The present study was undertaken to study the effect of various genetic and non-genetic factors on persistency of milk production and to identify the most appropriate persistency method that fits best in environment of Punjab. Effect of different non-genetic factors viz. year of calving, season of calving, level of production and genetic group of animals based on the level of exotic inheritance on persistency of milk yield in crossbred cattle were studied. Data on 577 first lactation daily milk yield records of crossbred cattle maintained at GADVASU dairy farm over a period of 25 years from 1991-2015 were utilized to calculate persistency coefficients by Khmel’Nit skii (P1) and Sturtevent (P2) methods. Overall least squares means for persistency by Khmel’Nit skii and Sturtevent (P2) methods were 0.56 ± 0.11 and 84.2 ± 1.45. Persistency of milk production was measured in Holstein Friesian × Sahiwal cattle up to 42nd week of lactation and overall persistency (%) for weekly milk production in first lactation was found to be 84.22%. Effect of genetic group on Khmel’Nit skii and Sturtevent methods was non-significant. Season of calving and level of production had significant (P<0.01) effect on persistency of milk yield by Sturtevent method. Effect of period of calving on persistency of milk yield was found to be significant (P<0.05) by Khmel’Nit skii method. Present study revealed that Holstein Friesian × Sahiwal cattle have good persistency of milk production in first lactation.

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