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The pHu+ and pHu− lines, which were selected based on the ultimate pH (pHu) of the breast muscle, represent a unique model to study the genetic and physiological controls of muscle energy store in relation with meat quality in chicken. Indeed, pHu+ and pHu− chicks show differences in protein and energy metabolism soon after hatching, associated with a different ability to use energy sources in the muscle. The present study aimed to assess the extent to which the nutritional environment of the embryo might contribute to the metabolic differences observed between the two lines at hatching. Just before incubation (E0), the egg yolk of pHu+ exhibited a higher lipid percentage compared to the pHu− line (32.9% vs. 27.7%). Although 1H-NMR spectroscopy showed clear changes in egg yolk composition between E0 and E10, there was no line effect. In contrast, 1H-NMR analysis performed on amniotic fluid at embryonic day 10 (E10) clearly discriminated the two lines. The amniotic fluid of pHu+ was richer in leucine, isoleucine, 2-oxoisocaproate, citrate and glucose, while choline and inosine were more abundant in the pHu− line. Our results highlight quantitative and qualitative differences in metabolites and nutrients potentially available to developing embryos, which could contribute to metabolic and developmental differences observed after hatching between the pHu+ and pHu− lines.

International audience

In vertebrates, the embryonic environment is known to affect the development and the health of individuals. In broiler chickens, the thermal-manipulation (TM) of eggs during the incubation period was shown to improve heat tolerance at slaughter age (35 days of age) in association with several modifications at the molecular, metabolic and physiological levels. However, little is known about the Japanese quail (Coturnix japonica), a closely related avian species widely used as a laboratory animal model and farmed for its meat and eggs. Here we developed and characterized a TM procedure (39.5°C and 65% relative humidity, 12 h/d, from days 0 to 13 of incubation) in quails by analyzing its short and long-term effects on zootechnical, physiological and metabolic parameters. Heat-tolerance was tested by a heat challenge (36°C for 7h) at 35 days of age. TM significantly reduced the hatching rate of the animals and increased mortality during the first four weeks of life. At hatching, TM animals were heavier than controls, but lighter at 25 days of age for both sexes. Thirty-five days after hatching, TM decreased the surface temperature of the shank in females, suggesting a modulation of the blood flow to maintain the internal temperature. TM also increased blood partial pressure and oxygen saturation percentage at 35 days of age in females, suggesting a long-term modulation of the respiration physiology. Quails physiologically responded to the heat challenge, with a modification of several hematologic and metabolic parameters, including an increase in plasma corticosterone concentration. Several physiological parameters such as beak surface temperature and blood sodium concentration revealed that TM birds responded differently to the heat challenge compared to controls. Altogether, this first comprehensive characterization of TM in Japanese quail showed durable effects that may affect the response of TM quails to heat. ispartof: PLOS ONE vol:15 issue:1 ispartof: location:United States status: published

International audience; 1. The aim of the present study was to investigate increasing amount of n-3 fatty acids (FA) in common edible chicken meat cuts by testing different levels of extruded linseeds (LS) and rapeseed oil in growing and finishing diets. Another challenge was to replace a part of soybean meal by faba beans.2. For that purpose, 3168, one-day-old Hubbard JV15 strain chickens were distributed into six groups: R1 = control diet, R2 = 3% then 5% LS, R3 = 4% then 6% LS, R4 = 5% then 7% LS, R5 = 3% then 5% LS and a low amount of soybean meal in the finishing diet and R6 = 3% then 5% LS and no soybean meal in the finishing diet. The growing performance was recorded throughout the trial. At 30 days of age, all chickens were slaughtered in a commercial slaughter plant at an average weight of 1322 g, to mirror the production of low body weight ‘broiler griller’ birds commonly available for export markets. Thirty carcases per group were processed to determine cut yields. The edible parts from each half carcase were removed to determine the chemical composition and fatty acid composition of meat with skin. The sensorial quality of thighs was evaluated for 20 carcases per group, after roasting. The environmental and economic impacts of the feeding programmes were further evaluated.3. This study showed that it was possible to replace a part of the soybean meal in finishing diet by faba beans and to enrich meat with n-3 FA of broiler meat portions without altering growth performance, carcase composition and sensorial quality of meat. The environmental impact was reduced by these dietary interventions, whereby climate change parameters, expressed as kg CO2 eq./T, and phosphorus and fossil energy consumption were lower, but the land occupation was increased. The extra feed cost was +3 to +8% for groups fed R2 to R6 compared to the control group R1.

