Crossbreeding effect on sexual dimorphism of body weight in intergeneric hybrids obtained between Muscovy and Pekin duck

From a factorial crossbreeding experiment between two Muscovy and Pekin duck strains it appears that the increased body weight sexual dimorphism in favour of males in the Muscovy growing duck depends on the Muscovy mother in pure breds and in the reciprocal cross. The ratio of male to female body weight averages took the values of 1.19, 1.47, 1.75, 1.77, 1.84 and 1.64, respectively, at 4, 10, 16, 20, 30 and 40 weeks of age in the Muscovy progeny. This tendency was similar in the Pekin x Muscovy progeny. On the contrary this ratio took the values of 1.07 and 1.11 at 10 and 16 weeks of age in the Pekin progeny, being similar in the Muscovy x Pekin progeny (1.06 1.07 and 1.08, respectively, at 16, 20 and 30 weeks of age). These results are evidence of a contribution of the Muscovy female duck to increase the body weight sexual dimorphism in duck by depressing the body weight growth in female progeny and not in the male progeny either in pure or crossbreeding. If the maternal effects are assumed to be similar in male and female progeny, the ranking of the four genotypes in the female progeny could be explained by adding to the effect of sex-linked genes (Z chromosome) the effect of genes on the W chromosome. Within a Mendelian inheritance pattern it may be suggested that, besides the usual sex-linked gene effects, coding genes of the non-pseudo-autosomal region (NPAR) of the Muscovy W chromosome depress growth when compared to the Pekin W chromosome.Dans une expérience de croisement factoriel entre deux souches de canards de Barbarie et Pékin, il apparaît que le dimorphisme sexuel en faveur des mâles sur les caractères de croissance semble dépendre de la mère Barbarie en pur et dans le croisement réciproque : le rapport entre les moyennes des poids corporels prennent les valeurs de 1,19 ; 1,47 ; 1,75 ; 1,77 ; 1,84 ; 1,64 respectivement aux âges de 4, 10, 16, 20, 30 et 40 semaines dans la descendance Barbarie. Les résultats sont comparables dans la descendance du croisement entre mâle Pékin et femelle Barbarie. Au contraire ce rapport, lorsque la différence entre poids des mâles et des femelles est significative, prend les valeurs de 1,07 et 1,11 aux âges de 10 et 16 semaines dans la descendance des Pékin. Cela est comparable dans la descendance du croisement entre le mâle Barbarie et la cane Pékin, avec des valeurs du rapport de 1,06 ; 1,07 et de 1,08 respectivement aux âges de 16, 20 et 30 semaines. Ces résultats mettent en évidence une contribution de la cane Barbarie, en pur et en croisement, à l’accroissement du dimorphisme sexuel en poids par un effet dépressif sur la croissance corporelle sur sa descendance femelle et non sur sa descendance mâle. Si les effets génétiques maternels sont supposés être comparables dans les descendances mâle et femelle, le classement des quatre génotypes dans le sexe femelle peut s’interpréter en additionnant aux effets de gènes liés au sexe (chromosome Z) un effet de gènes qui seraient situés sur le chromosome W. Dans le cadre de l’hérédité Mendélienne, on peut faire l’hypothèse, outre les effets habituels chez les oiseaux de gènes liés au sexe, d’un effet dépressif sur la croissance de gènes de la région non pseudo-autosomale du chromosome W du Barbarie, comparativement au W du Pékin, si celle-ci contient des gènes codants

Estimation of genetic parameters for growth, carcass and overfeeding traits in a white geese strain

In an experimental strain of white plumage geese created in 1989, two experiments were carried out from 1993 to 1995 in order to estimate genetic parameters for growth, and carcass composition traits in non-overfed animals, and genetic parameters for growth and fatty liver formation in overfed animals. Four hundred and thirty-one non-overfed animals were bred and slaughtered at 11 weeks of age; they were measured for forearm length, keel bone length, chest circumference and breast depth before and after slaughtering. The carcasses were partly dissected in order weigh breast, breast muscle and skin + fat, and abdominal fat. Four hundred and seventy-seven overfed animals were slaughtered at 20 weeks of age; they were measured for "paletot" (breast meat, bone and meat from wings, bone and meat from thigh and legs) weight and liver weight. In these two experiments, the weights had moderate to high heritability values. Breast depth measured on live animals showed a low heritability value. In overfed animals, liver weight showed a high heritability value. Liver weight could be increased by selection without a great effect on "paletot" weight. Thus, obtaining a white plumage geese strain for fatty liver production by selection would be difficult because only 20% of overfed animals had fatty liver. The results did not allow to conclude on the influence of selection on liver weight on carcass traits such as muscle or fatty tissue weight

