Abstract
Overall, least square means for total milk yield, yield up to peak and persistency of first lactation from 257 Sahiwal cows were 1478.93 ± 30.62 litres, 572.65 ± ]2.40 litres and l.61 ± 0.04, respectively for progeny of 15 sires and calved during 1)80 to 1989 at Livestock Production Research Institute, Bahadurnagar (Okara). The effect of sire, sire group and year of calving was non-significant while season of calving had significant effect on these traits. The genetic, phenotypic and environmental correlation coefficients between total milk yield and yield up to peak were l.287, 0.734 and 0.66] while the heritability values of these two traits were 0.123 ± 0.132 and 0.109 ± 0.127, respectively. The phenotypic correlation between total milk yield and persistency was 0.305.
