Endocrine and metabolic profile of peripubertal Standardbred colts

Area of Science:

• Reproductive endocrinology
• Equine science
• Metabolic hormone research

Background:

• Understanding peripubertal hormone changes is crucial for equine reproductive health.
• Testicular development and body fat deposition are key indicators of puberty onset.

Purpose of the Study:

• To determine reproductive and metabolic hormone concentrations during the peripubertal period in Standardbred colts.
• To assess the relationship between these hormones, testicular development, and body fat deposition.

Main Methods:

• Collected blood samples from 23 Standardbred colts over 12 months.
• Monitored weight, body fat percentage, and testicular volume (ultrasound).
• Analyzed plasma concentrations of FSH, LH, leptin, estradiol-17β, androstenedione, IGF-1, insulin, inhibin-A, and inhibin-B.

Main Results:

• Puberty onset in spring-born colts occurred at 13 months, coinciding with rapid testicular growth.
• No significant increase in cutaneous body fat or leptin was observed at puberty onset.
• Plasma inhibin-B significantly increased post-puberty, while inhibin-A, androstenedione, FSH, LH, and estradiol-17β did not.

Conclusions:

• Testosterone rise and puberty onset in horses correlate with testicular growth, not increased gonadotropins, IGF-1, body fat, or leptin.
• Inhibin-B may serve as a specific marker for postpubertal changes in stallions.