AS-395 Sept. 1971


SELECTION AND MANAGEMENT OF HERD BULLS
W. L Singleton and L. A. Nelson, Animal Sciences Department
Selection
"Which bull should I buy? " This is one of the most important decisions a breeder will ever make. For a bull not only represents a sizeable investment, but also influences the economic return from the herd for years to come. Therefore, the breeder wants a bull that will both settle a high percentage of the cow herd with one service and sire calves with genetic potential for rapid and efficient growth.
"How do I find that kind of animal?" Following is a discussion of the factors to consider when selecting a future herd bull.
PERFORMANCE
First, select a bull on which performance information has been kept, paying closest attention to his weight adjusted to 365-days and weight ratio. His performance should be at least equal to the herd average in which he was produced or to the average of a group of bulls on test. His superiority (or inferiority) with respect to the average is indicated by the weight ratio, which is calculated as follows:
Individual Bull's 365-Day Weight
Average 365-Day Weight of Group of Bulls
A bull with a weight ratio above 100 is heavier than the group average. Likewise, individuals with adjusted weights below average have weight ratios less than 100. For example:
Generally speaking, only about 30% of a bull calf’s superiority at weaning (205 days) will be passed on to his progeny; but a much greater portion (50 to60%) of a bull's superiority as a yearling (365 days) should be transmitted to his calves. This means that a bull’s superiority is better determined at 365 days than at 205 days of age.
It is often said that a bull should weigh 1, 000 pounds at a year of age. This is a good rule-of-thumb for Angus and Hereford bulls under average nutrition and management conditions; however, Charolais or Simmental bulls should weigh more near 1,200 pounds.
Two bulls with the same genetic growth potential may vary 200 pounds or more just because they were fed differently. For that reason, find out what kind of ration the animal was fed, and try to estimate what portion
Beef Section • Animal Sciences Department
Cooperative Extension Service, Purdue University, West Lafayette, Indiana
Selection   Beef