Effects of Hypodynamy on the Reproductive Functions of Japanese Quail

Sabo, v., K. BocIa, V. Chrappa, P. Skrobdnek, P. Vyboh: Effects ofHypodynamy on the Reproductive Functions of Japanese Quail. Acta vet. Brno 1996.65: 65-71. Japanese quail kept individually in cages were inseminated under conditions of 22-day hypodynamy. Fertility and hatchability of their eggs were assessed. The efficiency of the insemination depended on the number of inseminations. Compared with the results obtained upon natural breeding, it was 58.2% lowerin quailinseminated twice and 35.9% lower in birds inseminated theree times in individual cages; under the conditions ofhypodynamy it was 62.8% lower aftertwo inseminations and41.7% lower aftertheree inseminations. There were no substantial differences in egg production between the groups. In male quail subjected to 22-day hypodynamy semen volume, sperm concentration and blood plasma testosterone level were reduced. It is recommended that under space flight conditions quail should be inseminated every two or three days and the male-female ratio should be 1: 1. Selection should be made of male quail having high semen volume and high sperm concentration on the basis of their blood plasma testosterone level under the conditions of hypodynamy. Japanese quail,fertility, insemination, plasma testosteron The results obtained so far both in model experiments on Earth and under space flight conditions have provided a basis for achieving a long-term objective to conclude the reproductive cycle of Japanese quail under microgravity conditions and to produce Japanese quail cosmic population ( Bod a 1979). Evidence has been obtained to indicate that in microgravity the embryonic development and hatching of Japanese quail from eggs that were fertilized and developed in the oviduct and uterus under gravity conditions is possible (Me Ie s hko etal. 1991; Bod a eta!. 1991). However, the question remains as to the effect of gravity on fertilization and embryonic development in the oviduct from fertilization to egg-laying and particularly on the development of dorso-ventral and cranio-caudal polarity. The blastoderm of a newly-laid egg is a bilateral symmetric system (V 0 n B ae r 1928). Some writers (Clevert et al. 1955; Vintemberg et al. 1960; Clevert 1963) have concluded that the bilateral symmetry is shifted by rotation of the egg in the uterus and that the inclination changes the position of the axis. These writers did not regard gravity as playing a major role in this process. According to other writers (Kochava et al. 1971; Eyal-Giladi et al. 1980; Fabian et al. 1981) gravity is a prerequisite for development of the cranio-caudal polarity. The definitive answer as to the possibility of fertilization in weightlessness and the influence of gravity on the development of symmetry can be given only by experiments conducted under the conditions of micro gravity. We attempted to contribute to the resolution of this problem on an experimental hypodynamy model used successfully in our previous experiments on Japanese quail (J u ran i et al. 1983; J u ran i et al. 1988) in studies on the processes of adaptation of the productive and reproductive functions of experimental birds.