Production system of animal also known as livestock which is domesticated animals raised in an agricultural setting to produce commodities such as food , leather and wool. The term often used to refer solely to those raised for food and sometimes only ruminants, such as cattle and goats
Definition of breeding goal
Definition of the goals of breeding is the best animals are selected. Typically, the goals for the breeding are a combination of different traits, which are important in the production. A breeding goal is the specification of the traits to be improved including the emphasis given to each traits. It gives the direction in which we want to improve the population.
A breeding program is a program aiming at defined breeding objectives for the production of a next generation of animals. It is the combination of recording selected traits, the estimation of breeding values, the selection of potential parents and a mating programme for the selected parents including artificial reproduction methods.
Collection of Information
Phenotypes and Genotypes
An individual’s genotypes is the composition, in the individual’s genome, of a specific region of DNA that varies within a population. The collection of the DNA in a cell’s chromosome is the genome of the individual, including the individual’s gene, and as well as the DNA sequencethat lie between them.
DNA nucleotide on a chromosome could represent a genotype. It could also be a sequence repeated multiple times, a large duplication, or a deletion. Most of variation in genotypes does not cause any difference in the protein being produce by the cell, because genes which code for the protein, occupy only about 2 percent of the total genome. However, when specific genotype does effect the composition or expression of a protein, disease or change in physical appearance can result. The physical effect of a particular genotype is known as it phenotype or trait. In order to develop the initial training population, animal with phenotype are needed. Ideally these animals have moderate to high accuracy EPD, which would require that they have several progeny .Genotyping strategies allocate resource to collect genomic information. To maximise the long-term genetic gain, genomic information could provide the information needed. With genomic information, we can trace the inheritance of chromosomal segments and estimate relationship between selection candidates more accurately. More accurate relationship not only increase the accuracy of Mendelian-samping term, they enable us to manage ancestral contributions more independently as relationship are functions of ancestral contribution.
Confirmation of the Parenthood
In many breeding associations the mating needs to be confirm by DNA test when the offspring is born. Important reason is to protect the quality of the pedigree recording. At the start of a breeding program, when little or no pedigree is available. An extensive DNA test (large SNP set for example) can be used to test how related two animals are with incomplete pedigreeTo discourage wrong mating. Especially in situations where the actual mating is expensive, the owner of the male might using an alternative when the number of mating is exceeding the potential of the male. Or when the fertility of the male is insufficient. Especially in the past, before the DNA test became available, some of these practices did occur in horses.
Determining selection criteria.
Selection is differential reproduction that preventing some animals from reproducing while allowing other animals to become parents of numerous offspring. In the latter situation, the selected parents should be genetically superior for the economically important traits. Factors affecting the rate of genetic improvement from selection include selection differential, heritability, and generation interval. Selection differential, sometimes called reach, is the superiority or inferiority of selected animals compared to the herd average. To improve weaning weights in beef cattle, producers cull as many below-average-producing cows as economically feasible. The replacement heifers and bulls are selected that are above the herd average age for weaning weight. For example, if the average weaning weight of the selected replacement heifers is 480 lB in a herd average 440 IB, then the selection differential for the heifers is 480 IB in a herd averaging 440 IB, then the selection is due to genetic differences, and the remaining part is due to differences caused by the environment.
There three typical role of selection which is tandem, independent culling level, andselection index. Tandem is selection for one trait at a time. This method can be effective if the situation calls for rapid change in a single, highly heritable trait. Tandem ineffective if selection is for more than two traits or if desirable aspect of one trait is associated with the undesirable aspect of another trait. Independent culling level establishes minimum culling levels for each trait in the selection program. Although it is the second most effective type of selection, it is the most prevalent because it is fairly simple to implement. Next, selection index. It recognizes the value of multiple traits and places an economic weighting on the traits of importance. Such a calculation allows an overall ranking of the animals from best to worst utilizing a highly objective approach. The selection index is the most utilizing a highly objective approach. The selection index is most effective system but the most difficult to develop.
The development and validation of the concept of the gene (dominant or recessive) for a single trait stemming from work of Gregor Mendel. A gene is the unit of hereditary and encodes single protein. Genes on the same chromosome tend to stay together except that there is crossing over at a single point on the chromosome.
