La suplementación de los piensos de las conejas con EPA y DHA mejora el perfil insaturado de los ácidos grasos de la leche y sus parámetros reproductivos

Se ha valorado la influencia del enriquecimiento de las dietas de conejas reproductoras con ácidos grasos poliinsaturados de cadena larga (AGPI) de origen animal (EPA y DHA) durante 2 ciclos sobre sus parámetros reproductivos y la composición de su leche. Un total de 124 conejas se alimentaron desde la recría hasta el segundo destete con dos dietas isofibrosas, isoenergéticas e isoproteicas formuladas con dos fuentes de grasa distintas. El grupo control (C;n=62) recibió un pienso con un 3% de grasa mezcla mientras que el del grupo experimental (P;n=62) contenía un 6% de un suplemento con un 50% de extracto etéreo concentrado en DHA y EPA a partir de aceite de salmón atlántico (Optomega-50, Optivite International Ltd., Barcelona, España)

Effects of feed restriction during pregnancy on maternal reproductive outcome, foetal hepatic IGF gene expression and offspring performance in the rabbit

Primiparous female rabbits have high nutritional requirements and, while it is recommended that they are subjected to an extensive reproductive rhythm, this could lead to overweight, affecting reproductive outcomes. We hypothesised that restricting food intake during the less energetic period of gestation could improve reproductive outcome without impairing offspring viability. This study compares two groups of primiparous rabbit does in an extensive reproductive programme, one in which feed was restricted from Day 0 to Day 21 of gestation (R021), and another in which does were fed ad libitum (control) throughout pregnancy. The mother and offspring variables compared were (1) mother reproductive outcomes at the time points pre-implantation (Day 3 postartificial insemination [AI]), preterm (Day 28 post-AI) and birth; and (2) the prenatal offspring characteristic IGF system gene expression in foetal liver, liver fibrosis and foetus sex ratio, and postnatal factor viability and growth at birth, and survival and growth until weaning. Feed restriction did not affect the conception rate, embryo survival, or the number of morulae and blastocysts recovered at Day 3 post-AI. Preterm placenta size and efficiency were similar in the two groups. However, both implantation rate (P < 0.001) and the number of foetuses (P = 0.05) were higher in the R021 mothers than controls, while there was no difference in foetal viability. Foetal size and weight, the weights of most organs, organ weight/BW ratios and sex ratio were unaffected by feed restriction; these variables were only affected by uterine position (P < 0.05). Conversely, in the R021 does, foetal liver IGBP1 and IGF2 gene expression were dysregulated despite no liver fibrosis and a normal liver structure. No effects of restricted feed intake were produced on maternal fertility, prolificacy, or offspring birth weight, but control females weaned more kits. Litter weight and mortality rate during the lactation period were also unaffected. In conclusion, pre-implantation events and foetal development were unaffected by feed restriction. While some genes of the foetal hepatic IGF system were dysregulated during pregnancy, liver morphology appeared normal, and the growth of foetuses and kits until weaning was unmodified. This strategy of feed restriction in extensive reproductive rhythms seems to have no significant adverse effects on dam reproductive outcome or offspring growth and viability until weaning

Selection for environmental variance of litter size in rabbits

[EN] Background: In recent years, there has been an increasing interest in the genetic determination of environmental variance. In the case of litter size, environmental variance can be related to the capacity of animals to adapt to new environmental conditions, which can improve animal welfare. Results: We developed a ten-generation divergent selection experiment on environmental variance. We selected one line of rabbits for litter size homogeneity and one line for litter size heterogeneity by measuring intra-doe phenotypic variance. We proved that environmental variance of litter size is genetically determined and can be modified by selection. Response to selection was 4.5% of the original environmental variance per generation. Litter size was consistently higher in the Low line than in the High line during the entire experiment. Conclusions: We conclude that environmental variance of litter size is genetically determined based on the results of our divergent selection experiment. This has implications for animal welfare, since animals that cope better with their environment have better welfare than more sensitive animals. We also conclude that selection for reduced environmental variance of litter size does not depress litter size.This research was funded by the Ministerio de Economía y Competitividad (Spain), Projects AGL2014-55921, C2-1-P and C2-2-P. Marina Martínez-Alvaro has a Grant from the same funding source, BES-2012-052655.Blasco Mateu, A.; Martínez Álvaro, M.; García Pardo, MDLL.; Ibáñez Escriche, N.; Argente, MJ. (2017). Selection for environmental variance of litter size in rabbits. Genetics Selection Evolution. 49(48):1-8. https://doi.org/10.1186/s12711-017-0323-4S184948Morgante F, Sørensen P, Sorensen DA, Maltecca C, Mackay TFC. Genetic architecture of micro-environmental plasticity in Drosophila melanogaster. Sci Rep. 2015;5:9785.Sørensen P, de los Campos G, Morgante F, Mackay TFC, Sorensen D. 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Correlated genetic trends for production and welfare traits in a mouse population divergently selected for birth weight environmental variability

