L'aide aux utilisateurs

Pour une utilisation optimale des applications et outils développés au sein du Cati Sicpa, l’aide aux utilisateurs est essentielle. Pour alimenter cette aide, les responsables de projet et les agents pivots multiplient les interven‑ tions comme les séminaires et les supports d’aides aux utilisateurs

Réponses au sevrage de porcs de lignées divergentes pour l’efficacité alimentaire en fonction de l’aliment

La sélection pour l’efficacité alimentaire peut affecter la capacité des porcs à répondre au stress. La réponse au sevrage a été étudiée dans deux lignées de porcs divergentes pour la consommation moyenne journalière résiduelle (CMJR). Un total de 132 porcs par lignée, placés en loges collectives, ont reçu un régime en post-sevrage conventionnel (deux phases) ou sécurisant (trois phases). Les poids vifs et diarrhées ont été enregistrés au sevrage (28 jours, J0), à J1, J2, J6, J12, J19, J26 et en fin de post-sevrage (J42). L’ingéré par loge a été enregistré. Aucun antibiotique n’a été distribué. Les porcs de la lignée à CMJR réduite (CMJR–, plus efficaces) étaient plus lourds au sevrage, avec moins de diarrhées à J1 et J2 que les porcelets de la lignée à CMJR haute (CMJR+) (P<0,01). A J42, les poids vifs n’étaient pas différents entre lignées. Les porcs CMJR–avaient un ingéré et une vitesse de croissance réduits entre J0 et J18 par rapport aux CMJR+ (P<0,001) et des teneurs en acides gras libres plasmatiques plus élevées (P<0,001). Ils présentaient plus de diarrhées à J6 (22% vs 14%), mais les teneurs plasmatiques en haptoglobine ne suggéraient pas d’inflammation majeure. Le régime sécurisant améliorait les performances en début de post-sevrage chez les CMJR–(P<0,001). En conclusion, la lignée la plus efficace semble plus sensible au sevrage mais aussi plus résiliente pour retrouver son niveau de performances initial, et le régime sécurisant a un effet chez les porcelets les plus sensibles

Testicular development, sex hormones and boar taint in pig lines divergent for residual feed intake

Improving feed efficiency and rearing entire male pigs are relevant strategies to reduce feed cost and environmental waste in pig production. The major constraint for rearing entire male pigs being boar taint, an experiment was performed to determine the consequences of a divergent selection on residual feed intake (RFI: low RFI = LRFI; high RFI = HRFI) on pubertal development and boar taint. Purebred French Large White male pigs from two divergent lines for RFI (9th generation of selection, n = 45 or 43 pigs/line from 33 litters) were reared in two batches (n = 19 to 24 pigs/line/batch). Blood samples were drawn at 15 and 166±1 days of age (mean±SD) and pigs were weighed. After slaughter at 167±1 days of age, a backfat sample was collected in the neck and the genital tract was removed for testis and epididymis weighing after tissue trimming. Percentages of testis and epididymis weight relatively to liveweight were calculated for statistical analyses. All data were analyzed by ANOVA using R, including line and batch as fixed effects and litter as a random effect. When necessary, a log transformation was applied before analysis and adjusted means were backcalculated. Before slaughter, LRFI pigs were lighter than HRFI pigs (100±2 vs 106±2 kg liveweight, P0.1). However, plasma oestradiol-17 before slaughter (9.0 vs 17.5 pg/ml), fat androstenone (0.22 vs 0.34 µg/g pure fat), testis (3.5 vs 4.4‰) and epidydimis (1.18 vs 1.62‰) relative weights were lower in HRFI than LRFI pigs (P<0.001). Fat skatole was lower in HRFI than in LRFI (0.10 vs 0.28 µg/g pure fat, P<0.001) in the first batch with slaughter performed on the 17th July 2016 during a summer heat wave. Fat skatole was low in both lines (0.08 µg/g) in the second batch with slaughter performed on the 29th August 2016. Overall, these data indicate a lower testicular activity in the HRFI than in the LRFI line, which suggests the existence of genetic links between feed efficiency and reproductio

Presence of causative mutations affecting prolificacy in the Noire du Velay and Mouton Vendéen sheep breeds

For many decades, prolificacy has been selected in meat sheep breeds as a polygenic trait but with limited genetic gain. However, the discovery of major genes affecting prolificacy has changed the way of selection for some ovine breeds implementing gene-assisted selection as in the French Lacaune and Grivette meat breeds, or in the Spanish Rasa Aragonesa breed. Based on statistical analysis of litter size parameters from 34 French meat sheep populations, we suspected the segregation of a mutation in a major gene affecting prolificacy in the Noire du Velay and in the Mouton Vendeen breeds exhibiting a very high variability of the litter size. After the genotyping of mutations known to be present in French sheep breeds, we discovered the segregation of the FecL(L) mutation at the B4GALNT2 locus and the FecX(Gr) mutation at the BMP15 locus in Noire du Velay and Mouton Vendeen, respectively. The frequency of ewes carrying FecL(L) in the Noire du Velay population was estimated at 21.2% and the Mouton Vendeen ewes carrying FecX(Gr) at 10.3%. The estimated mutated allele effect of FecL(L) and FecX(Gr) on litter size at + 0.4 and + 0.3 lamb per lambing in Noire du Velay and Mouton Vendeen, respectively. Due to the fairly high frequency and the rather strong effect of the FecL(L) and FecX(Gr) prolific alleles, specific management programmes including genotyping should be implemented for a breeding objective of prolificacy adapted to each of these breeds

