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Notice à Reprendre pas de clé UT au 13 Février 2020; International audience; Breeding entire males is an alternative to surgical castration to improve their welfare. However, entire males may have a major quality defect called boar taint. Boar taint is partly due to the presence of androstenone in fat. In this study, we estimated the genetic parameters between androstenone and production traits to evaluate the consequences of selection against boar taint for traits of interest. We focused on growth traits, meat quality, lesions, hormone levels and computerised tomography measurements in purebred Piétrain (P) or Piétrain cross Large White (X) entire males. The number of measured animals varied from 670 P and 734 X for hormones concentrations to 553 P and 645 X for computerised tomography measurements. Skin lesions were measured on live pigs shortly after mixing, at the end of the fattening period, and on carcasses. Heritabilities of traits measured by tomography ranged from low to high: femur density (P: 0.34, X: 0.69), loin eye area (P: 0.53, X: 0.88) and loin eye density (P: 0.12, X: 0.18). The mean number of lesions at each stage was lower in purebred pigs than in crossbreds (entering the fattening stage 4.01 in P and 4.68 in X; before slaughter 3.72 in P and 4.22 in X; on carcass 4.50 in P and 4.96 in X). We also observed a decrease in the average number of lesions between the two stages in live pigs. We found high genetic correlations between stages in purebred pigs (0.74 to 0.76) but low correlations (−0.30 to 0.29) in crossbred pigs. Selection aiming to decrease fat androstenone is feasible ( h2 = 0.57 in P and h2 = 0.71 in X). It would have overall positive effects on meat production and quality traits. Selection aiming to reduce plasma oestradiol would strongly reduce the level of fat androstenone (rg = 0.89 in P and rg = 0.84 in X). Selection against oestradiol is easier and less invasive since it would only require a blood sample rather than a fat biopsy in live animals.

Creating a new synthetic line by crossbreeding means complementary traits from pure breeds can be combined in the new population. Although diversity is generated during the crossbreeding stage, in this study, we analyze diversity management before selection starts. Using genomic and phenotypic data from animals belonging to the first generation (G0) of a new line, different simulations were run to evaluate diversity management during the first generations of a new line and to test the effects of starting selection at two alternative times, G3 and G4. Genetic diversity was characterized by allele frequency, inbreeding coefficients based on genomic and pedigree data, and expected heterozygosity. Breeding values were extracted at each generation to evaluate differences in starting selection at G3 or G4. All simulations were run for ten generations. A scenario with genomic data to manage diversity during the first generations of a new line was compared with a random and a selection scenario. As expected, loss of diversity was higher in the selection scenario, while the scenario with diversity control preserved diversity. We also combined the diversity management strategy with different selection scenarios involving different degrees of diversity control. Our simulation results show that a diversity management strategy combining genomic data with selection starting at G4 and a moderate degree of diversity control generates genetic progress and preserves diversity.

Steroid metabolism is a fundamental process in the porcine testis to provide testosterone but also estrogens and androstenone, which are essential for the physiology of the boar. This study concerns boars at an early stage of puberty. Using a RT-qPCR approach, we showed that the transcriptional activities of several genes providing key enzymes involved in this metabolism (such as CYP11A1) are correlated. Surprisingly, HSD17B3, a key gene for testosterone production, was absent from this group. An additional weighted gene co-expression network analysis was performed on two large sets of mRNA-seq to identify co-expression modules. Of these modules, two containing either CYP11A1 or HSD17B3 were further analyzed. This comprehensive correlation meta-analysis identified a group of 85 genes with CYP11A1 as hub gene, but did not allow the characterization of a robust correlation network around HSD17B3. As the CYP11A1-group includes most of the genes involved in steroid synthesis pathways (including LHCGR encoding for the LH receptor), it may control the synthesis of most of the testicular steroids. The independent expression of HSD17B3 probably allows part of the production of testosterone to escape this control. This CYP11A1-group contained also INSL3 and AGT genes encoding a peptide hormone and an angiotensin peptide precursor, respectively.

International audience; Male pigs are commonly surgically castrated, without anaesthesia, to avoid a meat quality defect called boar taint, partially due to accumulation of androstenone in fat. Androstenone is a steroid produced by the testes. To decrease boar taint without using castration, a selection against androstenone should be considered. The purpose of this study is to estimate the relationships between androstenone and reproductive traits in boars. In this study we collected 34 traits for 36 Duroc boars, 40 French Landrace boars and 38 Pietrain Axiom NN boars. Characteristics of the semen (number of spermatozoids, mobility, motility, volume, concentration, duration of ejaculation and viability), libido indicators (number of training sessions before the first successful collection and percentage of later refusals), plasma testosterone and oestradiol levels, backfat levels of androstenone, skatole and indole at 180 and 280 day old, the age at 100 kg, the weight of genital tract and indicators of animal behaviour, health and welfare (human-animal relationship test, tears, health and leg scores). We estimated a high Pearson correlation between plasma oestradiol and androstenone in backfat at around 180 days of age (0.57). This confirms that plasma oestradiol can be used as a proxy for androstenone at the standard slaughter age. From Principal Component Analyses, it seems that fat androstenone at 180 days of age is independent from health score, behaviour toward human, libido and semen characteristics. These results suggest that a selection for lower androstenone in fat or plasma oestradiol in pigs at a standard slaughter age would have very-limited impact on libido or semen production capacities of mature boars.

International audience; 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; and (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. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant no. 633531.

National audience; An unfavourable relationship between responses to stress and feed efficiency has been proposed. Parallel trials were run, including divergent lines for residual feed intake and divergent lines for plasma cortisol response 1 h after ACTH injection. At 6 weeks of age, 48 pigs from each of the four lines were injected with ACTH. Plasma cortisol was measured before injection, and 1 h and 4 h later. Growth rate, feed intake, feed efficiency, body composition and meat quality were measured during the growing-finishing period on the same pigs fed either a conventional diet (9.7 MJ net energy (NE) and 160 g crude protein/kg) or a diet with an increased proportion of dietary fibres to dilute NE and digestible amino acids (AA) by 10%. Comparison of the lines selected for feed efficiency showed that the response to ACTH was slightly stronger, and lasted longer, in the more efficient line (P < 0.05). During the feed challenge, the growth rate of the most efficient line decreased more with the diet with lower NE and AA contents than that of the less efficient line (P < 0.06). However, in terms of feed efficiency, the more efficient line remained more efficient. On the other hand, comparison of the 'response to ACTH' lines showed no difference for growth and feed intake during the growth period, but a higher carcass yield and a leaner body composition of animals with higher plasma cortisol after ACTH injection. Thus, the initial hypothesis of a negative association between feed efficiency and the HPA axis activity is not supported.; Une relation défavorable entre réponse au stress et efficacité alimentaire est souvent mise en avant. Deux lignées divergentes pour l’efficacité alimentaire, et deux lignées divergentes pour la réponse en cortisol plasmatique à une injection d’ACTH, indicateur de l’activité de l’axe corticotrope, ont été testées en parallèle. A 6 semaines d’âge, 48 porcs par lignée ont reçu une injection d’ACTH. Le cortisol plasmatique a été mesuré avant injection, 1 h et 4 h après injection. La vitesse de croissance, l’ingestion, l’efficacité alimentaire, la composition de carcasse et la qualité de la viande ont été enregistrées. La moitié des animaux a reçu un aliment croissance conventionnel (9,7 MJ d’énergie nette (EN) et 160 g de protéines brutes/kg), et l’autre moitié a été soumise à un challenge alimentaire avec un aliment contenant des fibres alimentaires pour diluer l’EN et les acides aminés digestibles dans une proportion de 10%. La réponse à l’ACTH a été légèrement plus forte, et prolongée dans le temps, dans la lignée la plus efficace (P < 0,05). La vitesse de croissance et l’ingéré de la lignée plus efficace soumise à un régime fibreux ont été plus diminués que ceux des porcs moins efficaces (P < 0,06), mais l’avantage d’efficacité alimentaire a été maintenu. D’autre part, la comparaison des lignées « réponse à l’ACTH » ne montre pas de différence pour les caractères de croissance et d’ingestion pendant la période de croissance, quel que soit l’aliment, mais montre une composition corporelle plus maigre des porcs ayant une concentration de cortisol plasmatique plus élevée. Ainsi, contrairement à l’hypothèse initiale, la sélection pour une meilleure efficacité alimentaire n’affecte pas négativement la réponse à l’ACTH, et la diminution de l’activité de l’axe corticotrope n’est pas favorablement corrélée aux performances.

