Description
In order to assess the effects of a long-term progestagen treatment associated with different doses of eCG (equine Chorionic Gonadotropin) to advance the breeding season in Portuguese Churra Galega Bragançana ewes, an initial group of 41 females (2 were later rejected) aged between 2 and 7 years was used. In middle May, all ewes were treated with an intravaginal sponge impregnated with 20 mg of fluorogestone acetate (FGA) for 12 days. Half ewes received an injection (i.m.) of 500 UI of eCG and the other half an injection (i.m.) of 750 UI of eCG at sponge removal time. Blood samples were taken for progesterone determination and 4 intact rams with harness marker were used to identify the estrus. A transrectal ultrasound scanning was performed for pregnancy diagnosis. In early May, 63.4% of all ewes were in seasonal anoestrous. Treatments resulted in 97.4% ewes in estrus and 89.7% ewes with corpora lutea (CL) (Chi2 = 60.595; P<0.001). The higher dose of eCG had a positive effect in estrus (94.4% vs. 100.0%; Chi2 = 6.186; P<0.05) and pregnancy (61.1% vs. 81.0%; Chi2 = 9.713; P<0.01) and fertility (61.1% vs. 76.2%; Chi2 = 5.214; P<0.05) rates. The eCG dose had no effect in ewes with CL (88.9% vs. 90.5%; Chi2 = 0.053; P>0.05) and prolificacy (1.5 ± 0.8 vs. 1.7 ± 0.6; P>0.05). In conclusion, a long-term FGA treatment may be used to advance the breeding season in Churra Galega Bragançana ewes and the reproductive response depends on the eCG dose.
; Azevedo, Jorge Manuel Teixeira de 
