Performance of and digestion in calves fed two levels of milk replacer and functional ingredients

Abstract Text: We compared growth and post-weaning digestion using 48 male Holstein calves (initial BW = 42.6 ± 1.50 kg; initial age = 2-3 d) fed to 56 d.  Calves were fed diets in a 2 x 2 factorial arrangement of feeding rate  (Low [L], 0.68 kg/d of milk replacer (MR) powder and High [H], up to 1.36 kg/d of MR powder) and inclusion of a functional ingredient (without [NT-] or with [NT+] NeoTec5g, Provimi North America, Brookville, OH).  The MR contained 27% CP and 17% fat (DM basis) and was fed to weaning at 49 d.  The NT+ treatment was administered in MR prior to weaning and in calf starter (CS) from weaning to d 56.  All calves were fed NT- CS before weaning.  The CS were textured (pellets, oats, corn) and contained 20% CP (DM basis).  Starter and water were available for ad libitum consumption throughout the study.  During d 51 to 55, fecal samples were collected from 5 calves per treatment selected at random. Selected nutrients and acid insoluble ash (as an internal marker) were analyzed in CS and feces to estimate digestibility.  Data were analyzed as a completely randomized design with a factorial arrangement of MR rate (L/H) and NeoTec5g (NT+/NT-) using a repeated measures ANOVA.  Pen was the experimental unit.  There were no interactions of main effects.  Average daily BW gain (ADG), change in body condition score (BCS) and average fecal score from d 0-56 were greater (P < 0.05) in calves fed H vs. L.  Calf ADG, hip height change, and BCS change were greater (P < 0.05) in calves fed NT+ vs. NT-.  Intake of CS during the digestion period tended (P < 0.10) to be lower in calves fed H vs. L.  Digestibility of  DM, OM, NDF, and ADF was reduced by 7, 7, 65, and 58%, respectively, in calves fed H compared to L (P < 0.05). Feeding NT+ increased digestibility of DM, OM, NDF, and ADF by 4, 4, 65 and 74%, respectively (P < 0.05) compared to NT-.  Feeding high rates of MR reduced ADG by 12% during the last 2 wk of the trial (0.58 vs. 0.65 kg/d for H and L, respectively), which was likely due to reduced intake and digestion of CS as calves transitioned from MR to CS.  Feeding NeoTec5g improved ADG, hip width change, and digestion of nutrients. 

Keywords: Calves, Milk Replacer, Digestion