Comparative ejaculatory response, fresh and frozen semen quality and fertility to artificial vagina vs electroejaculation method of semen collection in mithun ( Bos frontalis ) bulls

Abstract

Mithun, a semidomesticated and autochthonous bovine species of northeastern India, is reared under a free-range forest system.The 20 th livestock census shows an increase of 29.5% (3-3.9 lakhs) mithun over the previous census (20 th Livestock census, DAHD, Government of India, 2019). However, in recent times, denuding forest cover, commercialization of cropping systems, cross-breeding and sacrifice of potential elite mithun bulls have significantly decreased its habitat and the elite mithun population. The diminished population of superior breedable mithun bulls has increased the inbreeding within the population resulting in various reproductive problems including infertility. Therefore, elite bull selection, semen collection and artificial breeding programme need to be taken to overcome the inbreeding depression and to conserve and propagate this precious mountain bovine species.To have germplasm conservation, there is a need for an effective semen collection method from free-range mithun bulls. The rectal massage (Bhattacharyya et al., 2005) and artificial vagina (AV) (Bhattacharyya et al., 2009) methods have been used in collecting ejaculates from the farm mithun. Semen collected from the rectal massage method is poor in quality and quantity, resulted in

Assisted reproductive technologies (ARTs) in Mithun (Bos frontalis): What progress has been made so far? An overview

“…Fresh semen quality evaluation indicated creamy white colour, thick to medium consistency, volume in the range of 3–6 ml, concentration in the range of 500–1000 million/ml and progressive motility in the range of 70%–80% (Mondal et al, 2010; Nadaf et al, 2022). Immediately after collection, the tris‐egg yolk–glycerol or commercial diluents (BioXcell and BullXcell, IMV Technologies) were used for an initial and final dilution of semen and loaded into 0.5 or 0.25 ml semen straws before cryopreservation as per the protocol followed in other domestic cattle (Bhattacharyya et al, 2009; Nadaf et al, 2022). A significant difference was recorded in the semen quality parameters between fresh and frozen semen; however, adequate conception rates (Range: 50%–75%) were achieved after insemination with frozen–thawed semen (Mondal et al, 2010; Nadaf et al, 2022).…”

“…The morphology of the reproductive tract of Mithun is similar to bovines with a slightly longer tract (Perumal, 2018a) and the procedure of insemination is similar to other bovines. As the Mithun exhibit a longer estrus period, the twice insemination during the mid estrus (as determined by the fern pattern of cervical mucus) is beneficial to obtain the ideal conception rates (Nadaf et al, 2022). Accurate pregnancy diagnosis after successful artificial insemination is an important part of reproductive management and pregnancy diagnosis methods practiced in Mithun are similar to cattle and buffalo.…”

“…Mithun bulls usually do not mount on the non‐estrus cows, considering the limitation of regular availability of estrus cows, a Mithun cow's urine collected and stored during estrus was sprinkled over the perineal region of the dummy (Mondal et al, 2010) (Figure 2). Fresh semen quality evaluation indicated creamy white colour, thick to medium consistency, volume in the range of 3–6 ml, concentration in the range of 500–1000 million/ml and progressive motility in the range of 70%–80% (Mondal et al, 2010; Nadaf et al, 2022). Immediately after collection, the tris‐egg yolk–glycerol or commercial diluents (BioXcell and BullXcell, IMV Technologies) were used for an initial and final dilution of semen and loaded into 0.5 or 0.25 ml semen straws before cryopreservation as per the protocol followed in other domestic cattle (Bhattacharyya et al, 2009; Nadaf et al, 2022).…”

“…The 20th livestock census shows an overall increase of 29.93% (297,289–386,293) Mithun population over the previous census (20th Livestock census, DAHD, Government of India, 2019); however, a decline of 33.69% (34,871–23,123) and 10.58% (10,131–9059) in the Mithun population was recorded in Nagaland and Manipur states, respectively. The Mithun population is dwindling in some pockets due to increased deforestation, agricultural commercialization, outbreaks of foot and mouth disease and indiscriminate slaughtering of elite Mithun for table purposes (Lalsangpuii et al, 2016; Nadaf et al, 2022) and in addition, climate change is threatening its production and productive performance. The International Union for Conservation of Nature grouped Mithun under vulnerable species of mammals in India (IUCN, 2017) and emphasizes Mithun conservation.…”

“…In the free‐range system, natural breeding is practiced with dominant bull mating for years which has increased the inbreeding within the population resulting in various reproductive problems including infertility (Nadaf et al, 2022). The bigger‐sized and best‐quality Mithuns are sacrificed during ceremonies, leaving behind poor‐quality Mithun is another major hurdle to the genetic improvement of the population (Lalsangpuii et al, 2016).…”