Effects of heat exposure on Akt/S6K1 signaling and expression of genes related to protein and energy metabolism in chicken (Gallus gallus) pectoralis major muscle.

In order to improve understanding of the heat-induced changes in muscle growth, we determined the expression of genes related to protein and energy metabolism in the pectoralis major muscle of chickens. We also explored the protein kinase B (PKB also called Akt)/p70 S6 kinase (S6K1)/S6 pathway that mediates anabolic signals thereby regulating metabolism and hypertrophic/atrophic balance. Four-week-old chickens were exposed to 32 or 22 degrees C for 1 week. Chickens from both groups were then fasted for 16 h or left fed, and submitted to an oral administration of glucose-arginine to induce an anabolic response (30-min treatment) or left untreated. High ambient temperature and the associated decrease in feed intake modified the expression of certain energy-related genes (e.g. -40% for PGC-1alpha) and protein metabolism (e.g. about +80% for atrogin-1), but the expression of several muscle metabolism-related genes considered here was unchanged. The capacity for muscle protein synthesis, i.e. RNA/protein ratio, was reduced in warm conditions (approximately -20%). Slightly lower activation of S6 induced by glucose-arginine treatment was found at 32 degrees C compared to 22 degrees C, which might indicate somewhat lower efficiency of mRNA translation. Analysis of glucose/insulin balance suggested changes in glucose metabolism under heat exposure. However, this remains to be characterized

Early-life conditioning strategies to reduce dietary phosphorus in broilers: underlying mechanisms

International audienceChickens adapt to P and Ca restriction during the very first days of life by improving P utilisation efficiency. The present study was built to identify the mechanisms underlying this adaptive capacity, and to identify the optimal window of application of the restriction (depletion). A total of 1600 Cobb 500TM male broilers were used. During each phase (from age 0 to 4 d, 5 to 8 d, 9 to 18 d and 19 to 33 d), the animals received either a control diet (H) or a restricted diet (L) with reduced levels of non-phytate P (nPP) and Ca (between −14 and −25 % for both) with four dietary sequences: HHHH, HLHL, LHHL and LLHL. None of the feeding strategies affected growth. Tibia ash content at day 4 and 8 was impaired when the L diet was fed from 0 to 4 and 5 to 8 d, respectively (P = 0⋅038 and P = 0⋅005). Whatever the early restriction period or length between 0 and 8 d of age, the mineralisation delay was compensated by day 18. This was accompanied by an increased mRNA expression of the Ca transporter, CALB1, and an increased apparent ileal digestibility of Ca at day 8 (P < 0⋅001). This adaptation was limited to the starter phase in restricted birds. No effect was seen on P transporters mRNA or protein expression. In conclusion, birds adapted to mineral restriction by increasing Ca and nPP utilisation efficiencies. Depletion−repletion strategies are promising in improving the sustainability of broiler production but need to be validated in phytase-supplemented diets

Daily variations in dietary protein and energy content regulate protein metabolism in chicken skeletal muscle

National audienc

Acclimatation des volailles au chaud et au froid pendant l'incubation

National audienc

L'acclimatation embryonnaire : une technique innovante pour limiter les mortalités liées au stress thermique chez le poulet

Chantier qualité GANational audienceThe selection of fast-growing chickens has favored muscle mass without similar improvement of the cardiovascular and respiratory systems involved in thermoregulation. Indeed, broiler chickens have limited capacities to sustain high temperatures, with reduced performances during moderate and chronic heat exposure, and depressed welfare, morbidity and mortality during acute heat exposure. During the last decade, a great effort concerned early thermal acclimation. This strategy requires a fine tuning of incubation conditions (temperature, phasis of embryogenesis, duration of exposure) favoring long term thermotolerance. Consequences on growth performance and meat quality were also evaluated. Perinatal heat acclimation is aimed at inducing epigenetic thermoregulatory mechanisms that modulate body temperature on a long term. If it is further proved to be efficient on a large scale, early thermal acclimation could favor poultry sturdiness towards temperature variations without affecting growth performance. In this paper, we will review the main techniques of early thermal exposure and the physiological bases of their use. We will focus on the research axes concerning the comprehension of underlying mechanisms and the interest of this technique for poultry species.Les poulets à croissance rapide sont sensibles à la chaleur en période de finition. En effet, leur sélection pour la croissance a favorisé la masse musculaire au détriment d’organes impliqués dans la thermorégulation. Ceci peut se traduire par des baisses de performances en cas de chaleur modérée et chronique, mais également des problèmes de bien-être et des mortalités lors d’un coup de chaleur. Durant la dernière décennie les efforts ont porté sur l’acclimatation à la chaleur pendant la période périnatale, notamment pendant l’embryogenèse. Cette stratégie nécessite de mettre au point les conditions d’incubation (température, phase de l’embryogenèse, durée d’exposition…) qui favorisent la thermotolérance jusqu’en finition. Les conséquences sur les performances des poulets (croissance, qualité de viande…) sont évaluées. L’acclimatation périnatale met en jeu des mécanismes de régulation épigénétiques qui modulent à long terme la température interne des volailles. A terme, si cette technique se révélait applicable à grande échelle, elle pourrait favoriser la robustesse et le bien-être des volailles face aux variations de températures, tout en préservant leurs performances zootechniques. Dans cet article, sont rappelés les principales techniques d’exposition thermique embryonnaire et les fondements physiologiques de leur mise en œuvre. Sont évoquées ensuite les voies de recherche concernant la compréhension des mécanismes mis en jeu et l’intérêt potentiel de cette technique pour la filière avicole

Variations in egg incubation temperature enable chicken acclimation through long-lasting changes in energy metabolism

National audienc

Variations in egg incubation temperature enable chicken acclimation through long-lasting changes in energy metabolism

National audienc

Additional file 2: of Multi-tissue transcriptomic study reveals the main role of liver in the chicken adaptive response to a switch in dietary energy source through the transcriptional regulation of lipogenesis

Exploration by Principal Component Analysis (PCA) of transcriptomic data (all expressed genes) for each tissue to identify outlier samples. Out of 48, 46, 48 and 44 arrays for liver, adipose, muscle and PBMC respectively, 2, 1, 2 and 1 outlier microarrays were identified by PCA using all the expressed genes. For muscle and PBMC, an additional sample was removed because of an abnormal high number of Agilent-flagged spots or an abnormal background distribution on the array. (PPTX 173 kb

Additional file 4 of Multi-tissue transcriptomic study reveals the main role of liver in the chicken adaptive response to a switch in dietary energy source through the transcriptional regulation of lipogenesis

DEG in liver between the two diets and some features. Array_FC and Array_Pvalue provide the HF/LF expression ratio and the p-value adjusted for the multiple test obtained with the microarray technology. qPCR_FC and qPCR_Pvalue provide the HF/LF expression ratio and the p-value obtained with the RT-qPCR technology. (XLSX 70 kb