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This study was performed to analyses the persistency of lactation inHolstein Friesian cattle, by analyzing 168 lactation record from the period of 2006-2013 (8 years) at Government Dairy Farm Quetta, Baluchistan. The (PL) persistency of lactation was found lower in first lactation, while highest in 3rd lactation in season winter and summer calves. The overall average (PL) was found 85.99±7.30% in winter calves and 83.79±7.27% in summer calves, whereas calving season effect was observed non-significant (p>0.05). The highest (PL) was found in Sire-D followed by Sire- B Sire_ A and Sire_ C. The overall average(PL) in Holstein Friesian cattle was found 84.74±7.94%. The Sire-wise effect of (PL) was found non-significant. The heritability estimates of (PL) was estimated low (0.094), while the correlation estimates was found higher among lactation length vs milk yield length (0.814), milk yield vs (PL) (0.883) and (PL) vs lactation length (0.747). It was concluded that results of current study for (PL) and Heritability of production traits were low to moderate for heritable traits, which can be improve through the proper environmental and manage mental conditions.
Keywords: Holstein Friesian; Persistency; Heritability; Correlation