Beef production in Botswana relies mainly on the range using local and foreign breeds as either pure breeds or for crossbreeding. The foreign breeds and their crosses are large and do not usually finish well on the range. Supplementation has not been used extensively in Botswana due to high cost of imported feeds. This study investigated the use of locally available agricultural by-products for feedlot finishing of young crossbred males commonly used in Botswana. The low, medium and high roughage diets were balanced for crude protein and mineral content but differed in digestible energy.
Animals fed the low and medium roughage diets had average daily gains above 1.0 kg per day, except for Brahman and Santa Gertrudis crosses which had daily gains of 0.8 kg per day when fed the low roughage diet. Crosses of South-Devon, Charolais, Santa Getrudis and pure Brahman fed the low roughage diet had cold dressed mass above 200 kg, whilst the Sussex crosses had cold dressed mass of 188 kg.
Based on this information, it is recommended that for animals raised on the range, finishing off should be done using low roughage diets for all breeds. Medium roughage diets can be used but will result in lower gains. Further research is needed to evaluate the digestibility of diets by the animals and to carry out the economics of intensive fattening using locally available feed resources.
The beef industry in Botswana is made up of two production systems; the commercial sector which accounts for 20 percent of the total beef cattle population and the traditional sector which accounts for the remaining 80 percent. The traditional sector is characterized by low production inputs and low rates of off-take (7%), whilst the commercial sectors off-take accounts for 18% (Bostwana Agricultural Development Policy 1993). For both sectors, beef production is mainly off range with little or no supplementation. This has resulted in a marketing age of 2 and 5 years for the commercial and traditional sectors, respectively (Botswana Meat Commission, personal communication). Although the majority of slaughter cattle are finished on natural grazing, this does not provide adequate nutrition to enable the large and fast growing animals to express their genetic potential for growth. Nutrition is especially limited during the long dry season and drought years, when both dry matter availability and protein content of natural pasture are very low. Therefore, it may be necessary to supplement slaughter animals with suitable diets that would allow them to grow faster and attain a good carcass finish at marketing age. The market price for slaughter stock in Botswana is based mainly on carcass weight and carcass grade, which in turn is determined by age and finish of the animal. The advantage of using breeds with faster growth rates and high mature weights can not be sufficiently exploited unless adequate feed resources in both quantity and quality are available to support such growth rates.
Although the indigenous Tswana cattle provide the base for beef production in the country, the use of exotic breeds for crossbreeding purposes, to take advantage of potential heterotic effects, has long been popular. However, very little information was available on performance of such introduced breeds and their crosses in the country (Lethola et al 1984). Since the early 1970s, the Animal Production Research Unit (APRU) has been involved in the evaluation of indigenous and some exotic beef breeds and their crossbreds for beef production. The breeds evaluated as sire breeds include Tswana and Tuli, Brahman, Africander, Bonsmara, Simmental, Charolais, Sussex, South Devon and Santa Gertrudis. The result of these studies from some of the above breeds and their crosses showed that only when nutrition and health were not limiting, did the use of exotic breeds and their crosses increase productivity above that of the indigenous Tswana and Tuli cattle.
Despite the large variation in the quality and quantity of the range, feedlot fattenting is not popular in Botswana (Machacha 1993) because of high cost of conventional feedlot rations, which have to be imported from neighboring countries. In 1973/75 APRU conducted a feedlot experiment using imported Rumevite winter and summer concentrate on Brahman, Simmental crosses, purebred Tswana, Afrikaner and Tuli cattle. The study showed that growth rate for crossbred animals was increased during the feedlot period. However, financial benefits from the increase in live weight gains did not justify the higher cost of the feed. The use of locally available crop residues and agro-industrial by- products provides an opportunity for improving the livestock feed resources for use in feedlots. Sorghum s tover, a readily available by-product from sorghum grain production can be used as a source of roughage in feedlot diets. However, since sorghum stover has low nitrogen and higher fibre content , there is need to include feed grade urea in the diets to provide fermentable nitrogen to increase microbes that digest fibre. Other locally available feed resources include wheat bran from milling companies and feed grade sorghum and maize grain available at the Botswana Agricultural Marketing Board (BAMB). These ingredients can be utilized to formulate feedlot diets that will give the required finish for slaughter cattle.
This paper presents results of a study on the feedlot performance of crosses of Tswana and Tuli cattle fed three different levels of roughage from locally available feed resources.
The study was carried out as part of the beef cattle evaluation program of APRU to assess the performance of crossbreds of the local Tswana and Tuli cattle with exotic beef breeds. The Tuli was included in the cross breeding project because of its close genetic similarity to the Tswana cattle. The study was conducted using 113 entire F1 males of the following breed groups; Brahman (BR), Sussex x Tswana (SUTS), South Devon x Tswana (SDTS), Charolais x Tswana (CHTS) and Santa Gertrudis x Tuli (SGTU). These animals were originally used in the evaluation of sire breeds on range and received only dicalcium phosphate and salt as supplement. At the age of 21 months they were transferred to a central testing station for this study. Due to lack of facilities, the experiment was started in 1994 and repeated in 1995 and 1996. Due to low numbers of purebred Tswana and Tuli cattle in the experimental stations, the Brahman which is very popular with beef producers in both farming sectors, was used as a base line for comparison.
At the start of the experiment, animals were given a high roughage diet for an adaptation period of 10 days, drenched orally with V albazen for internal parasites and injected intramuscularly with vitamins A, D and E. They were then randomly assigned to three groups and allocated to three diets consisting of low (4 0 %), medium (55%) and high (65%) content of sorghum stover roughage, the rest being cracked maize grain and wheat bran (Table 1). The diets were balanced for protein and mineral content. These diets represent the anticipated feedlot production scenarios for the smallholder commercial sector in Botswana.