short note on-White yalk, Chiru, Dzo
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Answer:
Explanation:
The yak-rearing states of India are Arunachal Pradesh, Sikkim, Uttar Pradesh, Himachal Pradesh and Jammu and Kashmir. The first three of these, bordering the southern slopes of the Himalayas, have a cold, humid climate, while the two northerly states are cold and arid. Numbers of yak are shown in Table 11.2.10. The total of about 51 000 yak in 1997 represents a marked decline from the 132 000 yak reported for the year 1977 (Pal, 1993a). Gupta and Gupta (2000) and Nivsarkar et al. (1997) published even lower numbers of around 40 000 for recent years - largely because they suggested a lower number for Jammu and Kashmir. However, changes in numbers of yak over the years seem to differ among states - some having remained static in numbers.
Reasons suggested for the decline in size of the yak population include socio-economic causes, one of which is a desire for an easier and more comfortable lifestyle on the part of the younger generations (Pal, 1993a). The closure of the border with Tibet to the former traffic in yak may also be a contributory factor and has affected the availability of new sources of breeding stock. Nivsarkar et al. (1997) suggested that hybridization on a large-scale of yak with local Tibetan cattle was another factor leading to this sharp decline in the pure yak population.
Yak types
There are a number of different phenotypic types among Indian yak. The "common" yak resemble medium size hill cattle in conformation; "Bisonian" yak are bigger animals; "Bare-back" yak have a long body and little hair on their backs. Yak with a particularly hairy forehead, long-haired yak and white yak represent the fourth type described in more detail by Pal et al. (1994). It is not suggested that these types represent different breeds as such as they occur within the same districts or even within herds.
Among the ten colour patterns noted for yak in India, the majority are black (29 percent) or black with white patches (40 percent). Some 15 percent are grey in colour and the remainder of the population is made up of small proportions of brown with white patches, pure white and various mixtures, including piebald and skewbald animals.
Breeding and hybridization
The Indian yak population is thought to suffer from inbreeding due to the nonavailability of new yak germ-plasm from Tibet for the past five decades (as referred to earlier) and because of the practice of prolonged use of the same bull within herds. Exchange of breeding bulls among herds and selection schemes have not become established as regular practices, although the intentions appear to exist as part of the yak projects of the National Research Council.
Hybridization with local cattle is practised only randomly, although the F1 hybrid is generally more productive than either parental species. It has to be stressed, however, that yak and the F1 rarely run together on the same grazing, except in winter. During the growing season, the F1 are at mid-altitudes and the yak at the highest altitudes. Claims for higher growth and milk output from the F1 relative to the yak must therefore take account of a possible nutritional advantage enjoyed by the F1. In terms of milk output, though the quantity from the F1 is higher than from the yak, the fat content is less and total fat production may be similar for yak and F1. The F1 provides a lower income from hair and the fine undercoat than the pure yak, but both types are good pack animals. The performance of animals from successive stages of mating yak with cattle (beyond the F1 stage) was found to be inferior to the F1 (Pal, 1992) - and producing animals beyond the F1 is discouraged because the different types are also difficult to differentiate visually. Nivsarkar et al. (1997) also shared the concern, expressed in Chapter 3, that even when there was a case for hybridizing to increase milk output from the herd, the extent of this should be restricted so as not to threaten the replacement of the pure yak population.
As in neighbouring countries, different names are attached to each of the various types of hybrid offspring from any such matings.