Genetic parameters for milk yield, persistency, conductivity and milking efficiency in first lactation Jersey cows in Sri Lanka

Abstract

Dairy production in Sri Lanka is slowly changing from a small-scale extensive system within mixed farms to larger specialized units with intensive management based on temperate breeds and modern milking systems. The country's tropical climate may require a special breeding program for imported breeds to enhance adaptability to local conditions which could be based on data automatically recorded at the parlour. Therefore, the objective of this study was to estimate genetic parameters for milk persistency, milk electrical conductivity, flow rate, 305- day milk yield and daily am/pm milk yield using data collected automatically from November 2015 to March 2016 for imported first-lactation Jersey cows (826 cows) under an intensive management system in a single farm. Variance components and variance ratios were estimated as posterior means from a Bayesian Gibbs sampling analysis. As expected from the data structure, heritabilities were low to medium for all analysed traits and genetic correlations were all in the expected direction. Therefore, even in Sri Lanka's tropical conditions the genetic component of the phenotypic variation is sufficient to establish a breeding program based on imported Jersey cows to breed a locally adapted dairy cow.