Problèmes posés par la production de fourrure de lapin: bibliographie et projet d'étude

International audienc

Minimisation des coefficients de consanguinité moyens dans les petites populations d'animaux domestiques

International audienc

A note on divergent selection for total fleece weight in adult Angora rabbits: direct response to selection on total fleece weight at first and second harvest

[EN] In order to explore the genetic variability of wool production and other quantitative traits, an 8-cohort divergent selection experiment for total fleece weight (TFW) was carried out in French Angora rabbits. Studies were made on the wool production of a total of 669 female rabbits born between 1994 and 2001 and having produced wool from first to 12th harvests. The aim of the selection experiment was to obtain two divergent lines (low and high) on TFW. From preliminary analysis, the dataset was separated into three subsets according to the harvest number: one for each of the first two harvests and one for the third to the 12th harvests. In this paper, wool production data of the first and second harvests was analysed separately. Response to selection for total fleece weight at 3-12 harvest (TFW3-12) on this trait at first and second harvest was the aim of this paper. The second objective was to study the possibility of utilising values of the first or second harvest to estimate breeding values and as selection criteria for total fleece weight in the French Angora rabbit. Preliminary analysis of the data for non-genetic factors was done by the GLM procedure of SAS. Genetic parameters and breeding value estimates were carried out using a BLUP animal model using ASReml. A linear mixed model for a bivariate analysis of total fleece weight at first or second harvest and TFW3-12 was used. Heritability estimates of total fleece weight at first and second harvests were 0.36 and 0.38, respectively, and were similar to that observed at later harvests (0.35). The genetic correlation between TFW3-12 and fleece weight at first harvest was close to zero indicating that wool production at first harvest is a different trait from that of subsequent harvests. Genetic correlation estimates observed at second harvest were high (0.76) and response to selection at second harvest was similar to that observed for TFW3-12. These observations confirm that total fleece weight at first harvest is a different trait from TFW3-12. In French Angora rabbits, the high genetic correlation between TFW3-12 and total fleece weight at second harvest suggests the possibility of selection at this time for TFW3-12.The authors thank Gérard Auvinet, Jean Claude Musseau and Patricia Bayle of the Institut National de la Recherche Agronomique (INRA), Génétique Expérimentale en Productions Animales, Le Magneraud Poitou-Charentes Research Centre for the collection of data and the supply and care of Angora rabbits.Rafat, S.; Thébault, R.; Bonnet, M.; Deretz, S.; Pena-Arnaud, B.; De Rochambeau, H.; Allain, D. (2009). A note on divergent selection for total fleece weight in adult Angora rabbits: direct response to selection on total fleece weight at first and second harvest. World Rabbit Science. 17(1):39-44. doi:10.4995/wrs.2009.669394417

Sélection sur la vitesse de croissance post-sevrage chez le lapin

On a effectué une expérience de sélection massale sur la vitesse de croissance entre le sevrage (30 j) et 77 j dans une souche de lapin. La souche sélectionnée se composait de 12 mâles et 60 femelles pendant les 4 premières générations puis de 8 mâles et 40 femelles pendant les 4 suivantes. La souche témoin se composait aussi de 8 mâles et de 40 femelles. On a réalisé une intensité de sélection de 0,95. La vitesse de croissance post-sevrage est améliorée de 6,9 g pour 8 générations, soit un progrès de 0,83 g par génération. L’héritabilité réalisée est égale à 0,23. Pour une augmentation d’un g de la vitesse de croissance post-sevrage, on observe une diminution de 0,10 du nombre de lapins vivants à la naissance par portée. Simultanément, le nombre de lapins vivants à 77 j produits par femelle mise à la reproduction a tendance à diminuer. Cette réduction de la fitness est due principalement à une diminution du nombre de femelles ayant fait au moins une portée avec un lapin vivant à 77 j.A selection experiment was made on the growth rate between weaning (30 days) and 77 days in a rabbit strain. There were 12 bucks and 60 does in the selected strain during the first4 generations, then 8 bucks and l,0 does during the next 4 generations. There were 8 bucks and 40 does in the control strain. Selection intensity was 0.95. The response in post-weaning growth rate was 6.9 g after 8 generations, i.e. 0.83 g per generation. The realized heritability was 0.23. The increase in post-weaning growth rate was accompanied b an increase in 77-days body weight (58 g) and by a decrease in litter size at birth (-0.10) At the same time, the number of rabbits alive at 77 days per reproductive doe decreased. The main reason for the decrease of fitness was a decrease in the number of does with at least one rabbit alive at 77 days

Use of group records of feed intake to select for feed efficiency in rabbit

Models for genetic evaluation of feed efficiency (FE) for animals housed in groups when they are either fed ad libitum (F) or on restricted (R) feeding were implemented. Definitions of FE on F included group records of feed intake (¯FI_F) and individual records of growth rate (GF) and metabolic weight (MF). Growth rate (GR) as FE measurement on R was used. Data corresponded to 5,336 kits from a rabbit sire line, from 1,255 litters in 14 batches and 667 cages. A five-trait mixed model (also with metabolic weight on R, MR) was implemented including, for each trait, the systematic effects of batch, body weight at weaning, parity order and litter size; and the random effects of litter, additive genetic and individual. A Bayesian analysis was performed. Conditional traits such as ¯FI_F |M_F,G_F and G_F |M_F,¯FI_F were obtained from elements of additive genetics ( ( ¯FI_F |M_F,G_F )_g and ( G_F |M_F,¯FI_F )_g ) or phenotypic (( ¯FI_F |M_F,G_F )_p and ( G_F |M_F,¯FI_F )_p ) (co)variance matrices. In the first case, heritabilities were low (0.07 and 0.06 for ( ¯FI_F |M_F,G_F )_g and ( G_F |M_F,¯FI_F )_g, respectively) but null genetic correlation between the conditional and conditioning traits is guaranteed. In the second case, heritabilities were higher (0.22 and 0.16 for ( ¯FI_F |M_F,G_F )_p and ( G_F |M_F,¯FI_F )_p, respectively) but the genetic correlation between ( ¯FI_F |M_F,G_F )_p and G_F was moderate (0.58). Heritability of GR was low (0.08). This trait was negatively correlated with ( G_F |M_F,¯FI_F )_p and ( G_F |M_F,¯FI_F )_gof animals on F, which indicate a different genetic background. The correlation between GR and GF was also low to moderate (0.48) and the additive variance of GF was almost 4 times that of GR, suggesting the presence of a substantial genotype by feeding regimen interaction.info:eu-repo/semantics/acceptedVersio