| Summary: | 碩士 === 國立中興大學 === 畜產學系 === 87 === The purpose of this study was to evaluate the relationship between physical characteristics and hatchability of the ostrich ( Struthio camelus ) eggs, and to establish the basic data as references for the researchers and ostrich farmers to improve the hatchability of ostrich eggs. A total of 885 ostrich hatching eggs were incubated by 6 commercial ostrich farms in Taiwan since February 1998 to June 1999. The temperature and the relative humidity inside the incubator were 97.5℉ and 23-26﹪from day 1 to day 38, and 96.5-97.0℉ and 45-60﹪ from day 39 to day 41, respectively. Eggs were examined by candling and weighted regularly on day 0, 7, 14, 21, 28, 38, and 41, respectively, during the incubation period. Any infertile eggs, as determined by candling, were removed from the machine on day 14 or day 21, as early as possible. The numbers of infertile, dead-in-shell, hatched eggs were recorded. On the other hand, the other eggshell physical characteristics including the pore numbers of the eggs, egg shape index, egg weight loss and scanning electron microscopy, were measured. The relationship between the physical characteristics and fertility, hatchability of the eggs were analysed.
The results of this study showed that the ostrich egg shell containing cuticle, pores, and palisade, cone, and mammillary layers, as well as outer and inner shell membrane were similar to chicken eggs'. The structure of the pore of ostrich eggshell is branched, and the average numbers of pore on the large end, small end, equator were 20.10±8.07, 18.37±6.85, 17.51±4.85, per cm2 respectively, and the influence of pore numbers on hatchability was not significant. The average egg shape index of ostrich eggs was 0.783±0.042. The hatched eggs had significantly greater egg shape index than that of the infertile and early-dead eggs ( P＜0.05 ). The relative coefficient between egg shape index and hatchability was 0.41 ( P＜0.05 ), and there was a quadratic linear relationship. The hatchability of the eggs was the highest as the egg shape index was 0.82. The average fertility of ostrich eggs in this study was 55.6﹪, and the average fertile egg hatchability was 42.4﹪, both of them were lower than those of the other reports. The distribution of the ostrich egg weight showed a normal one, and the average egg weight was 1,405±146 grams, and 95﹪of the egg weight alloted between 1,119 and 1,691 grams. It had better fertility as the egg weights where in the range of 1,100 to 1,800 grams. There was a quadratic linear relationship between egg weight and hatchability. When the egg weights were in the range of 1,100 to 1,800 grams, the fertile egg hatchability was better. The fertility and hatchability were 0 as egg weights above 1,800 gram or below 1,000 gram. The incubation period and weight loss rate of the hatched eggs exhibited a quadratic linear relationship. The average egg weight loss rate of day 0-38, day 39-41 and day 0-41 were 13.38﹪, 1.63﹪, 14.47﹪, respectively, and the average weekly egg weight loss rate was 2.42﹪. The comparison of egg weight loss rate between dead and hatched eggs had no significant difference ( P>0.05 ). The fertile egg hatchability of ostrich in Taiwan in spring, summer, autumn and winter were 55.6﹪, 40.5﹪, 42.1﹪, 8.3﹪respectively. Overall, in order to obtain a better hatchability of ostrich eggs, one should be aware of selecting optimal egg weight, egg shape and control the egg weight loss during the incubation period.
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