Thyroid function in mature horses ingesting endophyte-infected fescue seed.

This research observes the impact of consuming endophyte-infected fescue seed on thyroid function in mature horses, and it concludes that this consumption has minimal effect on the thyroid function of non-pregnant adult horses.

Objective and Participants

• The study was undertaken to understand whether consumption of fescue seed infected with an endophyte named Neotyphodium coenophialum, impacts the functioning of the thyroid gland in adult horses.
• The participants of the test group comprised 4 adult mares that were not pregnant and 6 adult geldings.

Methodology

• Initially, Thyrotropin releasing hormone stimulation tests were performed on the horse participants while they were on a standard diet.
• In the next steps, these participants were fed with endophyte-infected fescue seed (2.3 kg per day) for one and two months.
• In order to confirm the absorption of endophyte by the horses, the researchers also measured the serum prolactin concentrations.

Findings

• Serum prolactin concentrations indicated successful absorption of the endophyte by at least 8 out of 10 horse subjects.
• However, key indicators of thyroid function — the baseline concentrations of thyroid stimulating hormone, total and free triiodothyronine, total and free thyroxine, and changes in these hormone concentrations in response to administration of thyrotropin releasing hormone were not altered by the horses’ ingestion of endophyte-infected fescue seed.

Conclusions

• The study concluded that the short term ingestion (of up to two months) of fescue seed infected with the endophytic fungus Neotyphodium coenophialum, has little to no significant effect on the thyroid function of non-pregnant adult horses.