Snehasmita Panda1*, Junaid Kar2, Prachurya Biswal3, M Monika4
1PhD scholar, Division of Animal Genetics, IVRI, Izatnagar, Uttar Pradesh
2Veterinary assistant surgeon, Department of Sheep Husbandry, Jammu & Kashmir
3PhD scholar, Livestock Production Management Section, IVRI, Izatnagar, Uttar Pradesh
4PhD scholar, Poultry science, CARI, Izatnagar, Uttar Pradesh
*Email id – sneha23437@gmail.com
Introduction:
Over the past twenty years substantial progress has been made in conserving animal genetic resources for food and agriculture. Globally, national programs, non-government organizations (NGOs), and producer-based activities are executing in vivo and in vitro conservation. Across regions well-established and newly formed national gene banks are operating and providing genetic security for AnGR. There are mainly two different methods for conservation of domestic animals i.e. in situ and ex situ conservation.
In situ conservation:
The in situ conservation involves the maintenance of live populations of animals in their adaptive environment. Therefore, animal populations continue to evolve and develop for more sustainable use. The active in situ conservation is equivalent to breed development by conducting well designed animal breeding programmes, while the passive in situ conservation is concerned with the maintenance of live animal populations of breeds at risk of loss within their agro-environment. Therefore, a well laid-out national action plan has to be prepared not only to preserve the live animals within their native environment but also to make them self sustainable under the given agro-ecosystem.
In situ or live animal:
conservation has several advantages as the breeds can gradually adapt to changing environmental conditions besides improvement by selective breeding may be approached through genetic improvement and sustainable management, institutional flocks, farmer’s flocks, pastoralists flocks, and through stack-holder’s involvement.
Genetic improvement and sustainable management:
Improvement of the breed through selection and breeding can help in making it self-sustainable. There are a number of biotechnological tools i.e. MOET and embryo transfer technology, which can help in development of a highly productive population, capable of sustaining the economic pressures.
Institutional flocks:
Institutional flocks managed under scientific lines can maintain a minimum breed -able population required in recreation of breed for future. It also supplies superior germplasm for conservation of the breed. The replacement must be regulated to preserve the gene structure of the given population as far as possible and the males and females must serve this main purpose. The rules for placement are given below:
Every breeding animal must be replaced by his/her progeny.
The percentage of the known or visible characteristics must be kept approximately around the foundation frequency.
Possibly the immunogenetics characteristics and DNA levels polymorphism data should also be taken into consideration to the extent possible.
The generation interval must be kept as long as possible according to the breed or species.
The number of males in consecutive years must be as many as possible.
In India, a large network of infrastructural facilities in terms of Research Institutes/Universities/Central and State Animal Breeding Farms and Artificial Insemination (AI) Centres exist. They have population of some important indigenous breeds. However, until recently their main emphasis was only on improvement of productivity by crossbreeding. There are some pure breeding herds also; however, the population size is too small to carry out effective selection for improvement. These institutional herds need to be strengthened both in terms of superior germplasm as well as modern tools and techniques.
Farmer’s flocks:
Involvement of the farmers who have been keeping a particular breed for years may be desirable. The most important case against preservation is the cost and the modern society may be reluctant to fund project like conservation from which little economic or financial return can be expected in near future. Under Indian farming system a number of indigenous breeds are to stay in for long run due to zero input requirement and disease resistance etc. Progressive farmers need to be identified and encouraged to conserve these breeds and compensate them for the low returns, as a national obligation for maintenance of animal biodiversity.
Stack-holder’s involvement:
In India, animals are raised by farmers and no data recording system is followed in field. Therefore, proper evaluation of indigenous animals for further improvement is not feasible at present. It may be very important to form the Breed Societies in India for the conservation of indigenous breeds. Moreover, the improvement of animal breeds through selection of outstanding animals true to their breed types from the larger population maintained in the breeding tract can be simultaneously taken up in collaboration with these Breed Societies. Dairy co-operative network in India has greatly helped in making large number of animals for initiating breed improvement programmes in cattle and buffaloes for milk, besides marketing their products at reasonable costs.
Ex situ conservation:
Ex situ conservation involves conservation of genetic material out of the environment in which it was developed (FAO, 2000).
In vivo methods: Ex situ conservation of live animals in the form of organized herd maintained in a research institution, state owned animal farm, zoo and breed safari comprises in vivo conservation. Keeping of large flock, especially of relatively less productive breeds is not feasible on economic grounds. In small populations, animals suffer from inbreeding and appearance of deleterious genetic defects. In such cases, it is very important to maintain the breeding population in such a manner that the inbreeding rate is kept at minimal level and production performance can be improved over the years to make the breed self sustaining. The effective population size of breeding females and males either through natural mating or through AI can be maintained either under scientifically managed farms of organized sector or with the farmers in their native breeding-tract or under breed safari/parks. The biggest limitation of conservation of breeds outside their home-tract is the population size avoiding the ill effects due to inbreeding. The effective population size is very important consideration and depends upon the ratio of male and females under different systems of selection.
In vitro methods:
Cryo-conservation of wide variety of living cells or tissues for long periods of time viz., sperms, oocytes, embryos and DNA etc. comprises in vitro ex situ conservation. The basic objectives of in vitro conservation are:
Regeneration of endangered breed
New breed development
Supporting the in vivo population
Research for determining the effect of single major gene
DNA studies and genome mapping
a. Sperms and oocytes-
The semen should be stored in frozen conditions at least in two locations to avoid any risk. It has been documented in several studies that many animal oocytes can be stored and fertilized in vitro after thawing as usual.
b. Embryos-
This is an excellent tool of conservation as all the genetic information is stored in one diploid zygote, which can give, rise to a new progeny. Embryos are usually frozen between 30 and 120-cell stage in 0.25 ml straws. These straws can be stored at -198°C for long-term storage and can be implanted successfully in the recipients. With limited resources in terms of facilities and trained manpower at some places this technique can be utilized for the ex situ conservation of only declining/endangered breeds of animal. However, it is still relatively expensive to obtain embryos, and their cryo-preservation technique needs further refinement for economical use.
c. Cloning-
Currently cloning has created revolutionary opportunities in both animal breeding and research by development of procedure for nuclear transfer in animal, where unlimited number of cloned animals are bred by nuclear transfer, using somatic cells cultured in vitro. This technology shall hold for conservation of available genetic diversity of threatened genetic resources. Cloning can be used to produce identical copies of elite stud males or females, more rapidly than conventional breeding.
d. DNA-
A new method of preservation now emerging is the preservation of sequences of catalogued DNA in perpetuity. Storage of DNA for conservation of breeds though has the advantage of disease free transportation across the countries, but it too has problems, which are preventing it from becoming the normal method of preservation. One is the fact that genome maps are not yet available to identify which sequences of DNA are responsible for specific traits in the live animal. The second is that the use of stored DNA to recreate an animal with specific traits is not yet possible as DNA reinsertion techniques with animal cells still produce random results.
A few new methods of conservation now emerging include establishment of embryonic stem cell lines and conservation of somatic cells. These techniques will offer an alternative approach to the preservation of genetic variation of endangered breeds in developing countrieslike India. The other important aspects of conservation of animal genetic resources involve establishment/strengthening of National Animal Data Bank, National Gene Bank, National Animal Conservation Board and Global Data Bank.
Conclusion:
Given the high costs of some in vivo conservation approaches, greater emphasis should be placed on in vitro collection development by national gene banks. Successful gene banking livestock populations may result in increased productivity per animal without the fear that genetic resources will be lost by policy changes, and institutional funding. In addition, governmental subsidies should be provided to keep in vivo populations.
