Bioconversion of Sweet Potato Leaves to Animal Feed | Chapter 07 | Recent Advances in Biological Research Vol. 4
Background:
High cost of conventional animal feed ingredients in Nigeria has made it
necessary to search for alternative local sources of feed. Crop residues
including sweet potato leaves abound in Nigeria. These have been explored as
feed sources. The ability of microorganisms to convert agricultural wastes to
more useful products could be harnessed to produce feed from sweet potato
leaves which can be obtained in high abundance at low cost.
Aim:
To examine the possibility of converting sweet potato leaves to animal feed
through fermentation with a co-culture of Chaetomium globosum and Saccharomyces
cerevisiae.
Materials
and Methods: Triplicate samples of sweet potato
leaves were fermented with a co-culture of C. globosum and S. cerevisiae for 21
days at 25±2°C and the effects of fermentation on nutrient composition was
determined. Fermentation and control samples were analysed for proximate, amino
acids, and elemental contents. Acute oral toxicity of the fermented leaves was
determined by the fixed dose method using mice and rats. Feed value of the
fermented sweet potato leaves for mice was determined. Parameters assessed
included feed intake, protein intake, weight gains, feed efficiency ratio, and
protein efficiency ratio.
Results:
Crude protein, crude fat and ash contents increased by 97.5%, 265.3% and 12.3%,
respectively, while crude fibre and nitrogen free extract values decreased by
22.7% and 61.4% respectively. Energy content increased by 14.5%. The observed
changes in the values of these nutritional components were significant (P <
.05). The percentage dry matter values of all the amino acids analyzed (lysine,
histidine, arginine, aspartic acid, threonine, glutamic acid, proline, glycine,
alanine, cystine, valine, methionine, isoleucine, leucine tyrosine and
phenylalanine) were found to increase, with the contents of seven of the amino
acids increasing significantly. Calcium, phosphorus, potassium and magnesium
contents increased significantly while those of copper and iron decreased. The
fermented leaves were found to be non toxic to mice and rats. Sole use of
fermented sweet potato leaves by the mice led to depression in feed intake,
weight gain, feed efficiency ratio and protein efficiency ratio. Mice fed with
commercial mice feed supplemented with
5% fermented sweet potato leaves had higher weight gains, feed efficiency and
protein efficiency ratios than those fed on the commercial mice feed.
Conclusion:
Fermentation of sweet potato leaves with a co-culture of C. globosum and S.
cerevisiae improved the nutritional value of the leaves. Fermented sweet potato
leaves can be included in mice feed up to 5% without negative effects. Sole use
of fermented sweet potato leaves as feed for mice and possibly other animals
would require mineral supplementation, energy enhancement, and further crude
fibre reduction.
Author(s) Details
Isaac A. Onyimba
Department of Science
Laboratory Technology, University of Jos, P.M.B. 2084, Jos, Nigeria.
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