Molecular Cytogenetic Study On Mule Duck (Muscovy(?)×Gaoyou Duck♀)

The molecular cytogenetic study and heterosis analysis of intergeneric hybrid from a cross between Muscovy♂(Cairina moschata L) and Gaoyou duck♀(Anas platyrhynchos var.domestica) were carried out with Muscovy,Gaoyou duck and their intergeneric hybrid, the results showed that:1. The karyotype,G-banding,C-banding and Ag-NORs(silver-staining nucleolus organizer regions) on chromosomes samples were obtained using the peripheral lymphocyte culture technique, trypsin,barium hydroxide and silver-staining. The peripheral lymphocyte culture technique was suitable for avian chromosome preparing, which offered a feasible approach of avian chromosome preparation.2. The diploid chromosome numbers of Muscovy,Gaoyou duck and their intergeneric hybrid were the same (2n=78), with 10 pairs of macrochromosomes including the sex-chromosome and 29 pairs of microchromosomes,but the type of No.1,Z and W chromosomes were different.The karyotype formulas of Muscovy,Gaoyou duck and their intergeneric hybrid were:mule duck 2n=78=2sm+2m +1st+73t(♂), 2n=78=2sm+2m+74t(♀);Muscovy 2n=78=2sm+2m+74t ;Gaoyou duck 2n=78=2sm+2m+2st+72t(♂), 2n=78=2sm+2m+1st+73t(♀) .3. Analysis of G-banded patterns for macrochromosomes of Muscovy,Gaoyou duck and their intergeneric hybrid indicated that the banded patterns were distinctive,mainly on the number and the width of the bands. The macrochromosomes of Muscovy duck in haploid were divided into 31 zones and 159 bands including 74 positive bands,that of Gaoyou duck were divided into 32 zones and 144 bands including 68 positive bands, while in male mule duck in diploid were 59 zones and 287 bands including 135 positive bands,56 zones and 277 bands including 130 positive bands in female mule duck.4. The chromosomes C-banding showed that:The C-banding characteristics of the chromosomes from different species,different individuals even if different cells of the same duck were distinctive,mainly on the existence,the location and the width of the bands.The C-banded patterns were observed that only parts of chromosomes were C-band positive,many microchromosomes were dark-stained, macrochromosomes were light-stained.and W chromosomes of female Muscovy duck and Gaoyou duck were totally dark-stained and easily indentified,which proved furtherly that C-banded technique could be used in avian sex indentification. But W chromosomes of female mule duck was stained lighter than both female Muscovy duck and Gaoyou duck and not easily indentified..5. The results of chromosomes Ag-NORs showed that:The Ag-NORs of ducks mainly distributed on No.1q,No.1p,No.2q and two microchromosomes.The Ag-NORs number varied from 1 to 6,on average Ag-NORs number of each cell was 3.60 in females and 3.53 in males.6. Study on infertility of hybridization in duck indicated that the abnormal development of gonad,normal gametes could not be produced because of heterogenetic chromosome pairings abnormality and the interaction between heterogeneous cell nuclear and cytoplasm were the causes of hybrids sterility.7. The growth courses of mule ducks in their early stage of growth were fitted by Logistic,Gompertz and Bertalanffy three kinds of commonly used growth curve models.The results showed that all the three models could describe the growth courses of mule ducks'body weight and body measurement,the indexes of fitness (R2) of three models were higher than 0.9851.But the comprehensive analysis indicated that Gompertz curves was the best model.The comparing between body weight and sternum indicated that the vigorous growth period of sternum was prior to that of body weight.8. Analysis of hybrid duck heterosis indicated:The hybrid ducks grew rapidly in early period.Comparative study on conventional traits of meat quality showed that there were no significant differences in PH value,OD value and water loss rate between hybrid ducks and Muscovy ducks which were good quality meat ducks,but there was significant difference in meat tenderness (P<0.05). Comparative study on conventional traits of slaughter showed that the eviscerated percentage ,leg muscle percentage and the percentage of abdominal fat of mule ducks were superior to that of Muscovy ducks.The mule ducks were perfect material for processing good quality meat ducks by comparative study on slaughter performance and meat quality.9. The hybrid ducks had obvious heterosis compared with their parents,but according to model fitness parameters and data of determination ,the breed of hybrid ducks (Muscovy♂×Gaoyou duck♀) had lower weight growth rate and lighter mature body weight than breed of hybrid ducks (Muscovy♂×cherry valley duck♀).Analyzed the causes based on comparison study,probally because hybrid ducks had strong maternal influence.10. Study on 45S rDNA localization on mule duck prophase ,metaphase chromosomes and interphase cells using fluorescence in situ hybridization (FISH) technique showed that at the same time 3 hybridization signals were detected on prophase cell, there were 3 hybridization signals on metaphase chromosomes of each cell and 3 signals on interphase cell,two of the 3 signals were stronger than the other one.The FISH result of metaphase chromosomes indicated that 45S rDNA were located on No.1p and two microchromosomes.