BIOLOGICAL DIVERSITY OF FARM ANIMALS IN BANGLADESH: A REVIEW

The present study attempts to examine the scenario of farm animal’s genetic diversity and their distribution pattern in Bangladesh. The major components of farm animals in Bangladesh are cattle, buffalo, goat, sheep, chicken and duck which are being raised in a mixed farming system integrated with crop agriculture. The biological diversity most of farm animals is of native origin. Cattle and chicken are the two major species which are being manipulated genetically either through inclusion of exotic blood and/or import of live animals and birds. Buffalo, goat, sheep and duck are also being crossed to some extent with exotic germplasms. Other species like pigeon, quail, and guinea fowl are also available in the country. This paper has also shown the population and list of different breed/type of farm animals available in Bangladesh which helps to meet the public priorities such as, their production and reproduction, their management practices, their survivability etc.


INTRODUCTION
The term, biodiversity or biological diversity denotes "the variety of life on earth". It refers, particularly, to the differences between living organisms at different level of biological organization: gene, individual species and ecosystems. Bangladesh is very rich in biodiversity. The rich genetic diversity in crops, livestock, fish, trees and wildlife directly and indirectly support the lives and livelihoods of the people of the country by supplying wide range of provisional, regulatory and cultural services.
Livestock species of Bangladesh includes cattle, buffalo, goat, sheep, chicken and duck. Other important species are horse, pig, geese, pigeon, guinea fowl, elephant, deer and gayal the latter three living principally in special forest areas. The overall contribution of livestock to agricultural production is 14.08% (Hamid et al., 2017a). In addition, livestock contribute 95% of draft power, 50% of rural transport and 25% of fuel for cooking in the country (DLS, 2016). Over 85% of livestock are raised by smallholder farmers who own 1-2 head of cattle, 2-3 head of sheep and goats and a few head of poultry and for whom the special characteristics of indigenous livestock adaptability to harsh climate and poor nutrition, resistance to endemic diseases and parasites are crucial.
Livestock plays an important role in the national economy of Bangladesh. The livestock sub-sector that includes poultry offers important employment and livelihood opportunities particularly for the rural poor, including the functionally landless, many of whom regard livestock as a main livelihood option. The contribution of livestock to GDP is 2.5% (DLS, 2014) and the overall trend of the livestock in Bangladesh has also been increasing (DLS, 2014). Moreover, the products from livestock; like milk, meat and egg have also shown increasing trend of production (DLS, 2014). In Bangladesh, during the last decade a large number of non-descriptive cattle have been replaced by cross-bred cattle. It was started in 1958 by Directorate of Livestock Services (DLS) with artificial insemination (AI) program which was strengthened in 1975-76. In 1960s, Savar Dairy Farm was established for dairy development program of the country The farm started to work with Shindhi, Shahiwal and Tharparkar breed to cross with indigenous cattle. In 1973, some Friesian and Jersey bull were imported from Australia and this was the initiating point of new dimension. These bulls were used for semen production for upgrading the indigenous cattle. In 1975, the AI program was extended throughout the country for cattle development. Haque, 2014 stated that there are 2.3 million high yielding cross bred cattle are available in Bangladesh. They can produce 1800-3000 kg milk in a lactation period, if they are well managed. The animals get mature at the age of 18-24 months and have calving interval of 13-15 months. Although Bangladesh is rich in biodiversity (species) but unfortunately, many plant and animal are facing severe threats to their survival and are disappearing at alarming rates. And human actions are the cause behind this biological degradation. However, there are no documented research studies so far that investigated the farm animal's biological diversity of the country. The purpose of this study is to estimate the present scenario of farm animal's biodiversity and their distribution pattern in Bangladesh.

Farm Animals and Their Biodiversity in Bangladesh
Cattle, buffalo, goat, sheep, chicken and duck as major components of farm animals in Bangladesh. Most of them are being raised in a mixed farming system integrated with crop agriculture and their biological diversity is of native origin. Cattle and chicken are the two major species of farm animals and they are being manipulated genetically either through inclusion of exotic blood and/or import of live animals and birds. Buffalo, goat, sheep and duck are also being crossed to some extent with exotic germplasms. The farm animals and their biodiversity of Bangladesh are as follows:-

