Ciência e Tecnologia Veterinária

Evaluation of Sires Using Different Sire Evaluation Methods on the Basis of First Lactation Traits in Sahiwal Cattle

Abstract

Jaswant Singh and CV Singh

The records of 1367 crossbred cattle sired by 112 bulls were analysed to estimate breeding values and to compare various methods of sire evaluation viz. BLUP, LSM and sire evaluation methods on the basis of age at first calving, first service period, first lactation period, first dry period, and first calving interval. The average breeding value for FLMY. FLL, AFC, FCI, and FDP were estimated as 1711.63 kg, 320.38 days, 1299.54 days, 524.25 days and 207.60 days by method, 1941.16 kg, 321.60 days, 1287.12 days, 514.86 days and 195.57 days by LSM method and 1890.06 kg, 313.70 days, 1281.25 days, 508.56 days and 194.46 days by BLUP method. The accuracy, efficiency and stability of EBV’s of sires for the first lactation and lifetime traits were compared by different methods to judge their effectiveness. The estimated breeding values of sires for all the first lactation traits by , LSM and BLUP revealed that EBV’s of sires estimated by least squares method showed smaller genetic variation in comparison to and BLUP methods. The LSM was adjudged as the most efficient method of sire evaluation. The LSM had minimum error variance for most of the first lactation traits and considered to be more superior over other two methods i.e., and BLUP. The product moment correlations among the estimated breeding value of sires for first lactation traits by , LSM and BLUP methods ranged from medium to very high and significant (P<0.01) in all the three methods of sire evaluation. The rank correlations among the breeding value of sires estimated based on first lactation traits were medium to high and significant (P<0.01). The results indicated that least square method (LSM) had the lower error sum of square for all the first lactation traits and least square method (LSM) is relatively more accurate as compared to best linear unbiased prediction (BLUP) method but not overall. The LSM had higher R2 value for the first lactation traits as 40.50% (FLMY), 18.17% (FLL), 23.94% (FCI), 24.59% (FDP) and 48.47% (AFC) than the BLUP method. The estimated R2 values are less which indicates that both methods are less suitable for present data. Therefore as for as stability is concerned among the methods of sire evaluation, the LSM method was most stable being its CV (%) which is closest to the CV (%) of unadjusted data. The rank correlations obtained were highest and statistically significant (P<0.01) and ranged from 0.74 ( and BLUP) to 0.88 ( and LSM). The highest rank correlations among the breeding values estimated from different methods revealed that rankings of sires were similar to the extent of 74 to 88 per cent from these methods of sire evaluation.