Contribuction for a characterization of Beira Baixa Merino : reproducive, productive and genetic parameters of a flock

Abstract

A collection of data has been carried on the Merino Beira Baixa sheep at the Escola Superior Agrária (Agriculture School)in Castelo Branco (ESACB)in Portugal from 1981 to 1987. According to the birth type of females (single of double), their average age at the time of first lambing amounted to 600,10 ± 158,86 days and to 583,90 ± 159,78 days.Differences were not significant. However this parameter was influenced by the "year" factor (P<0,01). It was shown that the intervals between lambings (I.P.) did not depend on the parturition months inside the seasons, but depended on parturition months between the two parturition seasons (from January to March 296,4 ± 64,22 days and from September to November 380,0 ± 71,5 days). The "I.P." revealed significant differences (P<0,01) in terms of the conception age. The average apparent fertility rate amounted to 86,6%, the prolificacy to 114,2% and the average numerical productivity to 92,7%. All these rates were influenced by the ewes age at lambing. Analysis were carried on further reproductive parameters.