Milk replacer galacto-oligosaccharide inclusion rates for neonatal calves

Galacto-oligosaccharide (GOS) is a prebiotic isolated from whey. This study evaluated the optimal inclusion rate for improving the growth and health performance of neonatal calves. Eighty-eight 2 to 5-d old Holstein bull calves were blocked by initial BW and randomly allocated to 1 of 4 treatments using a randomized complete block design. Treatments comprised a 22:20 (CP:fat) AA-balanced milk replacer (MR) with GOS added at the rate of 0 g/d (control or GOS0), 2 g/d (GOS2), 4 g/d (GOS4), and 8 g/d (GOS8). Calves received 0.283 kg MR in 1.9 L fed 2×/day for the first 14 d, then increased to 0.42 kg in 2.84 L fed 2×/d through d 35, followed by 0.42 kg MR in 2.84 L fed 1×/d through d 42, followed by weaning. The GOS inclusion rate remained constant as the milk volume increased. Calves fed GOS at 2, 4, and 8 g/d demonstrated similar growth performance compared with calves fed GOS0. Calves fed GOS4 demonstrated a carryover effect into postweaning resulting in a tendency for increased BW (82.5, 83.0, 85.3, and 83.1 kg for GOS0, GOS2, GOS4, and GOS8, respectively), BW gains (37.8, 38.2, 41.3, and 38.6 kg), and ADG (687, 696, 751, and 701 g/d). The ADG was increased by 9.3% when feeding calves GOS4 compared with calves fed GOS0. Calf starter DMI was greater at 7 (1.73,1.86, 1.95, and 1.83 kg/d) and 8 (2.34, 2.50, 2.60, 2.49 kg/d) wk of age for calves fed GOS4 compared with calves fed GOS0, with the remaining treatments being intermediate and similar. Feed conversion (0.552, 0.529, 0.563, and 0.545 kg/kg) was greater for calves fed GOS0 and GOS4 g/d compared with calves fed GOS2, with calves fed GOS8 being intermediate and similar. Body frame gains were similar for calves fed all GOS inclusion rates. A treatment by week interaction at wk 2 indicated that calves fed GOS2 demonstrated a greater number of of days with a fecal score = 0 than calves fed the remaining treatments, indicating less scours. In conclusion, supplementing GOS to a MR at 4 g/d fed to neonatal calves improved growth performance without compromising health conditions.