Abstract #T226

# T226
Direct-fed microbial efficacy and milk plan: Effect on heifer growth in an automated feeding system.
Melissa C. Cornett*1, Amy L. Stanton1, 1University of Wisconsin-Madison, Madison, WI.

Automated feeding systems (AF) offer flexible nutrition programs for pre-weaned dairy calves. The technology offers the option of changing daily milk allotment as calves grow and providing feed additives, such as direct-fed microbial (DFM). This study determined the effect of DFM efficacy and 2 milk plans (SLW, FST) on growth. Holstein heifers (n = 104) from a commercial Wisconsin herd were enrolled at birth in a 2 × 2 factorial design. Factor 1 was a DFM protocol versus a placebo (PLAC) from birth to weaning. Factor 2 compared 2 feeding plans (SLW and FST) offering 543L pasteurized whole milk over 53 feeder days (FD). The SLW initially offered (7L/d), and peaked milk at 28 FD (13L/d). The FST initially offered 11L/d, and peaked milk at 21 FD (15L/d). Both plans stopped milk at 53 FD. Rate of passive transfer was 86%. Calves were housed individually before AF. Ability of calf to drink milk unassisted triggered AF move. During AF, ad libitum Ampli-Calf (Land O’ Lakes, MN) calf starter was provided in a bunk. No individual starter intakes were recorded. Calf weight (WT) was measured 2×/wk from age 3 ± 2 d (Mean ± SD) until 1 wk post-weaning. The effect of treatments on WT was evaluated using PROC MIXED in SAS, controlling for initial WT, age, and study period, study month was a random effect and calf nested in treatment for repeated measure. Study period was divided into 4 times: Period 1 birth to AF (P1), Period 2 FD1 – FD28 when FST offered more milk/d than SLW (P2), Period 3 FD29-FD53 (P3), and Period 4, the 7 d post-weaning (P4). Average milk consumption was 430.9 ± 89.0L for SLW and 378.5 ± 78.7L for FST. Initial feeder enrollment age was 7 ± 2 d. Milk plan, DFM, and study period interacted (P = 0.03). In P2, FST DFM calves weighed 3.6 ± 1.5 kg (LSM ± SEM) more than FST PLAC (P < 0.02). In P3, FST DFM calves weighed 3.2 ± 1.5 kg more than FST PLAC (P < 0.04). In P3, SLW PLAC weighed 3.0 ± 1.5 kg more than FST PLAC (P < 0.05). In P4, FST DFM tended to weigh 2.9 ± 1.6 more than FST PLAC (P = 0.07). These results suggest DFM effectively improves growth in dairy calves on a rapid increase milk plan. Calves provided peak milk at 28FD had higher growth than calves with peak milk at 21FD. Growth can be optimized by AF and DFM.

Key Words: calves, growth, probiotic