DEVELOPMENT OF EFFICIENT MINERAL SUPPLEMENTATION REGIMES FOR GRAZING RUMINANTS IN THE TROPICS

This special evaluation covers the period since project initiation in 1974 to 6/79, with a focus on areas identified for further study in the previous review of 1976. Through the excellent work of the University of Florida (UOF), the project has been a success. Significant research has begun in 16 countries. Mineral deficiency and toxicity surveys are underway, and mineral supplementation efficiency is being explored in many locations. Extensive data indicate low correlations among soil-plant-animal for minerals studied (Fe, Mn, Na, Zn). Liver samples collected from the most productive animals toward the end of the wet season were often found best for determining the mineral status of grazing animals. In experiments in five Latin American countries, mineral supplementation increased calving percentage from 50% to 75%. A doubling of weight gains were reported in one experiment. Preliminary cost-benefit data indicate returns of at least double the investment by correcting mineral deficiencies. It was found that many mineral supplements sold in Latin American countries are of poor quality, particularly in regard to phosphorus content, and do not meet label guarantees. Research programs to develop methodologies applicable to host countries have begun in three Asian countries. In countries where project activities are far along (e.g., Brazil, Costa Rica, and Columbia), research responsibility should gradually be transferred to in-country scientists, following an evaluation of the country's scientific and political readiness. In countries where the project is still developing, technican training and technology support will be necessary for program success. Team recommendations include a two-year extension of the project beyond the proposed 11/80 termination date in order to develop in-country research capabilities; and joint consideration by AID and UOF of a similar and expanded program in Africa and Asia.