The addition of cottonseed hulls to the starter and supplementation of live yeast or mannanoligosaccharide in the milk for young calves

The objectives of this study were to investigate the effects of the addition of cottonseed hulls (CSH) to the starter and the supplementation of live yeast product (YST) or mannanoligosaccharide product (MOS) to milk, on growth, intake, rumen development, and health parameters in young calves. Holstein (n = 116) and Jersey (n = 46) bull (n = 74) and heifer (n = 88) calves were assigned randomly within sex at birth to treatments. All calves were fed 3.8 L of colostrum daily for the first 2 d. Holstein calves were fed 3.8 L of whole milk, and Jersey calves were fed 2.8 L of whole milk through weaning at 42 d. Calves continued on trial through 63 d. Six treatments were arranged as a 2 x 3 factorial. Calves received either a corn-soybean meal-based starter (21% crude protein and 6% acid detergent fiber; -CSH) or a blend of 85% corn-soybean meal-based starter and 15% CSH (18% crude protein and 14% acid detergent fiber; +CSH) ad libitum. In addition, calves received whole milk with either no supplement (NONE) or supplemented with 3 g/d of mannanoligosaccharide product (MOS) or 4 g/d of live yeast product (YST) through weaning at 42 d. Twelve Holstein steers [n = 6 (per starter type); n = 4 (per supplement type)] were euthanized for collection and examination of rumen tissue samples. Dry matter intake (DMI) was greater for Holstein calves fed +CSH (0.90 kg/d) than -CSH (0.76 kg/d). Final body weight at 63 d of Holstein calves fed +CSH (75.8 kg) was greater than that of those fed -CSH (71.0 kg). Average daily gain (ADG) was greater for Holstein calves fed +CSH (0.58 kg/d) than -CSH (0.52 kg/d). However, Holstein calves fed -CSH had a greater feed efficiency (FE; 0.71 kg of ADG/kg of DMI) than those fed +CSH (0.65 kg of ADG/kg of DMI). Also, Holstein calves fed +CSH had narrower rumen papillae (0.32 mm) compared with those fed -CSH (0.41 mm). There were no significant effects of CSH on DMI, ADG, or FE in Jersey calves. There were no significant effects of YST or MOS on DMI, ADG, FE, or rumen papillae measures in Holstein calves. Jersey calves fed YST or MOS had greater final body weight at 63 d (51.2 kg and 51.0 kg, respectively) than calves fed NONE (47.5 kg). However, there were no significant effects of YST or MOS on DMI, ADG, or FE in Jersey calves.