Sex ratio of offspring in domestic animals:Swine (7)
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概要
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Data on sex ratio in swine were collected from the experiment stations of animal husbandry in Akita(Ak), Gumma(Gu), Kanagawa(Kn), Chiba(Ch), and Fukuoka(Fo) Prefectures. They covered five breeds, Large White (W), Yorkshire (Y), Landrace (L), Hampshire (H), and Duroc(D), and their hybrids (Hyb). They were collected froma total of 12, 528 which consisted of 2, 739 in Ak (W, Y, L, H, Hyb), 1, 362 in Gu (W, L, H, D, Hyb), 5, 936 in Kn (W, Y, L, H, D, Hyb), 1, 958 in Ch (W, Y, L, H, D, Hyb), and 533 in Fo (W, L, H, Hyb). The results obtained from each breed were discarded and only the results obtained from all the breeds as a whole were described in the present report. These results were compared with those given in the preceding parts of the present series of studies.2-7) Analysis on sex ratio was performed by the same method as mentioned in part 1 of this series.2) The classes which showed a shift of sex ratio to either sex were cited mainly in tables. <BR>The results obtained from this study are summarized as follows. <BR>A shift to male (high sex ratio) in the total sex ratio was observed only in Kn. The lowet sex ratio (not significant) was noted in Gu. There were, however, no significant differences in sex ratio among the five stations (Table 1). There were boars and sows showing a shift of sex ratio in their offspring in all the five stations. The percentage of these boars and sows was in the same range as presented in previous reports<SUP>2-6)</SUP> (Table 2). A shift of sex ratio was seen in one or two classes of litter series in all the stations, except that in Kn. A high sex ratio was seen in these stations, ex-cept one class in Ch (Table 3). In one or two classes of litter size, a shift of sex ratio (a low sex ratio in allthe stations, except one) was recognized in all the stations, except that in Ak (Table 4). <BR>There was no seasonal shift of sex ratio at all in any station. Significant differences among the seasons, however, were seen only in the station of Gu (Table5). A shift of sex ratio was found in neither natural mating nor artificial insemination. There was no significant difference in sex ratio between the two typesof mating (Ak Table 6). A shift of sex ratio was noted in one or two classes of paternal age in three stations (Ak, Gu, and Ch). It was high in these stations, except one. A high sex ratio was seen in one class of maternal age bothin Kn and Fo (Table 7). A shift of sex ratio was observed in one or two classes of age difference between the parents in all the prefectures, ex-cept Ak. There were shifts of sex ratio both to the same and to the opposite sex of the older parent (Table 8). Shifts of sex ratio (both low and high) were observed in two classes of maternal age at the first mating and of calendar year in Ch, respectively (Tables 9 and 10).
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