Abstract
Aim:The aim was to estimate genetic factors affecting the first lactation milk production traits in Kankrej cattle of North Gujarat.Materials and Methods:The 475 first lactation records of Kankrej cows that were maintained at the Livestock Research Station, Sardarkrushinagar Dantiwada Agricultural University, Sardarkrushinagar, Gujarat, over a period of 35 years from 1980 to 2014 were studied. The least squares maximum likelihood program was used to estimate genetic parameters of first lactation traits. Heritability was estimated through paternal half-sib analysis in adjusted data.Results:The heritability estimate for production traits was 0.40±0.17, 0.45±0.17, 0.35±0.18, and 0.20±0.14 for standard 300 days milk yield (F300Y), total lactation milk yield (FLY), wet average (FWA), and lactation length (FLL), respectively, in the first parity. All the genetic and phenotypic correlations among different production efficiency traits were high and positive. Genetic correlations between F300Y and FLY, FLL, and FWA were 0.80±0.20, 0.59±0.16, and 0.81±0.32, where as the phenotypic correlations were 0.969, 0.688, and 0.868, respectively. Genetic correlations of FLY with FLL and FWA were 0.60±0.13 and 0.79±0.20, whereas the phenotypic correlations were 0.777 and 0.817, respectively. Genetic and phenotypic correlation between FLL and FWA was 0.63±0.28 and 0.31, respectively.Conclusion:The heritability estimate of all first parity lactation traits waslow to medium (0.20-0.45) indicated the scope for further improvement in this trait through selection as well as managemental practice. Higher genetic and phenotypic correlation between thefirst lactation milk production traits gives theidea that genetic gain due to selection for one trait also givesmorecorrelated response of selection for other traits which is economically advantageous.
Highlights
Kankrej cattle breed of India is considered as the best dual purpose cattle breed, i.e., female animals are used for milk production as well as male used for draught purpose in temperate region.Cattle in the tropics have, on average, lower milk yields and shorter lactations length than cattle in temperate countries
The heritability estimate of all first parity lactation traits waslow to medium (0.20-0.45) indicated the scope for further improvement in this trait through selection as well as managemental practice
The heritability estimates for first milk production traits are presented in Table-1, viz., first standard 300 days milk yield (F300Y), first lactation milk yield (FLY), first wet average (FWA), and first lactation length (FLL)were 0.40±0.17, 0.45±0.17, 0.35±0.18, and 0.20±0.14, respectively
Summary
Kankrej cattle breed of India is considered as the best dual purpose cattle breed, i.e., female animals are used for milk production as well as male used for draught purpose in temperate region.Cattle in the tropics have, on average, lower milk yields and shorter lactations length than cattle in temperate countries. The difference is due to genetic and non-genetic factors. The genetic composition of a population can be studied by considering the relative importance of heredity and environmental factors affecting the performance of individuals in that population [2]. Precise and accurate knowledge of genetic parameters is of paramount importance for planning appropriate selection and breeding strategies for the genetic improvement of dairy animals [3]. A basic prerequisite for planning of breeding program is the variability existing in the population and how much of this is caused by differences in the genetic make-up of the individuals. With the help of heritability, one can predict the breeding value of the individual. The magnitude of heritability dictates the choice of the selection method and breeding system [4]
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