A Japanese study using infertile mares has found that many have elevated levels of adrenocorticotropic hormone (ACTH). ACTH is linked to the endocrine disorder pituitary pars intermedia dysfunction (PPID).
Dr. Takeru Tsuchiya and a research team used 67 Thoroughbred broodmares with unknown fertility issues for the study. Each horse had a physical exam and was deemed healthy.
The mares were tested for PPID in the fall using baseline plasma ACTH concentrations; they were divided into three groups based on their ACTH concentration level: low, intermediate, and high.
The team found 77.3 percent conception rates in the low ACTH group, and 56.5 percent in the high ACTH group. The high ACTH group didn’t have a significant difference in the number of breedings, but it had lower conception rates.
PPID affects 15 to 30 percent of horses over 15. High ACTH concentrations are common in older horses. Almost two-thirds of the mares used in the study had elevated ACTH hormones. ACTH may indirectly affect reproductive performance.
The study team concluded that if infertile mares are tested for ACTH concentration levels early, it may be possible to improve reproduction performance. They recommend that other factors, including other reproductive hormones, be investigated for their effect on reproductive performance.
Read the article here.
Read more at HorseTalk.
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