The indigenous cattle breeds and their diversity have evolved over a long period of time and developed as milch, draught or dual purpose breeds. Many of these breeds in spite of their satisfactory performance in low input system are fast depleting due to their economical non-viability, hence there is an urgent need of preserving this rich indigenous genetic resources biodiversity which is genetic insurance for sustainable development in future. Artificial insemination and semen freezing is well established technology, which is being used successfully in cattle propagation and breed improvement programme, and can simultaneously be utilized to conserve the cattle biodiversity by storing frozen semen for posterity.
Such conservation programme involves long term storage of germplasm in semen bank and its replenishment through utilization and exchange. The Gaushalas are playing significant role socially and culturally for protecting cattle wealth of our country, therefore they have potential of becoming an important and meaningful partner in both in in situ and ex situ conservation programme. Cattle Wealth of India India has a rich reservoir of genetic diversity and possesses some of the well known breeds of cattle. There are 30 well defined breeds of cattle in India apart from several other undefined populations.
These breeds of cattle are the result of thousands of years of selection, evolution and development in the process of domestication suitable to the local agro climatic conditions. Milch breeds like Sahiwal, Red Sindhi, Gir and Rathi are high milk producers but bullocks of these breeds have poor draft potential. Majority of the cattle breeds belong to draft category providing a little amount of milk.
The dual purpose cattle breeds are fairly good milkers and bullocks provide good draft power. Kankrej and Tharparkar, though, dual purpose breeds, produce good quantity of milk often comparable to those of milch breeds. These breeds are resistant to common tropical diseases and can subsist on poor quality crop residual roughages, grasses and scanty drinking water. With the advent of “Green revolution” and introduction of mechanical and chemical inputs in the agricultural practices, importance of cattle animal drought power has reduced.
Changing socio-economic scenario coupled to agricultural diversification, low productivity and loss of utility, alternate economic opportunities and developmental apathy is resulting in decline of cattle population from year 1992 onward and some indigenous cattle breeds are getting endangered at an alarming rate. This situation demands immediate attention and as a precautionary measure, an ex situ conservation programme has been undertaken at National Bureau of Animal Genetic Resources, Karnal in which frozen semen of cattle breeds is stored for posterity.
This stored germplasm diversity will equip farmers and breeders to improve their livestock and utilize it to meet the needs of local communities in future. Considering the large cattle diversity to be conserved many agencies will have to participate in such programmes, hence there is need to explore the possibility of utilizing Gaushalas and their infrastructure in the country for conserving cattle biodiversity. Conservation methods Conservation methods can be broadly categorized as in situ and ex situ.
In situ conservation means that animals are kept within their production system, in the area where the breed developed its characteristics. Ex situ ( in vivo) conservation applies to situation where animals are kept outside their area of origin (herds kept in experimental farms, farm parks, within protected areas or in zoos) or more often (in vitro), when genetic material is conserved and stored in gene banks in the form of semen, ova, embryo or DNA.
Conservation through any of these methods has its own merits and demerits. Frozen semen is ideal for genetic resources utilization ctivities, providing sample half of the genetic material of preserved breeds in a form that permits convenient introgression into recipient population. However, regeneration of a breed from frozen semen in one generation is possible only if living females of that breed are available, otherwise several generation of up gradation are required to reestablish a breed. In spite of this fact, well established semen freezing technology especially in cattle and buffalo, and presence of semen freezing infrastructure across the country makes it method of choice for conserving indigenous livestock biodiversity.
The National Bureau of Animal Genetic Resources (NBAGR) is playing a pivotal role in ex situ conservation by establishing a National Semen Bank at Karnal and cryopreserving the semen of indigenous livestock. Prioritizing breed Conservation High costs of collection and limited use of preserved material restricts development of ex situ collection. Hence it may be appropriate to prioritize breeds for undertaking them in ex situ programme and evaluation of many factors (population and production trends ) may make basis of such prioritization.
The unique genes possessed by a breed and the likelihood of its extinction may be an important parameter to set the priority of conserving a breed. The data on immunogenetic and biochemical polymorphism may make the basis of determining such urgency of a breed (Miller, 1977). The quantification of relatedness among breeds can group them in different sets, each set consisting of genetically closer/ related breeds which are different than breeds of another set. Such arrangement will drastically reduce the conservation costs as conserving a single breed in a set will represent all breeds of respective set.
Such phylogenetic differentiation of breeds is possible by mapping the genes in livestock species using microsatellite markers. The usefulness of these markers for estimation of genetic distances among closely related population in different species of livestock has been documented by numerous studies (Bowcock et al. , 1994, Buchanan et al. , 1994, Cianpolini et al. , 1995, Bradley et al. , 1996, Mac Hugh et al. , 1997). The need of doing livestock diversity conservation, breeds characterization including their differentiation and relationship as also been recognized worldwide ( FAO, 1995a, 1995b).
The population trend of a breed is an important parameter to suggest, whether a breed should be undertaken for its conservation. However census information is generally available for total cattle population only, now new census exercise is being done breed wise. The endangered status of an animal breed can be determined by the size of breeding stock, expressed through number of breeding females and sex ratio, which may differ among different species.
