The ergot alkaloids produced by endophyte-infected (EI) varieties of tall fescue are beneficial to the plant but detrimental to cattle, as they induce different negative responses that are commonly referred to as fescue toxicosis (FT). The increased ambient temperature and humidity commonly experienced during the summer aggravate the symptoms of FT and this interaction significantly reduces animal performance and productivity. Vasoconstriction is one of the major signs associated with this disease, and it negatively impacts the cardiovascular system. Therefore, the objective of this study was to evaluate changes in the pulmonary arterial pressure (PAP) and different physiological parameters in replacement beef heifers consuming an EI ration. Considering that PAP assessments are exclusively implemented in regions with increased elevations to identify tolerant animals to high-altitude disease, the adoption of this technique to further investigate the vasoconstrictive effects induced by FT is a pioneering approach in beef cattle research. The results presented by this study provide new insights about the complex interaction between FT and heat stress and their impact on the cardiopulmonary system of cattle and highlight the need for an extensive research framework that can generate improved selection and management strategies to improve cattle performance.

Read the full article in the Journal of Animal Science.