Cattle
The indigenous cattle are considered potential in some locality and are identified by its local name, such as Pabna cattle, Red Chittagong cattle, North Bengal Grey cattle, Munshiganj cattle and Non-descript native cattle (Hamid et al., 2017b). Mating with Bos indicus bulls started in 1936 in some localities and resulted in improved cattle in the selected areas of the country. Artificial insemination program started in 1958 and is widely extended in the country and a good number of crossbred cattle have already been added to the herd of different parts of the country (DLS, 2010). Thus, cattle population of the country consists of i) Indigenous type ii) Exotic type (Holestein, Friesian, Holestein and Friesian, Shahiwal, Sindhi, Hariana and Jersey etc.) and iii) Crossbred type (DLS, 2010).
BLRI, 2004 stated that, there are about four (4) local varieties and four (4) exotic breeds of cattle are reared in the country (Table 1). All the local varieties (Pabna, Red Chittagong, North Bengal Grey, Munshiganj) are at the risk of extinction due to indiscriminate use of cross breeding programs throughout the country. Farmers interest for more milk, absence of initiatives for conservation of local variety and absence of organized programs for identification and characterization of their production and reproduction performances in the past or even in the present lead to the local cattle germplasms at risk. All the cattle germplasms reached at the risk of extinction were used widely. During the last 50 years the country already lost potential local cattle germplasms and Jersey exotic breed.
The cattle populations of Bangladesh during last 10 years are presented in Table 2. The list of indigenous, exotic and crossbred cattle genetic diversity and their distribution in Bangladesh are presented in Table 3. Namikawa et al. (1987) reported the blood groups, blood protein polymorphism and karyotypes of the native cattle. They reported the blood protein polymorphism for 6 loci. These are haemoglobin, albumin, transferrin, carbonic anhydrase, amulase-I and diaphorase-II. The most frequently occurred genes were Hbb A , Alb B , TfD 2 , Am-1B, CA S and Dia-II c . They detected 9 blood group systems. These were A, B, C, F, L, J, S, Z and R'. They found 60 chromosomes in diploid cells of native cattle, 58 autosomal chromosomes were acrocentric, X and Y chromosome (sex chromosome) were submetacentric and acrocentric, respectively.

Buffalo
The water buffaloes of Bangladesh may be grouped into types on the basis of their history of domestication, distribution and morphology. These are (i) Native buffaloes in the eastern part. (ii) Native buffaloes in the western part, (iii) Native buffaloes in the central part, (iv) Native buffaloes in the southern part and (v) Nili-Ravi breed in the Buffalo Breeding Farm at Khulna (Faruque, 2000).
As described above there are about four types of native buffaloes in the country and all of them are used widely in different regions. At the beginning, the exotic buffalo germplasms Nili-Ravi was imported to use widely for crossing with the local cows and the Nili-Ravi is at risk at present (Table 1). The buffalo populations of Bangladesh during last 10 years are presented in Table 2.
Blood protein polymorphism studied by Amano et al. (1987) indicates the existence of 7 polymorphic loci in buffalo populations of Bangladesh. These are albumin, transferrin, haemoglobin-α, haemoglobin-β, carbonic anhydrase, alkaline phosphatase and peptidase-B. Alb X , gene of typical swamp buffalo was found only in the populations of the eastern and southern part. Tf A , gene of typical swamp buffalo was detected only in the population of the eastern part. Amano et al. (1987) determined the karyotypes of water buffaloes of Bangladesh. They reported 50 chromosomes for the water buffaloes of the central part and 48 chromosomes for those of the eastern part (Sylhet district). The mtDNA cytochrome b gene sequence of different populations of water buffaloes of Bangladesh also reveals the existence of swamp buffaloes in the Sylhet district. The genotypes determined indicate that water buffaloes of the western and the central part are river type. The water buffaloes of the north-eastern part are swamp type and those of the south eastern part are river type. The water buffaloes of the southern part are swamp type or crossbred type (Swamp X Nili-Ravi). The list of indigenous, exotic and crossbred buffalo genetic diversity and their distribution in Bangladesh are presented in Table 4.

Goat
It is estimated that more than 90 percent of total goat population in Bangladesh is comprised of Black Bengal (Table 1) and the remainder being Jamunapari and their crosses (Hussain et al., 1998). The goat populations of Bangladesh during last 10 years are presented in Table 2.
Black Bengal goat has some reputed features: early sexual maturity, high prolificacy, adaptability to hot and humid environment and yields superior quality skin and meat (Amin et al., 2000, Chowdhury et al., 2002. The coat color of Black Bengal goat is not only black but black & white, brown, brown and white & white are also common in the population.
Black Bengal goat is more or less evenly distributed throughout the country. But concentration is relatively higher in the north-western areas of Bangladesh and it belongs to the high gangas river flood plain agro-ecological zone. Moreover, they are also found throughout the eastern and north eastern India from Bihar through northern Orissa to entire West Bengal, Assam, Monipur, Tripura and Meghalay province.
Jamunapari, an Indian bigger size goat breed is popularly known as Ram Chhagal. They are found in a limited scale in urban and peri-urban areas of Bangladesh in the form of pure or Jamunapari x Black Bengal cross with varying degrees of inheritance. They are reared both in intensive and semi intensive management system. However, the population size of Jamunapari is not so large (about 6-7 %) in the country (Table 1).
In addition, some Missionary's have few small flocks of goat in the country and they maintain exotic breeds such as Beetal and Jamunapari in a limited scale aiming at producing bucks for distribution among the landless and marginal farmers as a part of their poverty alleviation programme in Bangladesh. Their target is to produce crossbred kids with improved production potentials (particularly, milk) to meet the demands of landless and marginal farmers. However, the Govt. restricted crossbreeding programme of Black Bengal goats at present. The list of indigenous, exotic and crossbred goat genetic diversity and their distribution in Bangladesh are presented in Table 5.
Nozawa and Katsumata, 1984 reported blood protein polymorphism at 7 loci (Hball.Tf, Alp, pa-3, Amy, MDH-A).  (Sharma et al., 1999). The list of indigenous, exotic and crossbred sheep genetic diversity and their distribution in Bangladesh are presented in Table 6. Blood protein polymorphism of 11 loci was reported but large frequency differences were observed at Alb, Tf, x-p, Dia, Ly and K (Tsunoda et al., 1998).

