# Adding a Yeast Blend to the Diet of Holstein Females Minimizes the Negative Impacts of Ingesting Feed Naturally Contaminated with Aflatoxin B1

## TL;DR

Adding a yeast blend to Holstein calves' diets helps reduce the harmful effects of aflatoxin-contaminated feed on their health and growth.

## Contribution

This study shows a yeast blend can mitigate aflatoxin B1's negative effects in calves' diets.

## Key findings

- Calves given the yeast blend showed greater weight gain and better feed efficiency.
- The additive reduced liver damage biomarkers and oxidative stress markers.
- Yeast blend consumption was linked to an anti-inflammatory response in calves.

## Abstract

Agriculture and livestock farming have faced challenges due to constant climate change, which has contributed to mycotoxin contamination in feed. Prolonged droughts or rainfall contribute to food with low nutritional quality, in addition to contamination by fungi, which, in grain or silage storage environments, tend to produce mycotoxins. In this study, aflatoxin contamination of corn silage caused negative impacts on the growth and liver health of calves. However, when a yeast blend was included in the diet, the negative impacts of the mycotoxin were avoided or minimized.

Although a yeast-based additive was initially employed as a performance enhancer, subsequent analysis revealed high aflatoxin B1 levels in the corn silage. Therefore, the objective of this study is to determine if the use of a yeast blend in the diet of Holstein calves that consumed feed naturally contaminated with high levels of aflatoxin can minimize the negative impacts of mycotoxins on animal health, contributing to improved performance. For this, we used 24 Holstein calves (6 months old) divided into two groups: Control (n = 12; no additive) and Treatment (n = 12; 5 g additive/animal/day). During the 100-day experiment, animals were weighed, feed intake was measured, blood samples were collected to assess health, and ruminal fluid was analyzed for ruminal fermentation. We observed greater weight gain and better feed efficiency in cattle that consumed the yeast-based additive compared to the control group. Yeast ingestion increased the concentration of propionic acid in the experimental environment, as well as increasing the protozoan count. Higher lymphocyte counts combined with higher levels of immunoglobulin G in the blood of females that consumed the additive were observed. Lower activity of enzymes that are biomarkers of liver damage, as well as markers of oxidative stress, was observed when animals consumed the yeast blend compared to the control group. Lower levels of ceruloplasmin (positive acute phase protein) and higher levels of transferrin (negative acute phase protein) are indicative of an anti-inflammatory response to the additive. The results preliminarily suggest that the consumption of the yeast blend is a nutritional tool capable of acting as a performance enhancer, even under challenging conditions, such as diets contaminated with aflatoxin at levels exceeding international limits.