The effect of feed withdrawal during lairage on meat quality characteristics in ostriches.

Commercially reared ostriches (n=84) were randomly allocated to one of two groups. The first group (stressed: n=38) was deprived of food for a period of 2.5 days prior to slaughter, to simulate the stress experienced by slaughter ostriches held in holding pens (lairage) at a commercial ostrich abattoir over a weekend. The second group (control: n=46) was fed normally until 24 h prior to slaughter. Initial live weight as well as hot and cold drumstick weight were independent (P>0.05) of treatment. Stressed birds lost on average (±SE) approximately three times more weight than control birds over the experimental period (-3.2±0.6 vs. -1.0±0.5 kg, respectively). Full stomach and alimentary tract weights did not differ between treatments although there was a tendency for that derived from stressed birds to have lower stomach contents. The intra-muscular (Muscularis iliofibularis) pH(f) of stressed birds was 0.22 units higher (P<0.01) than that of contemporaries in the control group 1 h post-slaughter (6.03±0.06 vs. 5.81±0.05, respectively). After 26.5 h in a refrigerated room, this difference still remained at 0.25 units (6.46±0.07 vs. 6.21±0.07, respectively; P<0.05). Post-slaughter changes in intra-muscular pH followed approximately the same trend in stressed and control birds. Intra-muscular temperature was largely independent of treatment, although there was a suggestion of a slightly higher (P=0.18) temperature in stressed birds immediately post-slaughter. Cooking loss, drip loss and shearing values were not affected (P>0.05) by the withholding of food for 2.5 days. It can thus be concluded that withholding feed from ostriches on lairage over a period of 2.5 days does not have any negative influence on the meat yield or physical quality traits thereof.

The true metabolisable energy content of canola oilcake meal and full-fat canola seed for ostriches (Struthio camelus).

1. The true metabolisable energy (TME) of canola oilcake and full-fat canola seed was determined for ostriches to broaden our knowledge of canola as a potential protein and energy source for ostriches. 2. Both test materials were diluted with a basal diet, fed to ostriches and TME-values estimated by multiple regression analysis. 3. The TME values for canola oilcake meal and full-fat canola seed for ostriches were respectively 13.76 MJ kg(-1) and 22.5 MJ kg(-1). 4. The TME values obtained for these 2 important protein sources will assist in the more accurate formulation of diets for ostriches.

Hatching success of ostrich eggs in relation to setting, turning and angle of rotation.

1. Three trials were designed to study the effects of axis of setting, turning frequency and axis and angle of rotation on the hatching success of ostrich eggs. The joint effects of axis of setting and angle of rotation were investigated in a fourth trial. 2. The hatchability of fertile ostrich eggs artificially incubated in electronic incubators (turned through 60 degrees hourly) was improved substantially in eggs set in horizontal positions for 2 or 3 weeks and vertically for the rest of the time. 3. The hatchability of fertile eggs set in the horizontal position without any turning was very low (27%). It was improved to approximately 60% by manual turning through 180 degrees around the short axis and through 60 degrees around the long axis at 08.00 and 16.00 h. A further improvement to approximately 80% was obtained in eggs automatically turned through 60 degrees around the long axis in the incubator. Additional turning through 180 degrees around the short axis twice daily at 08.00 and 16.00 h resulted in no further improvement. 4. The hatchability of fertile eggs set vertically in electronic incubators and rotated hourly through angles ranging from 60 degrees to 90 degrees around the short axis increased linearly over the range studied. The response amounted to 1.83% for an increase of 10 (R2=0.96). 5. The detrimental effect of rotation through the smaller angle of 60 degrees around the short axis could be compensated for by setting ostrich eggs in the horizontal position for 2 weeks before putting them in the vertical position.

Repeatability and phenotypic correlations for body weight and reproduction in commercial ostrich breeding pairs.

1. Reproduction is an important aspect of ostrich farming, where income is mainly derived from hides and meat. No estimates of repeatability or phenotypic correlations for reproduction and body weight are currently available for commercial ostriches. 2. Means, standard deviations, repeatability coefficients and phenotypic correlations for and among reproductive traits and body weight were computed for the average yearly production of 42 to 67 mixed age ostrich breeding pairs maintained on the Klein Karoo Agricultural Development Centre from 1990 to 1994. The among-breeding-pair variance component was used in the repeatability estimations, as the pairing off of the same male:female combinations repeatedly resulted in the confounding of these effects. 3. Phenotypic correlations of male body weight with egg production performance (-0.20) and female body weight with hatchability percentage (-0.16) were negative. Correlations of egg production performance with infertility (-0.20) and hatchability (0.23) percentages were favourable. 4. The repeatability of annual adult body weight was 0.68 +/- 0.05 in male ostriches and 0.61 +/- 0.05 in females. 5. Ostrich reproduction traits were extremely variable. An appreciable portion of this variation could be attributed to the repeatable nature of breeding pair performance from year to year. All the reproduction traits analysed were moderately repeatable, ranging from 0.38 +/- 0.07 (hatchability percentage) to 0.51 +/- 0.06 (percentage of embryonic deaths). Egg production performance during the first breeding season of 17 breeding pairs for which data were available predicted subsequent performance satisfactorily, suggesting that selection decisions can be made at quite an early age.