SCIENTIFIC RESEARCH.

Southland Times, Issue 19546, 9 May 1925, Page 15

SCIENTIFIC RESEARCH.

DIFFERENCES IN BULLS. The selection of a bull that will transmit his characteristics to his offspring to the highest degree is not a new problem of the cattle breeder, but it is one which the earliest improvers met with. It is a known fact that sometimes a bull of excellent individuality does not prove to be a good breeder.” In other words, he does not have the power to transmit his likeness to his offspring. The bull that can transmit his characteristics to his offspring to a marked ’ degree is said to be prepotent. Prepotency is not a property of the bull only, but cows may be prepotent also, i It is often believed that prepotency is a characteristic of an animal as a whole, and that it is closely related to vigour. Vigour and masculinity are of the utmost importance in animal breeding, but there is no convincing evidence that prepotency of any specific characteristic is due to masculinity. An animal may be prepotent for one characteristic and not prepotent for others. In other words, prepotency is concerned with certain parts of an animal instead of with the animal as a whole. The inheritance of animals is made up of units and the power to transmit these is determined for each unit by the inherent make-up of the animal. When the Aberdeen-Angus,

pure for black and polled, is crossed on a red-horned individual,' the offspring is black 'and polled. Then we may say that the Aberdeen-Angus is highly prepotent for these two characteristics. However, if the offspring from this cross is crossed with a red-horned individual the offspring in the long run will be of four different kinds, namely: Black-polled, black-horned, redpolled and red-horned. It is evident that the Aberdeen-Angus which is pure for these two characteristics is more prepotent than the crossbred. It is now clear that prepotency depends on the purity of the animal mated. Individuals that are pure (homozygous) for the largest number of characteristics show the highest prepotency. As a rule, animals that have been constructively line-bred for several generations are more prepotent than those that have been promiscuously bred. Therefore a careful study of an animal’s pedigree aids the breeder in selecting prepotent animals. Individual merits should not be sacrificed, however.

Purebred animals merit our attention for two main reasons: (1) Individual merits, (2) prepotency. Its individual merits are as a rule evident. Its claim to prepotency rests upon the fact that its ancestors, or at least its immediate ancestors, possessed the v same individual merits, and that it is apt to be much more prepotent for these merits than is an animal of equal merit, but lacking uniform ancestry.