154 Growth, Libido, Semen Quality, and Reproductive Organ Weights of Hair Sheep Rams Rendered Short-Scrotum at Birth or Weaning

Abstract Rendering male lambs short-scrotum interferes with testicular development and thermoregulation, has been proposed as a management tool to control reproduction. This study evaluated at the effect of timing procedure (birth or weaning) on growth rate, testis size, libido, ejaculate characteristics carcass traits in landrace hair sheep lambs. April- (n = 31) August-born 23) Barbados Blackbelly (BB) St. Croix (SC) lambs, balanced by breed birth type, were rendered (SS) using elastrator bands (B) weaning (W), left intact (I). Lambs born pasture, weaned 9 weeks, transitioned pens for two months post weaning, then rotationally grazed single group target weight 40 kg. At 6-mo age (peri-pubertal), again (post-pubertal), mating behavior was recorded (day) samples collected (day 2). Mating a0-min test males individually exposed estrus-induced ewes pen. An initial attempt made collect semen an teaser ewe, if not successful, sample electro-ejaculation. harvested, scrotal content collected, (April cohort) determined. Data analyzed model sex class, cohort main effects. Pen pasture ADG (142 129 g/d, respectively) (287 d) affected (P > 0.1) SS treatment. However, April-born grew 19 g/d less < 0.01) reached d later 0.001) than males. As breed, STX had greater (139 vs 124 g/d; P 0.05) days earlier (P< BB Libido (number mounts services) treatment, cohort. The frequency ejaculates containing sperm (26 33%) (97%) increased but I Sperm concentration motile Testis epididymis larger (300 44.3 g) B (134 20.0 W (154 23.8 g), which different. Cohort no behavior, characteristics, organ weights. Results suggest that its rate behavior. Though depressed presence decreased weight, suppression complete, caution is warranted utilizing technique facilitate co-grazing ewe