Page 18 - Spring Graduation Booklet (SESSION-1)(19Oct2022)

DOCTORATES...

SCHOOL OF AGRICULTURE AND FISHERIES SCIENCES
FACULTY OF AGRICULTURE, ENGINEERING
& NATURAL RESOURCES
DOCTOR OF PHILOSOPHY IN AGRICULTURE
(ANIMAL SCIENCE)
CANDIDATE: SHININGAVAMWE Katrina L

CANDIDATE’S DISSERTATION

NUTRIENT CONTENT AND THE EFFECTS OF FEEDING FOUR
NAMIBIAN ENCROACHER BUSH SPECIES ON GROWTH,
METHANE PRODUCTION AND CARCASS CHARACTERISTICS
OF DAMARA SHEEP

The doctoral study was undertaken and completed under the supervision of Prof John F.
Mupangwa of the University of Namibia as Main-Supervisor and Dr Emmanuel Lutaaya
of the University of Namibia as Co-Supervisor

The candidate evaluated the nutritional and feeding potential of four Namibian
encroacher species with a special focus on the effects of bush-based feed on the
digestibility, growth, methane production and carcass characteristics of Damara
sheep. In Namibia up to 45 million hectares of rangelands are affected by bush
encroachment, resulting in reduced carrying capacity, loss of habitats and posing
a threat to livestock and wildlife production. The availability of encroaching bushes
presents an opportunity to be explored as possible alternative feed resource for
livestock. A combination of research methods including laboratory analysis, digestibility
studies, growth and carcass evaluation were conducted. The encroacher bush species
had moderate protein contents with a high proportion of the protein bound to fibre
making it unavailable to animals. The in vitro methane production produced during the
late dry season from all four species was higher than in the early rainy season, which
demonstrated the need for seasonal manipulation on bush-based diets to reduce their
contribution to atmospheric methane concentration. Bush-based diets produced from
the four species fed to Damara weaners, supported good growth in terms of average
daily gains and had carcasses of great quality according to the approved Meat
Classification Standards used in Namibian abattoirs.
This study concluded that milled bush from the selected encroacher species can
replace traditional roughage sources such as grass hay at 40% inclusion rate in properly
formulated and balanced ruminant diets without adverse effects on the dry matter
intake, digestibility, growth performance and carcass characteristics of growing lambs.
The milled bush from encroacher bushes does not have sufficient nutritional value as
sole feed to meet animal maintenance hence there is need to add supplements in the
bush-based diets of ruminant livestock.

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