Testicular development, sex hormones and boar taint in pig lines divergent for residual feed intake

Improving feed efficiency and rearing entire male pigs are relevant strategies to reduce feed cost and environmental waste in pig production. The major constraint for rearing entire male pigs being boar taint, an experiment was performed to determine the consequences of a divergent selection on residual feed intake (RFI: low RFI = LRFI; high RFI = HRFI) on pubertal development and boar taint. Purebred French Large White male pigs from two divergent lines for RFI (9th generation of selection, n = 45 or 43 pigs/line from 33 litters) were reared in two batches (n = 19 to 24 pigs/line/batch). Blood samples were drawn at 15 and 166±1 days of age (mean±SD) and pigs were weighed. After slaughter at 167±1 days of age, a backfat sample was collected in the neck and the genital tract was removed for testis and epididymis weighing after tissue trimming. Percentages of testis and epididymis weight relatively to liveweight were calculated for statistical analyses. All data were analyzed by ANOVA using R, including line and batch as fixed effects and litter as a random effect. When necessary, a log transformation was applied before analysis and adjusted means were backcalculated. Before slaughter, LRFI pigs were lighter than HRFI pigs (100±2 vs 106±2 kg liveweight, P0.1). However, plasma oestradiol-17 before slaughter (9.0 vs 17.5 pg/ml), fat androstenone (0.22 vs 0.34 µg/g pure fat), testis (3.5 vs 4.4‰) and epidydimis (1.18 vs 1.62‰) relative weights were lower in HRFI than LRFI pigs (P<0.001). Fat skatole was lower in HRFI than in LRFI (0.10 vs 0.28 µg/g pure fat, P<0.001) in the first batch with slaughter performed on the 17th July 2016 during a summer heat wave. Fat skatole was low in both lines (0.08 µg/g) in the second batch with slaughter performed on the 29th August 2016. Overall, these data indicate a lower testicular activity in the HRFI than in the LRFI line, which suggests the existence of genetic links between feed efficiency and reproductio

Responses to weaning in two pig lines divergently selected for residual feed intake depending on diet1

International audienceWeaning is a stress every piglet has to face. It is a main cause of antibiotic uses due to digestive disorders. In this study, response to weaning was analyzed in pigs from two lines divergently selected for residual feed intake (RFI) during growth. A total of 132 pigs from each line, housed per line and diet in conventional postweaning units of 12 castrated males and 12 females, were fed either a conventional control (two successive diets) or a complex (three successive diets) dietary sequence during the postweaning period (4 to 10 wk of age). BWs were recorded at weaning (days 0 and 28 of age), days 1, 2, 6, 12, 19, 26, and 42 (10 wk of age), and at 23 wk of age. Feces texture was examined before weaning (day −1), at day 1, 2, 6, 12, and 19. Feed intake was recorded at pen level from days 0 to 42 after weaning, and individually thereafter. Plasma was collected after blood samplings at days −1, 6, 19, and 42 on half of the piglets: all piglets of a given sex in each pen were sampled, to achieve a balanced number across factors. Pigs of the low RFI (LRFI) line were heavier at weaning, had greater glucose concentration, and lower levels of diarrhea at days 1 and 2 than pigs from the high RFI (HRFI) line (P < 0.01). At day 42, there was no BW difference between lines, and G:F ratio did not differ between lines (P = 0.40). The LRFI pigs had lower feed intake and growth rate from day 0 to day 19 (P < 0.005), and greater plasma concentration of non-esterified fatty acid (P < 0.001), indicating an increased mobilization of body lipids and proteins immediately after weaning compared with HRFI pigs. They also had greater levels of diarrhea at day 6 (22% for LRFI vs. 14% for HRFI, P = 0.002), but the concentration of plasma haptoglobin did not indicate acute inflammation. The complex diet sequence improved feed intake and growth, and reduced diarrhea, mainly in the LRFI line (P < 0.001). To conclude, pigs from the LRFI line were more negatively affected by weaning stress, but managed to recover afterwards. The complex diet sequence ameliorated some of the negative effects that weaning had on the LRFI pigs, but limited effects of nursery period feeding sequence on growth performance were observed during the growing-finishing period

Responses of pigs divergently selected for cortisol level or feed efficiency to a challenge diet during growth

