The stunning of ostriches (Struthio camelus) has traditionally been carried out with hand-held tongs whilst birds are held in a restraining area by applying pressure normally from behind by gently pushing on the tail feathers. The area is often a V-shaped structure, high enough that the stunning operator is not kicked. After stunning, the birds are rocked backwards and a rubberised leg clamp placed over the legs at the tarso-metatarsal bone allowing the birds to be chain-shackled by the big toes. This stunning procedure has been replaced by a new restraining and stunning mechanism which completely envelops the ostrich in a padded clamp holder. Double-padded sides restrain the bird's upper thighs and a rubberised foot clamp holds the feet so there is no physical damage to the bird. As the bird is electrically stunned with electrodes placed both sides of the head, the entire stunning box rotates 180° so that toe clamps can be applied without any danger to the stunning operators. Within 20 s of stunning, the birds are bled by means of a complete ventral cut to the neck and/or by thoracic sticking.

Although ostriches are herbivores, their diets in commercial farming in Israel consist mainly of concentrates. The objective of this study was to evaluate an alternative for fattening ostriches aged 10 to 30 weeks, which combines pasture with concentrate feeding. Chicks were allotted to three treatments. Diet of group C40 consisted of concentrate only, provided at 40 g/kg body mass (mb). Groups CG20 and CG30 received concentrate at 20 and 30 g/ kg mb, respectively, and grazed 4 to 6 h/day on lush green alfalfa (Medicago sativa), sown barley (Hordeum vulgare), natural pasture or sulla (Hedysarum coronarium). During the last 10 weeks of experiment, groups CG20 and CG30 were merged into one group, managed as CG20 and grazed natural pasture, sulla, alfalfa, or vetch (Vicia sativa). Ostriches from group CG20 and CG30 consumed 390 (s.e.30) g and 260 (s.e. 20) g DM per day at pasture, i.e. 0·46 and 0·28 of their total daily intake, respectively. Pasture intake for CG20 was higher (P < 0·05) than for CG30. Intake of pasture (both grazing treatments combined) was twice as much as on natural pasture or alfalfa as on barley. These results were consistent with the ostriches’ preference for forbs rather than grasses in the natural pasture. The mean organic matter digestibility was 0·84 (s.e. 0·01), ostriches gained at 347 (s.e. 13) g/day, and the food conversion ratio was 3·05 (s.e. 0·16), with no effect of group. Also, grazing did not affect the dressing rate (0·47, s.e. 0·015) or the size and mass of the different parts of the gastro-intestinal tract, with the exception of the glandular and muscular stomachs, which were proportionately 0·4 (P < 0·05) heavier in grazing birds. Lower (P < 0·05) fat content (33·8 v. 26·5 g/kg) but not tenderness, of a selected muscle (fibularis longus) was found for grazing birds. This study suggests that, in young ostriches, grazing lush green pasture may reduce concentrate intake by proportionately 0·4, without altering growth performance or carcass yield and quality.

Due to a belief in the special healthy characteristics of their meat, ratites (ostriches, emus, rheas) are receiving more and more attention as meat producers for developed markets. All three kinds of ratites can be slaughtered by the same technique. At the scientific level, avian nomenclature is applied to the muscles used in meat production, while a variety of trade names is being used commercially. Dressing percentage, meat production on a live and carcass weight basis, as well as proportional weight of individual muscles are of the same order for all three species. Ratite meat is characterized by a high final pH value which may result in a limited shelf life. Nutritional information, especially about emu and rhea meat, is rarely found.

The farming of ostriches is well established in South Africa and is gaining in popularity in agriculture around the world but few scientific data are available for rates of egg production and the factors affecting incubation and hatching. Production and hatchability of over 1200 ostrich eggs on a farm in the United Kingdom were recorded during the 1995 season. Females of breeding ages (no. = 43) were kept in 13 enclosures in sex ratios of 1: 1 or 1: 2 (M: F). Productivity of all ostriches over the laying season was 25·2% although when results from individual enclosures, and from individual birds, were examined higher rates of production were achieved although only one bird achieved her full laying potential. As group size increased productivity decreased. Overall fertility was 78·7% although fertility greater than 90% was achieved by females kept in pairs or trios. Larger group sizes had lower fertility. Mean weekly hatchability was only 24·1% with hatch of fertile eggs being 31·9%. Maximum hatchability of eggs produced from an individual female was 73% of fertile eggs. Microbial contamination of eggs was 32·6% and this was the biggest cause of failure to hatch, although rates of contamination varied between females. These results for productivity are similar to those published for ostriches in Israel and South Africa. Hatchability is lower, and microbial contamination is higher than published information although this is the most comprehensive study of ostrich production yet published. Future development of ostrich breeding programmes needs to concentrate on small breeding groups, preferably pairs, and on improvements in nest site hygiene and post-laying egg management.

