IMPROVING NUTRIENT DIGESTIBILITY TO ENHANCE FORAGE UTILIZATION IN LACTATING DAIRY COW FEEDING SYSTEMS
Location: Dairy Forage and Aquaculture Research
Title: Changes in rumen bacterial communities and rumen chemistry in primiparous Holstein cows during the periparturient period
Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: April 10, 2012
Publication Date: July 15, 2012
Citation: Mohammed, R., Stevenson, D.M., Weimer, P.J., Penner, G.B., Beauchemin, K.B. 2012. Changes in rumen bacterial communities and rumen chemistry in primiparous Holstein cows during the periparturient period [abstract]. Journal of Dairy Science. 95(suppl 2):615.
The objectives of this study were to study the changes in: 1) rumen bacterial community composition (BCC) and fermentation as influenced by feeding regimen and period; and 2) pH and VFA profiles among selected cows with minimum (stable) and maximum variation (unstable) between pre- and post-parturient periods. Fourteen Holstein heifers paired by expected calving date and BCS were allotted to one of two prepartum feeding regimens: low-concentrate regimen (2 diets ranging from forage:concentrate, F:C = 80:20 to 54:46); or a high-concentrate regimen (4 diets ranging from F:C = 68:32 to 46:54). All cows received the same lactation diet postpartum. Microbial DNA extracted from 58 rumen digesta samples collected prepartum (d -50, -31, -14) and postpartum (d +14, +52) and amplified by PCR were subjected to automated ribosomal intergenic spacer analysis. Changes in rumen chemistry data (pH, VFA, and acidosis indicators at d -54, -35, -14, -3, +3, +17, +37, +58) were analyzed using principal component analysis (PCA). The ARISA profiles did not show a diet effect; however, 4 out of 14 cows showed a shift in BCC from the prepartum to the postpartum period. The PCA profiles did not show a diet effect on rumen fermentation. However, 4 cows (stable) showed minimal changes while 4 other cows (unstable) had greater changes in rumen fermentation when PCA profiles of individual cows were examined. The remaining cows had a PCA profile intermediate between the stable and the unstable form. Cows with a stable profile had greater minimum rumen pH, mean pH, less bouts under pH 5.5 and 5.2, and less duration and area of moderate (pH < 5.5) and acute ruminal acidosis (pH < 5.2) compared to cows with an unstable profile. Milk fat content tended to be greater for cows with a stable profile than those with an unstable profile, with no difference in milk yield or FCM. A lack of diet effect with greater changes in rumen chemistry and small changes in BCC before and after calving reflect physiological adaptations of the cows during the periparturient period.