Definition and Scope of Animal breeding :-
Animal breeding is simply defined biologically as the mating or coupling process between male and female organism to reproduce the young. In this context it is a reproduction term. That is a layman’s understanding of the term. It has wider scope and meaning when considered in a more scientific context. Breeding is thus the art of skillful application of the science and principles of genetics for the purposes of producing better species and types of animals.
Ibe (1999), defined Animal breeding as the application of genetic principles for the improvement of economically important characters in domestic animals. It is worthy of note that factors such as good nutrition, conducive environment (example, housing) and good health management are indispensable complements of genetic techniques for animal improvement.
Animal breeding techniques utilizes our knowledge of the cell structure and it two vital divisions namely, Meiosis and Mitosis, their consequence in population, growth and structure, it encompresses the intricate utilization of the various forms of gene action such as intra-allelic and inter-allelic gene relationships and on their progeny, generation after generations.
This is so because, by the Mendelian laws of particulate inheritance and the genelinkage exception, the breeder can manipulate the situation to improve upone the pre-existing animal populations in their adaptations, production and other expressions.
There are several traits in farm animals which breeders desire to improve upon. Some of these are qualitative, while others are quantitative. The qualitative represent the economic characters which are governed by polygenes. Examples of these characters are milk yield, butter-fat percentage, liver weight, calving interval, weaning weight, birth weight and fertility, egg number, growth rates, shank length, shell thickness, hatchability, litter size, number weaned, weaning weight, fat depth, carcass length, eye muscle area, birth weight, yearling weight, milk production, fleece weight and yield in cattle, poultry, pig and sheep etc.
Quantitative genetic methods are useful in bringing about improvements in these economic characters. The methods commonly employed are selection and various breeding method.
In addition to polygenes, these are single major genes which either govern some economic character directly or govern qualitative characters which have very close relationships with economic (quantitative) characters. Example is growth hormone gene for improved growth in animals, dwarf gene for improving feed efficiency in poultry, halothane sensitivity gene (for leanness in pigs) etc. Molecular genetic techniques for example recombinant DNA technology are important in using such major genes to bring about improvement in domestic animals. Also, various reproductive biotechnologies, include multiple ovulation and ombryo transfer (MOET), are employed in animal breeding. Most of all these techniques employed in Animal breeding are geared towards animal improvement performance for the benefit of Man.
Objectives of Animal Breeding
The breeding of animals practically seeks to achieve the following:
- To understand the populations he is confronted with, their genetic and out ward characteristics.
- To understand their behavior, adaptability and compatibility when brought in contact biologically with other populations that are of the same or different species.
- To identify individuals or groups of individuals that show higher or lower, better or worse inclinations in the character of interest, and to sort out or select such individuals or groups.
- To concentrate or disperse genes that are related depending on how we value their expression or their manifestation in animals.
- To obtain hybrid vigour i.e. the benefit of increased performance due to the enhanced or invigorated situation in an individual, originating from a cross between non-related parents. The breeder utilized his knowledge of the characteristics of the two parents, arranges a mating between them.
The offspring he abtains in most cases shows better performance in the character of interest when compared to the average performance of the two parents.
This hybrid vigour, technically, it is called “heterosis”.
Some heterosis is exhibited at a level (a) merely above the average of the parent’s (b) well above the average of the parent and (c) exceedingly large that it supercedes the performance shown by the parent with higher measurement.
In certain cases, heterosis does not occur in which case, the progeny performs at par with the average of the parents. Negative heterosis can result when the crossbred performance is below the mid-parent performance.
6. To generally improve the average performance of his population, stock and therefore to increase the production level of his animal. This is the intention of the breeders. Generally, the breeders aims to change permanently the mean phenotype of a population.
7. To eradicate deleterious, detrimental or harmful effects of certain genes in animal populations.
8. To reduce the incidence of certain diseases that are genetically transmitted from parents to offspring.
9. To reduce or increase the incidence sometimes the variation of phenotype with or without changing the mean phenotype of a population. The observed performance, the phenotype of an animal is the result of the interacting development of its genotype in its specific environment throughout life from the time of fertilization. Phenotypic differences or most probably from a combination of both.
In conclusion, the fundamental objective in animal breeding is to estimate the nature and environmental differences between individuals in population he is dealing with.
PROBLEMS OF ANIMAL BREEDING
The basic problems encountered in animal breeding are mainly those that are genetically rooted.
- We have to understand or estimate the nature of the genes or genetic factors controlling the character in the organism. For example, if we are interested in the size of a pig specie, (sus scrofa), and we want to develop new size that will be bigger or smaller then the earlier existing ones, we have to know first, whether the genes controlling size in pigs are allelic to one another, whether there are inherited to express size character, the nature of interaction of the genes, intra allelic or epistatic, all these are some of the questions that the breeder must ask and provide their answers before embarking on organized pig breeding to create size differences.
- There is problem with mating individuals that are carriers of deleterious genes.
- The insufficiency of the number of individuals in the population he may be working with; This often leads to wrong estimates of the population parameters.
- Breeding work is dependent on the breeding cycle of the species, generation interval and the reproductive age of the species. Therefore it is time related. This shows that breeding work could take long time to accomplish. Selection programme can take between 10 – 30 years in cattle 5 – 15 years in poultry and swine, 5 – 50 years in sheep and goats, etc.
- The costs of engaging a breeding programme might pose a problem, since we have to acquire a large number of the breeding individuals and groups. For example, in animal breeding, we to shelter all the animal, feed them and medicate them as long as the programme will last. Most especially as the number will increase each generation and after each successful mating. All in all, it takes a lot of money to achieve a desired objective in animal breeding.