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Bull Production

Strategies and programmes

Better performing animals are expected to have better genotype. Since parents pass on half of genes to their progenies, better performing animals selected as parents produce offspring that have better average genetic values than the previous generation.

The amount of genetic progress that can be achieved through selection of parents to produce the next generation depends on four basic factors: genetic variation, intensity of selection, accuracy of selection, and generation interval.

Selected parents contribute to the overall genetic progress in the target population through four paths: (i) Selection of sires to produce the next generation of sires; (ii) Selection of dams to produce the next generation of sires; (iii) Selection of sires to produce the next generation of dams, and (iv) Selection of dams to produce the next generation of dams. The genetic progress achieved on each path depends on how the four factors i.e. selection intensity, accuracy of selection, genetic standard deviation and generation intervals are applied on each path.

The three basic methods used in selection of parents to produce the next generation of animals include: Pedigree Selection (PS), Open Nucleus Breeding Systems(ONBS), and Progeny Testing. The genetic progress achieved under each approach depends on how four basic factors are applied on all four above mentioned paths in any practical scheme.

Since in a well-organized progeny-testing programme, it is possible to increase selection intensity and accuracy of selection on sire-to-sire path, increase intensity of selection on dam-to-sire path, and increase selection intensity and accuracy of selection on sire-to-dam path, relatively higher genetic progress is possible in a field-based progeny testing programme compared to what is possible in other approaches. Progeny testing, therefore, is considered as the best tool for achieving higher genetic progress in any population. However, putting in place an effective progeny-testing programme needs an extensive infrastructure for AI in the field, an adequate infrastructure for milk recording, and a right institutional technical and financial support for running and maintaining such programmes for a very long time.

Progeny Testing

Under NDP, the breeds identified for establishing progeny testing programmes include: Holstein Friesian, Holstein Friesian crossbred, Jersey crossbred, Sunandini cattle and Murrah and Mehsana buffalo. To ensure that better and better quality bulls are produced generation after generation, it is planned to set up infrastructure for progeny testing of bulls of these breeds in their respective native tract and make sure that all programmes follow Standard Operating Procedures (SOP) to implement progeny testing programmes, achieve the minimum standards set and are evaluated annually to ensure that they adhere to standards laid down.

The institutions that are capable of meeting the eligibility criteria for implementing progeny testing programme set under NDP would be entrusted to implement progeny testing to produce the required number of bulls.

Each progeny testing programmes is expected to be implemented through an independent project team and governed by a Management Committee.

The details of progeny testing programmes approved under NDP including progress made under each programme are given in the Table below:
 

​Sr.No PT Programme​ ​Breed ​EIA ​Location ​Starting date ​Progress details
1​ ​HF PT ​HF ​KMF ​Bangalore and Kolar districts in Karnataka ​1st April, 2012 Progress

 

 Pedigree Selection

Under NDP, the breeds identified for establishing pedigree selection programmes include: Rathi, Kankrej, Tharparkar, Gir, Sahiwal and Hariana cattle and Nili Ravi, Jaffarbadi, Banni, and Pandharpuri buffalo.

To ensure a steady genetic progress in the target population of indigenous breed, it is planned to set up infrastructure for pedigree selection of these breeds in their respective native tract and make sure that all programmes follow Standard Operating Procedures (SOP) to implement pedigree selection programmes, achieve the minimum standards set and are evaluated annually to ensure that they adhere to standards laid down.

The institutions that are capable of meeting the eligibility criteria for implementing pedigree selection programmes set under NDP would be entrusted to implement pedigree selection programmes in the native tracts of respective breeds.

Each pedigree selection programmes is expected to be implemented through an independent project team and governed by a Management Committee.

The details of pedigree selection programmes approved under NDP including progress made under each programme are given in the Table below:

​Sr.No ​PS Programme ​Breed ​EIA ​Location ​Starting date ​Progress details
​1 ​Kankrej ​Kankrej ​Banas Union ​Banas district in Gujarat ​1st April, 2012 Progress
​2 ​Rathi ​Rathi ​Urmul Trust ​Bikaner and Sri Ganganagar districts in Rajasthan ​1st April Progress
 

Determinants of Genetic Progress of any genetic improvement programme

Four Key Factors of Genetic Improvement

Better performing animals are expected to have better genotype. Since parents pass on half of genes to their progenies, better performing animals selected as parents produce offspring that have better average genetic values than the previous generation.

The amount of genetic progress that can be achieved through selection of parents to produce the next generation depends on four basic factors: genetic variation, intensity of selection, accuracy of selection, and generation interval. The genetic progress per year or response to selection per year defined as deviation of mean of offspring from the population mean can mathematically be represented as follows: 

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Where, Ry is the selection response per year; i is the intensity of selection; r is the accuracy of selection; s is the genetic standard deviation, and L is the generation interval.
 
If there is no variation in traits to be improved (i.e if s = 0 ) no genetic improvement is possible. In other words, higher the genetic variation in a trait higher will be the genetic progress.
 
Lesser the number of individual selected out of available individuals for selection for producing the next generation of animals higher will be the average of individual selected and therefore there will be higher genetic progress. Proportion of individual selected is better represented by selection intensity. The selection intensity is the superiority of selected individual in standard normal units. Lesser the proportion of animals selected higher will be the intensity of selection. The intensity of selection directly depends on the proportion of selected individuals provided the trait is normally distributed.
 
Better we find true genetic merit of animals, more of what we see as good will be pass on to the next generation. In other words higher the accuracy of selection, higher will be the response to selection.

Lesser the time selected individuals take to produce their offspring higher will be the genetic progress per year. Time period is represented by generation interval. The generation interval is defined as the average age of parents when their offspring is born.

Four Paths of Genetic Improvement
 
Selected parents contribute to the overall genetic progress in the target population through four paths: (i) Selection of sires to produce the next generation of sires; (ii) Selection of dams to produce the next generation of sires; (iii) Selection of sires to produce the next generation of dams, and (iv) Selection of dams to produce the next generation of dams. The genetic progress achieved on each path depends on how the four factors i.e. selection intensity, accuracy of selection, genetic standard deviation and generation intervals are applied on each path. The overall genetic progress can be represented by the following formula:
 
 
 
Where iSS is the intensity of selection on sire-to-sire path, rSS is the accuracy of selection on sire-to-sire path, LSS is the generation interval on sire-to-sire path and  is the genetic standard deviation for the trait. Similarly, the intensity of selection, accuracy of selection, and generation interval for dam-to-sire, sire-to-dam and dam-to-dam paths are defined. The overall genetic progress achieved in the target population, thus depends on how selection intensity, accuracy of selection and generation interval are applied to achieve the higher genetic progress on all four paths.
 
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