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This study aimed to analyse the relationship between rabbit semen characteristics and semen fertilising ability after insemination, which is generally found to be weak. Our hypothesis was that using high semen dilutions (1 : 19), non-oestrus-stimulated does, and homospermic inseminations would make it easier to predict semen fertilising ability. Semen characteristics were evaluated on 275 ejaculates of 128 INRA1001 bucks, distributed into five successive batches. A total of 1970 inseminations were performed. The continuous semen variables were subdivided into three classes of similar size to account for any non-linear relationship between semen characteristics and fertilising ability. Mass motility was divided into two classes according to the presence or absence of waves under microscope observation. Libido, the presence or absence of gel, volume, percentage of progressive sperms, curvilinear velocity, beat frequency of the flagellum, and straightness and linearity of sperm movement did not affect fertility, prolificacy or productivity. It was confirmed that mass motility, estimated by visual observation under the microscope, significantly influenced fertility as well as the percentage of motile and of rapid sperms, and the amplitude of lateral head displacement, estimated by a computer-assisted semen analysis system. To a lesser extent, the percentage of motile cells and of rapid cells significantly influenced prolificacy. Consequently, mass motility and the percentage of motile cells significantly influenced rabbit doe productivity (+1 live births/AI when the semen showed at least a beginning of wave movement, or when the percentage of motile cells was >84%). Interestingly, a gain of 1.5 rabbits was observed when the percentage of rapid cells changed from 64% to 79%, whereas productivity significantly dropped beyond 83% of rapid cells, reflecting a non-linear relationship.
Duck breeding in France is directed mainly towards ‘foie gras’ (duck fatty liver) production. Nowadays the roasted duck, produced from the pure Muscovy, is economically a less important industry. About 95% of foie gras production comes from force-fed mule duck, the remaining 5% being from the Muscovy duck. After an overview of the French economical and technical context of this production, the paper will focus on the genetic aspects of the mule duck, at the level of theoretical knowledge and considering practical applications for selection. As the mule duck is an infertile hybrid between a female common duck (Anas Platyrhynchos) and a Muscovy drake (Cairina moschata), selection approaches are carried out on both parental strains. But to implement selection, genetic parameters (heritability and genetic correlations) and cross-breeding parameters (direct and maternal additive genetic effects, heterosis effect) need to be known. Our review covers both the reproductive mule parental traits, either in pure strain or in cross-breeding, with main results on the dam side for laying, fertility and hatchability and also considers the mule productive traits, such as growth, feather colour, behaviour, feed efficiency, body composition, force-feeding ability and products quality. Genetic variability of mule duck traits can be established from estimates on either the dam's side, on the sire's side, or on both sides simultaneously. This review represents a comparison of fatty duck selection, which is operated by three major private French companies, with outlines of the breeding scheme specificity.
In Europe, more than 60 breeds are described by the national associations of rabbit breeders. However, these breeds are scarcely used in the commercial production of rabbit meat in Europe, which is based mainly on commercial strains. A European programme, coordinated by the I. N. R. A., has been initiated to realise the inventory of all these breeds and to evaluate the zootechnical value and the genetic characteristics of some of them. Through the European association of rabbit breeders and the FAO national focal points, all the European countries have been asked to fill out a questionnaire describing their populations of rabbits. A data bank is being set up, which will be included in the FAO (DAD-IS) and EAAP data banks. A sample of 10 breeds has been chosen (Flemish Giant, French Lop, Belgian Hare, Vienna White, Champagne Argente, Thuringer, Fauve de Bourgogne, Chinchilla, Himalayan, British). Their zootechnical value (reproduction, growth and carcass traits) is being evaluated on three experimental farms, in comparison with a control breed. At the same time, their genetic polymorphism and the genetic distances between these 10 breeds are calculated on the basis of microsatellites, mitochondrial DNA, other genetic markers and protein polymorphism. Finally, a bank of frozen embryos from these 10 breeds is being constituted.
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