The objective of this work was to study the changes that, selecting for environmental variability of birth weight (BW), could bring to other interesting traits in livestock such as: survivability at weaning (SW), litter size (LS) and weaning weight (WW), their variability assessed from standard deviations of LS, standard deviation of WW (SDWW) and also the total litter weight at birth (TLBW) and total litter weight at weaning. Data were registered after eight generations of a divergent selection experiment for BW environmental variability in mice. Genetic parameters and phenotypic and genetic evolution were assessed using linear homoscedastic and heteroscedastic models in which the traits were attributed to the female, except BW and WW that were in some models also attributed to the pup. Genetic correlation between the trait and variability levels was −0.81 for LS and −0.33 for WW. Clear divergent phenotypic trends were observed between lines for LS, WW and SDWW. Although animals were heavier in the high line, TLBW and at weaning was greater in the low line. Despite the negative genetic correlation that was obtained, SDWW was also higher in the high line. Heritabilities were 0.21 and 0.06, respectively, for LS and SW. Both phenotypic and genetic trends showed clear superiority of the low line over the high line for these traits, but inferior for WW. Heteroscedastic model performed similar to the homoscedastic model when there was enough information. Considering LS and survival, the low line was preferred from a welfare point of view, but its superiority from the productivity perspective was not clear. Robustness seemed higher as shown by a low variation and having a benefit to the animal welfare, but this still remains unclear. It was concluded that low variation benefits the welfare of animals.info:eu-repo/semantics/publishedVersio

Feed restriction effect on progeny of mice selected for birth weight environmental variability

International audienceIn line with aspects of the H2020 Feed-a-Gene project (grant agreement no. 633531) aiming to understand the genetic relationship between feed efficiency and robustness, we analysed the influence of mice feeding restriction on their offspring birth weights (BW) in two lines divergently selected for birth weight environmental variability. A total of 120 females (four full-sib females from 10 random different litters of the 12, 13 and 14 generations of selection) were chosen within high and low selected lines and split in four groups of feeding type combining restriction or not in two periods: from weaning at 21 to 77 days, and one week before mating to the 2nd parturition. Restriction consisted of feeding with 75, 90 and 85% of ad libitum consumed feed in the respective three studied generations. The data included 158 litters with 1,275 BW and 4,093 animals in the pedigree. A heteroscedastic model (using ASReml Release 4.1 software) was fitted to ascertain the genetic and environmental factors affecting the BW mean and its residual variance. The model included the diet type of the dam (restricted or not during the growing period and during the reproductive period), its line, generation, litter size where it was born and its parity, as well as the litter size of the progeny and its sex; including also all diet, line and generation interactions. The line (lower BW for the low variability line), and the generation effect for the progeny of dams restricted both during the growing and the reproductive period had significant effects on the progeny BW. Whereas the sex, the interaction diet-line (in dam pregnancy period) and the dam genetic effect have had effect on the BW variability. The interaction dietline produced a decrease in environmental variability of 5 and 18% in low and high variability lines respectively. It seems that selection for BW variability has conferred a lower sensitivity of the dams to the environmental conditions, which could be interpreted as higher robustness

Estimation of direct and maternal genetic correlation of Birth Weight with its environmental maternal variability in mice

International audienceEstimation of direct and maternal genetic correlation of Birth Weight with its environmental maternal variability in mice N. Formoso-Rafferty1, I. Cervantes1, J.P. Gutiérrez1, L. Bodin2 1Universidad Complutense de Madrid, Facultad de Veterinaria, Departamento de Producción Animal, Spain 2 INRA, GenPhySE, Castanet-Tolosan, France [email protected] (Corresponding Author) In polytocous species like pig, rabbit and mice, environmental variability of birth weight (BW) is generally studied assigning each BW record of a litter to the dam and considering that all genetic effects are maternal. However a direct effect might exist and could induce bias in the parameter estimations. In this paper, analyses of genetic parameters for the mean (location) and the variability (dispersion) of BW has been made on mice data from a divergently selection experiment on BW considering maternal genetic effects on the location and on the dispersion of BW together with a direct genetic effect on its location. They were done through a DHGLM procedure implemented in the ASReml software which could deal with both direct and maternal effects and which provided their variances and covariances for the location and the dispersion. The correlation between maternal genetic effects for the BW location and the BW dispersion was positive and confirmed results previously obtained. The new genetic correlation between a direct genetic effect on the location and the maternal genetic effect on the dispersion of BW was also positive. Thus increasing the individual BW, whatever the direct or maternal component concerned by the selection, should be avoided if BW variability is ignor

Estimation of direct and maternal genetic correlation of Birth Weight with its environmental maternal variability in mice

International audienceEstimation of direct and maternal genetic correlation of Birth Weight with its environmental maternal variability in mice N. Formoso-Rafferty1, I. Cervantes1, J.P. Gutiérrez1, L. Bodin2 1Universidad Complutense de Madrid, Facultad de Veterinaria, Departamento de Producción Animal, Spain 2 INRA, GenPhySE, Castanet-Tolosan, France [email protected] (Corresponding Author) In polytocous species like pig, rabbit and mice, environmental variability of birth weight (BW) is generally studied assigning each BW record of a litter to the dam and considering that all genetic effects are maternal. However a direct effect might exist and could induce bias in the parameter estimations. In this paper, analyses of genetic parameters for the mean (location) and the variability (dispersion) of BW has been made on mice data from a divergently selection experiment on BW considering maternal genetic effects on the location and on the dispersion of BW together with a direct genetic effect on its location. They were done through a DHGLM procedure implemented in the ASReml software which could deal with both direct and maternal effects and which provided their variances and covariances for the location and the dispersion. The correlation between maternal genetic effects for the BW location and the BW dispersion was positive and confirmed results previously obtained. The new genetic correlation between a direct genetic effect on the location and the maternal genetic effect on the dispersion of BW was also positive. Thus increasing the individual BW, whatever the direct or maternal component concerned by the selection, should be avoided if BW variability is ignor