May 26, 2020


Lallemand: Live yeast helps maintain dairy cow performance, rumen health during heat stress




A recent study published by a team led by Professor José E.P. Santos from the University of Florida indicates that the rumen specific yeast Saccharomyces cerevisiae CNCM I-1077 (Lallemand's LEVUCELL SC) helps alleviate the negative effects of heat stress on feed efficiency in dairy cows.


Researchers credit the positive effects on the ability of S. cerevisiae CNCM I-1077 to impact rumen pH and feeding behavior.


Heat stress impacts rumen function and feeding behavior


One of the many challenges of dairy production under hot and humid climates is decreased milk yields when cows are exposed to heat stress. Heat stress also represents challenges for the rumen, leading to increased risk of subacute ruminal acidosis (SARA). The compilation of more than 500 rumen efficiency audits indicates that in farm settings across many regions and farming systems under heat stress conditions, 60% of farms present suboptimal rumen efficiency. Indicators linked to feeding behavior are affected by heat stress, in particular rumination activity.


Nutritional strategies to preserve dairy performance under heat stress should focus on supporting nutrient utilisation by optimising diet digestion while preserving rumen function. In this context, the rumen specific yeast S. cerevisiae CNCM I-1077 -- demonstrated to improve both nutrient digestion and rumen efficiency -- has already been shown to effectively alleviate the toll of heat stress on dairy production and improve rumination behavior. A recent study by Perdomo et al. (2020) further demonstrates the benefits of the live yeast on rumen fermentation profiles and feeding behavior, two parameters that are intimately linked. This is translated into better feed efficiency.


Improved rumen efficiency and feeding behavior under stressful conditions


The trial was conducted on lactating Holstein cows fed 40% corn silage, 10% alfalfa hay and concentrate, including 240g/head/day of sodium bicarbonate. The average daily temperature-humidity index (THI) during the trial was 81 and the lowest point was 75, which is still equivalent to high heat stress conditions.


The cows received either no supplement (control) or S. cerevisiae CNCM I-1077 at the recommended dose for stressful conditions, 20X109 CFU/cow/day (LEVUCELL SC).


The live yeast supplement led to improved feeding behavior:

- Increased chewing activity;

- Improved rumination behavior with reduced time between rumination bouts



Overall, the longer time spent chewing and ruminating had a positive impact on rumen function and helps maintain rumen health.


Chewing and ruminating can contribute to increased saliva production, hence the higher buffer effect, as translated into improved rumen pH (+0.34 pH units on average with the live yeast) and reduced risks of SARA. This is also confirmed by reduced levels of the inflammation biomarker in the blood, Amyloid A.


Higher feed efficiency under heat stress and a 5:1 ROI


As a result, dairy performance was improved with the supplementation of LEVUCELL SC without impairing milk solids (no dilution effect):

- Feed efficiency is improved by 7.6% (+130g energy-corrected milk/Kg DMI);

- Energy-corrected milk is improved by 2 Kg cow/day;

- Effect of live yeast supplementation on dairy cow feed efficiency (P<0.05) (adapted from Perdomo et al., 2020, results of one supplementation regimen among two different doses tested)


The authors of the study explained that "improvement in feed efficiency is likely related to improved digestion of fiber, protein and dry matter, perhaps due to the direct effects of the live yeast on rumen microbial metabolism that favored a more stable ruminal environment. The changes in feeding behavior with reduced eating rate and increased chewing time per unit of DM and NDF consumed should also favor optimised digestion with reduced acidosis."


- Lallemand

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