The endangered status of an animal breed depending upon minimum population size in different species have been suggested by different workers for Indian conditions as well as other countries. Based upon above mentioned considerations some breeds of different species have been undertaken for ex situ conservation at NBAGR and frozen semen of some breeds have been kept in National Semen Bank. Sample size in preservation programme Sample size in preservation programs are influenced by both genetic considerations and cost.
To produce 20 viable offspring having a dominant gene, 100 units of semen (a unit of semen is the amount appropriate for one insemination) should suffice, but somewhat more semen (possibly 200 units) may be desirable in preserving a recessive gene. The preservation of quantitative variation within a population or breed would require about 100 units of semen from each of 10 to 20 unrelated males (CAST, 1984). As per Smith 1984, conserving collection of frozen semen from 25 sires would be adequate for all species.
However it is appropriate to have frozen stores, which are large enough to provide a good representation of the conserved stock and to prevent much genetic drift or inbreeding. Semen replenishment in GeneBank It is difficult to suggest an organized programme of animal germplasm preservation and its utilization, because a breed demanding urgent conservation has declining population and at times it is difficult to procure germplasm source. Simultaneously it is also difficult to utilize the stored germplasm as animals of threatened breed are unacceptable to stakeholders in its production environment.
However to encounter the genetic change taking place in a population included in its long term storage, it can be replenished regularly. For this purpose the desirable number of semen doses may always be kept at two locations (National Semen Bank and Regional Semen Bank) and replenishing the semen each year by its utilization. Such kind of breed conservation system may be more meaning full if linked to its in situ conservation and breed improvement programme simultaneously and Gaushalas are perfect fit for such kind of arrangement.
Quality control and data storage in semen bank The quality of semen kept in semen bank for long term cryopreservation is an important issue and is to be addressed seriously and carefully. The bulls used for semen collection should be healthy and kept in quarantine/ artificial insemination centres over six months prior to semen collection and declared negative for genital and infectious diseases viz. , Tuberculosis, Brucellosis, Vibriosis, Trichomoniasis, Blue Tounge, Foot and Mouth Disease, Contagious Bovine Pleuropneumonia, Rinderpest etc. (Kumar, 2004).
The fertility of the bulls should be good and semen should have acceptable levels of motility, livability, acrosomal integrity and membrane permeability etc. The sire details for its phenotypic characteristics, health status, pedigree record, sire index, semen quality parameters should be recorded and kept in semen bank for future reference. Gaushals in India The Gaushala movement is synonymous with the protection of cows and cattle wealth of our country. In early vedic period social customs and rules laid great emphasis on protection, preservation and development of cows for home and oxen for agriculture fields.
Gaushalas constitute a strong network of local cattle maintained throughout the country. They are located in the remotest areas of the country and have close associations with local livestock keepers of the area. These Gaushalas because of their concept of cow service and large infrastructure can be very important institutions for indigenous cattle biodiversity conservation. Such initiative can be more productive if Gaushalas are supported in their efforts by making them to introduce scientific management practices and proper record keeping, which is essential for conservation and improvement programme.
Further, there is a need of preparing a database having all information of Gaushalas in the country and prompting them to have stronger liaison with department of animal husbandry in their respective states. Semen Banking and Gaushalas India is a repository of 30 breeds of cattle which is spreaded over large territory of country, hence it becomes a gigantic task to conserve even those breeds where population is decreasing. This necessitates the involvement of many agencies in undertaking ex situ conservation programme and Gaushalas can play an important role in running such programme.
The Gaushals can utilize the quality semen available with NBAGR for improving production potential of their animals. This will also result in propagation of breed, thereby helping in conservation programme. Some elite animals are also available at the Gaushalas. These can be used for production of males from nominated matings, which can be raised at bull mother farms as future bulls. As the Gaushalas don’t have facilities for semen freezing, the later can be done at the Semen stations of State Livestock development Board.
The germplasm should be stored at two locations to cover risk of damage during storage. One of such location could be National Semen Bank managed at NBAGR and another at Regional Semen Bank, which is Semen Station under State Livestock development Board.
Conclusion
Frozen semen production and its utilization through artificial insemination is well established in cattle. Frozen semen provides the genetic material in a form which can be conveniently introgressed into recipient population, however regeneration of a breed using semen is possible only if females of the breed are available.
In spite of this limitation frozen semen banking is an effective mean to conserve livestock biodiversity, as the infrastructure for semen freezing exists throughout the country, which substantially cuts the cost of conservation programme. The different breeds of indigenous livestock species may be prioritized for including them in ex situ conservation programme based on their utility and status of endangerment.
The vastness of indigenous livestock resources biodiversity necessitates the participation of many agencies in semen onservation programme, which can be implemented through National Semen Bank and Regional Semen Banks working in a network with Gaushalas across the country. The germplasm should be circulated among these banks by suitably managing the semen production and utilization. Such semen banking system should also be linked simultaneously to in situ conservation and improvement programme of a breed.
References
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