Summary of the co-ordinated research project on development of feed supplementation strategies for improving the productivity of dairy cattle on smallholder farms in Africa

Livestock are an important and integral part of most farming systems in Africa. Recent nutritional research has demonstrated the possibility of substantial increases in the productivity of milk-producing animals fed poor quality roughages through small alterations to the feed base. In some cases, improvements have been demonstrated at the farm level: milk yield has increased, body condition of the animals has improved and age at puberty and the interval between calvings have been reduced. These advances have been brought about by the addition of critical nutrients to the diet, e.g. nitrogen or minerals for the rumen micro-organisms or rumen non-degradable protein or all of these. The introduction of improved feeding practices such as strategic supplementation using locally available feed resources (e.g. tree legume leaves, brewers waste, fish waste, multinutrient blocks, etc.) will not only enhance milk production but will also introduce a sustainable fanning practice that will ensure a continuous supply of milk and milk products to local populations. To introduce effective supplementation there is a need to identify the nutrient or combination of nutrients that are the limiting factors for achieving optimum rumen fermentative digestion of the basal diet or the efficiency of utilization of the major products of digestion. In many of the dairying systems operating in Africa this is far from easy, mainly because of the difficulties encountered in effectively measuring feed intake and selection and the efficiency with which the nutrients absorbed are used for productive purposes. In order to circumvent these difficulties it may be possible to measure biochemical indicators in the cows themselves that provide an assessment of nutrient status. The specific objectives of the co-ordinated research project (CRP) were to: - btain baseline information on production and reproductive parameters using a comprehensive survey, progesterone radioimmunoassay and clinical observations, and thereby identify major nutritional and management constraints to productivity, - investigate approaches for improving productivity in dairy cattle by increasing the utilization of basal diets and other locally available fed resources, - monitor the effectiveness of nutritional and management interventions by measuring performance indicators such as body weight, body condition, milk production and reproductive performance (using radioimmunoassay and other clinical observations), - establish whether differences in productivity correlate with selected metabolic indicators in blood, which might thereby prove useful as predictors of nutritional constraints