Growth results of 43 ostrich males and females were used to compile growth parameters of a flock that is representative of Oudtshoorn birds, using the Gompertz model. Growth results comprised 19 recordings of body weight for each individual commencing from 1-day-old to day 520. Individual fits of data to the growth model were exceptionally good, resulting in low CV values of 0·02 and 0·03 for the mean values of all estimates of mature live weight for male and females respectively. The estimated mean mature body weights for the flock were 119·2 kg for males and 122·3 kg for females. Rates of maturing were 9100 and 8500 for males and females respectively which corresponded to ages of 180·83 and 199·2 days at which maximum gain in weight were achieved. None of these parameter estimates differed significantly between sexes. Results in the present study suggested substantial adjustments to growth parameters for Oudtshoorn ostriches published by du Preez, Jarvis, Capatos and de Kock, 1992.

Although the extent of ossification between the caracoid and clavicle bones of the pectoral girdle (ossa cinguli membrii thoracici) in the ostrich carcass can be used to determine between ossification classes within the age range 8 to 14 months (considered as the optimal time of slaughter of ostriches), it is not an accurate tool for estimating the exact age at slaughter. It is possible to distinguish between carcasses originating from the birds between 10 and 12 months of age, at which ostrich meat toughens.

In an experiment involving 30 roosters and 15 mature male ostriches the apparent metabolizable energy (ME) values, corrected for zero nitrogen retention (AMEn), were determined by balance method for maize and lucerne meal. A group of 10 roosters received maize as the sole dietary component. For the second group of 10 roosters a blend of 750 g/kg maize and 250 g/kg lucerne was prepared. The diet of the third group consisted of 500 g/kg maize and 500 g/kg lucerne meal. The ostrich basal diet consisted of 1000 g/kg lucerne, and was blended in the ratios 50 lucerne: 50 maize and 25 lucerne: 75 maize. Each dietary treatment was given to five ostriches, individually housed in metabolism crates. Food intake and excreta collection was carried out over a period of 5 days after the ostriches had been accustomed to the diets for 7 days. For roosters food intake and excreta collection lasted for 72 h after an adaptation period of 24 h.

The AMEn value for maize was 14·49 (s.e. 0·046) MJ/kg in roosters while in ostriches AME,, values of 14·3 (s.e. 1·81) and 14·5 (s.e. 0·845) MJ/kg for the 500 g/kg inclusion and 250 g/kg inclusion respectively were found.

In roosters lucerne meal yielded AME,, values of 4·49 (s.e. 0·506) and 4·05 (s.e. 0·321) at 250 g/kg and 500 g/kg inclusion levels respectively. For the ostriches a value of 8·9 (s.e. 0·755) Mj/kg was found for lucerne.

True ME, corrected for zero nitrogen retention, (TMEJ was computed by regressing gross energy output on gross energy input over all feeding levels. Maize yielded values of 14·65 (s.e. 0·0455) and 14·9 (s.e. 0·351) for roosters and ostriches respectively while corresponding values for lucerne were 4·03 (s.e. 0·118) and 8·6 (s.e. 0·296) MJ/kg.

It was concluded that the ostriches were capable of digesting a high starch diet such as maize to the same extent as adult roosters but ostriches were capable of digesting a high fibre ingredient such as lucerne meal much more efficiently.

The Gompertz equation was used to compute growth curves for three groups of ostriches (Struthio camelus), from Oudtshoorn in South Africa, the Namib desert in Namibia and from Zimbabwe. All were reared under typical intensive farm conditions with ad libitum feeding. There were no significant differences in mature mass between regions but the maximum daily weight gain for males occurred later (day 163) for Oudtshoorn birds, compared with day 121 for Namibian and day 92 for Zimbabwean. Oudtshoorn females reached maximum rate of gain on day 175 compared with day 115 for Namibian and day 114 for Zimbabwean. Comparisons might prove important when planning programmes for the genetic improvement of commercial flocks, but possible influences of food composition and environment should be investigated.

Growth rate, total body water volume (TBW), dry-matter intake (DMI) and water consumption were determined in ostriches from hatching to 350 days at which time they weighed approximately 100 kg. A Gompertz equation was used to describe the sigmoidal growth curve; mature body mass (Mmb) wascalculated as 104·1 kg from this equation. Highest average daily gain (ADG) was 455 g/day which occurred between 70 days and 98 days. Time to reach 0·5 Mmb and to grow from 0·25 to 0·75 Mmb per Mmb025 were 46·8 days and 39·7 days, respectively. Maintenance energy requirements were 1·07 MJ/kg063per day and energy requirements for kg mb increase were 0·260 MJ/kg109: thes e values were derived from a non-linear regression model. TBW as a fraction of mb declined from 0·84 in 35-day-old chicks to 0·57 in 322-day-old birds, indicating a concomitant increase in the fraction of body lipid content. Mass specific DMI decreased from 0·061 g/g mb in chicks to 0·020 g/g mb in 322 to 350 day old birds, while mass specific water influx decreased from 0·21 ml/g mb to 0·046 ml/g mb during this time. The ratio of DMI to ADG increased steadily from 1·07 to 17·1; the ratio of water consumption to DMI remained relatively constant at approximately 2·3.