International audience; We assessed whether the ratio of dietary n-6/n-3 polyunsaturated fatty acids (PUFA) during egg formation engenders transgenerational maternal effects in domestic chicks. We analyzed yolk lipid and hormone concentrations, and HPA-axis activity in hens fed a control diet (high n-6/n-3 ratio) or a diet enriched in n-3 PUFAs (low n-6/n-3 ratio) for 6 consecutive weeks. Their chicks were tested for neophobia during the first week of life. We found higher corticosterone metabolites in droppings of hens fed the diet enriched in n-3 and significantly higher concentrations of yolk progesterone, androstenedione, and estradiol in their eggs compared to controls. Chicks of hens fed the n-3 enriched diet showed a lower body mass at hatch than controls and expressed higher neophobia when exposed to a novel object. These results add support to the hypothesis that the nutritional state of female birds produces variation in yolk hormone levels and engender maternal effects.

The welfare of ducks can be affected by unwanted behaviors such as excessive reactivity and feather pecking. Providing long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA) during gestation and early life has been shown to improve the brain development and function of human and rodent offspring. The aim of this study was to test whether the pecking behavior of Muscovy ducks during rearing could be reduced by providing LC n-3 PUFA during embryonic and/or post-hatching development of ducklings. Enrichment of eggs, and consequently embryos, with LC n-3 PUFA was achieved by feeding female ducks (n-3F) a diet containing docosahexaenoic (DHA) and linolenic acids (microalgae and linseed oil). A control group of female ducks (CF) was fed a diet containing linoleic acid (soybean oil). Offspring from both groups were fed starter and grower diets enriched with DHA and linolenic acid or only linoleic acid, resulting in four treatment groups with 48 ducklings in each. Several behavioral tests were performed between 1 and 3 weeks of age to analyze the adaptation ability of ducklings. The growth performance, time budget, social interactions, feather growth, and pecking behavior of ducklings were recorded regularly during the rearing period. No significant interaction between maternal and duckling feeding was found. Ducklings from n-3F ducks had a higher body weight at day 0, 28, and 56, a lower feed conversion ratio during the growth period, and lower reactivity to stress than ducklings from CF ducks. Ducklings from n-3F ducks also exhibited a significantly reduced feather pecking frequency at 49 and 56 days of age and for the whole rearing period. Moreover, consumption of diets enriched with n-3 PUFA during the starter and grower post-hatching periods significantly improved the tibia mineralization of ducklings and the fatty acid composition of thigh muscles at 84 days of age by increasing the n-3 FA content.

Decades of genetic selection have generated 2 different, highly specialized types of chickens in which 1 type, known as the layer-type chicken, expresses high laying performance while the other type, known as the broiler-type chicken, is dedicated to the production of fast-growing birds. Selected lines for the latter type often express disorders in their reproductive performance including early sexual maturation and accelerated, non-reversible seasonal decline of their semen production and mating behavior. The aim of the present study was to characterize some metabolic markers of the Sertoli cell populations. Sertoli cells are somatic cells known to support, coordinate, nourish, and protect the germ cell populations from onset to the end of their meiotic process. Comparisons of gonadal development between males of the 2 genetic types taken at their pre-pubertal period indicated that the testes of layer-type chickens are significantly less developed than in broiler-type males taken at the same age. In addition, cultures of purified Sertoli cells from the 2 types revealed in vitro a higher proliferative capacity when issued from layer compared to broiler-type chickens. This was associated with a higher expression of the genes involved in the beta-oxidation of fatty acids (CPT1; PPARβ) as well as a 4-fold increase in the Lactate Dehydrogenase-A expression and activity. In contrast, Sertoli cells from broiler-type chickens presented an elevated activity of citrate synthase and mitochondria, suggesting a better efficacy of aerobic metabolism in Sertoli cells from broiler compared to layer-type chickens. Moreover, the testis from broiler-type chickens seems to be more sensitive to oxidative stress due to the lower global antioxidant capacity compared to layer-type chickens.In conclusion, these results suggest that the metabolic activity of testicular tissues is different in the layer and broiler breeder chickens. The aerobic metabolism more prevalent in broiler-type chickens could be a factor to reduce the male fertility such as germ cell quality.

