PhD (AGR) (Animal Science) / Department of Animal Science / Horticultural by-products such as seed and nut oil residues have the potential to replace
conventional protein and energy sources in diets for ruminants.
The objective of the study was to evaluate the nutritive value of Macadamia oil cake and
Baobab seed cake as nutrient supplements for feedlot animals. Several experiments were
carried-out to evaluate the nutritive value of Macadamia oil cake and Baobab seed cake as feed
for ruminants. The nutrient composition of the cakes were determined using both proximate and
modern methods of analysis of feeds and a t-test was used to compare the means of
Macadamia oil cake and Baobab seed cake. The in sacco technique was used to determine the
rumen degradability parameters of dry matter, crude protein and Amino acids of the cakes. This
experiment was conducted using a completely randomized design. A three step-in vitro
technique was used to conduct a post ruminal digestibility trial and the study was arranged in a
completely randomized design. An apparent digestibility trial was conducted using metabolism
cages and fecal bags to avoid the mixing of urine and faeces and the experiment was carried
out as a completely randomized design arranged in a 2 x 2 factorial. A growth trial was
conducted using a completely randomized block design arranged in a 2x2 factorial with two
protein supplements and two inclusion levels as factors and blocked by sex of the lambs.
The two cakes had similar (P>0.05) dry matter, fat, hemicellulose and gross energy contents.
Baobab seed cake had significantly (P<0.05) higher ash, crude protein, acid detergent lignin
and nitrogen free extract than macadamia oil cake. Macadamia oil cake had significantly
(P<0.05) higher crude fiber, acid detergent fiber, neutral detergent fiber and cellulose
concentrations. Baobab seed cake had significantly (P<0.05) higher calcium, magnesium,
potassium, phosphorus (macroelements), zinc, and copper than macadamia oil cake.
Macadamia oil cake was significantly (P<0.05) higher in manganese and iron contents than
Baobab seed cake. Sodium content was not significantly (P>0.05) different between the two
cakes. Baobab seed cake had more (Tryptophan, Cysteine, Arginine, Aspartic acid, Glutamic
acid, Valine, Phenylalanine, Isoleucine, Leucine) Amino acids which were significantly (P<0.05)
higher in quantity than macadamia oil cake with the two cakes having similar (P>0.05)
remaining Amino acids contents. Generally Macadamia oil cake had more (P<0.05) saturated
and mono-unsaturated fatty acids than Baobab seed cake whereas Baobab seed cake had
more (P<0.05) poly-unsaturated fatty acids.
v
The in sacco rumen degradability characteristics of baobab seed cake and macadamia oil cake
were estimated for dry matter and crude protein of the cakes. Macadamia oil cake had
significantly (P<0.01) higher a value for dry matter than boabab seed cake. Baoaba seed cake
had significantly (P<0.01) higher a value for crude protein than macadamia oil cake. the b, c,
and a+b values for dry matter of both Baobab seed cake and Macadamia oil cake were not
significantly (P>0.05) different form each other. However, the potential degradability (a+b) value
for crude protein of baobab seed cake was significantly (P<0.01) higher than that of macadamia
oil cake. The b and c constants of the two cakes for crude protein were not significantly
(P>0.05) different from each other. The ED (Effective degradability) values calculated at three
outflow rates (0.02, 0.05, 0.08) were estimated for dry matter and crude protein of Baobab seed
cake and macadamia oil cake. The ED of the two cakes calculated at 0.02 outflow rate did not
significantly (P>0.05) differ from each other. However, baobab seed cake had significantly
(P<0.05) higher ED value at outflow rate of 0.05 whereas macadamia oil cake had significantly
(P<0.05) higher ED value calculated at outflow rate of 0.08. The ED values of baobab seed
cake for crude protein calculated at the three outflow rate were significantly (P<0.01) higher
than those of macadamia oil cake. The two cakes did not significantly (P>0.05) differ in dry
matter ruminal degradability but baobab seed cake had significantly (P<0.05) higher ruminal
crude protein disappearance from 16 to 72 hours of incubation than macadamia oil cake. The in
situ Amino acid degradation was determined on 0, 12, 16, 24, and 48 hour of ruminal incubation
of the cakes’ samples and generally they were significant (P<0.05) differences for both cakes
according to different incubation periods. The 3-step in vitro digestibility trial revealed that
baobab seed cake had significantly (P<0.05) higher dry matter, crude protein and Amino acids
digestibility values than macadamia oil cake. Apparent digestibility study revealed that nutrient
intake, faecal and urine outputs, and digestibility of nutrients were not significantly (P>0.05)
different between baobab seed cake and macadamia oil cake. However, lambs on 10%
macadamia cake having retained significantly (P<0.05) more nitrogen than the lambs on 15%
macadamia oil cake, 10% and 15% baobab seed cakes diets. However, the inclusion of either
baobab seed cake or macadamia oil cake at 10% or 15% in the diets of lambs did not
significantly (P>0.05) affect the DOMR, microbial protein yield and purine derivates output.
For the growth trial the lambs were offered four diets formulated to contain 10% MOC (control),
15% MOC, 10 BSC and 15% BSC. The inclusion of 15% MOC and 10% BSC in the diets of
lambs did not significantly (P>0.05) affect their final body weight, total weight gain, average
daily feed intake, average daily weight gain, warm and cold carcass masses between these two
vi
groups. The inclusion of 10% MOC and 15% BSC in the diets of lambs did not significantly
affect average daily feed intake and animal performance between these two groups. However,
lambs on 10% MOC and 15% BSC had significantly (P<0.05) higher average daily feed intake
and animal performance compared to lambs on 15% MOC diet. The feed conversion efficiency
and of the lambs in the four diets were not significantly (P>0.05) different. The dressing
percentage, carcass length, neck weight, fat thickness, body weight thickness and rib eye area
of the carcasses of lambs in this trial did not differ significantly (P>0.05) except for spleen and
skin with lambs on 10% BSC diets having the least skin weight and lambs on 10% MOC diet
having heaver spleens.
Generally BSC had higher (P<0.05) nutrient content than MOC. BSC and MOC were highly
degradable in the rumen whereas BSC was higly digestible post-ruminally compared to MOC.
The diets of fattening lambs formulated to include 10% or 15% of BSC or MOC as protein
supplements did not affect the apparent digestibility of the diets. Macadamia oil cake can be
incomporated in the diet of finishing lambs as a protein supplement at 10% inclusion level
without compromising the growth and carcass characteristics of the lambs. Baobab seed cake
as a protein supplement can be included in the diet of finishing lambs at up to 15% inclusion
level without deleteriously compromising on the growth and carcass characteristics of the
animals.
______________________________________ / NRF
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:univen/oai:univendspace.univen.ac.za:11602/1199 |
| Date | 21 September 2018 |
| Creators | Mikasi, Masiza Samuel |
| Contributors | Baloyi, J, J,, Bhebhe, E. |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 1 online resource (x, 143 leaves) |
| Rights | University of Venda |
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