Effect of nucleotides in milk replacers on growth and health of male dairy calves

Forty-eight male Holstein calves (16 per treatment) were fed milk replacer (MR; 27% CP, 17% fat powder) with 0, 10, and 20% nucleotides (NU). The MR were fed at 0.66 kg of DM daily divided into 2 equal meals fed at 0630 and 1600 h for d 1 to 25, then 0.33 kg of DM in only the a.m. feeding for d 26 to 28. Free-choice starter (20% CP) and water were fed from d 1 to 56. Calves were initially 2 to 3 d of age and 46 ± 0.9 kg. Data were analyzed as a completely randomized design with repeated measurements over time. When NU treatment was P < 0.1, means were analyzed with linear and quadratic polynomial contrasts. Calf ADG and feed efficiency declined linearly (P < 0.05) from 0 to 4 and 0 to 8 wk as NU increased in the MR. Calf ADG and starter intake tended to decline linearly (P < 0.08) from 4 to 8 wk as NU increased in the MR. Abnormal fecal score days decreased linearly (P < 0.05) from 0 to 4 wk as NU increased in the MR; however, medical days among treatments did not differ. Change in hip width and BCS declined linearly (P < 0.05) from 0 to 4 and 0 to 8 wk as NU increased in the MR. Nucleotides at 10 and 20% reduced calf growth and did not improve calf health as measured. Concentrations of ≥10% NU cannot be recommended for MR intended for neonatal dairy calves.