# Molasses-Based Block Supplements for Cattle Fed Endophyte-Infected Tall Fescue (Festuca arundinacea) Seed: Effects on Growth Performance, Circulating Biomarkers, Heat Stress, and Coccygeal Artery Diameter

## TL;DR

This study shows that molasses-based supplements can help cattle cope with toxic effects of tall fescue by improving blood flow and reducing heat stress.

## Contribution

The study introduces molasses-based block supplements as a practical solution to mitigate ergot alkaloid effects in cattle.

## Key findings

- Cattle consuming molasses-based supplements showed improved weight gain and blood vessel diameters.
- Supplemented cattle had better thermoregulation and blood flow compared to non-supplemented cattle.
- No significant differences were found between different supplement formulations.

## Abstract

Tall fescue is a widely used forage for cattle, but it can be infected with a microorganism that produces toxic compounds called ergot alkaloids. These toxins reduce blood flow, causing heat stress, poor weight gain, and even tissue damage in cattle. Currently, there are limited options to prevent these negative effects besides removing animals from infected pastures. This study tested whether molasses-based block supplements could help cattle tolerate ergot alkaloids by improving blood circulation and reducing heat stress. Cattle were given different types of block supplements, including those containing menthol or capsaicin, compounds known for their ability to influence blood flow. The results showed that cattle consuming crude protein-enriched blocks had better growth performance and improved blood circulation compared to those that did not receive supplements. In particular, cattle that consumed these supplements had larger blood vessel diameters and better heat regulation. These findings suggest that molasses-based block supplements may offer a practical and accessible way to mitigate the harmful effects of ergot alkaloids in cattle grazing on tall fescue pastures.

Ergot alkaloids present in endophyte-infected tall fescue can cause a series of negative effects in exposed cattle. This study evaluated the effectiveness of molasses-based block supplements (MBSs) in alleviating vasoconstriction, which leads to reduced peripheral blood flow, heat stress, and impaired growth performance in cattle. A total of 100 crossbred steers were assigned to five treatment groups: a negative control with no tall fescue seed; a positive control with ergot-infected tall fescue seeds; and three MBS treatments, including a control block, a block containing menthol, and a block containing capsaicin. Blood flow was assessed through ultrasound imaging of the coccygeal artery, while thermal imaging was used to monitor body temperature regulation. Growth performance, feed intake, and blood biomarkers were also measured. Cattle consuming MBS had improved weight gain, greater arterial diameters, and enhanced thermoregulation compared to those without supplements. No significant differences were observed between the different MBS formulations. These results suggest that molasses-based block supplementation can help mitigate heat stress and poor growth performance associated with ergot alkaloid consumption, potentially providing a practical nutritional strategy for cattle producers managing cattle exposed to ergot alkaloids.