed meal-based supplement formulated to maintain BCS, whereas, thin condition cows (BCS = 3.7 ± .10) received 2.6 kg/d of a corn/whole cottonseed-based supplement formulated to increase BCS to 5 by parturition. Both supplements contained elevated levels of S and Fe designed to antagonize Cu absorption; however, due to lower than predicted supplement intake by moderate condition cows, thin cows consumed 72% and 52% more S and Fe, respectively, than moderate cows during the prenatal period. Thirty d prior to the start of calving season (d 0), cows within each supplement group were randomly assigned to trace mineral/vitamin E (TM/E) or control treatments. The TM/E cows received s.c. injections of Multimin[TM] and vitamin E to provide 0.4 mg Zn, 0.4 mg Mn, 0.2 mg Cu, 0.1 mg Se and 6 IU vitamin E per kg BW on d 0 and 96 (21 d prior to breeding). Prenatal energy supplementation effectively reduced cow BW and BCS differences at parturition with no subsequent effects on conception rates or calf performance. Due to lower intakes of S and Fe during the prenatal period, liver Cu concentrations were 23% and 36% higher (P < .01) in moderate vs thin condition cows on d 28 and 96, respectively, and 24% higher (P = .10) in calves born to moderate vs thin condition cows on d 179. The TM/E treatment increased (P < .01) cow liver Cu concentrations 59, 105, 164 and 57% on d 28, 96, 179 and 257, respectively, but did not affect Zn or Se status of cows or calves. The TM/E treatment had no effect on calf survival, calf serum IgG concentrations, return to estrus or conception rates of cows. The lack of TM/E treatment effects on calf survival and cow reproductive performance was likely due to the adequate trace mineral status of this herd at the start of the experiment.