To get insights into selection criteria for feed efficiency, 2 rabbit lines have been created: the ConsoResidual line was selected for residual feed intake (RFI) with ad libitum feeding and the ADGrestrict line was selected for ADG under restricted feeding. The aim of the present study was to evaluate the impact on carcass and meat quality of the genetic selections. This comparison was performed using 2 different feeding strategies corresponding to the selection design. Carcass and meat quality traits were recorded for the 3 lines (ConsoResidual, ADGrestrict, and an unselected control [generation 0 {G0}]) in the 2 feeding systems (ad libitum and restricted) for 163 animals. Concerning the line effect, the BW at 63 d old was higher for the ADGrestrict line compared with the G0 and ConsoResidual lines ( < 0.0001). There was no line effect on the gastrointestinal tract. The rabbits did not exhibit a different carcass yield but showed different carcass traits. Indeed, the ConsoResidual rabbits had a higher hind leg yield ( < 0.0001) but no difference in the meat-to-bone ratio of the hind leg. On the contrary, the ADGrestrict line had a higher proportion of forelegs plus thoracic cage ( = 0.03). We also found lower perirenal ( < 0.0001) and scapular fat yields ( < 0.0001) in ConsoResidual rabbits. The ADGrestrict line had an intermediate perirenal fat yield compared with the other 2 lines. The G0 line always exhibited higher fat yields. Concerning meat quality, the ConsoResidual rabbits showed a lower ultimate pH ( < 0.0001) and higher water loss (drip and cooking loss; < 0.002) compared with the G0 and ADGrestrict rabbits. The feeding level had a strong effect on the gastrointestinal tract ( = 0.0004) and the carcass yield ( = 0.001). The latter was decreased in restricted rabbits. The effects of feeding strategy on meat quality were detrimental in the case of restricted feeding. Even if the ultimate pH was slightly higher in restricted rabbits ( = 0.0002), the carcass chilling loss ( = 0.0005) and the drip loss during 6 d ( < 0.0001) were higher. The selection on ADG with restricted access to feed seems to be less adversely correlated with carcass traits and meat quality traits but it leads to an increase in the live weight of the rabbits. Adversely, the selection on RFI, without affecting growth rate, would not modify age at slaughter because growth rate is not affected, but it might induce detrimental effects on meat quality.

To get insights into selection criteria for feed efficiency, 2 rabbit lines have been created: the ConsoResidual line was selected for residual feed intake (RFI) with ad libitum feeding and the ADGrestrict line was selected for ADG under restricted feeding (-20% of voluntary intake). The first objective of this study was to evaluate, after 9 generations of selection, the direct and correlated responses to selection on production traits in the 2 lines for traits recorded during growth. Second, applying the 2 feeding conditions used for selection to both selected lines plus the control unselected line (generation 0, G0) in a 2 × 3 factorial trial, the line performances were compared and the gut microbiota of the lines was characterized. The correlated responses in feed conversion ratio (FCR) were remarkably equivalent in both selected lines (-2.74 genetic σ) but correlated responses in other traits were notably different. In the ConsoResidual line, selection for decreased RFI resulted in a small negative correlated response in BW at 63 d old (BW63) and in a null response in ADG. In the ADGrestrict line, on the contrary, the correlated response in BW63 was substantial (+1.59 σ). The 2 selected lines had a FCR reduced by 0.2 point compared with the G0 line, and the same difference was found in both feeding regimens ( < 0.001). Indeed, selection on ADG would lead to heavier animals with no significant reduction of feed costs, whereas selection on RFI leads to lower feed costs and no increase of animal BW under ad libitum feeding. Altogether, our results do not suggest any genotype × environment interaction in the response to feeding regimens. The intestinal microbial communities from efficient rabbits differed from their unselected counterparts in terms of fermentation end products and microbial phylotypes, suggesting a central role of these microbes in the better feed efficiency of the rabbits.

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.

International audience; The plasma cortisol levels measured one hour after injection of ACTH reflects the hypothalamic-pituitary-adrenocortical (HPA) axis activity. The test was performed on piglets at 6 weeks of age. It was investigated as a potential selection criterion to improve pig robustness. From a base population of Large White pigs, two divergent lines were derived for 3 generations of selection, one selected for a high cortisol level (H line), one for a low cortisol level (L line). All breeders, as well as unselected animals, were also genotyped on a 70kSNP chip. At the 3rd generation of selection, the divergence between the two lines was about 5 genetic standard deviations. The high heritability of the trait was confirmed (h² = 0.64 ± 0.03). The genetic correlations with individual body weights and growth rates measured during lactation, post weaning and finishing periods were very low except for the genetic correlation between cortisol level and post-weaning growth rate (rg=-0.22 ± 0.10). The genome-wide association study revealed a quantitative trait locus influencing post-ACTH cortisol level, located on chromosome 2. It was suggested that divergent selection modified the frequency of NR3C1 alleles, favouring the hypersensitive glucocorticoid receptor in the low line.

International audience; Cette synthèse fait le point sur les principales évolutions de l’amélioration génétique du porc en France depuis la loi sur l’élevage de 1966. Elle évoque rapidement les 20 premières années, qui ont fait l’objet d’une synthèse en 1986, puis décrit plus en détail les évolutions ultérieures. Les objectifs de sélection, initialement limités aux caractères de production, se sont complexifiés avec la prise en compte de la qualité de la viande, puis de la prolificité et enfin des aptitudes maternelles des truies. La mise en place d’une évaluation génétique utilisant la méthodologie du « BLUP - modèle animal » au milieu des années 1990 et le développement de l’insémination artificielle ont profondément changé le travail des sélectionneurs. Une nouvelle évolution majeure, la sélection génomique, a récemment été mise en place. La sélection a conduit à des améliorations importantes des performances pour les principaux caractères de l’objectif de sélection depuis 1970 : plus de 200 g de gain moyen quotidien, plus de 0,5 point d’indice de consommation, plus de 12 points de taux de viande maigre dans la carcasse, jusqu’à près de six porcelets nés vifs par portée supplémentaires. Ces évolutions favorables ont réduit l’empreinte environnementale de la production, mais ont également eu des effets défavorables : une augmentation la mortalité des porcelets avant sevrage et une plus grande hétérogénéité des performances. Les enjeux pour l’avenir en termes d’objectifs d’amélioration génétique (prise en compte de caractères liés au bien-être, à la robustesse et à l’adaptation…), de méthodes et d’outils sont ensuite discutés.

La présence d’odeurs indésirables dans la viande de porcs mâles entiers est principalement liée à l’accumulation d’androsténone et de scatol. L’androsténone est synthétisée par les testicules et le scatol par les bactéries du colon à partir du tryptophane. Leur teneur dans le tissu adipeux résulte du bilan entre leur synthèse, leur élimination et leur réabsorption. Le principal levier d’action pour réduire la teneur en androsténone est la sélection génétique. Pour le scatol, les principaux leviers d’action concernent la conduite d’élevage : propreté des cases, gestion de l’environnement microclimatique et conduite alimentaire, notamment. La mixité des groupes et l’instabilité sociale ont peu d’impact sur les teneurs en composés odorants, mais sont importantes à contrôler pour réduire les risques de bagarres et de lésion. Même en réduisant fortement la teneur en composés odorants, il ne sera pas possible d’obtenir des niveaux indétectables sur toutes les carcasses. Une stratégie d’utilisation des carcasses odorantes de porcs mâles entiers doit être définie. Elle implique de comprendre les facteurs de rejet des viandes odorantes par les consommateurs. La perception d’odeurs sexuelles dépend de facteurs liés à l’animal, au type de produit, au mode de préparation/consommation et au consommateur lui-même. De plus, les deux molécules odorantes semblent interagir. La prise en compte des différents cas de figure peut être envisagée par une approche de modélisation, avec en préalable la mise en œuvre d’une détection des odeurs sur la chaine d’abattage. Or actuellement, seule la détection par le nez humain est opérationnelle au niveau des chaines d’abattage et des méthodes instrumentales restent à développer., Boar taint in pork comes mainly from the presence of two molecules: androstenone and skatole. Androstenone is produced by the testes and skatole is synthetized from tryptophan by bacteria in the colon. Their content in fat tissues results from the balance between synthesis, elimination and reabsorption. The main way to decrease the androstenone concentration is genetic selection. Regarding skatole, the main ways involve husbandry, cleanliness of pens, management of microclimatic conditions and feeding strategy. Gender mixing and social instability have little influence on boar taint but it is important to control them to decrease the risk of fighting and lesions. Even if it is possible to drastically decrease the boar taint level, it will not be possible to reach undetectable levels in every single carcass. It is necessary to define an entire male pig carcass-use strategy. It involves understanding the factors leading to consumers’ rejection of tainted pork. The perception of sexual odors depends on factors related to the animal, the type of pork product, the way of cooking/consumption and the consumer oneself. Moreover, the two odorant molecules seem to interact. A modelling approach is necessary to consider the different specific cases, which requires methods to detect the odors on-line. Currently, only the detection by the human nose is operational in slaughterhouses and instrumental methods still have to be developed.

