Abstract. The present study aims to investigate the age-related changes in testicular
parameters and their association with plasma triiodothyronine (T3),
thyroxine (T4), and testosterone in male Murrah buffaloes. Testicular
measurements and single blood samples were collected from male Murrah
buffaloes (n= 103) aged between 6 months and 8 years. The correlation
coefficients of average testicular length (ATL), paired testis width (PTW),
and scrotal circumference (SC) in relation to age were 0.88, 0.91, and 0.90,
respectively. The regression equation between testicular weight (TW) and age
was Y=1.48×x0.005 (r= 0.90; R2= 0.79). Plasma
T4 and testosterone increased significantly (p< 0.001) with age and
their levels ranged between 12.9 and 41.8 and 0.05 and 1.48 ng mL−1, respectively.
With respect to associations between testicular parameters and plasma hormone
levels, we observed significant (p< 0.01) correlations between ATL, PTW,
SC, TW, and plasma T4. A significant correlation (r= 0.31; p< 0.01) between plasma T4 and testosterone levels was also observed.
However, the correlations between plasma T3 and testicular parameters
and plasma T3 and testosterone were non-significant. From the present
study, we conclude that plasma T4 is positively correlated with
testicular parameters and plasma testosterone, indicating its role in testis
development and steroidogenesis.
Age-related Changes in Thyroid Hormones in M-SHRSP and SHRSP
