Breeding Program

The following steps appear to be appropriate to develop such a program:

• Select a suitable breed of dairy animals with consideration given to breed preference, the market for milk, and the value of surplus animals.

• Select or purchase the best animals available, based mainly on their genetic potential for milk production, but with due consideration given to type.

• Decide about the breeding system to be followed.

• Evaluate the strong points and the weak points of the animals in the herd (herd analysis).

• Use sires that offer the greatest promise of improvement in traits of offering, the best potential economic return in the future, based on predicted transmitting ability and reliability of the sire's proof, but with consideration given to the price of the semen.

• Follow a feeding and management program that permits the animals in the herd to fully express their genetic potential.

Objective of Breeding Program

The fulfillment of this objective requires dairy animals that can produce large amounts of milk efficiently and with a minimum care, animals that can compete at the manger, animals that will be strong and healthy throughout the rigors of a long productive life. This goal can be attained through a balanced breeding program which utilizes the best genetic merit for economically important traits available both in cow and bulls. The attainment of this objective will result in a herd of animals with outstanding genotype for total economic merit. The ideal genotype may vary from herd to herd because the relative economic importance of different traits varies depending on the herd's management program and the country or the region in which it is located. Breeding towards the ideal genotype for a particular herd environment requires the evaluation of many alternatives in the selection program and consideration of how many different traits affect the herd's profitability status.

High Yielding Dairy Animals in a Breeding Program

Dairy Animals in the Breeding Program:
The dairy animals for which most dairymen strive are usually referred to as `foundation animals'. These animals have following characteristics:

• They have outstanding phenotypes and have transmitted superior genotypes to their progeny

• They are valuable as breeding stock

• They possess most of the qualities of a strong constitution.

• They have high milk yield

Unfortunately, few animals possess all the desirable qualities. Therefore, genetic improvement should be evaluated in terms of the economic importance of each trait for making an animal profitable in a particular herd. One economically important end result of a strong constitution is the capacity for longevity. Longevity in dairy animals means length of productive life and is usually measured in years of age or number of completed lactations. In addition, the ability for longevity is an ingredient of a profitable program in most herds. Every animal that is culled because of a weakness or defect, decreases the dairyman's opportunity for selection, reduces the effectiveness of his breeding program and costs him money. However, a high proportion of old dairy animals in a herd is a sign that the effectiveness of the breeding program has decreased. An effective breeding program should produce a steady flow of heifers that are genetically superior to older animals, no matter how good they were.

Milk Yield and Milk Components:
First lactation yield of each dairy animal is of primary importance to her profitability. In addition, initial selection of sires is mostly on the basis of first lactation yields of their daughters. A number of studies have shown that animals with higher first lactation yields tend to have a longer productive life. Positive phenotypic and genetic correlations exist between first lactation yield and lifetime, thus selection mainly on the basis of first lactation yield will result in animals with greater longevity.

The influence that milk components have on a farmer's income is determined largely by the milk pricing structure in a particular area. For a long time milk fat has been the only component paid for directly in most parts of Asia. The future, however, will be different since in many advanced countries, emphasis seems to have shifted from fat content alone to protein and solids-not-fat contents of milk as a basis for milk pricing. At the present time, the most efficient way for dairymen to increase income and to follow the changing trend in milk pricing is to increase milk yield while maintaining the level of components. It is possible that after a few years as component pricing becomes more widespread (especially with the arrival of western-based milk product manufacturing companies), component differentials may increase in importance, especially in areas where a high proportion of milk will be used for manufacturing purposes. The heritabilities of level of milk components are high, and yields are the same as milk yield. There are high positive genetic correlations between yield of milk and yield of milk components and strong negative genetic correlations between component percentages and milk yield. Therefore, it appears that dairymen should select for component yields rather than component percentages in genetic improvement programs.

Body Size and Efficiency of Feed Utilization:
Average differences apparently exist among the major dairy breeds in their efficiency of feed utilization. Within breeds, larger animals, as judged by several measurements of size, are less efficient in feed utilization than are smaller animals. These relations of size and efficiency of feed utilization are essentially the same in all breeds. The larger animals that have lower efficiency of feed utilization also have, on the average, lower income over feed cost and therefore lower relative profitability.

It is suggested that dairymen should not select directly for larger animals, rather they should select for high yield. By doing so, they will breed higher-yielding animals that on the average will also be larger in size.

Reproductive Efficiency:
Reproductive problems are often the second most frequent cause of dairy animal losses, after culling for low yield. A high incidence of reproductive problems reduces the opportunity for genetic improvement of yield by increasing days open and days dry; as a result the generation length is increased and the potential rate of genetic improvement is decreased over a given period of time. An unusual situation is probably due to the fact that higher yielding animals are known to have more breeding value on an average than low producers. An apparently positive genetic correlation exist exists between breeding problems and level of yield and longevity. Therefore, an effective herd program of diagnosis and treatment of reproductive problems is very important for maximum genetic progress.

Mastitis and Milking Rate:
Mastitis is probably the most costly disease afflicting dairy animals in the world. The heritability of resistance to mastitis is low (around 0.10).

Milking speed is also an economically important trait of dairy animals. Slow-milking animals require extra labour to milk and efficiency of labour utilization is one of the most important factors of profitable management. The heritability of milking speed is about 0.30.

The genetic correlations indicate that higher yielding animals have a tendency to contract more mastitis. Some evidence also exists that faster-milking animals tend to fall victim to mastitis, probably due largely to the tone of the teat sphincter muscle. A more relaxed sphincter muscle results in faster milking, but a greater incidence of mastitis since bacteria can enter the streak canal more easily. However, there is essentially genetic correlation between yield and milking speed. Therefore, one can select for higher yield independent of milking speed.

These relationships suggest that dairymen should select for high milk yield but should exercise restraint in selecting for rapid milking rate. Selection for both may result in animals with a higher susceptibility to mastitis and a tendency to leak milk.

Importance of Superior Bulls in Dairy Animals Breeding Program

• The greatest opportunity for genetic improvement in a herd is through the bulls that are selected for use in the breeding.

• The selection differential within each herd can be much higher for bulls than for cow, since bulls are selected from among the outstanding bulls in the entire country, especially when used by means of frozen semen, whereas the cows selected must constitute the majority of those in the single herd.

• The use of a superior sire for several consecutive generations can improve the genotype make up of a herd. In each generation, one-half of the remaining portion of original genotypes is replaced by the genes from the superior sires. Therefore, after only 3 generations of breeding to superior sires, seven-eighth of the herd's genetic makeup comes from the sires and only one-eighth of the original genotype remains.

• For most herds, the greatest potential for genetic improvement is through bulls available for artificial insemination.

• A dairyman who wisely selects bulls to be used in his herd can gain much additional income.

Copyrights © Dr. M Jassar Aftab, All Rights Reserved