For open heifers, choose from the sires normally used. However, select only those bulls whose calves will be born with the least expected difficulty. Avoid using difficult calving sires to breed cows having a history of calving problems. Place little emphasis on calving ease for second and later calving. Use sires with high fertility ratings on problem breeders.
Management skills can influence the generation interval and selection intensity.
Genetic progress and profit potential are reduced by management decisions that result in increases in the number of animals culled for involuntary reasons or lengthens the generations interval. Reproductive performance is a major management concern since extending the calving interval and forced or involuntary culling increase the generation interval, while involuntary culling also decreases the selection intensity. Producers without the management skills to use AI to attain the aforementioned goals make economic and genetic sacrifices. If heifers are not bred to superior AI sires, progress is reduced. Using genetically superior sires increases the genetic progress 3 to 4 times the rate of herds using natural service.