International audience; The aim of this study was to increase the n-3 fatty acid (n-3 FA) content of eggs without affecting their sensorial and/or technological properties or the laying performance of hens. Laying hens from line 477 were divided into 5 groups corresponding to 5 different diets over the laying period: control diet (C) and diets containing extruded linseed with a high level of fibre (ELHF), extruded linseed with a low level of fibre (ELLF), microalgae, or a combination of 75% ELLF and 25% MA (ELLF+MA). Dietary enrichment with n-3 FA had no effect on the laying performance, hen body weight or egg white viscosity. The egg yolks produced by hens fed the diet containing microalgae were redder than egg yolks from the other groups, suggesting the presence of red pigments in the microalgae preparation. However, the colour difference was low and not perceptible to the human eye. Moreover, colour measurement of egg yolks by sensorial analysis panellists using the Roche colour fan did not reveal a diet effect on this parameter. Egg yolk lipid content was not affected by diet. The egg yolk of hens fed on diets containing linseed and/or microalgae had greater n-3 FA content (×2.5 to 2.9 compared to group C). Linseed mainly increased the linolenic acid content (×3.0 to 3.4 compared to group C) and the microalgae increased the LC n-3 FA content (×4.1 compared to group C). Dietary enrichment with n-3 FA had no effect on the sensorial quality of shell cooked eggs except for the "unusual flavour" criterion for which the score was higher for the MA group compared to the other groups and corresponded to a fishy flavour.

The increasing use of unconventional feedstuffs in chicken's diets results in the substitution of starch by lipids as the main dietary energy source. To evaluate the responses of genetically fat or lean chickens to these diets, males of two experimental lines divergently selected for abdominal fat content were fed isocaloric, isonitrogenous diets with either high lipid (80 g/kg), high fiber (64 g/kg) contents (HL), or low lipid (20 g/kg), low fiber (21 g/kg) contents (LL) from 22 to 63 days of age. The diet had no effect on growth performance and did not affect body composition evaluated at 63 days of age. Glycolytic and oxidative energy metabolisms in the liver and glycogen storage in liver and Sartorius muscle at 63 days of age were greater in chicken fed LL diet compared with chicken fed HL diet. In Pectoralis major (PM) muscle, energy metabolisms and glycogen content were not different between diets. There were no dietary-associated differences in lipid contents of the liver, muscles and abdominal fat. However, the percentages of saturated (SFA) and monounsaturated fatty acids (MUFA) in tissue lipids were generally higher, whereas percentages of polyunsaturated fatty acids (PUFA) were lower for diet LL than for diet HL. The fat line had a greater feed intake and average daily gain, but gain to feed ratio was lower in that line compared with the lean line. Fat chickens were heavier than lean chickens at 63 days of age. Their carcass fatness was higher and their muscle yield was lower than those of lean chickens. The oxidative enzyme activities in the liver were lower in the fat line than in the lean line, but line did not affect energy metabolism in muscles. The hepatic glycogen content was not different between lines, whereas glycogen content and glycolytic potential were higher in the PM muscle of fat chickens compared with lean chickens. Lipid contents in the liver, muscles and abdominal fat did not differ between lines, but fat chickens stored less MUFA and more PUFA in abdominal fat and muscles than lean chickens. Except for the fatty acid composition of liver and abdominal fat, no interaction between line and diet was observed. In conclusion, the amount of lipids stored in muscles and fatty tissues by lean or fat chickens did not depend on the dietary energy source.

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n-3 PUFA are crucial for health and development. Their effects as regulators of lipid and glucose metabolism are well documented. They also appear to affect protein metabolism, especially by acting on insulin sensitivity. The aim of the present study was to investigate the role ofn-3 PUFA, i.e. the precursor α-linolenic acid (ALA) 18 : 3n-3 or long-chain PUFA (LC-PUFA), in chickens, by focusing on their potential function as co-regulators of the insulin anabolic signalling cascade. Ross male broilers were divided into six dietary treatment groups. Diets were isoproteic (22 % crude protein) and isoenergetic (12·54 MJ metabolisable energy/kg) and contained similar lipid levels (6 %) provided by different proportions of various lipid sources: oleic sunflower oil rich in 18 : 1n-9 as control; fish oil rich in LC-PUFA; rapeseed and linseed oils providing ALA. The provision of diets enriched withn-3 PUFA, i.e. rich in LC-PUFA or in the precursor ALA, for 3 weeks improved the growth performance of chickens, whereas that of only the ALA diet enhanced the development of the pectoralis major muscle. At 23 d of age, we studied the insulin sensitivity of the pectoralis major muscle and liver of chickens after an intravenous injection of insulin or saline. The present results indicate that the activation patterns ofn-3 PUFA are different in the liver and muscles. An ALA-enriched diet may improve insulin sensitivity in muscles, with greater activation of the insulin-induced 70 kDa ribosomal protein S6 kinase/ribosomal protein S6 pathway involved in the translation of mRNA into proteins, thereby potentially increasing muscle protein synthesis and growth. Our findings provide a basis on which to optimise dietary fatty acid provision in growing animals.