Breeding value estimation
Breeding value or parental worth for a trait can be defined as that portion of genotype that can be transferred from parent of offspring. Breeding value in mathematical terms is the total of all the independent genetic effects on a given trait of an individual. It estimate the breeding value of an animal that determine the phenotypic superiority of information source. Principle of estimating breeding value is based on regression and predicting difference in breeding value from phenotypic differences. Correction for fixed effects that use phenotypicdeviation from a contemporary mean such as population mean, herd or flock mean of all animals in herd, management group and all males. Breeding value is also called cumulative effects of each individual allele of loci concerned. Reflects genetic effect (genes) that are passed on to offspring. Estimate number of favourable genes. Individual breeding value (A) reflect the superiority/ inferiority of the values compared to their contemporaries. Mean breeding value is zero.
Response to selection
A few steps are needed to get the response to selection, and to get the genetic progress. To predict their genetic potential, animals need to be ranked. Then, the best breeder will be selected. These are few factor that will ensure the success of the selection:
1. How heritable is trait under selection
2. The number of genetic variation for that trait is there in the population
3. The average accuracy of the EBV
4. The proportion of the animals will be selected for breeding
The population parameters are heritability and genetic variance and it cannot be influenced by breeder. This mean that the phenotypes that were collected for estimate is a good quality.
A factor can be influenced by breeder is accuracy of selection. In sufficient value of offspring can be used to estimate the breeding value. Because of that, the accuracy will be higher if only performance of a few sibs is available,
The selected proportion cannot be unlimitedly small for two main reasons which is the intention to maintain population size. If few animals are selected, these need to be able toproduce sufficient number of offspring to replace entire generation of animals. Next, few animal selected as parents with large number of offspring, results in many animals that closely related in the next generation. So, rate of breeding that may exceed the limit of 0.5 to 1%.
Graph below shows a population that is ranked based on their phenotype for a certain trait. Most animals score an average phenotype, the remaining scoring very low or very high. The selection of the best animal can be made after rank it. The size of the proportion of the population that will be selected is based on the hoe many animals are required for breeding. The selected proportion is the easiest to influence. A smaller proportion results in larger generic response as the selected animals will be more superior to with a large selected proportionDISSEMINATION
Structure of breeding programme
A breeding program is a program that define breeding objective for the production for the next animal generation. The purpose of breeding programs is to generate genetic improvement in a population. Permanent selection response is created in breeding programs for breeding traits by collect the information of selection candidates, estimation of breeding value, selection among selection candidates in combination with a mating scheme for those candidates. Besides, genetic improvement generate by animal selection in the breeding programs dissemination.
Factor of decision making in breeding programs are reproduction capacity, social infra-structure, optimization aim, traits in aggregate genotype and genetic parameters. Reproduction capacity of female determines which mean “how many offspring can be produce in the population” and reproduction capacity in male is determines which mean “number of male that are needed”. Social infra-structure have different aspect which is average of farm size and distribution of farm location, degree of information networkstructure of market and state of technology. The average of farm size means large farm offer better opportunities for large scale field testing of young unproven male. The structure of market for an example it is possible to meet specific requirement with respect to product quality.
The different goals in a breeding programs is to maximise the genetic gain (in short term or in long term), genetic gain in one single trait or in a combination of trait and maintaining genetic variance in a population to avoid inbreeding. The optimizing of breeding program interbreeding over genetic gain. Direct method used is under the infinitesimal model interbreeding reduces genetic variation which reduce genetic gain while the indirect method is the fitness of the population may reduce to an extent where it affect the selection differential , when interbreeding depression is present. Other than that, trait in aggregate genotype is aggregate genotype that contains all traits that influence efficiency production. For the last one is genetic parameters which determine how much observation are needed for accurate selection. This related to large dominant effect favour used in crossbreeding.
Crossbreeding is the mating of two animals that are different breeds with the same species. Species refer to the organisations that have several same characteristic so they mate together naturally. The purpose of cross breeding is to take advantages of heterozygous, to use average breed effect, to design a cow herd, to target markets and to create breeding plan for a herd.