META-ANALYSIS OF THE EFFICACY OF YEAST IN IMPROVING MILK PRODUCTION IN LACTATING DAIRY COWS

Abstract

The objective of this study was to use meta-analytic methods to estimate the effect of diamond yeast on milk production in lactating dairy cows. Forty two published journal articles on effect of yeast on milk production in lactating cows were identified using Google search æ.ne. Eight separate studies met the criteria for inclusion in the meta-analysis. Data for each trial were extracted and analyzed using Open MEE software. Estimated effect size of yeast was calculated for milk yield (MY), milk fat (IMF), milk protein (MP) and milk lactose (ML). The overall pooled estimate for milk yield 0.395 kg/d, with a 95% confidence interval (CI) from 0.138 to 0.651 and the pooled estimate for MF was 0.282% with a 95% CI from 0.039 to 0.525. The pooled estimates for MP and ML were 0.915% and -0.183% with a 95% CI from -0.882 to 2.712 and -0.619 to 0.253, respectively. The analysis of MY (I² = 8.26%) showed a low level of heterogeneity as did MF (I² = 4.4%). MP had high level of heterogeneity (I² = 97.5%), while ML had moderate heterogeneity (I²= 45.69%). Yeast use in lactating cow significantly improved milk yield and milk fat but had no significant effect on milk protein and milk lactose.