O level Notes : Agriculture - Animal Improvement - Breeding
Animal improvement can be achieved through carefully planned mating (breeding) of animal breeds with desired commercially viable characteristics. Animal improvement requires that only the best animals be used for breading. Success of a breeding program is also influenced by inheritance and environmental factors. These play an important role in animal improvement. In animal breeding programs, keeping of critical breeding records of the animals is of paramount importance.
Records of the animals that are mated to produce the chosen offspring, should be kept so that the results thereof match with the correct characters. Disappointments and unexpected outcomes result, if planning and recording are not done properly.
Breeding is the art and science of using knowledge of genetics to improve animals in production efficiency. Breeding of animals is a process that is used by farmers to select and allow only animals with the desired characteristics to become parents of the next generation. The major observable importance of breeding is the increased multiplication of animals. However, there are many other associated benefits of animal improvement.
Importance of animal breeding or
- It improves the growth rate of animals.
- Breeding improves animal productivity. Animals yield better quality and quantity of products such as meat, milk, hides, wool and skins.
- Animal breeding improves resistance of animals to parasites and diseases.
- It improves adaptability of animals to harsh and adverse climatic conditions.
- This improves feed conservation ratio of animals, that is, animals will be able to change food meat thus increase monetary returns.
- Breeding improves animal fertility.
Types of breeding methods
- Pedigree breeding
Only in-breeding and cross-breeding will be discussed in detail in this chapter.
This is the type of breeding in which genetically related animals are mated. In-breeding is done when characteristics of economic and adaptive importance are to be maintained in the herd. Such type of breeding is practiced only if there are no other disadvantages associated with the breeding on the herd. An example of in-breeding is when a breed like Hereford in beef cattle is continuously inbred on the same farm using young stock from the same herd. Both males and females involved will be related.
Characteristics like true to type (pure breeds), are only achieved through in-breeding. The only problem that comes out of this method of breeding is accumulation of undesirable characteristics that may be found within the same breed of animals when the genes controlling the character come together.
Random fusion of male and female gametes
Advantages of in-breeding
- Superior desired traits are continuously passed on to offspring.
- In-breeding helps to maintain uniformity of the breed.
Disadvantages of in-breeding
- In-breeding can result in abnormalities occurring.
- In-breeding weakens genes, resulting in poor resistance to diseases, reduction in animal size and loss of fertility in animals, and reduced vigour of animals.
Cross-breeding is when two different breeds of animals of the same species are mated or bred. They will produce a hybrid offspring. Their offspring will tend to inherit those dominant characteristics of economic importance in their F1 generation. The tendency therefore is for the hybrids to become better performers in most characteristics than the average of their parents. This behavior is called hybrid vigour or heterosis.
- Cross-breeding leads to increased performance of offspring hybrid vigour.
- Offsprings produced are well adapted to the environment.
- Cross breeding results in improved performance, that is fast growth rate, high fertility, and better resistance to parasites and diseases.
Disadvantages of cross breeding
- Proper record keeping on individual animal performance is needed. Records are important in predicting outcomes and avoiding disastrous gene combinations.
The major differences between in-breeding and cross-breeding
- Inbreeding is the mating of closely related animals of the same breed and species whereas cross-breeding is the mating of unrelated animals of different breeds but of the same species.
- Cross-breeding can produce new breeds while inbreeding maintains the same breeds.
- Cross-breeding can produce animals with hybrid vigour whereas in-breeding cannot.
- In-breeding may cause accumulation of undesirable characteristics in the herd or family of animals whereas cross-breeding brings about genetic variation.
- There are more economic benefits from cross-breeding than from in-breeding.
Pure breeding is the mating of pure bred animals of the same species. For example, Brahman bull mated with a Brahman cow. Animals with superior characteristics are selected and mated to produce a pure-bred. Pure breeding is commonly done with dairy cows to produce p ure breed animals.
Advantages of pure breeding
- Offspring produced have superior traits like their parents.
- Mating of pure breeds registered under a particular head society results in pedigree breeds that are true to type.
Upgrading is a breeding system in which a male pure bred is mated with a female cross bred animal. Continuous mating of generations improves the physical appearance of the cross breed to that of pure breed. Offspring produced through upgrading are known as high grade because they perform better than their parents.
Advantages of upgrading
- The system is cheap and easy to practice.
- Offsprings produced outperform their parents, hence the name upgrade.