Performance and health of calves pre- and post weaning fed milk replacers with supplements for heat abatement in the summer months

Abstract Text: Two studies were conducted in the summer of 2012 and 2013 to evaluate pre- (d 1-42) and post-weaning (d 43-56) calf performance and health when fed  milk replacers (MR) with supplements  to aid in heat abatement. Calves were fed a non- medicated  20% fat:20% CP MR at 0.284 kg in 1.99 L water (12.5% solids) 2X daily for the first 35 d and 1X daily from d 36 to weaning at 42 d. From day 1 to 14, 1:1 neomycin:oxytetracycline was added to the MR solution to provide 22 mg/kg BW daily. Calf starter (CS; 18% CP) and water were fed free choice d 1 to 56. In study 1, fifty-one  (2 to 4 d old) individually fed Holstein heifer calves (38.5±0.96 kg) were assigned to MR supplements as follows: SA1= none; SA2= B-complex vitamin premix fed at 1.42 g/calf daily and SA3= betaine fed at 5 g/calf daily. There were no treatment differences in pre- and post-weaning ADG or total hip height (HH) gain which averaged 0.64 kg and 9.63 cm, respectively. There was a trend (P< 0.10) for increased 56-d CS intake when calves were fed the SA2 or SA3 compared to SA1 MR (0.81 vs 0.72 kg DM/d).There were no differences in BW gain, total DMI, gain/feed or scouring days across treatments. Calves fed SA2 had higher (P < 0.05) daily health treatment costs vs. SA1 calves but were not different from SA3 calves (P = 0.07). In study 2, seventy-five (2 to 4 d old) individually fed Holstein heifer calves (39.4±0.65 kg) were assigned to MR supplements SB1, none; SB2,  B-complex vitamin premix fed as in study 1 and SB3, B-complex vitamins as in SB2 plus an electrolyte mix fed at 28 g/calf daily.  There were no treatment differences in ADG and HH gain (0.68 kg and 10.85 cm, respectively over the 56-d study). Pre-weaning gain/feed was higher (P < 0.05) for SB3 compared to SB1 or SB2 calves. There were no differences in health parameters.  A heat index of 90 or more occurred on 34 d in 2012 and 26 d in 2013 studies, respectively. Under the conditions of these studies, heat abatement supplements added to MR did not consistently enhance calf performance. 

Keywords:  : milk replacers, supplements, performance