The aims of this study were to investigate variation in content of androstenone (AND), skatole (SKA), and indole (IND), quantified in adipose tissue of intact male pigs at 160 d of age (105 kg BW) and 220 d of age (155 kg BW), to estimate genetic parameters and to investigate the genetic relationships for AND, SKA, IND, and growth traits. A sample of adipose tissue was collected in vivo, using a biopsy device, from the neck of 500 intact males at the 2 ages and at slaughter from the ham of 100 of the investigated animals. Backfat depth was measured at 220 d of age, whereas BW was recorded at each sampling. Quantification of AND, SKA, and IND was performed by HPLC with fluorescence detection. Estimates of genetic parameters were obtained through Bayesian analyses after logarithmic transformations of original measures. Contents of boar taint compounds (BTC) measured at 220 d were higher than those at 160 d of age. Correlations between contents of BTC in backfat and ham fat ranged from 0.7 (IND) to 0.88 (SKA). Medium-high h were estimated for BTC at both ages, but estimates at 220 d (0.58, 0.60, and 0.69 for AND, SKA, and IND, respectively) were greater than those at 160 d. The genetic correlation between contents at 160 and 220 d of each BTC was positive, but the probability that such estimates were greater than 0.8 was very low, indicating that contents at 160 and 220 d were traits controlled by different genetic backgrounds. Different rankings were observed when breeding values for the content at 160 and 220 d of age were used to rank animals. As a consequence, performance testing programs for BTC should be based preferably on phenotypes measured at 220 d of age. Weak genetic correlations were observed between content of BT compounds and growth traits (BW, backfat depth, and daily gain from 160 to 220 d of age), indicating that selective breeding to reduce the risk of tainted pork is expected to exert trivial effects on growth performance and fat deposition. Results indicate that prevalence of BTC is high in mature and heavy pigs relative to young and light pigs. High heritability; positive genetic correlations between AND, SKA, and IND; and trivial effects on growth traits suggest that reduction of BTC through selective breeding is feasible and exploitable as an alternative to surgical castration also for pigs slaughtered at heavy BW.

Breeding intact boars is a promising alternative to surgical castration of piglets. Genetic selection should enable farmers to solve problems due to boar taint and aggressiveness while taking into account potential consequences on other traits of interest. The aim of the study was to estimate genetic relations between sexual development, boar taint, health, and aggressiveness. About 1,600 Pietrain (purebred) or Pietrain × Large White (crossbred) boars were raised in a testing station. Blood samples were collected at about 105 kg BW for measuring sex hormones (testosterone and estradiol) and indicators of the inflammatory status (C-reactive protein [CRP], pig major acute-phase protein [pigMAP], and blood formula). Animals were slaughtered 9 d later and measured for boar taint compounds present in fat (androstenone and skatole) and skin lesions on carcass, an indicator of aggressiveness. For both genetic types, heritability was moderate for sex hormones (from 0.17 to 0.29) and skatole (0.24 for purebred and 0.37 for crossbred) and high for androstenone (0.63 and 0.70 for purebred and crossbred, respectively). Genetic correlations between sex hormones and boar taint compounds were moderate to high (from 0.31 to 0.95). Heritability was moderate for CRP (0.24 and 0.46 for purebred and crossbred, respectively) and very low for pigMAP (0.06 and 0.05 for purebred and crossbred, respectively. Numbers of leukocytes had moderate to high heritabilities according to the genetic type (from 0.21 to 0.52). Heritability of skin lesions was moderate for both genetic types (0.31). Genetic correlations were negative between sex hormones and inflammatory measures (from -0.46 to -0.05), positive between testosterone and number of lesions (0.43 and 0.53 for purebred and crossbred, respectively), and low between androstenone and lesions (-0.06 and -0.17 for purebred and crossbred, respectively). Overall, both breeds of pigs had very similar estimations of heritabilities, but estimates of genetic correlations were different for some pairs of traits. It would be possible to select boars based on their plasma concentration of sex hormones to decrease boar taint and aggressiveness without important consequences on the immune response. However, because of the strong links between boar taint and reproductive function, the possible consequences on the reproductive performance should be evaluated.

In the search for biological basis of robustness, this study aimed (i) at the determination of the heritability of the cortisol response to ACTH in juvenile pigs, using restricted maximum likelihood methodology applied to a multiple trait animal model, and (ii) at the study of the relationships between basal and stimulated cortisol levels with corticosteroid-binding globulin (CBG), IGF-I and haptoglobin, all important players in glucose metabolism and production traits. At 6 weeks of age, 298 intact male and female piglets from 30 litters (30 dams and 30 boars) were injected with 250 µg ACTH(1-24) (Synacthen). Blood was taken before ACTH injection to measure basal levels of cortisol, glucose, CBG, IGF-I and haptoglobin, and 60 min later to measure stimulated cortisol levels and glucose. Cortisol increased 2.8-fold after ACTH injection, with a high correlation between basal and stimulated levels (phenotypic correlation, r p=0.539; genetic correlation, r g=0.938). Post-ACTH cortisol levels were highly heritable (h 2=0.684) and could therefore be used for genetic selection of animals with a more reactive hypothalamic-pituitary-adrenocortical axis. CBG binding capacity correlated with cortisol levels measured in basal conditions in males only. No correlation was found between CBG binding capacity and post-ACTH cortisol levels. Basal IGF-I concentration was positively correlated with BW at birth and weaning, and showed a high correlation with CBG binding capacity with a strong sexual dimorphism, the correlation being much higher in males than in females. Basal haptoglobin concentrations were negatively correlated with CBG binding capacity and IGF-I concentrations. Complex relationships were also found between circulating glucose levels and these different variables that have been shown to be related to glucose resistance in humans. These data are therefore valuable for the genetic selection of animals to explore the consequences on production and robustness traits, but also point at pigs as a relevant model to explore the underlying mechanisms of the metabolic syndrome including the contribution of genetic factors.

In boars, social relationships could influence pubertal development and feeding behaviour. The objectives of the present study were to determine the relationships between behaviour (agonistic, mounting and feeding behaviours), plasma sex steroids (oestradiol, testosterone) and fat androstenone.A total of 270 Pietrain x Large White boars, derived from four distinct genotypes were used. They were raised in groups of 11-12 pigs/pen. Animals were observed for about two times 10 h/day at the beginning or about 6 h at the end of fattening. Agonistic (fighting, hitting, biting, threatening, chasing) and sexual (mounting) behaviours were counted in early fattening shortly after a social mixing (for 177 of the 270 animals) and in late fattening after several weeks of social stability. Skin lesions were counted in the same periods and on carcasses. Data obtained from electronic feeders were used to determine the number and duration of meals, and the feed intake over 96-h periods in the middle and at the end of fattening. At the end of fattening, blood was sampled to measure oestradiol and testosterone. At slaughter, fat was collected to measure androstenone. Using the agonistic behaviours, a dominance index was calculated (DRrank).As expected, numbers of skin lesions and agonistic acts were higher in early fattening (P < 0.0001) whereas that of mounting acts was lower in early than in late fattening (P < 0.05). The feeding characteristics (r = 0.25 to 0.39) were significantly correlated between ages, whereas numbers of mountings (r = 0.18), of skin lesions (r = 0.05) and agonistic acts (r =-0.05) were not. The number of agonistic acts was significantly correlated with that of mountings only-in early fattening (r = 0.38). At both ages, no difference between dominance groups was observed for feeding characteristics. This was probably related to low competition between boars for access to feed. Dominant boars had a higher concentration of androstenone in fat than subordinates (P < 0.05) but no difference was observed for plasma steroids. An active role of androstenone in controlling social behaviour but not reproductive function may explain this phenomenon.

