Abstract #541

# 541
Body condition score prior to parturition is associated with abundance of ruminal bacteria during the peripartal period in Holstein dairy cows.
A. Elolimy*1, K. Wilachai1,2, A. Alharthi1, P. Paengkoum3, J. J. Loor1, 1Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois, Urbana, IL, 2Program of Animal Science, Faculty of Agricultural of Technology, Rajabhat Maha Sarakham University, Thailand, 3School of Animal Technology and Innovation, Institute of Agricultural Technology, Muang, Nakhon Ratchasima, Thailand.

The objective of the current study was to evaluate the influence of prepartal body condition score (BCS) on ruminal bacteria during the peripartal period in dairy cows. Twenty-six Holstein dairy cows individually fed were retrospectively classified by BCS at d −30 before parturition into BCS ≤3.25 (LoBCS) and BCS ≥3.50 (HiBCS) groups (n = 13/group). Ruminal contents were collected from each cow 4 h postfeeding via stomach tubing at d  −30 and d −15 before expected calving date and at +15 and +30 d in milk (DIM). Ruminal contents were immediately frozen in liquid nitrogen and stored at −80°C. The MIXED procedure of SAS was used for repeated measures analysis of dry matter intake (DMI), milk yield, and bacterial abundance. The fixed effects in the model were BCS and time (week or day), and the random effect was cow. Significance was determined at P ≤ 0.05. Although DMI did not differ prepartum (BCS P = 0.65), HiBCS cows had ~1.5 kg/d greater DMI postpartum (P = 0.04). A BCS × day interaction (P = 0.03) was observed for postpartum DMI due to greater DMI in HiBCS cows during the last wk of the study. The HiBCS cows produced more milk overall (BCS P = 0.02; 42.5 vs. 37.1 kg/d). Results of 16S rRNA copy number of the total ruminal bacterial community indicated that HiBCS cows had greater overall (P < 0.01) bacterial density. However, HiBCS cows had lower (P < 0.05) overall relative abundance of ruminal bacteria with key roles in cellulose (Eubacterium ruminantium, Fibrobacter succinogenes), xylan (Butyrivibrio proteoclasticus), and starch degradation (Streptococcus bovis, Rumicoccus flavefaciens, Prevotella ruminicola). Cows in HiBCS also had lower overall abundance (P < 0.01) of lactate utilizers (Selenomonas ruminantium) and lipolytic bacteria (Anaerovibrio lipolytica). Overall, data suggest the existence of some associations between prepartal BCS, postpartal dry matter intake, and ruminal bacteria profiles during the peripartal period.

Key Words: BCS, rumen, bacteria