PRACTICAL ASPECTS AND CONSTRAINTS IN THE COMMERCIAL PRODUCTION OF OSTRICHES (Struthio camelus) AND EMUS (Dromaius novaehollandiae) IN SAUDI ARABIA

This study was conducted to record, analyze and discuss the day-to-day practical aspects and constraints affecting the commercial production of ostriches (Struthio camelus) and emus (Dromaius novaehollandiae) in two ratite farms, A and B, in Al-Qassim area, Central Region of Saudi Arabia. In Farm A, where the original ostrich breeders were imported from France the new breeders (breeders produced in the Farm) started egg laying at the age of 19 months while the new emu breeders in the same Farm started egg laying at 22 months old. Ostriches in the two farms laid most of their eggs (73.5% and 64.9%) during day time (before sunset) while emus laid most of their eggs (98.1%) during night. Both original breeders of ostriches and emus were found to be more persistent in egg laying (85.9% and 72.6%) than their descendant breeders. About 11% of the ostrich eggs laid in Farm A throughout three seasons were found to be defective whereas 6.7% of the eggs laid in Farm B were defective. In emus, however, the average of the defective eggs throughout four production seasons was found to be 8.9%. The fertility of ostrich eggs in Farm A was found to be improving successively from season to another (32.4%, 55.6%, 60.7% and 61.2%) as well as with the progress of the single season before it drops at the end of the season (36.5%, 45.2%, 65%, 67% and 47%). Heat stress was found to reduce the fertility rate of ostriches. Emus were found to have higher overall mean fertility rates (70.3%) than ostriches in both Farms (52.5% and 58.4%). The overall mean hatchability rate of ostrich eggs (72.8%) was found to be higher than the overall mean fertility rate of ostrich eggs (52.5%) in four seasons. However, the overall mean hatchability rate of emu eggs (62.9%) was found to be lower than the overall mean fertility rate of emu eggs (70.3%) in three seasons. Developing ostrich and emu embryos had higher late embryonic mortality (60% and 66.4%) compared to early embryonic mortality (40% and 33.6% respectively). Emu chicks had higher (19.4%) incidence of congenital deformities than ostrich chicks (4.1%). The total weekly body weight gain of ostrich chicks in Farm B at the end of the first 14 weeks of life was higher (18350 g) compared to that in Farm A ostrich chicks (2600 g). The mean weekly body weight gain per ostrich chick that was hatched during summer was found to be higher (657.5 g; p<0.05) than the mean weekly body weight gain in chicks that were hatched during winter (356.75 g). The mortality rate of ostrich chicks during rearing phase (first 3 months of life) was 29% with non-consistent pattern throughout the season. The overall emu chick mortality rate during rearing phase (21.6%) was lower than that in ostrich chicks (29%), similarly, without specific pattern or behaviour. The main causes of mortality in ostrich chicks in Farm A were leg deformities, fading chick syndrome (F C S), Newcastle disease (N C D) and enteritis whereas the main causes of mortality in Farm A ostrich growers were sand impaction, Newcastle disease, leg deformities and enteritis. In Farm A ostrich breeders, the main causes of mortality were septicaemic pasteurellosis, wound infections, accidents, particularly those terminated into broken necks, and peritonitis. Causes of mortality in Farm B ostrich chicks included fading chick syndrome, leg deformities, enteritis and sand impaction. In Farm B growers, the main causes of mortality were leg deformities and septicaemic pasteurellosis whereas for Farm B breeders septicaemic pasteurellosis, accidents and fractures comprised the main causes of lethality. Leg deformities were the most common cause of mortality in Farm A emu chicks throughout the four seasons of study. There were no mortalities attributed to sand impaction or Newcastle disease in the emu chicks although these chicks were sharing the same premises with the ostrich chicks that suffered a severe NCD outbreak in Farm A in the year 2000. In emu growers, the main causes of mortality were leg deformities, suffocation and infected fighting wounds. Escherichia coli was isolated from 35.5% of the samples cultured from dead ostrich chicks in Farm A whereas Salmonella sp. organisms were isolated from 12.9% of the cultured samples. However, 22.6% of the cultured samples did not reveal any bacterial growth. For the emus, Escherichia coli was isolated from 33.3% while Salmonella species were isolated from 16.7% of the specimens (liver, yolk fluid and intestinal content) cultured from dead emu chicks. Among the different forms of leg deformities terminating lethally, tibiotarsal rotation (84%) comprised the most common one in ostrich chicks followed by splayed legs (11.9%). In ostrich growers in Farm A, again tibiotarsal rotation was found to be the most common killing form of leg deformities (78.5%) followed by slipped tendon (14%). In emu chicks, tibiotarsal rotation (98.8%) was the most common killing form of leg deformities followed by splayed legs (1.2%) whereas in emu growers, tibiotarsal rotation (99.4%) was the most common killing form of leg deformity followed by valgus rotation (0.6%).