356 Neonatal Holstein Calves fed a Pelleted Calf Starter Containing a Botanical Extract and Direct fed Microbial Alone or in Combination

Abstract Botanical extracts (BE; Adisseo North America, Altanta, GA) are known to enhance dry matter intake (DMI) and gut health, while direct-fed microbials (DFM), such as a Lactobacillus acidophilus fermentation product (RC: RumaCell DF 5G; Pacer Technology, Inc., Murtaugh, ID), had shown improved gut health and growth performance of growing Holstein calves. The hypothesis was this combination may be synergistic to neonatal calf growth performance. Eighty 2- to 5-day old Holstein bull calves were blocked by body weight (BW) and randomly assigned to 1 of 4 treatments in a randomized complete block design. Treatments were: 1) Control: no additives; or 2) BE added at 496 mg/kg to the calf starter (CS); 3) RC added to the CS at 2.50 g/kg with RC added to the milk replacer (MR) at 5 g/d; and 4) BE&RC: BE and RC added to CS at same rates and added RC to MR. The CS was a 25% crude protein dry matter basis and MR was a 22:20 (CP:fat) fed 2x/d at 0630 and 1800 h along with free choice water. Weaning occurred after d 49 for the 70 d experiment. Calves fed RC demonstrated greater (P < 0.05) BW gain compared with calves fed BE&RC with calves fed Control and BE being intermediate and similar (63.9, 63.5, 65.0, and 59.7 kg for Control, BE, RC, and BE&RC, respectively). Total experiment DMI (MR+CS) was less (P < 0.05) for calves fed BE&RC than calves fed the remaining treatments (116.5, 114.2, 116.4, and 104.9 kg). Total experiment BW gain/DMI was greater (P < 0.05) for calves fed BE&RC compared with calves fed Control with calves fed BE and RC being intermediate and similar (0.55, 0.56, 0.56, and 0.57 kg/kg). This experiment demonstrated that specific BE should not be fed in combination with specific DFM.