Breeding Control in Awassi x Sarda ewes

Abstract

The main aim of this paper was to study the efficiency of short-term progestogens treatments (six days) plus eCG in the breeding control of Awassi × Sarda ewes on May. The effects of previous treatment with exogenous melatonin and PGF_2α administration route (intramuscular vs. subcutaneous) were also assessed.

The present study took place in a commercial farm (Mateus Lda) at the village of Carviçais, in Torre de Moncorvo (Portugal), between March and August of 2013. Fifty seven adult lactating ewes and five adult rams were used in this assay. They were all crossbred Awassi × Sarda sheep. Ewes were first divided in two groups: Control (n = 28) and Melatonin (n = 29). Melatonin ewes received an exogenous melatonin implant (18 mg). Fifty days later all ewes were divided in two subgroups: 31 ewes were treated with an intravaginal sponge impregnated with 20 mg of FGA and the other 26 ewes with an intravaginal sponge containing 60 mg of MAP. Simultaneously all ewes were injected intramuscularly (i.m.) (n = 28) or subcutaneously (s.c.) (n = 29) with 100 µg of PGF_2α. Intravaginal sponges were removed six days later. At the same time all ewes were injected i.m. with 500 IU of eCG. Pre and post treatments ovarian cyclicity, sexual behaviour and fertility rate were assessed.

Short-term progestogens plus eCG treatments were highly efficient in controlling the breeding activity of Awassi × Sarda ewes. Melatonin reduced the percentage of ewes in anoestrous before short-term progestogens plus eCG treatments but had no significant effect on the reproduction response to these treatments. FGA and MAP effects were similar. MAP only improved significantly the ovarian response. PGF_2α administration route had identical effects on the reproduction response. Subcutaneous administration of PGF_2α just increased the percentage of ewes presenting progesterone levels higher than 0.5 ng/ml.