TAILIEUCHUNG - Encyclopedia Of Animal Science - R

Từ điển khoa học động vật vần R | Ratites Biology Housing and Management Dominique Blache Graeme B. Martin Irek Malecki The University of Western Australia Crawley Australia INTRODUCTION The large flightless ostrich emu cassowary and rhea and the small flightless kiwi compose the ratite family. The emu ostrich and rhea have been used in farming systems in which their biology influences management and housing. Ratite farming is in its infancy and requires further research and development to overcome inherent constraints before each species can reach its full productive potential. BIOLOGY OF RATITES The flat raftlike ratis sternum provided the name for the family. There is no keel and the pectoral muscles are absent or vestigial. In all except rheas the body feathers lack barbicels so the plumage is loose and fluffy. The feathers of the emu have two shafts. The rhea and the ostrich have longer wings than the emu and they use them during elaborate displays Fig. 1 . Female emus and rheas are larger than males but the male ostrich is the largest. 1 All extant ratites are endemic to the Southern Hemisphere whereas their ancestors were found in both The ostrich emu and rhea are found in temperate and Mediterranean regions but can survive in a wide range of climates. 1 2 The ratites have very strong legs and their muscles have a specific distribution and physiology due to the mechanic constraints of bipedal locomotion. Ratites walk most of the day and can run at considerable speed Table 1 . They are nomadic and follow food availability but are territorial during the breeding season. Ratites can also crouch a posture between standing and sitting Fig. 1 . The females lay eggs in this position. 1 2 Vigilant ratites stand with the neck stretched upward their heads are very mobile and can turn almost 360 degrees. Vision is believed to be very efficient because of the elevated position of the eyes and also because of acuity. Thus they are able to see and detect from long distances few .

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