The aim of this study was to compare the energy balance and dynamic of body reserves in rabbit females divergently selected for longevity. One hundred and twenty-nine females from a high longevity line (HL) and 131 females of a low longevity line (LL) were studied from the 1st to the 3rd kindling. Litter size and weight and female body weight were measured at kindling (1st, 2nd and 3rd), insemination (2nd and 3rd) and at weaning (1st and 2nd). The total body electric conductivity (TOBEC) method was used to estimate the body reserves in all females at artificial insemination and at weaning, and at kindling in females that achieved parturition. Energy balance between the 11th and the 21th d of lactation was also calculated for these females. No significant difference was found for fertility or for the number of offspring born alive and weaned. However, the total number of offspring born was higher in the LL line than in the HL line at the 2nd parturition (+1.12±0.46 g; Pnd artificial insemination (+107.0±29 g; P=0.049), leading to a similar weight between the lines at the 2nd artificial insemination. There was no significant difference between lines for estimated energy used for growth between the 11th and the 21th d of lactation, or for estimated milk production (2365±30 g in HL line vs. 2398±30 g in LL line), estimated using the weight gain of the kits between the 11th and 21st d of lactation, for feed intake measured during this period (351±5 g/d in HL line vs. 359±5 g/d in LL line) or for energy balance (–6.11±0.3 MJ in HL line vs. –6.30±0.3 MJ in LL line). However, body energy content was higher in HL females than in LL (+2.72±0.64 MJ; P=0.001). In conclusion, selection for higher functional longevity results in a better ability of females to use body reserves in their early reproductive life.

L’agro-écologie utilise les processus naturels et les ressources locales plutôt que des intrants chimiques pour assurer la production tout en limitant l’impact environnemental de l’agriculture. A cette fin, des innovations en génétique sont nécessaires pour disposer d’animaux productifs et adaptés à des contextes locaux variés. Pour toute filière d’élevage, réorienter les programmes de sélection actuels semble plus utile que développer des programmes spécifiques qui peineront à être efficaces en termes de coûts et de progrès génétiques attendus. Améliorer la robustesse des animaux vise à promouvoir leurs capacités d’adaptation en intégrant de nombreux critères de sélection, en particulier de reproduction, santé, et d’adaptation à des ressources alimentaires peu digestibles et au changement climatique. Cela amène à considérer les interactions génotype-environnement dans la prédiction des valeurs génétiques et à évaluer les performances des animaux dans des systèmes à bas intrants pour sélectionner ceux qui sont adaptés à des conditions limitantes. La standardisation tant des animaux que des conditions d’élevage paraît antinomique avec les principes de l’agro-écologie prônant une adaptation des animaux aux ressources et contraintes locales dans des systèmes peu artificialisés et très liés à leur environnement physique. Il n’y a donc pas UN animal type agro-écologique, mais DES animaux aux profils variés permettant de répondre aux attentes de l’agro-écologie. Face à la diversité des milieux et des systèmes d’élevage, il faut conserver une diversité génétique importante intra-race, mais aussi préserver la diversité génétique entre races. Cela nécessite une caractérisation phénotypique et génétique des races locales. Enfin, il s’agit de favoriser l'appropriation par les éleveurs et les techniciens d’élevage des outils et des ressources génétiques disponibles pour répondre à leurs besoins., Agroecology uses natural processes and local resources rather than chemical inputs to ensure production while limiting the environmental footprint of agriculture. In this context, breeding innovations are necessary to obtain animals that are both productive and adapted to a broad range of local contexts. Whatever the animal sector, reorienting current breeding programmes seems to be more useful than developing programmes dedicated to agroecological systems that will struggle to be really effective in terms of costs and expected genetic progress. Breeding for robustness aims to promote individual adaptive capacities by considering various selection criteria including reproduction, health, and adaptation to rough feed resources, warm climate or fluctuating environmental conditions. It leads considering genotype-environment interactions in the prediction of breeding values. Animal performance should be evaluated in low-input systems in order to select those animals adapted to limiting conditions. Standardization of both animals and breeding conditions appears contradictory to the agroecological paradigm that calls for an adaptation of animals to local opportunities and constraints in weakly artificialized systems tied to their physical environment. There is thus not a single agroecological animal type, but animals with various profiles that meet the expectations of agroecology. As well as supporting the value of within-breed diversity, we must preserve between-breed diversity to maintain numerous options for adaptation to a variety of production environments and contexts. This may involve to phenotypically and genetically characterize local breeds. Last but not least, improved assimilation by farmers and farm technicians of available genetic resources and breeding tools is necessary.

The objective of this study was to assess the feasibility of selecting for functional longevity in rabbits, defined as an ability to delay involuntary culling. Functional longevity was measured as the total number of AI performed after the first kindling. Breeding values were estimated using a discrete survival model. Male parents were selected on the basis of their progeny test results, and the efficiency of selection was estimated in the second generation, as was the correlated response on reproduction traits. A total of 48 males were progeny tested, based on the longevity of 10 daughters bred in 2 different farms. Based on their estimated genetic merit, 5 "high longevity" (HL) and 5 "low longevity" (LL) males were selected divergently and produced a new generation (5 bucks/sires and 10 daughters/bucks). A difference in longevity (+0.75 AI, i.e., 32 d) was observed between the 2 lines. In farm 1, the differences were mainly due to culling (26% in the LL line vs. 14% in the HL line) whereas mortality was similar in the 2 lines. In farm 2, mortality and culling were both higher in the LL line than in the HL line (33 vs. 15% and 19 vs. 7%, respectively). There was no difference between the 2 lines in terms of the reproduction traits recorded for each kindling. Nevertheless, because of the difference in the litter number between the 2 lines, the sum of young rabbits born alive per doe over her lifetime and the sum of young rabbits weaned per doe were higher in the HL line (+5 kits; P < 0.01). Selection for functional longevity using survival analysis is feasible for modifying lifetime reproduction traits.

Improvement of feed efficiency can be achieved by genetic selection directly on feed to BW gain ratio or for alternative traits. In the present study, 2 different traits were explored in the growing rabbit and their heritability and genetic correlations with traits recorded between weaning (30 d) and 63 d of age: i) residual feed intake (RFI), to select animals having low ad libitum feed intake independently from their production level, and ii) ADG under restricted feeding (ADGR; with a restriction level of 80% compared with ad libitum feeding of a control group), to select animals having high growth rate despite limited feed intake. To study these traits, 2 rabbit lines were established named i) ConsoResidual line and ii) ADGrestrict line. Under ad libitum or restricted feeding, it comes to select animals that waste less energy for maintenance, metabolism, or activity and retain more for tissue deposition. The selection process was similar in both lines. Data comprised records from generations 0 to 6 for about 1,800 rabbits per line measured for their BW at weaning and 63 d of age (BW63) and their individual feed consumption. Under ad libitum feeding, the heritability estimates were moderate for RFI (0.16 ± 0.05), ADG (0.19 ± 0.05), and feed conversion ratio (FCR; 0.22 ± 0.05). The high genetic correlation estimated between RFI and FCR (0.96 ± 0.03) was in accordance with the literature. The genetic correlation between RFI and ADG traits was not significant. Thus, selection for low RFI with ad libitum feeding was confirmed as a potential trait to improve FCR and reduce feed intake, with little effect on ADG. To our knowledge, there is no previous selection experiment on growing rabbits with restricted feeding. Our heritability estimates for ADGR and feed conversion ratio under restricted feeding (FCRR) were moderate (0.22 ± 0.06 and 0.23 ± 0.07, respectively) and had very high negative genetic correlation. Both selection criteria were found with high and favorable genetic correlations with feed efficiency recorded under each feeding regimen. However, their different genetic correlations with BW at weaning and at 63 d of age (BW63R; respectively, 0.85 and 0.17 for RFI and -0.25 and 0.81 for ADGR) suggested different impacts on major production traits that need further analyses to decipher the relative advantages of the 2 selection criteria, together with interactions between genotypes and feeding regimen.

