| dc.description.abstract | 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. | en |
