ABSTRACT


Daniel Claro M.1
 
Mating weight and infertility rate were measured in Magallanes for Corriedale flocks from 1971 to 1973. In Scrub Country a total of 1.380 adult ewes and 422 two-tooth ewes were controlled. In Tussock Country 1.018 adult ewes and 212 two-tooth. For adult ewes in Scrub Country a mating weight of 49.2 Kg (37-69 Kg), 0.4% of sheep being below 40 Kg and infertility rate of 15.9% were found. In Tussock Country mating weight was 42.6 Kg (30-66 Kg), 14% ewes below 40 Kg and infertility rate of 22% were found, the difference in mating weight and infertility being significant (P ≤ 0.01).
In well reared two-tooth ewes, a mating weight of 43.3 Kg (33-60 Kg), 13.4% below40 Kg and infertility rate of 28.1% were found in Scrub Country. In TussockCountry mating weight was 42.4 Kg (34-53 Kg), 11.8% of ewes were below 40 Kgand infertility rate was 28.8%. Difference between both ecological zones was non significant.Infertility rate of two-tooth was higher (P ≤ 0.01) than in adult ewes even at similarmating weight like in Tussock Country.Importance of good rearing in determining the liveweight at first mating and itsinfluence in reproductive perfomance is enhanced.
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1Ing. Agr., M. Agr. Sci., Programa Producción Ovina. Estación Experimental La Platina, Instituto de Investigaciones Agropecuarias (INIA) , Casilla 5427, Santiago, Chile.