L'axe corticotrope est une composante majeure des régulations métaboliques et des mécanismes biologiques de l'adaptation. L'activité de l'axe corticotrope et sa fonction sont fortement influencées par des facteurs génétiques. Les expériences présentes ont été conçues pour tester l'hypothèse que la sélection génétique pour un axe corticotrope plus actif peut améliorer la robustesse des porcs. Les expériences ont été faites avec des porcs Large White en race pure. Nous avons d'abord confirmé que la réponse du cortisol à l'ACTH est hautement héritable (h2 = 0,68 ± 0,12) dans cette population et peut donc être utilisée pour réaliser une expérience de sélection divergente. Dès la deuxième génération, de grandes différences dans le caractère de sélection ont été obtenues (concentration plasmatique de cortisol post-ACTH : 84,8 vs 127,5 ng/ml dans les lignées basse et haute, respectivement, P < 10-16), mais aussi dans les caractères de reproduction (35% de spermatozoïdes en plus par éjaculat (P = 3.10-4), un taux de mise bas de 11 points de plus (P > 0,10) et 1,5 porcelet vivant de plus par portée (P = 0,06) dans la lignée haute de reproducteurs G1). Les concentrations élevées de cortisol ont eu une influence négative sur la croissance en post-sevrage (418 vs 394 g/jour, P = 0,0013) et en engraissement (799 vs 754 g/jour, P < 0,0001), mais favorable sur la composition de carcasse (TVM : 58,8 vs 60,4%, lignée basse vs lignée haute, P < 0,001). Ces résultats confirment que l’axe corticotrope a des effets contrastés sur les caractères fonctionnels et de production. Ils devront être confirmés dans la 3° génération de sélection en cours et un bilan global sera réalisé avant de pouvoir proposer le test à l’ACTH comme critère de sélection pour obtenir des animaux plus robustes., The adrenocortical axis is a major component of metabolic regulation and biological adaptation processes. Its activity and functions are strongly influenced by genetic factors. The present experiments were designed to address the hypothesis that genetic selection for a more active adrenocortical axis could improve robustness. They were carried out with purebred Large White pigs. We first confirmed that the cortisol response to ACTH is highly heritable (h2 = 0.68 ± 0.12) in this population and can therefore be used for a divergent selection experiment. As early as the second generation of selection, large differences were obtained in the selection trait (post-ACTH plasma cortisol concentration: 84.8 vs 127.5 ng/mL in the low and high lines, respectively, P < 10-16); differences were also obtained in several reproduction traits (35 % more sperm per ejaculate (P = 3.10-4), 11 points higher pregnancy rate (P > 0.10), and 1.5 more piglets born alive per litter (P = 0.06) in the high line). Higher cortisol concentrations had a negative influence on growth rate during both post-weaning (418 vs 394 g/jour, P = 0.0013) and fattening (799 vs 754 g/jour, P < 0.0001) but improved carcass composition (lean%: 58.8 vs 60.4, low vs high line P < 0,001). These results confirm that the adrenocortical axis activity has a contrasted influence on functional and production traits. They have to be confirmed in the third generation for a comprehensive evaluation of the interest of selecting a more active adrenocortical axis to obtain animals that are more robust.

Les anomalies congénitales sont définies comme des défauts de structure ou de fonction présents à la naissance. Bien que la fréquence des anomalies congénitales soit relativement faible, leur impact en production porcine est significatif. Elles provoquent le plus souvent un mal-être des animaux et une dépréciation des carcasses à l’abattoir induisant des pertes économiques. Les anomalies congénitales peuvent être de nature diverse, mais les défauts les plus courants rencontrés chez le porcelet sont de type urogénital (les hernies inguinales et scrotales, la cryptorchidie et l’intersexualité). Ces défauts peuvent être dus à des problèmes nutritionnels, aux conditions d’environnement ou à la conduite de l’élevage, mais une part de leur déterminisme est très souvent génétique. Les développements récents des outils de génomique permettent désormais d’entreprendre, à grande échelle, des études d’association afin d’identifier les régions chromosomiques des gènes impliqués. L’identification des mutations causales est devenue une priorité afin de proposer de nouveaux schémas de sélection. L’objectif de cet article est de présenter une synthèse des connaissances génétiques sur les anomalies congénitales les plus fréquentes chez le porc et les stratégies mises en œuvre pour gérer ces défauts en sélection., Congenital diseases are defined as physical or functional defects, which are present at birth. Although the incidence of congenital disorders is quite low, it is a significant problem in the pig industry. These defects have a serious impact on animal welfare and induce economic losses due to carcass depreciation. Congenital diseases are various but the most common defects occurring in piglets are urogenital diseases (scrotal or inguinal hernias, cryptorchidism, and intersexuality). Defects can arise from nutritional, environmental, management causes, as well as hereditary. Recently the developed genomics tools enable large scale, genome wide association studies to identify chromosomal regions containing causal genes. Identification of causal mutations became a priority to propose new selection schemes. The aim of this article is to present an overview of genetic knowledge on the most frequent congenital diseases in pigs, and the strategies implemented to manage these defects in selection.

Agroecology uses ecological processes and local resources rather than chemical inputs to develop productive and resilient livestock and crop production systems. In this context, breeding innovations are necessary to obtain animals that are both productive and adapted to a broad range of local contexts and diversity of systems. Breeding strategies to promote agroecological systems are similar for different animal species. However, current practices differ regarding the breeding of ruminants, pigs and poultry. Ruminant breeding is still an open system where farmers continue to choose their own breeds and strategies. Conversely, pig and poultry breeding is more or less the exclusive domain of international breeding companies which supply farmers with hybrid animals. Innovations in breeding strategies must therefore be adapted to the different species. In developed countries, reorienting current breeding programmes seems to be more effective than developing programmes dedicated to agroecological systems that will struggle to be really effective because of the small size of the populations currently concerned by such systems. Particular attention needs to be paid to determining the respective usefulness of cross-breeding v. straight breeding strategies of well-adapted local breeds. While cross-breeding may offer some immediate benefits in terms of improving certain traits that enable the animals to adapt well to local environmental conditions, it may be difficult to sustain these benefits in the longer term and could also induce an important loss of genetic diversity if the initial pure-bred populations are no longer produced. As well as supporting the value of within-breed diversity, we must preserve between-breed diversity in order to maintain numerous options for adaptation to a variety of production environments and contexts. This may involve specific public policies to maintain and characterize local breeds (in terms of both phenotypes and genotypes), which could be used more effectively if they benefited from the scientific and technical resources currently available for more common breeds. Last but not least, public policies need to enable improved information concerning the genetic resources and breeding tools available for the agroecological management of livestock production systems, and facilitate its assimilation by farmers and farm technicians.

A quantitative trait loci (QTL) for accumulation of androstenone in fat has been identified in an Large White × Meishan cross in a region of SSC7-containing TEAD3. In humans, TEAD3 is a transcription activator, known to be able to regulate the transcription of HSD3B. This enzyme is involved in the degradation of androstenone in the liver. In this study, porcine transcripts of TEAD3 were characterized and compared with mammalian transcripts. The complete structure of porcine TEAD3 gene was characterized including two 5' non-coding exons and one exon 5 not used in porcine transcripts. Variations were screened in sequences related to TEAD3: in exons, in flanking sequences of exons and in the promoter region. A SNP characterized at 726 bp at 5' of the first exon was tested on several pig populations without coherent and convincing results concerning its association with androstenone levels. We showed that in the liver of adult boars, the transcripts levels of TEAD3 and HSD3B were correlated. As in humans, it is possible that HSD3B is a target gene of TEAD3 in porcine liver. Nevertheless, no expression variation was observed for TEAD3 or HSD3B in liver between animals with different genotypes at the SNP. We concluded that this SNP was not the causal mutation of this QTL.

