# Long-Term Saccharomyces cerevisiae Supplementation Enhances Milk Yield and Reproductive Performance in Lactating Dairy Cows on Smallholder Farms

## TL;DR

Feeding dairy cows a yeast supplement for 90 days improved milk production and udder health, but had mixed effects on reproduction.

## Contribution

The study demonstrates that extended Saccharomyces cerevisiae supplementation improves milk yield and udder health in lactating dairy cows.

## Key findings

- Cows supplemented with Saccharomyces cerevisiae for 90 days had higher milk yield and better feed intake.
- Extended yeast supplementation reduced somatic cell counts, indicating improved udder health.
- Body condition scores were higher in supplemented cows, but reproductive outcomes were not significantly affected.

## Abstract

Early lactation is a challenging period for dairy cows, often associated with high nutrient demands and variable productive responses. This study evaluated the effects of long-term supplementation with Saccharomyces cerevisiae on feed intake, milk production, and selected reproductive indicators in lactating dairy cows. Cows receiving live yeast for 90 days showed higher dry matter intake, increased milk yield, higher milk fat and lactose concentrations, and lower somatic cell counts compared to unsupplemented cows. Body condition score was also higher in cows supplemented for 90 days. Circulating progesterone concentrations and pregnancy rate did not differ significantly among treatments. These findings indicate that the duration of live yeast supplementation influences production performance and udder health in lactating dairy cows under the condition of this study.

This study examined the effects of long-term Saccharomyces cerevisiae supplementation on feed intake, milk production, milk composition, and selected reproductive indicators in lactating dairy cows. Twenty-four multiparous Holstein–Friesian crossbred cows were blocked by parity and randomly allocated to three treatments: a control group without supplementation (CON; n = 7), live yeast supplementation for 60 days (YS-60; n = 10), and live yeast supplementation for 90 days (YS-90; n = 7). Dry matter intake and body weight gain were significantly higher in cows receiving live yeast, with the greatest responses observed in the YS-90 group (p < 0.05). Milk yield and energy-corrected milk were increased by supplementation, particularly in YS-90 cows (p < 0.01), along with higher milk fat and lactose concentrations. Somatic cell count was consistently lower in YS-90 cows throughout the 14-week experimental period. Body condition score differed among treatments (p < 0.01), with higher values observed in yeast-supplemented cows. Feed efficiency did not differ among treatments. Reproductive parameters, including estrus detection and pregnancy rate, were not significantly affected by live yeast supplementation, although plasma progesterone concentration was higher in supplemented cows (p < 0.05). Given the limited number of animals per treatment, reproductive outcomes should be interpreted cautiously. Overall, extended live yeast supplementation improved production performance and udder health, while its effects on reproductive performance warrant further investigation.