author(s)
Garima Choudhary, U Pannu and GC Gahlot

abstract
The present investigation was conducted to study the efficiency of sire’s breeding values by incorporating auxiliary traits with first lactation milk yield (FLMY). Age at first calving (AFC), first service period (FSP), first calving interval (FCI), first dry period (FDP) and first lactation length (FLL) were considered as auxiliary traits. The data for the present investigation were obtained from Records of 91 cows maintained at Livestock Research Station, Beechwal, Bikaner, over 15 years (2002 to 2016). Sires were evaluated for first lactation milk yield by simple daughter’s average method (^D), Contemporary comparison method (CC), least-squares method (LSM), best linear unbiased prediction (BLUP) and by incorporating auxiliary trait. The results revealed that LSM method of sire evaluation was more efficient than all other methods for FLMY. When auxiliary traits were used with FLMY for sire evaluation the error variance was very high for all auxiliary traits. Among the sire indexes incorporating auxiliary traits, the lowest error variance was found when FDP was considered as auxiliary trait. This indicated that considering one auxiliary trait along with first lactation milk yield may not be very effective criteria for ranking sires for FLMY in comparison to any other sire evaluation method. The rank correlation among auxiliary sire indices ranged from 0.98 to 1, indicating similar ranking of sire for breeding values of milk production in all the auxiliary sire indices.