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Meta-analysis of the effect of direct-fed bacteria on intake, digestibility, milk production, and ruminal fermentation of lactating dairy cows.

A. A. Pech-Cervantes

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06-24-2020

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Abstract:

W99
Meta-analysis of the effect of direct-fed bacteria on intake, digestibility, milk production, and ruminal fermentation of lactating dairy cows.
A. A. Pech-Cervantes*1, I. M. Ogunade2, A. Oyebade3, D. Vyas3, A. T. Adesogan3. 1Agricultural Research Station, Fort Valley State University Fort Valley, GA, 2Division of Food and Animal Science, Kentucky State University Frankfort, KY, 3Department of animal sciences, University of Florida Gainesville, FL.

The objective of this study was to estimate the magnitude of effects of dietary supplementation of direct-fed bacteria (DFB) on the intake, digestibility, milk production and rumen fermentation of lactating dairy cows. A systematic search in the literature from 2002 to 2018 was conducted and data from 24 peer-reviewed papers with 39 treatments and 480 dairy cows were used for the analysis of raw mean differences (RMD) between DFB supplementation and control. The means were weighted by inverse variance in a mixed model and the heterogeneity was calculated by meta-regression analysis using bacterial strain (Bacillus spp., Propionibacterium spp., Enterococcus f, and Lactobacillus spp.), days in milk (DIM) and dose as covariates. Dietary levels of DFB ranged from 2 � 108 to 2 � 1011 cfu/cow/d. Compared with the control, DFB did not (P > 0.05) increase DMI (RMD = −0.01 kg/d [−0.33,0.32]), milk fat (RMD = 0.02% [−0.01, 0.07]), and milk protein (RMD = 0.07% [−0.01 0.03]). However, total-tract digestibility (RMD = 0.72% [0.001, 1.45]), milk yield (RMD = 1.23 kg/d [0.73, 1.73]), and feed efficiency (0.06 [0.03, 0.08]) were increased (P < 0.05) by DFB supplementation. Addition of DFB tended to increase (P = 0.07) total VFA in the rumen (RMD = 5.12 mM [−0.48, 10.74]) and tended to decrease acetate:propionate ratio (RMD = −0.09 [−0.20,0.01]). High doses of DFB (2 � 1011 cfu/cow/d) increased total VFA concentrations in the rumen compared with low doses (2 � 1010 cfu/cow/d or lower). Compared with the control, Bacillus and Lactobacillus strains were more effective (RMD = 1.94 kg/d [0.53, 3.36] and RMD = 1.09 kg/d [0.49, 1.68], respectively) at increasing milk production. In conclusion, dietary supplementation of DFB improved rumen fermentation, digestibility, and milk yield in dairy cows

Keywords: direct-fed bacteria, dairy cow, meta-analysis.