Effects of Different Nutritional Regimens during Pre-Weaning Period on Body and Testis Growth, Sexual Behavior, Hormonal Profile and Genes Expression in Male Beetal Goat Kids

From birth till puberty, body weight (BW), scrotal circumference (SC), serum hormonal profile, genes expression pattern and pubertal onset were longitudinally studied in male Beetal goat kids reared on two nutritional regimens during preweaning period. Kids were reared either on suckling (NR; n=26) or milk replacer (AR; n=26) from day-10 to 12 weeks of age. Body weight and SC showed linear increase till puberty, although pubertal onset was earlier (P<0.05) in NR than AR kids (175.00 +/- 12.00 vs 235.00 +/- 8.00 days). Serum testosterone and TSH concentrations remained higher (P<0.05) in NR than AR kids from 2 months of age till puberty. Interestingly, kids of both groups started showing sexual behavior activities when serum testosterone achieved a threshold level (1.36 ng/ml for NR and 1.34 ng/ml for AR kids). There were significant differences in anti-mullerian hormone levels at 2-6 months of age between two groups. The mRNA level of spermatogenic genes (ODF2, PRM1, STRA8) was higher at 4-8 months than 1-3 months of age in both groups. However, the expression pattern of Sertoli cells specific genes (SOX9, FSHR) was higher at 0-1 month of age in NR and 2-4 months of age in AR kids. The androgenic gene (CYP19A1) expression increased (P<0.001) at 4-6 month of age in NR and 6-8 months of age in AR kids. In conclusion, sexual behavior activities started in both groups of Beetal goat kids when testosterone level achieved cutoff value around 1.3 ng/ml. Kids reared on suckling attained puberty earlier than those reared on milk replacer during preweaning period. Relationship of age with BW (r(2=)0.9) and SC (r(2)=0.9) may be used as selection indices for these kids. (C) 2021 PVJ. All rights reserved