ABSTRACT
INICIATION OF BREEDING SEASON AND OESTRUS SYNCRORONIZATION OF ADULT EWES IN MAGALLANES

Daniel Claro M.1 y Etel Latorre V.2
 

The iniciation fo ovulation was studied with 286 ovaries of Corriedale 5 year old ewes, collected at Punta Arenas abattoir from January 2nd to February 28th 1973. During January no ovulations were detected although follicular size indicated the approaching reproductive season. Ovulations were present from February 15th onwards.
In 1972, at Otway Research Campus, in Magallanes province, from January 25th to March 15th, 216 Corriedale adult ewes were alloted to 6 groups of 36 animals each. Every 10 days one of the groups was exposed to entire rams for a 10 days period. The control group was kept isolated from rams.
Induced synchronization of oestrus was obtained, being February 4th the optimum time for introduction of rams. Where ram induced synchronization of oestrus was good, up to 62% of ewes lambed within one week.
From February 27th onwards, fertile mating was detected. February 15th is the most likely time for begining of ovulation.

Keywords:
1Ing. Agr., M. Agr. Sci., Programa Producción Ovina, Estación Experimental La Platina, Instituto de Investigaciones Agropecuarias (INIA), Casilla 5427, Santiago, Chile.
2Med. Vet., Programa Producción Ovina, Estación Experimental Kampenaike, Instituto de Investigaciones Agropecuarias (INIA), Casilla 616, Punta Arenas, Chile.