Potential interactive effects between corn grain forms (ground vs. whole) of starter feed and forage provision: Effects on growth and health status of intensified milk-fed Holstein calves

Increasing starter intake has been correlated with greater average daily gain (ADG) and less digestive problems in pre-weaning calves. Forage inclusion in mash starter feed as well as the whole (compared to the ground) grain provision in the starter feed are among the studied ways to increase starter intake. Forty-four Holstein female calves (body weight = 39.67 ± 5.9 kg) were randomly assigned to 1 of 4 the dietary treatments in a completely randomized design with a 2 × 2 factorial arrangement of treatments. Treatments were: (1) mash starter feed containing ground corn grain and without forage provision (WS0-GC); (2) mash starter feed containing whole corn grain and without forage provision (WS0-WC); (3) mash starter feed containing ground corn grain with 100 g/kg forage provision (WS10-GC); and (4) mash starter feed containing whole corn grain and with 100 g/kg forage provision (WS10-WC). The calves were housed in individual pens bedded with clean wheat straw. Calves were weaned at 60 d of age and stayed on study until d 75. The dry matter intake (DMI) as well as starter intake were different among treatments within the pre-weaning period; significant interaction between forage and corn grain physical form indicated that WS10-GC group had the greatest DMI and starter intake (P = 0.05), but this greater intake did not result in greater ADG for those calves. Regardless of forage, whole corn grain inclusion resulted in less starter intake during post-weaning period. Neither pre-weaning nor post-weaning ADG was affected by treatments. Without any effect on pre-weaning gain:feed ratio, forage provision led to the least gain:feed (P = 0.04) but whole corn grain inclusion tended to improve gain:feed (P = 0.10) during post-weaning. Pre- and post-weaning blood total protein concentrations were greater in whole corn grain fed calves (P < 0.01), but feeding forage resulted in greater blood beta-hydroxybutyrate (BHB) during post-weaning period; whole corn grain interaction with forage inclusion led to lesser BHB in WS10-WC than in WS10-GC group (P < 0.05). No differences were observed for rumen fluid parameters and health status among treatments, except a tendency for greatest rumen propionate and butyrate in forage fed calves compared to others at d 45 (P = 0.06). Present results indicated that, with an intensive plan of milk feeding, whole or ground corn had no effect on growth performance and blood metabolites and the forage provision only resulted in greater starter intake but not greater ADG.