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Effects of different weaning strategies when feeding moderate and high milk replacer rates on ruminal bacteria taxonomic profile, diversity, and community structure in Holstein calves.

A. Poulin

Events

06-23-2020

Abstract:

183
Effects of different weaning strategies when feeding moderate and high milk replacer rates on ruminal bacteria taxonomic profile, diversity, and community structure in Holstein calves.
A. Poulin*2, J. Romero1, R. Klopp3, V. Richards4, F. Suarez-Mena5, T. Dennis5, T. Hill5, R. Causey1, R. Schlotterbeck5, G. Lascano3. 1Animal and Veterinary Sciences, SFA, University of Maine Orono, ME, 2Department of Molecular and Biomedical Sciences Orono, ME, 3Department of Animal and Veterinary Sciences, Clemson University Clemson, SC, 4Department of Biological Sciences, Clemson University Clemson, SC, 5Nurture Research Center, Provimi Brookville, OH.

Ruminal bacteria profile can be greatly affected by pre-weaning diet and the strategy (STEP) used to wean calves. A 2 � 2 factorial design [moderate (MOD) or high (HI) milk replacer (MR) feeding rates and one step (ONE) or gradual (GR) weaning] was utilized to study how pre-weaning programs affect ruminal bacteria diversity from 2 to 4 mo of age. Calves (n = 50, 56 d of age) were randomly assigned to 1 of the 4 pre-weaning treatments. The initial BW for HI and MOD calves was 78.9 and 74.3 � 1.92 (kg). Bacterial diversity was determined using the 16S rRNA gene (V4 region) for 0, 14, 28, 42, 56 d after weaning. The statistical model included the fixed effects of MR, STEP, DAY and their interactions and the random effect of calf nested within treatment. Differences were declared at P ≤ 0.05. At MOD feeding, Prevotellaceae relative abundance (rA, %) was reduced for GR vs. ONE weaning (48.8 vs. 55.4 � 2.1%) only at MOD feeding. For GR weaning, a reduction was also observed in MOD compared with HI feeding. Furthermore, MOD feeding reduced the rA of Succinivibrionaceae vs. HI feeding (3.8 vs. 5.5 � 0.64%). At HI feeding, ONE weaning reduced Veillonellaceae rA compared with GR (5.4 vs. 7.5 � 0.8%) but no differences were observed within MOD (6.2%). As calves went from 0 to 56 d postweaning, Lachnospiraceae rA was decreased for 56 vs. 0 to 42 d (3.2 vs. ~11.8 � 1.29%); Succinivibrionaceae was increased for 56 vs. 14 to 42 d (22.1 vs. ~2.37 � 1.88); Veillonellaceae was higher for d 14 compared with 28, 42, and 56 d (8.4 vs. 4.8, 5.7, and 5.8 � 0.77); and unidentified Clostridiales was reduced for d 56 vs. 0 to 42 d (1.30 vs. ~3.27 � 0.26). The phylogenetic diversity (richness) was higher for d 42 (15.1 vs. 12.8 for the rest) and 56 vs. 0 and 14 d (13.8 vs. 11.9 � 0.38). Concurrently, a PERMANOVA analysis of weighted UNIFRAC distances indicated a difference in community structure across periods and treatments (P < 0.01). In conclusion, both MR feeding rate and weaning strategy influenced ruminal bacterial rA independent of time after weaning; nonetheless had no effect on richness.

Keywords: calves, post-weaning, microbiome.