The effect of biological, management and economic factors on economic values for different traits in traditional and industrial systems of dairy cattle

Economic values for milk production, growth, reproduction and functional traits were estimated using a bio-economic model and the information collected on the traditional and industrial rearing systems of dairy cattle. Rearing methods were divided according to management system into four types: pasture, migratory rearing methods and industrial rearing of crossbred and Holestain cows. Economic value of each trait was estimated as the amount of change in the annual profit of systems by one unit increase of mean of the trait while the means of other traits were constant. In traditional rearing methods, the economic values for traits related to growth, survival and milk production traits, except for milk protein, were positive and the economic values for reproductive traits and longevity were negative. In industrial rearing methods, the economic values for milk production, survival rate and productive life, were positive and the economic values for reproductive, growth traits, other than live weight in adult animals in Holstein rearing method, were negative. Results indicated that calf rearing system had the main role in variation of economic values for production and survival traits. On the other hand, the pricing system for surplus heifers is the main factor affecting economic values for growth and longevity traits. The sensitivity analysis of economic values to20% change in prices showed that the price of live weight was the most effective factor on economic values.