The nutritive value of some Kenya feedstuffs and the effect of protein and energy rich concentrate supplementation on the utilization of chloris gayana tray by wether sheep.
The need to study the nutritive value of local livestock feeds in the tropics is advocated in section 1. That field of study was felt to be the more important in tropical countries where production from the domiciled livestock is very low as a result of a number of factors, the most important of which was felt to be the poor level of nutrition. It was decided, as a first step, to study in vivo digestibility and nutritive value of S0me improved local pasture grasses, fodders and arable farm by-products and to extend the field of study to include evaluation of the effects of the levels of protein and energy rich concentrate supplementation on the utilization of one of the commonly used pasture grasses, C. gayana. Wether sheep were used in all these studies. 2. Current knowledge on the pasture grasses, fodders and the arable farm by-products studied is reviewed in section 2 together with factors affecting digestibility and the effects of protein and energy supplementation on feed intake, digestibility and on nitrogen excretion, retention and utilization. Methods used in estimating digestibility were also included in that section. 3. Results: Section 3 gives results and discussion of in vivo digestibility and nutritive value of the feedstuffs studied. The results and discussion of the effects of the levels of protein and energy rich concentrate supplementation on the utilization of C,.gay-ana hay are given in section 4. 4. Conclusions: Conclusions of the studies carried out in sections 3 and 4 are given in section 5 and are here summarized as follows:- 4.1. Section 3 4.1.1. In all the pasture grasses studied digestibility and nutritive value decreased with maturity although the rate of decrease in a few of the pasture grasses studied was not as fast as in others. There was also a tendency for the voluntary dry matter intake to decrease with maturity when the grasses were considered individually; but there was no correlation between voluntary dry matter intake and either crude protein, digestible energy or digestibility of organic matter when the grasses were considered together. In all the pasture grasses studied crude fibre was more digestible than the nitrogenfree extract. 4.1.2. Phosphorus and sodi.umlevels were low in almost all the pasture grasses and at all the stages of regrowth. 4.1.3. In almost all the pasture grasses studied available digestible crude protein decreased much faster, as the grasses matured, than either available digestible energy or starch equivalent. However, it was apparent from the calQqlated examples in tables 52, 53 and 54 that available energy from the pastures was the major limiting nutrient for milk production~ 4.1.40 D.uncinatum and I~ 'batata vines were considered to be important nutritious'fodders and could play an important role in increasing livestock production, especially in small scale farming areas. 4.1.5. Both the arable farm by-products studied were shown to be important sources of supplementary protein and energy but nutritive value of the cottonseed cakes studied f1actuated very widely even within the decorticated and the undecorticated grades. At the marketed prices prevailing then both digestible crude protein and starch equivalent were cheapest per unit weight in "wishwa". Starch equivalent was most expensive per unit weight in the maize germ and bran meal. Digestible crude protein was most expensive in the wheat bran but it was cheaper in its starch equivalent than maize germ and bran meal. 4.2.' Section 4 4.2.1. With the levels of supplementation to the C. gayana hay, which ranged from 7 percent to 28 percent of the dry matter intake of the hay, both bean meal and maize meal did not significantly increase the voluntary dry matter intake of the hay. Voluntary dry matter intake of the hay was in fact apparently but not significantly decreased as the levels of supplementation by bean meal and maize meal were increased from 50 g to 100 g/wether/day; but levels of hay intake were never lower than in the non-supplemented animals, 4.2.2. Digestibility of all the nutrients in the C.gayana hay (except crude fibre by bean meal and crude protein and crude fibre by maize meal) were linearly, but not significantly, improved by both bean meal and maize meal supplementation. 4.2.3. Nitrogen retention was apparently increased as a result of bean meal and maize meal supplementation. 4.2.4. There were no significant liveweight gains resulting from bean meal and maize meal supplementation to the C. gayana hay; most probably as a result of either lower levels of supplementation used in the experiment or, possibly, as a result of the problems inherent in determination of liveweight. There was, however, an apparent increase in liveweight gain as the levels of maize meal supplementation were increased, even though ingested digestible energy levels were not very much higher than the digestible energy levels attained with bean meal supplementation. It was thought that, possibly, the higher levels of maize meal supplementation increased the efficiency of utilization of the resultant rumen metabolites. 4.2.5. Calculated metabolizability of digestible energy tended to decrease as a result of bean meal and maize meal supplementation but percent metabolizability was apparently least decreased at higher levels of maize meal supplementation. 4.2.6. It was concluded that if higher levels of supplements had been used and/or if the numbers of replicates had been increased, the trends of the parameters studied would, most likely, have been more marked and statistically more clear cut.