Abstract #T121

# T121
Effect of feeding milk replacer at a moderate rate, ad libitum, or with a step-up program on calf performance through 4 months of age.
F. X. Suarez-Mena*1, T. S. Dennis1, T. M. Hill1, W. Hu1, J. D. Quigley1, R. L. Schlotterbeck1, 1Provimi-NA, Brookville, OH.

The objective of this study was to evaluate 3 milk replacer (MR) feeding programs on calf performance up to 4 mo of age. Neonatal Holstein male calves (n = 48; 44 ± 1.5 kg BW) were randomly assigned to either a moderate rate of MR (MOD; 0.66 kg/d for 39 d then 0.33 kg/d for 3 d), an ad libitum rate of MR (ADLIB; offered twice daily between 0630 and 0830 h and between 1430 and 1630 h for 35 d, 0.66 kg/d for 4 d, and 0.33 kg/d for 3 d), or a step-up rate of MR (STEPUP; increased from 0.32 to 0.62 kg/d in first 12 d, 0.66 kg/d for 27 d, and 0.33 kg/d for 3 d). The MR (25% CP, 18% fat) was fed 2× daily up to d 39 and 1× daily thereafter. Texturized starter (40% starch, 21% CP) and water were offered ad libitum. Calves were housed in individual pens through d 56. Calf BW was measured initially and weekly thereafter. Hip widths (HW) were measured initially and every 2 wk thereafter. Feces were scored and feed intake recorded daily. From 56 to 112 d, calves were grouped by the 3 MR programs and moved to group pens (4 calves/pen). The same starter blended with 5% chopped grass hay was offered ad libitum. BW and HW were measured on d 56, 84, and 112. Data, within period, were analyzed as a completely randomized design with repeated measures when appropriate. Experimental units were calf in first period and pen in second. Total MR intake per calf averaged 27, 51, and 25 kg for MOD, ADLIB, and STEPUP programs, respectively, with a range of 42 to 63 kg for ADLIB. In the first 56 d, starter intake and feed efficiency were less for ADLIB vs. MOD (P < 0.05), while fecal scores and abnormal fecal score days were greater for calves fed ADLIB vs. MOD (P < 0.05). Calves fed STEPUP had lesser ADG than calves fed MOD (P < 0.05). In the second 56 d, initial BW was greater for ADLIB vs. MOD (P < 0.05), though final BW was not different between MOD and ADLIB or STEPUP (P > 0.05). Calves previously fed MOD had greater ADG, feed efficiency, and HW change than calves fed ADLIB (P < 0.05). Though BW were greater at weaning when MR was fed ad libitum, calves were less efficient and growth advantages were lost by 4 mo of age.

Key Words: calf, feeding rate, growth