IntroductionGenetic potential of dairy breeds in the tropics is low yet hardly exploited because the common objective has been to meet the limited milk requirements of the household. The levels of animal husbandry in most tropical countries, exceptIsrael andAustralia, are low. The breeds perform under harsh and unfavourable climates, varying between equatorial (rainfall above 2032 mm/annum and a temperature range of 21-32癈) totropical arid (low and erratic rainfall less than 500 mm/annum and temperature extremes of 0-60_C). Large variations in climate and vegetation, and shortage of feeds across the region are major constraints to dairy production. Field recording in most tropical countries is almost negligible and virtually no information on the performance potential of cattle and buffalo breeds in their native environments is available. Change in cattle and buffalo population dynamics, in relationto calves born, disposal patterns through sale of heifers and cows in a village has never been looked into. Against this background, the development of breeds has produced distinct characteristics suited to different conditions.Dairy cattleBreedsDomestic cattle belong to the family Bovidae, sub-family Bovinae and can be classified intoBostaurusandBosindicus. They have 30 pairs of chromosomes, interbreed and are distributed throughout the tropics. The third type,Bibos banteng(Bali cattle) andBibosfrontalis(mithun) belong to genus Bibos and are present only in south and south east Asia.Domestication ofBostauruscattle took place some 8000 to 9000 years ago and Homitic longhorn and shorthorn types are believed to be their ancestors. The origin ofBosindicusbreeds (humped cattle) was in western Asia (Payne 1970). Both humped and humpless cattle were introduced to Africa from western Asia and into America and Australia from Europe by the immigrants.European cattleBostauruswere introducedin the tropics to be raised as pure-breds and crossbred with indigenous breeds. As aresult of crossing of native cattle with European dairy breeds, large numbers of crossbreeds have been produced in varioustropicalcountries, which are being used in selection programs. ZebuBosindicuscattlewere introduced into United States in the nineteenth century for crossbreeding with European breeds. Breeds resulting from crosses are used in the southern regions of north America and tropical south America.Most of the cattle breeds in the tropics evolved, through natural selection, for adaptability and survival to local environments. Often, breeds resemble eachother with slight morphological differences,butbecause of constant inbreeding in one locality, independent breeds have evolved. In general, the cattle from drier regions are well built and those from heavy rainfall areas, coastal and hilly regions are of smaller build.The physical characteristics, utility and production performance of cattle breeds available in tropical and sub-tropical regions of the world have been described by Payne (1970). Most indigenous cattle breeds in the tropics are multipurpose (milk, meat, draught) and that only a few breeds have good milk potential. Physical and economic parameters for some of the important indigenous dairy breeds and new crossbred types developed in the tropics are discussed below:DamascusAnimals of this breed are found in Syria, Turkey, Iraq, Cyprus, and Egypt and are crosses between humpless and humped cattle. The breed appears to have been developed in the Ghuta, the oasis of Damascus and then spread to other regions. Animals are of medium size with a narrow body and long thin legs. The coatcolour is light or reddish to dark brown. Thehead is long and narrow with short horns. The hump is absent; the dewlap is relativelywell-developed particularly in males. The udder is medium sized with long thin teats. Damascus is one of the best milch breeds in western Asia. The females yield between 1500 and 3000 kg in a lactation period of 200 to 300 days with four to five per cent fat.GirAlthough, the breed is native of Gujarat, it isalso found in Maharashtra and Rajasthan States in India. The peculiar features of the breed are a protruding-broad and long forehead, and pendulous forward turned ears. The popular colour is white with dark red or chocolate-brownpatches distributed all over the body. Entire red animals are also encountered although it is usually mottled withyellowish-red to almost black patches. Gir cows are good milkers and milk yield ranges from 1200 to 1800 kg per lactation. The age at first calving variesfrom 45 to 54 months and the intercalving period from 515 to 600 days. The Gir breed has been exported to other parts of the world. In Brazil where large herds are found,it is known as Gyr. Brazil has also evolved astrain called Indubrasil which is a cross between Gir and Kankrej. Gir animals are highly prized by Brazilian breeders who have created a breed society. Gir animals have also beenexported to the USA, especially Texas, Florida and Lousiana states.HarianaThe native breeding tract of this breed encompasses large parts of Rohtak, Hisar and Gurgaon district of Haryana State and is aprominent dual-purpose breed of north India. It has been extensively used in grading up non-descript cattle particularly to improve their draught capacity in the Indo-Gangetic plains. Hariana cattle are characterised by a long and narrow face, flat forehead and well marked bony prominence at the centre of the poll. Horns are small. The muzzle is usually black. Eyesare large and prominent. The udder is capacious and extends well forward with a well-developed milk vein. The teats are welldeveloped, proportionate and medium sized. Good specimens of cows yield up to 1500 kg of milkper lactation. The age at first calving is 40 to 60 months depending on management and feeding conditions. The intercalving period varies from 480 to 630 days. Males are powerful work animals.IraqiThe breed is found in southern Iraq and resembles Red Sindhi. It is medium sized breedwith short legs. The coat colour is golden to bright bay. The hump and dewlap though prominent are not large. Average milk yield per lactation is around 600 kg and calving interval 400 days. The breed is extensively being used in upgrading with temperatedairy breeds.KankrejThe home tract of this breed isGujarat (India). It is the heaviest of the Indian breeds. The animals have a broad chest, straight back and a well-developed hump. The dewlap is moderately developed. These cows are average milkers and yield about 1400 kg under farm conditions while yield under village conditions is low. The age at first calving varies from 45 to 47 months and the intercalving period from 486 to 510 days. Bullocks are fast and powerful draft animals. This breed has beenexported to a number of countries to be raised as pure-bred and for crossbreeding. Today excellent herds of this breed are found in Brazil where it is known as Guzerat. Many beef breeds in some Latin American countries and southern states of the USA have some inheritance of Kankrej.LebaneseThis breed isfound in Lebanon and Syria. It is a short-bodied medium size animal with short, strong legs. The coat is yellowish to reddish brown, reddish brown or black in colour with black tips. The skin is medium in thickness with short hairs. The horns are of medium length and white in colour. The dewlap is well developed. The milk yield varies between 1000 and 2500 kg per lactation.Mauritius CreoleThis is a humpless polled breed. The animals are small, neatand compact. The predominant coat colours are white, white with brown, dun or dark markings and brown. The skin is thin and un-pigmented. The dewlap and sheath are very small. The breed is primarily used for milk production. Milk yield varies between 2225 and 3481 kg in a lactation length of 180 to 300 days.OngoleThe native tract of this breed is the Guntur district of Andhra Pradesh, India. This is essentially a large muscular breed suitable for heavy draft work. An average milk yield of 600-1000 kg is common. Good specimens yield up to 1500 kg per lactation.The age at first calving is 38 to 45 months and the intercalving period 470
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