Studies on genetic and non-genetic factors affecting prediction of first lactation milk yield from part records in crossbred cattle
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Date
2015
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Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana
Abstract
In the present study effect of different genetic and non-genetic factors viz. sire, animal genetic group, period, season, weight at birth, age at first service, age at first calving, 305 day milk yield, lactation milk yield, first lactation length, test day milk yield, fortnightly milk yield, monthly milk yield and prediction of first lactation milk yield from test day, monthly and fortnightly milk yield and breeding value of sires were studied. A total of 642 production and reproduction records of crossbred cattle from the year 1991 to 2014 were utilized in the present study to calculate breeding value of sire maintained at GADVASU Dairy Farm. Breeding value was calculated by BLUP and least square of Harvey (1979). The least square mean of crossbred cattle for different traits were, for WAB was 28.32±0.35 kg, for AFS was 604.79±13.24 days, for AFC was 942.39±12.00 days, for WAC was 399.98±4.24 kg, for AAD was 1363.00±20.13 days, for MY 305 was 3594.58 ±89.08 kg, for LMY was 4399.99 ± 146.09 kg, for LL was 393.12±9.93 days, for FMY 305 was 3427.00±80.69 kg, for TMY 305 was 3498.61±77.84 kg, for MMY 305 was 3461.55±78.44 kg, for FLMY was 4128.94±125.71 kg, for TLMY was 4227.67±129.53 kg for MLMY was 4211.83 ± 120.35 kg. The least square mean for fortnightly, monthly and test day milk yield ranged from 227.54±5.49 to 138.16±5.79 kg, 886.26±20.00 to 276.58±10.99 kg, 14.91±0.39 to 9.00±0.33 kg respectively. The heritability of different traits were, for WAB was 0.14±0.10, for AFS was 0.52±0.14 for AFC was 0.40±0.13, for WAC was 0.29±0.12 for AAD was 0.32±0.12 for MY 305 was 0.49±0.14, for LMY was 0.40±0.13, for LL was 0.26±0.11. The heritability for fortnightly, monthly and test day milk yield ranged from 0.30±0.15 to 0.44±0.15, 0.32±0.14 to 0.62±0.16 and 0.51 ± 0.16 to 0.16 ± 0.12 respectively. The effect of sire was highly significant for all traits. The effect of season was also significant for almost all the traits. The effect of animal genetic group was non-significant for all the traits. The effect of period was non-significant for almost all the traits. AFC had significant influence on milk yields. The genetic and phenotypic correlation among WAB, AFS, AAD, LL was moderate. The phenotypic and genetic correlation of MY 305 with fortnightly, monthly and test day milk yield were moderate to high. For predicted 305 day milk yield R2 value from fortnightly, monthly and test day milk yield were 71.01, 72.92 and 69.60% respectively. For predicted lactation milk yield R2 value from fortnightly, monthly and test day milk yield were 57.08, 58.55 and 56.50%, respectively. Breeding value of 77 sires for lactation milk yield averaged to be 4519 kg and 4630 kg by LS and BLUP method. The average breeding value by LS method on the basis of fortnightly, monthly and test day milk yield were 4332, 4382 and 4349 kg respectively. The average breeding value by BLUP method on the basis of fortnightly, monthly and test day milk yield were 4241, 4295 and 4286 kg.