This study aims to estimate genetic and phenotypic parameters for the Morada Nova, Santa Inês e crossbred Texel x Morada Nova in Federal District of Brazil. Data were available on 2337 lambings over a period of 14 years (1986 to 1999) from a commercial holding for meat production. The herd had no fixed breeding season. The effects of sex, number of lambs per lambing, month and year of lambing were determined for weights at birth, 30, 120 and 210 days of age as well as lambing interval and age at first lambing using analysis of variance procedures in the SAS program. Heritability, repeatability as well as genetic and phenotypic correlations for the Morada Nova sheep in the herd were estimated using MTDFREML. The generation interval was 952 days, with a mean litter size of 1.25 lambs. Lambings were distributed throughout the year, but 77% occurred between March and September, indicating a possible influence of day length or food availability on reproductive traits. Direct heritabilities for birth weight, weight at 30, 120 and 210 days were, respectively, 0.15, 0.11, 0.07, and 0.21 for Morada Nova sheep. The correlations between these traits were positive (0.19 at 0.64). The heritability for lambing interval was 0.17 and 0.93 for number of lambs per litter. The results indicate that the breed and birth weight were highly significant for all weights studied. Lambing number and birth month affect all the traits examined.
correlation; heritability; Morada Nova; repeatability; Santa Ines; weights