Selection responses for the number of fertile eggs of the Brown Tsaiya duck (Anas platyrhynchos) after a single artificial insemination with pooled Muscovy (Cairina moschata) semen

A seven-generation selection experiment comprising a selected (S) and a control (C) line was conducted with the objective of increasing the number of fertile eggs (F) of the Brown Tsaiya duck after a single artificial insemination (AI) with pooled Muscovy semen. Both lines consisted of about 20 males and 60 females since parents in each generation and each female duck was tested 3 times, at 26, 29 and 32 weeks of age. The fertile eggs were measured by candling at day 7 of incubation. The selection criterion in the S line was the BLUP animal model value for F. On average, 24.7% of the females and 15% of the males were selected. The direct responses to the selection for F, and correlated responses for the number of eggs set (Ie), the number of total dead embryos (M), the maximum duration of fertility (Dm) and the number of hatched mule ducklings (H) were measured by studying the differences across the generations of selection between the phenotypic value averages in the S and C lines. The predicted genetic responses were calculated by studying the differences between the S and C lines in averaged values of five traits of the BLUP animal model. The selection responses and the predicted responses showed similar trends. There was no genetic change for Ie. After seven generations of selection, the average selection responses per generation were 0.40, 0.33, 0.42, 0.41 genetic standard deviation units for F, M, Dm, and H respectively. Embryo viability was not impaired by this selection. For days 2–8 after AI, the fertility rates (F/Ie) were 89.2% and 63.8%, the hatchability rates (H/F) were 72.5% and 70.6%, and (H/Ie) were 64.7% and 45.1% in the S and C lines respectively. It was concluded that upward selection on the number of fertile eggs after a single AI with pooled Muscovy semen may be effective in ducks to increase the duration of the fertile period and the fertility and hatchability rates with AI once a week instead of twice a week

Eleven generations of selection for the duration of fertility in the intergeneric crossbreeding of ducks

A 12-generation selection experiment involving a selected line (S) and a control line (C) has been conducted since 1992 with the aim of increasing the number of fertile eggs laid by the Brown Tsaiya duck after a single artificial insemination (AI) with pooled Muscovy semen. On average, 28.9% of the females and 17.05% of the males were selected. The selection responses and the predicted responses showed similar trends. The average predicted genetic responses per generation in genetic standard deviation units were 0.40 for the number of fertile eggs, 0.45 for the maximum duration of fertility, and 0.32 for the number of hatched mule ducklings' traits. The fertility rates for days 2–8 after AI were 89.14% in the S line and 61.46% in the C line. Embryo viability was not impaired by this selection. The largest increase in fertility rate per day after a single AI was observed from d5 to d11. In G12, the fertility rate in the selected line was 91% at d2, 94% at d3, 92% at days 3 and 4 then decreased to 81% at d8, 75% at d9, 58% at d10 and 42% at d11. In contrast, the fertility rate in the control line showed an abrupt decrease from d4 (74%). The same tendencies were observed for the evolution of hatchability according to the egg set rates. It was concluded that selection for the number of fertile eggs after a single AI with pooled Muscovy semen could effectively increase the duration of the fertile period in ducks and that research should now be focused on ways to improve the viability of the hybrid mule duck embryo

Duck (Anas platyrhynchos) linkage mapping by AFLP fingerprinting

Amplified fragment length polymorphism (AFLP) with multicolored fluorescent molecular markers was used to analyze duck (Anas platyrhynchos) genomic DNA and to construct the first AFLP genetic linkage map. These markers were developed and genotyped in 766 F2 individuals from six families from a cross between two different selected duck lines, brown Tsaiya and Pekin. Two hundred and ninety-six polymorphic bands (64% of all bands) were detected using 18 pairs of fluorescent TaqI/EcoRI primer combinations. Each primer set produced a range of 7 to 29 fragments in the reactions, and generated on average 16.4 polymorphic bands. The AFLP linkage map included 260 co-dominant markers distributed in 32 linkage groups. Twenty-one co-dominant markers were not linked with any other marker. Each linkage group contained three to 63 molecular markers and their size ranged between 19.0 cM and 171.9 cM. This AFLP linkage map provides important information for establishing a duck chromosome map, for mapping quantitative trait loci (QTL mapping) and for breeding applications

Roger Rouvier : témoignage

National audienc

Roger Rouvier : témoignage

National audienc