The present study was undertaken on data of 113 Gir cows maintained at Kasturba Gram Dairy Farm, Indore, Madhya Pradesh, India over a period of 18 years from 1995 to 2012, based on age at first calving. The overall means for weight at first calving (WFC), age at first calving (AFC), and first lactation milk yield (FLMY) were 402.22± 1.28 kg, 1709.04± 51.92 days and 1664.95± 280.72 litres respectively. The heritability estimates for WFC, AFC and FLMY were 0.248± 0.234, 0.307± 0.206 and 0.112± 0.252 respectively. The genetic correlation between WFC and AFC was positive and significant, while it was negative in between WFC and FLMY. The genetic correlation between AFC and FLMY was low and negative. The phenotypic correlations between all traits were positive.
The present study was undertaken on data of 150 Frieswal cows (a new strain of Sahiwal x Holstein Friesian) maintained at Military Dairy Farm, Agra, over a period of 15 years from 1996-2010, based on age at first calving. The overall means for age at first calving (AFC), weight at first calving (WFC), first lactation milk yield (FLMY), first lactation period (FLP), first dry period (FDP) and first calving interval (FCI) were 928.07±0.08 days, 369.87±0.92 kg, 4054.35±22.14 litres, 301.84±0.26 days, 99.40±0.15 days and 401.33±0.33 days respectively. The period of calving has significant influence on AFC and WFC, whereas non-significant influence on FLMY, FLP and FDP. The season showed significant influence on all the traits under study except FLMY. Both period and season has highly significant influence on FCI.
A total record of 113 Gir individuals spread over a period of 18 years from 1995 to 2012, were analyzed to estimate the effect of genetic and non genetic factors on first lactation period, first lactation milk yield and first dry period. The overall means for first lactation period (FLP), first lactation milk yield (FLMY) and first dry period (FDP), were 343.58± 10.37 days, 1664.95± 280.72 litres and 177.29± 10.59 days respectively. The heritability estimates for FLP, FLMY and FDP were 0.168± 0.238, 0.112± 0.252 and 0.419± 0.234 respectively. The genetic correlation between FLP and FLMY was positive and significant, while it was low and negative between FLP and FDP. The genetic correlation between FLMY and FDP was positive and highly significant. The phenotypic correlations between all traits were high and positive.
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