Breeding in the fat-tailed dunnart following ovarian suppression with the gonadotrophin-releasing hormone agonist Lucrin® Depot

Abstract

Lucrin Depot (AbbVie), a 1-month microsphere gonadotrophin-releasing hormone (GnRH) agonist preparation, was investigated as a potential agent to synchronise cycling in the fat-tailed dunnart (Sminthopsis crassicaudata). Forty-eight randomly selected females were treated with 5 or 10 mg kg−1 Lucrin Depot (n = 24 per dose). Eighteen females per treatment had their reproductive activity scored at 4, 8, 12 and 16 weeks using two ovarian (Graafian follicle and corpus luteum status) and two reproductive tract (uterine and vaginal muscularity and vascularity) parameters that formed a reproductive activity score. Six females per treatment were paired with a male at 4 weeks. Fertility was assessed between 8 and 16 weeks by pouch check, and thereafter by dissection. The effects of the 5 and 10 mg kg−1 doses were statistically equivalent. Females showed suppression at 4–8 weeks, an increase in reproductive activity at 8–12 weeks and all were cycling normally at 16 weeks. Six pouch young were born at 12 weeks to two females treated with the 5 mg kg−1 dose. Nine embryos were recovered at 16 weeks from two females treated with the 10 mg kg−1 dose. In conclusion, Lucrin Depot can suppress breeding, and fertile mating can occur in subsequent cycles in the dunnart. There is potential for Lucrin Depot to be used as an assisted breeding tool, but it may need to be combined with ovarian stimulation treatment to achieve practical levels of synchronisation in the fat-tailed dunnart.