Studies on economic traits and replacement rate in crossbred cattle
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Date
2019-07
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
The present study was undertaken on 2204 calvings of 390 crossbred cattle produced by 54 sires and maintained at Instructional Dairy Farm, Nagla of Govind Ballabh Pant University of Agriculture and Technology, Pantnagar (Uttarakhand). The data had a spread of over of period of 36 years (1981-2016).The least-squares analysis of variance for the first lactation traits revealed that the effects due to sires were significant for age at first calving (AFC), first lactation 305 days milk yield (FLMY-305), first lactation milk yield (FLMY), first lactation length (FLL) and first service period (FSP), and non-significant for first dry period(FDP) and first calving interval (FCI). The effects due to the period of calving were
found significant for FLL, FSP, whereas they were non-significant for all other traits. The effect due to the season of calving was found to be significant on FLMY-305 whereas nonsignificant effects were found for all other remaining traits. The effect due to the AFC was found highly significant (P 0.01) for FLMY whereas non-significant effects were found for all other remaining traits. The overall least-squares means for first lactation traits viz. age at first calving, first lactation 305 days milk yield, first lactation milk yield, first lactation length, first service period, first dry period and first calving interval were found as 1277.75 ± 101.56 days, 2673.48± 81.29 kg, 2746.23± 85.51 kg, 346.02 ± 7.44 days, 245.91± 5.39 days, 139.15± 7.53 days and 489.01± 9.79 days respectively. The heritability estimates for first lactation traits viz. age at first calving, first lactation 305 days milk yield, first lactation milk yield, first lactation length, first service period, first dry period and first calving interval were
observed as 0.31 ± 0.14, 0.37 ± 0.12, 0.27 ± 0.07, 0.17 ± 0.08, 0.17 ± 0.08, 0.17 ± 0.11, 0.24 ± 0.13 and 0.21 ± 0.09 respectively.The period effect on replacement rate and its components viz., mortality, culling and replacement rate were found to be significant. The season of birth had significant effects on abnormal birth and replacement rate whereas they were nonsignificant for female mortality and culling rate in female calves.The average values of abnormal births, mortality and culling of female calves upto AFC were found to be 9.12, 15.70 and 30.15 percent respectively. The replacement rates on female calf basis and total pregnancies basis were estimated as 54.18 and 25.27 percent, respectively. About half (45.18percent) of total female calves were lost from the herd till they attain AFC due to mortality and culling. Only one fourth (25.27 percent) of the total pregnancies turned into replacement heifers. It may be concluded that performance of crossbred herd under study is
comparable to other herds. Low to moderate heritability estimates obtained indicates presence of adequate genetic variation within the herd and hence improvement in traits under study is possible by genetic selection along with managemental interventions.
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