The Endocrine Function of Testes in 12- and 18-Month-Old Boars of Different Breeds

Testes have several primary functions, such as male gametes production (spermatozoa) and secretion of several endocrine factors, including the production of steroid and protein hormones which facilitate elements in the healthy reproductive function of mammals. The potential of an animal functional endocrine reservoir could be an interesting finding in animal reproduction management. Therefore, the current study aimed to analyze the functional endocrine reserves of testes in 12- and 18-month-old boars of four different boar breeds, namely Large White, Landrace, Duroc, and Tempo, as the animal model in this research (n=10). To determine the functional endocrine reserves of the testes at 12 and 18 months of age, boars received injections of human chorionic gonadotropin (hCG) 3 times every 72 hours. Testosterone was measured in blood samples (10 mL) taken from the jugular vein before the administration of hCG as well as 2, 12, 24, 48, and 72 hours after administration of each of three hCG injections. The index of endocrine activity of the testes was determined by the formula: I_ta = T₁ -T₀ / T₀ , where I_ta is the index of endocrine activity of the testes, T₀ is the testosterone concentration before the administration of hCG, and T₁ is the maximum testosterone concentration after the third administration of hCG. The effects of the hCG injection on boar testes at different age periods indicated that the testes of Large White and Duroc boars have higher potential endocrine reserves compared with the Landrace and Tempo breeds.