Optimization of Progeny Testing Programs for Iranian Holstein Dairy Cattle

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Abstract

A deterministic model was employed to simulate various progeny testing programs compatible with the conditions of Holstein dairy cattle population in Iran. In simulated programs, the selection intensity of bulls was increased by increasing the ratio of cow population in mate with young bulls. Selection accuracy in the programs was fixed because of the fixed progeny group. Economic efficiency (the ratio of return to cost) increased with a decline in the increase in the number of young bulls reaching to its maximum value of 6.07 by 29 young bulls. Genetic gain per generation and return of progeny testing programs increased by increase in the number of young bulls, until their maximum values reached. The maximum genetic gain values were 430.7683 Kg, and 21924417479 Rials, with 29 and 99 young bulls, respectively. The cost of program increased linearly with a value of 51984332 Rials per bull. As a consequence, the program with maximum genetic gain per generation or return would not necessarily maximize the economic efficiency. Sensitivity of economic efficiency and number of young bulls of optimized programs were investigated through a 20% fluctuation in economic parameters. As a result, economic efficiency of optimized program had the most sensitivity at 20% increase in discount rate and as well the economic value of milk production, and number of young bulls in the optimized program showed the most sensitivity to the 20% increase in discount rate. No change in the number of young bulls in the optimized program was observed through an incease of 20% in bull price, bull survival rate, semen storage costs, price of culled sires and economic value of milk production.

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