Effect of cottonseed oilcake meal on ostrich growth performance, meat chemical composition and sensory attributes

[摘要] ENGLISH ABSTRACT:This research study consists of three investigations with regard to ostrich (Struthio camelus var.domesticus) production, meat quality and the processing of ostrich meat into a value added meatproduct.The first study was conducted in order to establish whether the gradual replacement of soybeanoilcake meal with cottonseed oilcake meal (CSOCM) as a protein source in the diet of slaughterostriches would affect ostrich growth performance and meat quality. A total of 105 ostriches weredivided into five feeding groups according to the CSOCM inclusion level: Control (0% CSOCM),3%, 6%, 9% and 12% CSOCM, and fed with experimental diets from 6 to 13 months of age. As aresult of feeding CSOCM, the final live weight and the average daily gain significantly increased inthe 12% CSOCM group compared to the other treatment diets. The proximate composition,cholesterol content, mineral and fatty acid profile of the meat remained unaffected. Considering allthe results, CSOCM may be used as an alternative protein source to soybean oilcake meal inostrich nutrition, resulting in decreased feed costs.Secondly, a descriptive sensory analysis, together with chemical and physical measurements, wasperformed to determine whether the manipulation of the fatty acid composition in the fan fillet(Iliofibularis muscle) as a result of feeding CSOCM would be detected on a sensory level. Twolevels of CSOCM were investigated; 0% as a control and 9% CSOCM. No significant differenceswere found for the physical measurements (cooking loss (%) and shear force) as well as for the pHand proximate composition of the raw fan fillet. The Control group presented a higher (P<0.05)mono-unsaturated fatty acid (MUFA) content in the cooked fan fillet whereas the 9% CSOCMgroup showed a favourable increased (P<0.05) poly-unsaturated fatty acid (PUFA) content whencompared to the cooked Control samples. As a result, the poly-unsaturated:saturated fatty acid(PUFA:SFA) ratio in the 9% CSOCM group was also higher (P<0.05). No differences (P>0.05)were found between the treatments for the n-6:n-3 (omega 6 to omega 3) ratio. The 9% CSOCMgroup had a more intense beef aroma, had a higher level of initial and sustained juiciness as wellas increased tenderness (P<0.05). Inclusion of 9% CSOCM resulted in a favourable cooked ostrichfan fillet.Finally, the effect of feeding CSOCM on a processed ostrich meat product was investigated. Fanfillet (Iliofibularis muscle) from 13 month old birds receiving no cottonseed oilcake meal (Control) or9% cottonseed oilcake meal (9% CSOCM) was used. Olive oil was used as a replacement forpork fat, and warthog (Phacochoerus africanus) meat was used to replace commercial pork meatin the production of a semi dry sausage, cabanossi. Olive oil was included at three levels (0%, 1%and 2%). Six treatments were investigated: Control 0% olive oil, Control 1% olive oil, Control 2%olive oil, 9% CSOCM 1% olive oil, 9% CSOCM 2% olive oil en 9% CSOCM 2% olive oil. TheControl and 9% CSOCM ostrich meat did not differ significantly in chemical composition nor fattyacid profile. After smoking and drying the fat content in the cabanossi containing 0%, 1% and 2% olive oil averaged 7.2%, 7.45% and 8.65% respectively. Processed meat products containing lessthan 10% fat are classified as a low-fat meat product. Olive oil is a mono-unsaturated vegetable oilcontaining mainly Oleic acid (C18:1n9c), and low quantities of saturated fatty acids andpolyunsaturated fatty acids. Total mono unsaturated fatty acids in the cabanossi increased from47.0% to 73.0% of total fat, whilst total saturated fatty acids and total polyunsaturated fatty acidsdecreased from 40.6% to 19.9% and 11.6% to 6.6% respectively as olive oil increased from 0% to2%. The inclusion of olive oil at 2% resulted in cabanossi with increased (P<0.05) tenderness,juiciness and cured red meat colour, all factors that appeal greatly to the consumer. Overall flavourwas not adversely affected by the inclusion of olive oil.This investigation indicated that the use of CSOCM had no negative effect on the productionperformance of ostriches whilst a 9% CSOCM inclusion level resulted in meat that was found to befavourable by a trained sensory panel. Furthermore, the use of CSOCM as a feed component alsohad no negative effect on a processed product (cabanossi) derived from the meat obtained fromthe birds fed this feed component. The CSOCM used in this investigation had low levels ofgossypol (10 to 20ppm) and more research is required on the effect of the use of CSOCM withhigher levels of gossypol on the production performance of ostriches.

[发布机构] Stellenbosch University