Abstract
Deer are sensitive to stressful stimuli by handling and their reproductive physiology could be altered by these procedures, making it necessary to develop less invasive protocols for ART. Melengestrol acetate (MGA), a synthetic progestin administered orally, appears as an alternative for estrous synchronization protocols (ESP), such as reported in cattle. Firstly, we compared two MGA doses (0.5 and 1.0 mg/day/animal), which would have suppression effect in estrous behavior (EB). Eight females were randomly and equally distributed in Group 1 (G1) and Group 2 (G2), which received 0.5 and 1.0 mg/day/animal respectively for 15 days (D1 to D15). Two cloprostenol (CP) applications were performed on D0 and D11. Estrus detection (ED) was performed every day. All females from G1 displayed estrus during treatment period, whereas all females from G2 displayed estrus after treatment, suggesting a suppressive effect of 1.0 mg in the EB. Once the suppressive MGA dose (1.0 mg) was defined, we used this dose for assessing ESP. The same eight females received 1.0 mg/animal for eight days (D-8 to D-1), followed by 0.25 mg of estradiol benzoate on D-8 and 265 μg of CP on D0. Feces for fecal progesterone metabolites (FPM) measurement were collected from D0 until seven days after the last day of estrus. Seven females displayed estrus between 12 and 72 h after CP application, which was followed by a significant increase in FPM levels (except female MG6), suggesting the formation of corpus luteum. After ED, females were placed with a fertile male to assess the fertility of the protocol. Pregnancy was confirmed by ultrasound 30 days after mating in 3/6 individuals. Although the low effectiveness of MGA protocol, it should be considered as a promising alternative in deer ESP since this protocol has less stressful effect on the animal during reproductive management when compared to other ESP.
Highlights
The brown brocket deer (Mazama gouazoubira) is classified as “LC” (“Least Concern” – not immediately threatened) by the International Union for Conservation of Nature (IUCN) Red List of Threatened Species (Black-Decima and Vogliotti, 2016)
Once the dose was determined, it was used in the estrous synchronization protocol (Experiment 2)
Despite the small number of animals used in the present study, our results suggest a suppressive effect on estrous behavior in M. gouazoubira, when offering 1.0 mg/animal/day of Melengestrol acetate (MGA) to females (Experiment 1), similar dose that has been used for contraception proposes in other deer species and members of the family Bovidae (Roughton 1979; Raphael et al, 2003; Patton et al, 2007)
Summary
The brown brocket deer (Mazama gouazoubira) is classified as “LC” (“Least Concern” – not immediately threatened) by the International Union for Conservation of Nature (IUCN) Red List of Threatened Species (Black-Decima and Vogliotti, 2016). It is considered a polyestrous and non-seasonal breeders and births have been observed throughout the year (Pinder, 1992; Zanetti et al, 2010), but birth peaks have been described during mid-winter and wet season (Stallings, 1986; Bisbal, 1994).
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