Daily alterations in plasma testosterone in boars at different ages

Area of Science:

• Animal Science
• Endocrinology
• Reproductive Biology

Background:

• Endogenous testosterone concentrations are crucial for male reproductive development and function.
• Understanding testosterone secretory patterns in boars is essential for optimizing breeding programs and animal management.
• Previous research has not fully elucidated the developmental trajectory of testosterone secretion in young boars.

Purpose of the Study:

• To investigate endogenous testosterone concentrations and secretory patterns over a 24-hour period in purebred Yorkshire boars of different ages.
• To determine if age influences the mean concentration, frequency, or magnitude of testosterone secretory spikes.
• To establish when testosterone secretory patterns become established in boars.

Main Methods:

• Eighteen purebred Yorkshire boars were divided into three age groups (approximately 5, 6.5, and 8 months).
• Blood samples were collected at 30-minute intervals over a 24-hour period.
• Plasma testosterone concentrations were quantified using radioimmunoassay, and secretory spikes (mean concentration, frequency, magnitude) were analyzed.

Main Results:

• No significant differences (P > .10) were observed in the mean concentration (C), frequency (F), or magnitude (M) of testosterone secretory spikes across the three age groups.
• Averaged across all ages, the mean values for C, F, and M were 1.4 ng/ml, 2.9 spikes, and 3.0 ng/ml per spike, respectively.
• Testosterone secretory patterns did not appear to change significantly between 5 and 8 months of age in these boars.

Conclusions:

• Testosterone secretory patterns are established in Yorkshire boars by approximately five months of age.
• The studied age range (5-8 months) did not reveal significant developmental changes in testosterone secretion patterns.
• Environmental factors, such as the degree of daylight, may influence established testosterone secretory patterns in boars.