PHENOTYPIC AND GENETIC CORRELATIONS BETWEEN FIRST LACTATION MILK YIELD AND SOME
PERFORMANCE TRAITS IN SAHIWAL CATTLE
K. Javed, M. Abdullah1 , M.
Akhtar2 and M. Afzal3
University
of Veterinary and Animal Sciences,
Lahore, 1Deptt. of Livestock Management,
University of Agriculture,
Faisalabad, 2Livestock Experiment Station, Khizerabad Distt.
Sargodha and 3 Livestock Production Research Institute, Bahadurnagar,
Okara
Abstract
Data on 8948 pedigree, breeding and
performance records of a purebred herd of Sahiwal cattle maintained at the
Livestock Experiment Station Jahangirabad district Khanewal (Pakistan)
during the period 1939-98 were analysed. The phenotypic, genetic and residual
correlations between first lactation milk yield and some first lactation and
lifetime traits were estimated, using Bivariate REML analysis. Phenotypic,
genetic and residual correlations between first lactation milk yield and age at
first calving were 0.67, 0.61 ± 0.30 and 0.73; between first lactation milk
yield and first lactation length were 0.35, 0.48 ± 0.38 and 0.31; between first
lactation milk yield and first calving interval were 0.39, 0.46 ± 0.46 and 0.39;
between first lactation milk yield and first dry period were 0.35, 0.49 ± 0.46
and 0.30; between first lactation milk yield and lifetime milk yield were 0.02,
0.01 ± 0.77 and 0.05. Positive and high genetic correlation between first
lactation milk yield and age at first calving indicated that the selection for
higher first lactation milk yield would increase the age at first calving, which
is not advantageous.
Key words:
First lactation; milk yield; genetic and phenotypic correlations; Sahiwal
cattle.