Abstract #159

# 159
Effects of pre- and postweaning nutrition on growth, efficiency, and rumen fermentation of Holstein calves.
Tana S. Dennis*1, Michael W. Grott1, Brad W. Shelton1, Tamilee D. Nennich1,2, 1Purdue University, West Lafayette, IN, 2Famo Feeds, Freeport, MN.

The objective of this study was to evaluate the interaction of preweaning and postweaning nutrition on calf performance, blood metabolites, and rumen fermentation. Holstein calves (43.5 ± 5.1 kg BW at birth; 39 heifers and 18 bulls) were assigned at 1 d of age to 1 of 4 treatments in a randomized complete block design with a 2 × 2 factorial arrangement of treatments. Preweaning milk replacer (MR) treatments were a 22% CP, 20% fat (as-fed basis) MR (C) or 28% CP, 20% fat MR (H), with weaning based on starter intake. Postweaning treatments were low NFC (27% NFC on DM basis; LC) or high NFC (42% NFC; HC) grower diets fed individually for ad libitum intake from 12 to 28 wk of age. Weights, skeletal measurements, and blood were taken every 2 wk during the preweaning period. Postweaning, BW were taken every 2 wk and skeletal measurements, blood, and rumen fluid were collected monthly. Pre- and postweaning periods were analyzed separately and overall from birth to 28 wk. Calves fed H were 15 d older, 18.0 kg heavier, and consumed 58% more DM through weaning compared with C (P < 0.01); however, feed efficiency (FE) was similar between H and C from birth to weaning (P = 0.24). From weaning to 11 wk, DMI was 53% greater for C (P < 0.01); however, ADG from weaning to 11 wk was similar, resulting in greater ADG from birth to 11 wk for H (P < 0.01). Hip height, hip width, and heart girth increased 2.7, 3.6, and 3.7%, respectively, for H over C at 8 wk (P < 0.01). Postweaning, ADG was improved for HC (P = 0.01), resulting in an 8.7 kg advantage in BW at 28 wk (P = 0.04). Total DMI was similar between postweaning treatments, and FE was significantly improved for HC from 12 to 28 wk (P < 0.01). Rumen fermentation and blood profiles were altered in favor of decreased acetate (P = 0.09), increased butyrate (P = 0.01), and reduced rumen NH3 and plasma urea N (P < 0.01) for HC. Overall, calves fed H+HC were 12.4 kg heavier at 28 wk compared with calves fed H+LC, but similar in BW to calves fed C+HC. These results suggest calves fed a high plane of nutrition preweaning should continue to receive high planes of nutrition postweaning to maintain growth advantages.

Key Words: dairy calf, weaning, growth