Control of breeding activity in Churra Galega Bragançana ewes

Abstract

The main aim of this paper was to study the effect of exogenous melatonin and the efficiency of two short-term progestogens protocols in controlling breeding activity of Portuguese Churra Galega Bragançana ewes on May. Forty five adult ewes were divided in two groups: Control (n=24) and Melatonin (n=21). Melatonin ewes received a subcutaneous implant of melatonin (18 mg). Forty five days later ewes were divided in two subgroups: FGA (n=22) and MAP (n=23). FGA ewes were treated with 20 mg of FGA and MAP ewes with 60 mg of MAP (intravaginal devices). At sponge insertion all ewes were injected with PGF_2α (100 µg). Progestagen treatment lasted for six days. At sponge removal 500 IU of eCG were administered.

Ovarian activity was assessed by measuring the plasmatic levels of progesterone. Four adult rams with markers harnesses were used to estrus detection. Pregnancy diagnosis was carried out by transrectal ultrasonography (5 MHz).

Two weeks before sponge insertion 64.4% of all ewes presented plasmatic levels of progesterone higher than 0.5 ng/ml. Difference between Control and Melatonin ewes was no statistically significant. Melatonin improved the rate of ewes presenting high plasmatic levels of progesterone (95.2% vs. 83.3%) and fertility (95.2% vs. 75.0%). FGA and MAP treatments were equally efficient in controlling breeding activity in Churra Galega Brgançana ewes.