CYTOGENETICS OF PEKIN (Anas platyrhynchos L.), PHILIPPINE MALLARD (Anas platyrhynchos L.), MUSCOVY (Cairina muschata L.) DUCKS AND THEIR CROSSES

摘要

The cytogenetic aspects of partial sterility in Pekin (Anas platyrhynchos), Philippine. Mallard (Anas platyrhynchos), Muscovy (Cairina muschata), Pekin x Philippine Mallard and Muscovy x (Pekin x Philippine Mallard) crosses were investigated using themethod of smear preparation by Meredith (1968) with modifications. Five sexually mature drakes from each of the genetic groups were used in a Completely Randomized Design experiment. The meiotic indices of Pekin, Philippine Mallard, Muscovy and Pekin×Philippine Mallard did not differ significantly from each other. The meiotic index of the Muscovy×(Pekin×Philippine Mallard) however was found to be lower (P<0.01) compared to the other four genetic groups. The chromosome number for all five genetic groups was 2n = 80. The reported low fertility in the intraspecific cross Pekin×Philippine Mallard and intergeneric cross Muscovy×(Pekin×Philippine Mallard) seem to have a cytogenetic basis because a high proportion of abnormalities such as loose pairing, terminal and interstitial loops at pachynema, univalents at metaphase I, non-synchronized and unequal segregation at anaphase I and II, and micronuclei, multiple nuclei and unequal distribution of chromatin at telophase I and n were observed in the meiotic cells. The rather low reported fertility in the Philippine Mallard and Muscovy could be attributed to some post gametic or post fertilization rather than pregametic factors.