A quantitative trait locus (QTL) for boar fat androstenone levels has been identified near the SSC7 centromere in a Large White × Meishan cross. Backcrosses were produced to isolate the Chinese haplotype in a European genetic background. The expression of 25 genes from the QTL region was studied in the testes and livers of 5-month-old backcross boars, with the aim of identifying the causal gene. Using Fluidigm, a new high-throughput technology, the expression of 25 genes was measured in a single real-time PCR experiment. This study found six significantly down-regulated genes (C6ORF106, C6ORF81, CLPS, SLC26A8, SRPK1 and MAPK14) in the testes of MS-LW backcross boars. However, according to current knowledge, none of the genes appear to be related to androstenone metabolism. In the livers, none of the genes were significantly up- or down-regulated, including TEAD3, which was previously designated as a possible candidate to explain this QTL.

International audience; Meta-analyses have been carried out to quantify the effect of dietary vitamin E on α-tocopherol accumulation and on lipid oxidation in porcine M. longissimus. Published results of 13 (vitamin E accumulation) and 10 (lipid oxidation) experiments respectively were used for the analyses. After a number of standardization procedures, a nonlinear relationship was found between the supplementary vitamin E and the accumulation of α-tocopherol in pork which approached a maximum value of 6.4 μg/g tissue. Pork lipid oxidation levels were described in terms of Thiobarbituric Acid Reacting Substances (TBARS) values. The statistical analysis revealed significant effect of vitamin E dose, muscle α-tocopherol concentration and supplementation time on TBARS, resulting in two prediction models for lipid oxidation. Meta-analysis has proven to be a valuable tool for combining results from previous studies to quantify the effects of dietary vitamin E. Further studies, carried out with standardized experimental protocols would be beneficial for model validation and to increase the predictive power of the derived models.

Technological meat quality is a significant economic factor in pork production, and numerous publications have shown that it is strongly influenced both by genetic status and by rearing and slaughter conditions. The quality of meat is often described by meat pH at different times postmortem, as well as by color and drip loss, whereas carcass quality is often characterized by lean percentage. A meta-analysis of findings relating to 3,530 pigs reported in 23 publications was carried out to assess the effects of the halothane gene, sex, breed, and slaughter weight of animals on 7 selected variables: pH at 45 min postmortem, ultimate pH, reflectance (L*-value), redness (a*-value), yellowness (b*-value), drip loss, and lean percentage. Two statistical methods were used in the meta-analysis: the method of effect size and the better known random effects model. The method of effect size was associated with Markov chain Monte Carlo techniques for implementing Bayesian hierarchical models to avoid the problems of limited data and publication bias. The results of our meta-analysis showed that the halothane genotype had a significant effect on all analyzed pork quality variables. Between-study variance was evaluated with the Cochran (1954) Q-test of heterogeneity. Meta-regression was used to explain this variance, with covariates such as breed, sex, slaughter weight, and fasting duration being integrated into different regression models. The halothane gene effect was associated with the breed effect only for the following variables: L*-value, b*-value, and drip loss. Slaughter weight contributed significantly only to the explanation of differences in ultimate pH between homozygous genotypes. In response to inconsistencies reported in the literature regarding the difference between the genotypes NN and Nn, results of the meta-analysis showed that the difference between these 2 genotypes was significant for all the analyzed variables except the a*-value.

L’objectif de cet article est de définir et illustrer la notion de robustesse telle qu’elle est vue par les généticiens. Pour ces derniers, il existe deux concepts de robustesse. Le premier considère que la robustesse correspond à la capacité de survie de l’animal et au maintien d’un potentiel global de production dans des environnements stressants et fait notamment référence au rôle de l’axe corticotrope. Le second concept définit la robustesse comme le maintien d’un potentiel de production spécifique : dans ce cadre, un animal est dit robuste pour un caractère donné si ce caractère est stable dans des environnements variés, ce qui rejoint la notion d’interaction génotype-milieu et s’explique par différentes hypothèses génétiques (modèle de surdominance, modèle pléiotropique, modèle épistatique). La canalisation d’un caractère correspond alors à l’action de sélectionner pour diminuer la sensibilité aux variations environnementales. Cette canalisation est intéressante pour répondre, par exemple, aux attentes des producteurs (optimum de production), des transformateurs (homogénéité des productions) ou aux nouvelles contraintes environnementales (agriculture durable). La mise en pratique de cette dernière passe par différentes modélisations des interactions génotype-milieu ; la plus novatrice utilise les modèles dits structuraux qui considèrent une variabilité génétique de la variance du caractère considéré et pour lesquels des développements méthodologiques sont encore nécessaires. Différentes expériences de sélection canalisante ont été mises en place sur des animaux de rente avec plus ou moins de succès. A l’heure actuelle, seule la sélection canalisante sur l’homogénéité des poids des lapereaux à la naissance est pratiquée en routine, The objective of this article was to define and illustrate the meaning of robustness in the animal genetic context where this word pointsto two concepts. The first one considers that robustness is the ability to maintain a global production level in stressing environmentsand is mainly related to the role of the corticotrop axis. The second one defines the robustness as the ability to maintain the expressionof a given trait with a low variability in different environments. This concept refers to different genetic hypotheses and to theso-called «overdominance», «pleiotropic» and «epistatic» models, respectively.The canalisation of a trait is the selection to reduce its sensitivity to environmental variations; it is an interesting strategy to reach anoptimum production level, to homogenise production levels, to respond to the relaxation of environmental conditions (low input system)…Different genotype by environment interaction models can be used to canalise a trait. The most recent one is the structural model, which deals with the hypothesis that the expression of a trait is controlled by two sets of genes i. e. one set controlling the meanof the trait and the other set controlling the environmental variability of the trait. Several canalising selection experiments have beenperformed in farm animals but only canalisation for rabbit weight at birth is routinely used at the present time.

Two-dimensional electrophoresis was used to compare Longissimus sarcoplasmic protein abundance between two groups (tough meat and tender meat), defined on the basis of extreme Warner-Bratzler shear force values measured on cooked pork. Fourteen protein spots differed in quantity (P0.05) between the two groups and were identified. Adypocyte fatty acid binding protein and acyl-CoA binding protein involved in lipid traffic and in the control of gene expression regulating cell proliferation and differentiation, and Enoyl-CoA hydratase, aldose reductase and triosephosphate isomerase indirectly related to lipid metabolism were overrepresented in the tender group. The tender group was further characterized by increased levels of proteins involved in protein folding and polymerization (initiation factor elf-3beta, chaperonin subunit 2, profilin II). The results suggest that the lower post-cooking shear force could at least in part be related to muscle adipogenetic and/or myogenetic status of which the possible underlying mechanisms are discussed.

BACKGROUND: To fulfil consumers' requirements for food traceability, it is necessary to have effective tools to differentiate food products according to their origin. The aim of the study was to identify a limited number of physico-chemical measurements that could differentiate rabbit meat from three different rearing systems: standard production system or a high quality norm system or a very low growth breeding system. RESULTS: The stepwise linear discriminant analysis (LDA) provided 14 physico-chemical variables, then combined into two discriminant factors. Most of them (n = 8) were related to bone traits, and especially (n = 5) to mechanical femur assessments. Mechanical characteristics of meat were also relevant in this analysis. Decision tree analysis (DTA) selected two variables only (femur stiffness, and ratio of femur weight to chilled carcass weight) to discriminate the three groups. A total of 96% and 90% of rabbits were correctly assigned to their original group according to LDA and DTA, respectively. CONCLUSION: This work demonstrated that simple physico-chemical traits recorded in carcasses and meat were efficient to discriminate rabbits from three different rearing systems using LDA or DTA procedures. These systems could have further implications for future traceability of breeding origin. Copyright © 2007 Society of Chemical Industry