Chicken
The chicken germplasms of Bangladesh is composed of indigenous or native type, exotic type, crossbred type and commercial hybrid. The native germplasms; such as Non-descript Deshi, Naked Neck and Hilly are the main germplasms of indigenous chicken (Bhuiyan et al., 2005). On the other hand; Aseel and Native dwarf are the rare germplasms of indigenous chicken. The non-descript Deshi chicken is more acceptable to rural people as an important source of meat and eggs (Barua and Howlider, 1990)  x Naked Neck are also used in the country. There are many commercial hybrids of chickens such as grandparent stock (GP), parent stock (PS), commercial broiler, commercial layer which are used widely for meat and egg production in the country (Table 1). The chicken populations of Bangladesh during last 10 years are presented in Table 2. The volume of work pertaining to the genetic constitution of the indigenous chickens of Bangladesh is very thin. In the 1980s collaboration between Japan and Bangladesh Agricultural University attempted to clarify the gene constitution at the morphological and blood group loci of the Deshi chicken in Bangladesh (Okada et al., 1988, Zaman et al., 1991. Genetic distance was estimated from gene frequencies at 4 blood groups and plasma polymorphic proteins (the AKP, AKP-2, ES-1, Amy-1, Amy-3, Alb, Pas and Tf loci). Okada et al. (1988) suggested that the average genetic distances between the Domestic fowl and Jungle fowl were small for the Red Jungle fowl, intermediate for the Grey Jungle fowl, and very large for the Ceylonese and the Green Jungle fowls. The gene frequencies at morphological loci were also used to compare chickens of different districts (geographical areas of the country). The morphological characteristics observed were: a) comb shape; b) ear lobe colour; c) feather colour; and d) shank colour. Concerning the gene frequency at each locus some variations were observed among the districts. Good variation in the frequencies of the E and I alleles controlling feather colour was noticed. The genetic distances among indigenous Deshi populations were very small but the distance between the Deshi and Aseel was relatively large which almost corresponded to the differences between the breeds. These studies further revealed that no systematic selection had been carried out on those morphological characteristics of the indigenous chickens of Bangladesh. The list of indigenous, exotic and crossbred chicken genetic diversity and their distribution in Bangladesh are presented in Table 7.  Table 8.

Pigeon
There is a single native type of pigeon but about six (6) exotic types of pigeon are found in the country (Table 1). Indigenous "Jalali" pigeon is widely used by peoples.
Most of them are reared on free flying system i,e the farmers provide only shelter for their squab production. They used to collect their feed from different sources. The list of indigenous and exotic pigeon genetic diversity and their distribution in Bangladesh are presented in Table 9.

Quail
Both native and exotic types of quail are available in the country. Jungle quails are mostly found in the forest area under free flying conditions but indigenous type is reared in semi-urban area under intensive condition. Japanese, Brown and Dhakai are the three exotic types of Quail are reared in the semi-intensive or intensive systems. The exotic Japanese Quail is widely used and indigenous type is at the risk of extinction (Table 1). The list of indigenous and exotic quail genetic diversity and their distribution in Bangladesh are presented in Table 10.

Guinea fowl
Native Guinea fowl of indigenous type is reared by the farmers and found to be popular in some regions of the country. However, no survey works on their habitats or production system or any initiative for characterization of the germplasm is done except some individual evaluation at farm level (Table 1).

CONCLUSION
The farm animal genetic diversity is very important for a country's economic, social and cultural aspects. It is very essential for a country to demonstrate the linkages between biodiversity, livelihoods and socio-economic structure. The essential way of achieving sustainable conservation of biodiversity is through collaboration between local communities, national body or institution of a country.