Selection for feed efficiency is questioned as reducing the ability of farm animals to face stress and overcome challenges. The hypothalamic-pituitary-adrenocortical (HPA) axis activity, measured by the cortisol level in plasma after ACTH injection, has been proposed as an indicator of robustness. The objectives of this study were to evaluate 1. if a modified cortisol level in pigs alters their feed efficiency and their production performance, 2. if alternative dietary resources would affect these responses. Parallel trials including divergent lines for plasma cortisol 1 hour after ACTH injection and divergent lines for residual feed intake (RFI) were run during growth with a conventional diet and a diet with high fibres, low energy and low protein content. Selection for higher or lower plasma cortisol levels after stimulation of the adrenal gland did not impact growth and feed intake traits, but it had a significant impact on body composition and carcass yield, with improved composition in the high cortisol animals. The two lines had similar responses to an alternative diet, with decreased growth rate and feed intake, and increased feed conversion ratio. On the other hand, lines selected for divergent RFI had different responses to the alternative diet, the more efficient line having a more reduced growth rate with the diet with lower energy and AA contents. However, in terms of FCR it remained more efficient. The initial hypothesis of decreased efficiency associated to increased cortisol was not validated

Genome wide association study of growth and feed efficiency traits in rabbits

[EN] Feed efficiency is a major production trait in animal genetic breeding schemes. To further investigate the genetic control of feed efficiency in rabbits, we performed a genome-wide association study (GWAS) for growth and feed efficiency on 679 rabbits genotyped with the Affimetrix Axiom Rabbit 200K Genotyping Array. After quality control, 127 847 single-nucleotide polymorphisms (SNP) were retained for association analyses. The GWAS were performed using GEMMA software, applying a mixed univariate animal model with a linear regression on each SNP allele. The traits analysed were weight at weaning and at 63 days of age, average daily gain, total individual feed intake, feed conversion ratio and residual feed intake. No significant SNP was found for growth traits or feed intake. Fifteen genome-wide significant SNPs were detected for feed conversion ratio on OCU7, spanning from 124.8 Mbp to 126.3 Mbp, plus two isolated SNP on OCU2 (77.3 Mbp) and OCU8 (16.5 Mbp). For residual feed intake, a region on OCU18 (46.1-53.0 Mbp) was detected, which contained a putative functional candidate gene, GOT1.This study is part of the Feed-a-Gene Project, funded from the European Union’s H2020 Programme under grant agreement nº 633 531.Garreau, H.; Labrune, Y.; Chapuis, H.; Ruesche, J.; Riquet, J.; Demars, J.; Benitez, F.... (2023). Genome wide association study of growth and feed efficiency traits in rabbits. World Rabbit Science. 31(3):163-169. https://doi.org/10.4995/wrs.2023.18215163169313Aggrey S.E., Lee J., Karnuah A.B., Rekaya R. 2014. Transcriptomic analysis of genes in the nitrogen recycling pathway of meattype chickens divergently selected for feed efficiency. Anim. Genet., 45: 215-222. https://doi.org/10.1111/age.12098Carneiro M., Rubin C.J., Di Palma F., Albert F.W., Alföldi J., Barrio A.M., Pielberg G., Rafati N., Sayyab S., Turner-Maier J., Younis S., Afonso S., Aken B., Alves J.M., Barrell D., Bolet G., Boucher S., Burbano H.A., Campos R., Chang J.L., Duranthon V., Fontanesi L., Garreau H., Heiman D., Johnson J., Mage R.G., Peng Z., Queney G., Rogel Gaillard C., Ruffier M., Searle S., Villafuerte R., Xiong A., Young S., Forsberg-Nilsson K., Good J.M., Lander E.S., Ferrand N., Lindblad-Toh K., Andersson L. 2014. Rabbit genome analysis reveals a polygenic basis for phenotypic change during domestication. Science, 345: 1074-1079. https://doi.org/10.1126/science.1253714Delpuech E., Aliakbari A., Labrune Y., Fève K., Billon Y., Gilbert H., Riquet J. 2021. Identification of genomic regions affecting production traits in pigs divergently selected for feed efficiency. Genet. Sel. 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Responses of pigs divergently selected for cortisol level or feed efficiency to a challenge diet during growth

Selection for feed efficiency is questioned as reducing the ability of farm animals to face stress and overcome challenges. The hypothalamic-pituitary-adrenocortical (HPA) axis activity, measured by the cortisol level in plasma after ACTH injection, has been proposed as an indicator of robustness. The objectives of this study were to evaluate 1. if a modified cortisol level in pigs alters their feed efficiency and their production performance, 2. if alternative dietary resources would affect these responses. Parallel trials including divergent lines for plasma cortisol 1 hour after ACTH injection and divergent lines for residual feed intake (RFI) were run during growth with a conventional diet and a diet with high fibres, low energy and low protein content. Selection for higher or lower plasma cortisol levels after stimulation of the adrenal gland did not impact growth and feed intake traits, but it had a significant impact on body composition and carcass yield, with improved composition in the high cortisol animals. The two lines had similar responses to an alternative diet, with decreased growth rate and feed intake, and increased feed conversion ratio. On the other hand, lines selected for divergent RFI had different responses to the alternative diet, the more efficient line having a more reduced growth rate with the diet with lower energy and AA contents. However, in terms of FCR it remained more efficient. The initial hypothesis of decreased efficiency associated to increased cortisol was not validated