International audience; Background In crossbreeding schemes, within-line selection of purebreds is performed mainly to improve the performance of crossbred descendants under field conditions. The genetic correlation between purebred and crossbred performance is an important parameter to be assessed because purebred performance can be a poor predictor of the performance of crossbred offspring. With the availability of high-density markers, the feasibility of using crossbred information to evaluate purebred candidates can be reassessed. This study implements and applies a single-step terminal-cross model (GEN) to real data to estimate the genetic parameters of several production and quality traits in pigs.MethodsPiétrain sires were mated with Piétrain and Large White dams to produce purebred and crossbred male half-sib piglets; growth rate, feed conversion ratio, lean meat, pH of longissimus dorsi muscle, drip loss and intramuscular fat content were recorded on all half-sibs. Animals were genotyped using the Illumina Porcine SNP60 BeadChip. The genetic correlation between purebred and crossbred performance was estimated separately for each trait. Purebred animals were evaluated using an animal model, whereas the additive genetic effect of a crossbred individual was decomposed into the additive effects of the sire and dam and a Mendelian sampling effect that was confounded with the residual effect. Genotypes of the Piétrain animals were integrated in the genetic evaluation by using a single-step procedure. As benchmarks, we used a model that was identical to GEN but only accounted for pedigree information (PED) and also two univariate single-step models (GEN_UNI) that took either purebred or crossbred performance into account.ResultsGenetic correlations between purebred and crossbred performance were high and positive for all traits (>0.69). Accuracies of estimated breeding values of genotyped sires and purebred offspring that were obtained with the GEN model outperformed both those obtained with the PED and the GEN_UNI models. The use of genomic information increased the predictive ability of the GEN model, but it did not substantially outperform the GEN_UNI models.ConclusionsWe present a single-step terminal-cross model that integrates genomic information of purebred and crossbred performance by using available software. It improves the theoretical accuracy of genetic evaluations in breeding programs that are based on crossbreeding.

Le néologisme « agro-écologie » est apparu dans la littérature dans les années 30, d’abord pour désigner une discipline scientifique au carrefour de l’écologie et de l’agronomie, puis à partir des années 70 un ensemble de pratiques et un mouvement social en réaction à l’intensification de l’agriculture (Wezel et al., 2009). Francis et al. (2003) ont encore élargi cette définition en considérant l’ensemble des dimensions environnementales et socio-économiques à l’échelle des filières. Dans son acception scientifique, qui est l’angle choisi dans cette étude, l’agro-écologie se définit comme l’application des concepts et principes de l’écologie à la conception et à la gestion d’agroécosystèmes durables. La question du bouclage des cycles pour limiter les intrants et les pollutions par une meilleure réutilisation des sorties des différents ateliers est au coeur de ces problématiques. On vise également un recours accru à des régulations biologiques et écologiques que l’on cherche à piloter au mieux des attendus de l’élevage. Ceci implique de prendre en compte la diversité biologique à tous ses niveaux d'organisation, de comprendre et d’utiliser les capacités adaptatives des animaux et les interactions biotiques dans les agroécosystèmes, en considérant les systèmes de culture ou les systèmes d'élevage comme des écosystèmes particuliers (Dumont et al. 2013). Ainsi, l’agro-écologie s’inscrit-elle dans un mouvement de fond autour du « Comment produire autrement ? » dans des systèmes de production dont on cherche à concilier les performances techniques, environnementales, économiques et sociales. Lancé le 18 décembre 2012, le Projet Agro-Ecologique pour la France (PAEF) vise à conjuguer l’ensemble de ces performances tant au niveau de l'exploitation qu’au niveau collectif (territoires, filières, etc.). Il s’agit d’engager une évolution des systèmes de production, qui remette l’agronomie au coeur des pratiques, pour combiner ces différentes performances. La Loi n° 2014-1170 du 13 octobre 2014 dite Loi d'avenir pour l'agriculture, l'alimentation et la forêt en donne la définition suivante : « Les politiques publiques visent à promouvoir et à pérenniser les systèmes de production agro-écologiques, dont le mode de production biologique, qui combinent performance économique, sociale, notamment au travers d’un haut niveau de protection sociale, environnementale et sanitaire. Ces systèmes privilégient l'autonomie des exploitations agricoles et l'amélioration de leur compétitivité, en maintenant ou en augmentant la rentabilité économique, en améliorant la valeur ajoutée des productions et en réduisant la consommation d'énergie, d'eau, d'engrais, de produits phytopharmaceutiques et de médicaments vétérinaires, en particulier les antibiotiques. Ils sont fondés sur les interactions biologiques et l'utilisation des services écosystémiques et des potentiels offerts par les ressources naturelles, en particulier les ressources en eau, la biodiversité, la photosynthèse, les sols et l'air, en maintenant leur capacité de renouvellement du point de vue qualitatif et quantitatif. Ils contribuent à l'atténuation et à l'adaptation aux effets du changement climatique.

Background HPA axis plays a major role in physiological homeostasis. It is also involved in stress and adaptive response to the environment. In farm animals in general and specifically in pigs, breeding strategies have highly favored production traits such as lean growth rate, feed efficiency and prolificacy at the cost of robustness. On the hypothesis that the HPA axis could contribute to the trade-off between robustness and production traits, we have designed this experiment to explore individual variation in the biological response to the main stress hormone, cortisol, in pigs. We used ACTH injections to trigger production of cortisol in 120 juvenile Large White (LW) pigs from 28 litters and the kinetics of the response was measured with biological variables and whole blood gene expression at 4 time points. A multilevel statistical analysis was used to take into account the longitudinal aspect of the data. Results Cortisol level reached its peak 1 h after ACTH injection. White blood cell composition was modified with a decrease of lymphocytes and monocytes and an increase of granulocytes (FDR

Semen production was analysed in two rabbit lines (low, L and high, H) derived by 5 generations of divergent selection for 63-d body weight from a commercial heavy breed. A total of 31 bucks were collected during 18 weeks, once a week, by 2 solicitations at a 15 min interval (giving the 1 st and 2 nd rank ejaculate). Performances were recorded only one week out of two, resulting in 9 collection series. Sexual activity did no t differ between lines. A total of 256 and 226 ejaculates were observed in the L and H lines, respectively. The percent of efficient ejaculates (= fit for insemination) was markedly higher in the L line (66.5% vs. 44.2% in the H line) due to lower potential elimination for presence of urine, or insufficient volume or insufficient mass motility. Considering only the main effect of the lines, the line influenced mass motility, the volume and the concentration of the ejaculates, as well as 4 parameters from a computer assisted sperm motility analysis (path velocity, VAP, track linearity, LIN, track speed, VCL and beat cross frequency, BCF). Mass motility and the volume of the ejaculates were higher in the L line while the semen concentration was higher in the H line. Overall, the total number of sperms and the number of motile sperms per ejaculate were similar in both lines. The interaction between line and rank of the ejaculate on concentration, percent of motile sperms per ejaculate and LIN was a very interesting feature of the results. For example, in the L line, both ejaculates had the same concentration, while in the H line, the 1 st ejaculate was more concentrated than the second one. This pattern was maintained all along the experiment. The L line had highe r values of VAP, LIN and VCL but lower value of BCF. The efficient number of sperms by ejaculate, a synthetic criteria taking into account the number of motile sperms per ejaculate and the ability of the ejaculate for insemination was significantly higher in the L line: 229 vs 170 x10 6 sperms per ejaculate in the H line.

The objective of the study was to analyze the reproductive longevity of 2 selected lines of rabbits. The first one was the Prat line, a line selected in Spain on litter size at weaning, and raised in overlapping generations. The second one was a French line, the A1077 line, selected on litter size at birth and individual weight at 63 d of age, managed in batches, and artificially inseminated with discrete generations. Reproductive longevity was measured beginning at the first successful mating, assessed by a pregnancy diagnosis in the Prat line, and at the first kindling in the A1077 line. In the A1077 line, culling for infertility occurred after 3 unsuccessful artificial inseminations. The trait analyzed, defined as the doe length of productive life (LPL), was the time in days between date of the first positive pregnancy diagnosis and date of culling or death in the Prat line. In the A1077 line, the trait was the number of AI after the first kindling. Effects included in the model were year-season, litter size at birth, reproductive cycle or physiological status x cycle interaction, age at first mating, batch (only for the A1077 line), and additive genetic value of the animal as a random effect. Survival analyses were carried out with a Cox model for the Prat line and a discrete model for the A1077 line. The estimated heritability values for LPL were around 0.16 in the Prat and A1077 lines with a model including physiological status x cycle interaction effect. Removing this effect from the model led to an increase in estimated genetic variance with h 2 = 0.24 and 0.19 in the Prat and A1077 lines, respectively. Including the traits LPL and number of AI from first fertile mating or AI in selection programs could increase reproductive longevity and decrease the replacement rate.

