Genetic and non-genetic factors affecting monthly test day milk yields and first lactation milk yield in crossbred cattle of Kerala

In this present study data of 936 crossbred cattle sired by 188 bulls spread over a period of 16 years (2002-2017) in seven different field centers of ICAR-Field Progeny Testing Scheme, Kerala were used. Least squares means for ten monthly test days starting from 20th day of calving at 30 days interval and first lactation milk yield (FLMY) were 10.35±0.15, 10.71±0.14, 10.25±0.14, 9.73±0.13, 9.11±0.13, 8.44±0.13, 7.80±0.12, 7.03±0.0.11, 6.16±0.12, 5.41±0.13 and 2510.71±30.49 kg, respectively. Period of calving and batches of sires had significant effect on some of the MTDMYs and FLMY. Season of calving had significant effect only on first MTDMY. Genetic group, sources of sires and age at first calving had non-significant effect on MTDMY and FLMY. Heritability estimates ranged from 0.004±0.107 in 9th MTDMY to 0.531±0.136 in 4th MTDMY. The correlations of other MTDMY were not estimable. Higher estimates of genetic and phenotypic correlations of MTDMYs with FLMY revealed that MTDMY and FLMY can be used as selection criteria for cow or sire evaluation in crossbred cattle of Kerala.