An integrated system of reproductive trait improvement in beef cattle under communal management conditions

Abstract

The continual rise in the production cost of agricultural products of animal origin makes the question of profitable livestock mainly dependent on the fertility of the animal. In order to bring about an improvement in animal production it is necessary that one should have a sound knowledge of animal reproductive performance as a base line" (Bembridge, 1987). There are many cattle breeds in Southern Africa. All cattle breeds may be classified into two major types, namely humpless and humped. The former group is taxonomically classified as Bos taurus and is exotic to Southern Africa. These breeds, introduced more recently into the country, are not necessarily well adapted to all South African environments. Humped cattle types may be classified into two groups, namely those with thoracic humps (Zebu) and those with cervi co-thoracic humps (Sanga). Zebu cattle are also not indigenous to Southern Africa. All Sanga types evolved from crosses between Zebu and humpless types. Sanga cattle accompanied black tribes in their migrations towards the southern regions of Africa. These cattle are known in Zululand as the Nguni and in Northern Transvaal as the Pedi. The Sanga cattle breed in Zimbabwe and Zambia are known as Nkoene cattle and in Botswana as Tswana and Tuli cattle (Schoeman, 1989). Livestock are raised in many different production systems or agro-ecosystems. Production systems evolve as a result of agro-ecological potential, the relative availability of land, labour and capital, and the demand for livestock products. Many production systems are currently at a sustainable equilibrium, with livestock being produced in harmony with nature and in environmentally sound systems. Livestock is a major component of agricultural production and always will be because 80 to 85 percent of the South African can potentially be used for grazing only . Livestock production a=unts for approximately 58 percent of the gross value generated by agricultural production (Bembridge, 1987). The majority of the livestock fanmers are subsistence farmers. Attention is focused on large ruminants, with most emphasis on beef cattle since they offer the greatest opportunities. Approximately two thirds of the world's domesticated ruminants are found in developing regions where they produce 30 percent of the world 's meat and 20 percent of the world's milk. However, their efficiency is only a quarter of that in developed communal farming due to low levels of nutrition and management in communal grazing areas (Bembridge & Tapson, 1992). Even so, 84 percent of the communal land in Southern Africa has a potential only livestock production, which contributes little to the cash economy. There is a dearth of infonmation on cattle production by small-scale stockowners in the less developed areas particularly of South Africa. Consequently, a considerable amount of research has been devoted to beef cattle fertility under intensive management conditions. However, little attention has been focused on the fertility of indigenous cattle under extensive communal management systems. Under extensive conditions, particularly in tropical and subtropical regions where animals are managed to survive under the stress of a resource poor environment. Cattle often experience prolonged dry seasons, nutritional deficiencies (drought) as a result of unreliable rainfall, as well as overgrazing due to overstocking, diseases and parasites, extreme temperatures and poor breeding strategies together with the utilization of traditional medicines in favour of modern medicines. These are viewed as the major factors that depress the overall herd fertility. The objective of this study was to evaluate fertility traits as influenced by environmental factors in order to develop an integrated approach to beef cattle improvement under communal management conditions.