Studying the muscular hypertrophy of Texel sheep by forward genetics, we have identified an A-to-G transition in the 3′UTR of the GDF8 gene that reveals an illegitimate target site for microRNAs miR-1 and miR-206 that are highly expressed in skeletal muscle. This causes the down-regulation of this muscle-specific chalone and hence contributes to the muscular hypertrophy of Texel sheep. We demonstrate that polymorphisms which alter the content of putative miRNA target sites are common in human and mice, and provide evidence that both conserved and nonconserved target sites are selectively constrained. We speculate that these polymorphisms might be important mediators of phenotypic variation including disease. To facilitate studies along those lines, we have constructed a database (www.patrocles.org) listing putative polymorphic microRNA‐target interactions.

We carried out a one-generation, divergent selection experiment on residual feed efficiency in order to estimate the genetic parameters of this trait. The selection criterion was the residual feed consumption. We measured the consequences of this selection on growth, feed efficiency, and carcass composition. One generation of selection was performed on young male rabbits from a heavy weight line. They were individually caged and measured for their weight gain and feed consumption between weaning (30 days) and 65 days of age. The fatness of all the males was estimated by ToBEC measurement (Total Body Electrical Conductivity) at 65 days of age. Their offspring were bred under the same conditions and 120 males were slaughtered at 65 days of age in order to estimate the correlated response on carcass traits: dressing yield, cutting parts, fatness, ultimate pH, and colour. Genetic parameters were estimated with restricted maximum likelihood applied to an animal model. The heritability value estimated for residual feed consumption was 0.45±0.11, which was of the same order as the heritability estimated for average daily gain (0.41±0.13) and higher than the heritability estimated for the feed conversion ratio (0.27). Residual feed consumption was negatively correlated with the hind part percentage (−0.71) and correlated positively with front part percentage (0.54). The genetic correlations with dressing percentage and carcass fatness were very low. Residual feed consumption may be introduced as a selection criterion for improving feed efficiency. Thus, no significant phenotypic differences were found between offspring of high and low residual feed consumption males, except for the hind part percentage, which was higher in the low residual feed consumption line.

Maîtriser la qualité des produits issus des animaux d’élevage suppose de pouvoir l’objectiver à partir de mesures fiables, faciles d’utilisation et si possible précoces et non invasives. Les programmes de recherche-développement mis en place au sein des différentes filières animales (ruminants, porcins, volailles, poissons) concernent notamment i) la détection et la quantification des contaminants biologiques ou chimiques des produits, ii) la détermination de la composition et des propriétés technologiques des produits grâce à des méthodes alternatives aux mesures analytiques de laboratoire (mesures optiques ou par imagerie, mesures physiques non invasives), et iii) la recherche de marqueurs biologiques précoces de la qualité (marqueurs génétiques, expression de gènes ou de protéines, teneurs en métabolites) et leur validation par des approches de modélisation. Appliqué à un panel de plus en plus large de critères de qualité, ce phénotypage à haut débit est nécessaire au développement de la sélection génétique ou génomique, à la biologie prédictive et à l’élevage de précision., In order to be able to control the quality of animal products, it is necessary to have reliable, easy to use and if possible early and non-invasive measurements. Research and development programs implemented in the various livestock sectors (ruminants, pigs, poultry, fish) concern i) the development and standardization of rapid methods both for the detection and quantification of biological or chemical contaminants, ii) the development of alternative methods to replace analytical measurements of the composition and functional properties of products through innovative technologies used in routine (optical or imaging methods, non-invasive physical methods...) and/or iii) the research of early biological markers of quality (genetic markers, gene expression or protein levels of metabolites) and their validation by the way of modeling. High-throughput phenotyping applied to a range of increasingly broad criteria of quality, is necessary for genetic or genomic selection, predictive biology and precision livestock.

Selection pour un abaissement du potentiel glycolytique du muscle chez le porc Large White. II. Reponses correlatives pour la qualite de la viande et la composition du muscle. Une experience de selection a ete conduite sur six generations dans une population de porcs de race pure Large White francais, presumee indemne des alleles HAL n et RN - . Deux lignees ont ete formees a partir de la meme population de base, et ont ete conduites de maniere contemporaine: une lignee temoin (C) et une lignee selectionnee (S) pour diminuer le potentiel glycolytique mesure in vivo (IVGP) sur le muscle longissimus. Au cours de cette experience, des animaux issus des deuxiemes portees ont ete abattus a 100 kg de poids vif afin d'etudier les effets de la selection sur la qualite de la viande et les caracteres de composition du muscle. Pour tous les caracteres, les valeurs d'heritabilite, les correlations genetiques avec IVGP et les reponses genetiques moyennes par generation ont ete estimees. Pour les caracteres mesures sur plusieurs muscles differents, les valeurs d'heritabilite varient d'un muscle a l'autre. Pour un meme muscle, les heritabilites du pH ultime et de la valeur de luminosite L * sont du meme ordre de grandeur. Les heritabilites des activites enzymatiques varient selon le muscle de 0,12 a 0,44 pour la lactate deshydrogenase (LDH), de 0,22 a 0,44 pour la citrate synthase (CS) et de 0,06 a 0,26 pour le rapport LDH/CS. Les heritabilites estimees pour la composition chimique du muscle longissimus sont moyennes (0,33 a 0,59), excepte pour la teneur en azote. L'heritabilite du rendement technologique de la fabrication du jambon cuit est de 0,32 ± 0,09. La plupart des caracteristiques physiologiques et chimiques du muscle longissimus ont peu evolue sous l'effet de la selection. Il en a ete de meme pour le rendement technologique, bien que la correlation genetique estimee entre ce caractere et IVGP soit de valeur moyenne (-0,42 ± 0,12). De plus, la lignee S a montre une reponse genetique significative pour les activites enzymatiques et pour la typologie des fibres du muscle longissimus. Les animaux de la liguee S avaient un metabolisme musculaire plus glycolytique que ceux de la lignee C, avec une proportion plus faible de fibres oxydo-glycolytiques, une proportion plus importante de fibres glycolytiques, une valeur plus forte du rapport LDH/CS et une teneur plus faible en pigment.

[b]Background:[/b] Replacing pedigree-based BLUP evaluations by genomic evaluations in pig breeding schemes can result in greater selection accuracy and genetic gains, especially for traits with limited phenotypes. However, this methodological change would generate additional costs. The objective of this study was to determine whether additional expenditures would be more profitably devoted to implementing genomic evaluations or to increasing phenotyping capacity while retaining traditional evaluations. [b]Methods:[/b] Stochastic simulation was used to simulate a population with 1050 breeding females and 50 boars that was selected for 10 years for a breeding goal with two uncorrelated traits with heritabilities of 0.4. The reference breeding scheme was based on phenotyping 13 770 candidates per year for trait 1 and 270 sibs of candidates per year for trait 2, with selection based on pedigree-based BLUP estimated breeding values. Increased expenditures were allocated to either increasing the phenotyping capacity for trait 2 while maintaining traditional evaluations, or to implementing genomic selection. The genomic scheme was based on two training populations: one for trait 2, consisting of phenotyped sibs of the candidates whose number increased from 1000 to 3430 over time, and one for trait 1, consisting of the selection candidates. Several genomic scenarios were tested, where the size of the training population for trait 1, and the number of genotyped candidates pre-selected based on their parental estimated breeding value, varied. [b]Results:[/b] Both approaches resulted in higher genetic trends for the population breeding goal and lower rates of inbreeding compared to the reference scheme. However, even a very marked increase in phenotyping capacity for trait 2 could not match improvements achieved with genomic selection when the number of genotyped candidates was large. Genotyping just a limited number of pre-selected candidates significantly reduced the extra costs, while preserving most of the benefits in terms of genetic trends and inbreeding. Implementing genomic evaluations was the most efficient approach when major expenditure was possible, whereas increasing phenotypes was preferable when limited resources were available. [b]Conclusions:[/b] Economic decisions on implementing genomic evaluations in a pig nucleus population must take account of population characteristics, phenotyping and genotyping costs, and available funds.