Studies On Determination Of Breeding Objectives And Optimization Of Breeding Plan For Dorper Sheep Breeding Enterprises

Based on the situation of Dorper sheep market and production characteristics of breedingenterprises, this paper studied the Dorper sheep breeding objective traits, used ZPLAN to simulatedifferent breeding scheme for the three main breeding system (1tier breeding system,2tier breedingsystem,2tier open nucleus group breeding system), compared cumulative expected profit of differentbreeding scheme over a specified period to determine the optimal breeding scheme through the breedingenterprise’s profit function.Objective traits of this study include eight-month live weight and conformation traits (head type,limbs structure, hoof type, conformation balance). This study measured the degree of conformationbalance by morphological index and the scoring system, and used two-step selection method tocomplete the breeding of the Dorper sheep.The results show that the profit of breeding enterprise increases first and then decreases with theproductive lifetime of the sheep (male, female) prolonging, and increases with the decreasing of malefemale ratio. The lower cost of breeding or the higher price of the sheep, the smaller optimal productivelifetime of the sheep. If wanting to maximize the profit, the breeding enterprises should strengthen themanagement to prolong the productive lifetime of the ewes to reduce the breeding cost and properlyshorten the productive lifetime of the ram (the optimal productive lifetime of the ram range from2to3production cycle, that is16to24months in this study) to increase the genetic progress. When the aim isto achieve the most genetic progress, enterprises can decrease male female ratio to expand the coverageof the excellent rams in the Dorper sheep population.With the increasing of breeding group proportion, the optimal productive lifetime of the rams inproduction group will decrease. The progeny test could improve the genetic progress of the population,income and profit, has higher newly-increased investment earning rate. If having enough breedingability, the breeding enterprises should use the progeny testing because of improving genetic progressover percent25compared without progeny test. Male female ratio has a diminishing marginal effect onprofit in progeny test, so breeding enterprises should determine the male female ratio according to theprogeny test group size and the number of rams to be tested, not ignoring the high cost of the pursuit ofprogeny test accuracy.