|dc.description.abstract||The aim of this study is to determine the effect of crossbreeding Zimbabwean Blue (ZB) and South African Black
(SAB) ostriches on the morphological, physical, chemical and sensory quality of the meat. However, it is also
necessary to determine the reproductive performance of these genotypes to scientifically support decisions
made in the ostrich industry.
In relation to reproductive traits and body measurements influencing these traits, results from the study
suggested that ZB birds are between 9 and 15% heavier than their SAB contemporaries. Regarding SAB
females, egg production was 47% higher, levels of shell deaths were lower, percentage of eggs not incubated
was lower (P<0.01) and 84% more (P<0.01) chicks were produced in a season compared to their ZB
contemporaries. Mates of SAB males produced a higher (P≤0.05) percentage of eggs not incubated and higher
shell death percentages than the mates of ZB males. It has to be conceded that ZB females had a lower
reproduction than SAB females, limiting the application of this genotype as a dam line in crossbreeding systems.
With regard to morphological properties, the pure Blue genotype in comparison to the pure Black
genotype differed significantly (P≤0.05), with 16 kg for live weight, 8.3 kg for carcass weight and 3.5 kg for leg
weight. However, when comparing carcass yields (expressed as %) there were no significant differences
(P>0.05) between genotypes. The M. gastrocnemius, M. femorotibialis accessorius, M. iliotibialis cranialis, M
iliotibialis lateralis, M. iliofibularis and M. iliofemoralis showed significant genotype differences (P≤0.05) for
individual muscle weight.
When comparing the physical meat quality characteristics between the pure Blue genotype and the pure
Black genotype, 70% of the muscles were higher (P≤0.05) in pH24, 50% of the muscles were redder (P≤0.05)
and significantly less (P≤0.05) saturated in colour, 67% of the muscles had a lower (P≤0.05) percentage drip
loss and 50% of the muscles had a lower (P≤0.05) percentage cooking loss. No significant (P>0.05) genotype
differences were observed regarding the sensory quality of the meat.
Regarding chemical meat quality characteristics, the percentage of moisture was higher and the
percentage of lipid was lower for eight of the ten muscle groups from the pure Blue genotype. No significant
differences (P>0.05) were found between genotypes or between muscles regarding the percentage of protein
present in the meat. The highest (P>0.05) content of soluble collagen, myoglobin and cholesterol was found in
the Blue x Black genotype, whereas the lowest percentage of the latter constituents was found in the pure Blue
genotype. For the pure Black genotype the concentration of saturated fatty acids in the meat was lower
(P≤0.05), the concentrations of total unsaturated fatty acids and desirable fatty acids in the M. illiofibularis were
the highest (P≤0.05), while the concentration of monounsaturated fatty acids was also higher (P≤0.05) in both
muscles of this genotype compared to the other two genotypes. Regarding both fat depots, the pure Black
genotype had a lower (P≤0.05) concentration of saturated fatty acids, a higher (P≤0.05) concentration of
monounsaturated fatty acids and total unsaturated fatty acids and a higher (P≤0.05) polyunsaturated:saturated fatty acid ratio. The percentage of desirable fatty acids in the abdominal fat depot was significantly higher
(P≤0.05) for the pure Black and the Blue x Black genotype.
In conclusion, crossbreeding between SAB and ZB ostriches seems to be a viable option to produce
larger birds with more meat, without negatively affecting the overall quality of the meat.||en