Genetic diversity of Mithun population in Bhutan was studied using 14 microsatellite markers. Two sets of two-step polymerase chain reactions were performed with multiplex and individual markers for genotyping 105 hair samples collected from Arong in Samdrupjongkhar (AS, 36) and Wangdigang in Zhemgang (WZ, 69). Fifty-three alleles were detected with average of 3.89 alleles and polymorphism information content of 0.44 ± 0.03 per locus. A low level of genetic variability within population was present with observed heterozygosity at 0.50 ± 0.06 and expected heterozygosity at 0.48 ± 0.06. Analysis of molecular variance attributed 58 percent of total variation to within the individuals. Mean F IS and F IT were −0.056 and 0.005 respectively, indicated low level of population differentiation and limited out-breeding. The normal L-shaped distribution of allelic frequencies without any mode-shift revealed the absence of recent genetic bottleneck in Mithun populations. Therefore to manage inbreeding in the small Mithun population of Bhutan, periodic assessment of inbreeding levels and exchange of animals between farms is recommended to reduce frequency of introduction of animals from India.

The study describes the standardization of a suitable semen cryopreservation protocol for the first time in mithun (Bos frontalis) and birth of the first mithun calf through artificial insemination. The semen samples were collected from adult bulls through the rectal massage method and cryopreserved in liquid nitrogen using tris–egg yolk–glycerol diluent. The diluted semen samples were packaged in 0.50 ml straws and kept at 5°C for 4 h for equilibration. Following the equilibration, the straws were frozen into liquid nitrogen vapour for 10 min and then plunged into liquid nitrogen for storage. It was observed that the progressive motility (%) decreased significantly (P < 0.01) in cryopreserved semen (43.3 ± 4.1) compared with fresh samples (76.6 ± 3.3). The percentages of live spermatozoa (P < 0.01) and spermatozoa with intact acrosome (P < 0.05) also decreased significantly in cryopreserved semen (54.0 ± 3.3 and 64.6 ± 5.3) compared with fresh samples (79.3 ± 2.6 and 85.3 ± 1.8). Simultaneously, the total morphological abnormality (%) was found to be significantly (P < 0.01) higher in cryopreserved samples (15.46 ± 2.68) than in fresh semen (3.85 ± 0.63). A total of three mithun cows were inseminated using the cryopreserved semen. All the cows conceived following insemination and gave birth to healthy calves. The study revealed that mithun semen can be cryopreserved efficiently using tris–egg yolk–glycerol diluent, which can be further used for artificial insemination.

Studies were conducted on two calves and a pregnant female captured from the forest to assess the feed utilization, growth pattern and milk composition in Mithun (Bos frontalis), a rare bovine species of north-eastern India. The DMI, kg/100 kg body weight was 0.05 with DM and OM digestibility of 56.95 ± 3.68 and 58.46 ± 3.51 percents, respectively, in calves. The growth was more during the May to October months, however, the average growth of 181.26 ± 23.51 g day-1 was obtained during the year on grazing. The Mithun was not a milk yielder, but became accustomed to milking. Fat content in milk varied from 6.8 to 7.8%. The total solids, protein, lactose, ash and solid not fat (SNF) were estimated at 18.0, 4.9, 5.0, 0.8 and 10.7% respectively with COB negative at 4°C. The birth weight of the male calf was estimated at 22.0 kg, and an average growth of 325.14 g day-1 was determined in 214 days with maximum weight gain during the first two months of age.