Intake, nutrient digestibility, and growth performance of Holstein dairy calves consuming a milk replacer at moderate or high feeding rates

Abstract

The objective of this study was to evaluate nutrient intake and digestibility, and growth performance of calves when fed a milk replacer (MR) at 2 feeding rates. Male Holstein calves [n = 49; 45.0 ± 5.2 (mean ± SD) kg of body weight (BW); 3 to 4 d of age] were randomly assigned to 1 of 2 MR [27% crude protein (CP), 18% fat, dry matter (DM) basis; 14% solid] feeding programs: (1) 0.66 kg of DM/d for first 39 d divided into 2 equal a.m. and p.m. meals followed by one-half of the allotment per day for 3 d fed in the a.m. feeding only (moderate); (2) 0.96 kg of DM/d for the first 42 d divided into 2 equal a.m. and p.m. meals followed by one-half of the allotment per day for 7 d fed in the a.m. feeding only (high). A textured starter fed to calves contained whole grains with 20% CP and 44% starch (DM basis). At d 56, calves were moved into groups by treatment (4 calves/pen) and fed the same starter blended with 5% hay until d 112. Data were analyzed as a completely randomized design, or as a completely randomized design with repeated measures when applicable. Over the entire nursery period (d 0-56), there were no differences in average daily gain (0.63 vs. 0.64 kg/d) and hip width change (4.44 vs. 4.57 cm) for moderate- versus high-fed calves. Apparent digestibility of DM (76.5 vs. 70.3%), organic matter (77.4 vs. 71.2%), CP (78.8 vs. 72.6%), and neutral detergent fiber (37.2 vs. 22.7%) differed between moderate- and high-fed calves when estimated at d 51 to 55. From d 56 to 112, average daily gain (0.99 vs. 0.91 kg/d), hip width change (5.32 vs. 4.68 cm), and gain/DM intake (0.335 vs. 0.307 kg/kg) were greater, but DM intake per kg of BW (0.028 vs. 0.028 kg/kg) did not differ for calves previously fed moderate versus high. Feeding calves more than 0.66 kg of DM/d from a 27% CP, 18% fat MR did not improve BW gain and structural growth in the nursery period (d 0-56), and decreased these in the grower period (d 56-112) partially through reduction in digestibility of the starter.