Abstract
ABSTRACTThe effectiveness of two routes of administration of human chorionic gonadotropin (hCG) upon oestrus induction in anoestrus mix-breed goats was evaluated. Goats [n = 27, 39.6 ± 2.18 kg live weight and body condition score of 1.71 ± 0.02 units (scale 1–5)] were primed with 20 mg P4-intravulvosubmucosal (IVSM) 24 h prior to hCG administration. Thereafter, goats were randomly allocated to three groups to receive 100 IU hCG (0.1 mL) intramuscular (IM, n = 9), or IVSM (n = 9), and saline (0.5 mL) IM injection (CONT, n = 9). Ovarian follicular or luteal tissue was monitored by transrectal ultrasonographic scanning 15 days pre- and 5 days post-treatment. Besides, goats were daily monitored (0800 and 1800 h) × 15 days to detect oestrus signs with the use of aproned sexually active bucks, treated with testosterone; 12 h after the onset of oestrus, goats were mated. While the CONT-goats never depicted neither oestrus nor ovulation (P < .05), the ovarian response from the IM and IVSM groups was 89% vs 68%, respectively (P > .05). Oestrus response (83.5%), pregnancy (60.6%) and litter size (1.55 ± 0.2) did not differ (P > .05) between the IM and IVSM groups. A single application of 100 IU hCG, irrespective of administration route, induced sexual activity in acyclic goats, generating key out-of-season reproductive outcomes.
Highlights
While reproductive technologies represent a unique opportunity for goat producers to improve the breeding value of their flocks, several efforts have been made to develop protocols to induce and synchronize oestrus and ovulation during both the breeding and non-breeding seasons (Simoes 2015)
This trial aimed to evaluate the use of a single shot of human chorionic gonadotropin (hCG) administered by two different routes, either IM or IVSM, upon oestrus induction and some other reproductive outcomes in acyclic mix-breed goats
The oestrus behaviour percentage observed in the present study is in agreement with that reported in other trials using a combination of fluorogestone acetate, prostaglandin F2ɑ (PGF2ɑ), equine chorionic gonadotropin or follicle stimulating hormone (FSH) (Greyling & Van der Nest 2000; Fonseca et al 2005a; Bukar et al 2012), or more simple protocols (López-Sebastian et al 2007)
Summary
While reproductive technologies represent a unique opportunity for goat producers to improve the breeding value of their flocks, several efforts have been made to develop protocols to induce and synchronize oestrus and ovulation during both the breeding and non-breeding seasons (Simoes 2015). Despite the specific anastomoses involving the vulva, vagina, uterus and ovaries, it is still elusive if such angioarchitectural scenario may allow a more efficient action of drugs injected throughout the intravulvosubmucosal (IVSM) than the intramuscular (IM) route (Meira et al 2006). This trial aimed to evaluate the use of a single shot of hCG administered by two different routes, either IM or IVSM, upon oestrus induction and some other reproductive outcomes in acyclic mix-breed goats
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