A study of the nutritive value of East African pastures for ruminant livestock with special reference to mineral nutrition in grazing dairy cattle

Abstract

The literature was reviewed on the nutritive value of pasture with special reference to mineral nutrition in grazing dairy cattle in East Africa. It is known that the gr-o.rth of herbage to maturity is accompanied by both physical and chemical changes. The chemical changes involve a change f'rom leafy veeclafy vegetative stage to morphological stemmy growth, the propotion of leaf to stem decreases resulting in building up structural materials (cellulose and lignin) Advancing stag of growth is also associated with change in chemical composition of plants. He content of cude protein and ash decrease while the content of CF AND NFE rises. As a result of both physical and chemical changes as the plant matures there is concomitant decrease in digestibility. Thus mature plants are low in digestibility and hence low in nutritive value, for it has been shown that digestibility affect feed intake- the higher the digestibility the higher the intake; and the converse is true. Other factors affecting the nutritive value of pastures have been reviewed. 2. It has been observed. That comparatively little work has been reported on tropical pasture grasses compared to temperate pasture grasses. Further more the little research that has been carried out on tropical pastures has ncetrated on botanical composition ,pasture management energy and protein values of pastures. In East African pastures at different stages of growth. On the other hand, there is space and scattered information on mineral contents of East African pastures and their effect on Livestock. Production. It was noted (l in the review of litcrature that in the case of mineral deficiency diseases in stock it is important to look at the whole of events which leads to deficiency d.ieease – a deficiency in the soil, Leads to a deficiency in pas ture which causes a deficiency in the grazing animals In the light of this the study described in this thesis was there for designed to study soil - plant-animal mineral relationships in different ecological Zones in Kenya and Tanzania. To the best knowl edge of the author, this study was the first of its kind to be carried out in Kenya and Tanzania. Since eneregy protein and minerals are inter-related in functions, this study looked at the invivo digestibility of pasture, CP and other chemical components of pasture to determine the nutritive Val ues of such pastures in which mineral analysis were carried out. 3. The results on energy and protein values of past urea show that: (a) Judging from the low vitro digestibility particularly in.dry season, insufficient bulk (and hence insufficient energy) was available to satisfy the animals energy requirements for maintenance and production as discussed in Sections 5.2.7 and 5.2.8. (b) Crude protein was also limiting even for maintenance on most stations, particularly, during the dry season , The low CP coupled with the low digestibility of pastures, again meant insufficient bulk was .availability to satisfy the animals for Crude Proteinrequirements for maintenance and production as discussed in Section. 5.2.3. Furthermore, H should be noted that crude protein showed high and significant correlation (p <0.001) wtith: (i) Phosphorus at high altitude (ii)Crude fibre and (iii) in vitro digestibility coefficients. This Shows how important cp is a measure of nutritive value of pastures The status of mineral contents in different ecological zones in Kenya and Tanzania. Examinat ion of soils, pastures and bovine plasma revealed that:…