Changes in Testicular Biometry, Steroid Hormones and Receptor Expression in the Peripubertal Period of Indigenous Tenyi-vo Male Pigs of North-eastern Himalayan Region in India

Abstract Present study was conducted to characterize the testicular changes in the peripubertal period in Tenyi-vo, a miniature size pig of North-eastern Himalayan (NEH) region of India. A total of twenty-four male pigs were randomly selected and categorised for castration at different age groups, G1 (Days 30-45), G2 (Days 60-65), G3 (Days 80-100) and G4 (Days 150-160), n=6 each category. Paired testes and epididymis were used for the assessment of biometry, cauda epididymal spermiogram, testicular histology and relative expression of the androgen receptor (AR), estrogen receptors (ERα and ERβ), aromatase (CYP19A1), and insulin like growth factor-1β receptor (IGF-1R) in qPCR. Plasma testosterone (T), estradiol (E2), tri-iodothyronine (T3), thyroxine (T4), and cortisol concentrations were estimated on the day of castration in each group of male using commercial ELISA kits. In pigs of G2, a greater testicular weight, volume, epididymis weight was observed relative to G1. The presence of live spermatozoa at 1240.9±304.2×106/mLconcentration with 0.65% proximal droplets was recorded as early as day 60. The concentration of T increased steadily over the age of G1 to G4 and a significantly higher concentration was observed in G4 relative to the other categories. Among the transcripts analysed in the testis, the relative fold change of AR was 10.8 fold in G2, which was subsequently reduced in G3 and then down-regulated in G4. CYP19A1 was abundantly expressed in the testis and the fold change ranged from 41-54 fold, although it did not differ significantly from 60-150 days of age. Further, the presence of well-developed seminiferous tubules was evident in the Tenyi-vo male from day 60 onward with a body weight as low as 4.28 kg. The study concluded that the male of Tenyi-vo pig attained puberty at the earliest age of 60 days.