Background Slow-growing lines are widely used in France for the production of high quality free-range chickens. While such production is mainly dedicated to the whole carcass market, new prospects are opening up for the development of cuts and processed products. Whether the body composition and meat quality of slow-growing birds can be improved by selection has thus become an important issue. The genetic parameters of growth, body composition and breast meat quality traits were evaluated in relation to behaviour at slaughter in a large pedigree population including 1022 male and female slow-growing birds. Results The heritability coefficients (h2) of body weight and body composition traits varied from 0.3 to 0.5. Abdominal fat percentage was genetically positively correlated with body weight but negatively correlated with breast muscle yield. The characteristics of the breast meat (i.e., post-mortem fall in pH, colour, drip loss, shear-force and lipid content) were all heritable, with h2 estimates ranging from 0.18 to 0.48. The rate and extent of the fall in pH were under different genetic control. Strong negative genetic correlations were found between the ultimate pH and the lightness, yellowness and drip loss of the meat. Wing flapping on the shackle line was significantly heritable and exhibited marked genetic correlations with the pH at 15 min post-slaughter and the redness of the meat. The genetic relationships between meat quality traits, body weight and body composition appeared slightly different between males and females. Conclusion This study suggested that there are a number of important criteria for selection on carcass and breast meat quality in slow-growing birds. Selection for reduced abdominal fatness and increased breast muscle yield should be effective as both traits were found to be highly heritable and favourably correlated. Substantial improvement in meat quality could be achieved by selection on ultimate pH which was highly heritable and strongly correlated with the colour and water-holding capacity of the meat. Moreover, this study revealed for the first time that the behaviour at slaughter is partly genetically determined in the chicken.

Le programme de recherches GENECAN repose sur 1) la production de familles informatives par un croisement entre 2 souches expérimentales d'origines et d'aptitudes différentes (INRA-UEPFG), 2) la mesure des phénotypes sur les canes back-cross (BC) et leurs descendants mulards (INRA-URA, INPENSAT, UPPA-CNRS, INRA-UEPFG) et mulardes (INRA-IASP), 3) le génotypage des animaux (plateforme de la Génopole toulousaine, INRA-LGC) à l’aide d’un panel de 116 marqueurs informatifs et 4) l'analyse statistique pour détecter les QTL (INRA-SAGA). A partir des performances des males mulards, 65 QTL ont pu être détectés : 13 pour des caractères de croissance, 18 pour des caractères métaboliques et pondéraux durant le gavage, 8 pour des caractères d’aptitude au gavage, 12 pour des caractères de qualité du magret et 14 pour des caractères de qualité du foie gras.

Chantier qualité GA; The susceptibility to development of hepatic steatosis is known to differ between Muscovy and Pekin ducks. Although some experiments were conducted to decipher these differences, few data have been produced to analyse the role of specific genes in this process. For this purpose, expression levels of genes involved in lipid (ATP citrate lyase, malic enzyme 1, fatty acid synthase, stearoyl-CoA desaturase 1, diacylglycerol O-acyl transferase 2, microsomal triglyceride transfer protein, apolipoprotein A1, apolipoprotein B, sterol regulatory element binding factor 1, hepatocyte nuclear factor 4, choline/ethanolamine phosphotransferase 1, carnitine palmitoyl transferase 1A, peroxisome proliferator-activated receptor alpha and sterol O-acyltransferase) and carbohydrate (activating transcription factor 4 or cAMP-response element binding protein, mitochondrial malate dehydrogenase 2 and carbohydrate responsive element binding protein) metabolism and in other functions were analysed in the liver of Pekin and Muscovy ducks fed ad libitum or overfed. A specific positive effect of feeding was observed on the expression of genes involved mainly in fatty acids and TG synthesis and glycolysis, and negative effect on genes involved in beta-oxidation. Interestingly, a strong species effect was also observed on stearoyl-CoA desaturase 1 and to a lesser extent on diacylglycerol O-acyl transferase 2 expression, leading to large differences in expression levels between Pekin and Muscovy overfed ducks, which could explain the difference in lipid metabolism and steatosis ability observed between the two duck species. These results should shed light on gene expression that might underlie susceptibility to hepatic steatosis in humans.

International audience; 1. The aim of this study was to examine the effect of sex and genotype on carcase composition and nutritional and sensory characteristics of chicken meat. The oGeline de Touraineo (GT) characterised by high carcase fatness was compared with an experimental crossbreed (EC) and oLabel rougeo (LR) genotype. 2. Females compared with males, and GT chickens compared with LR and EC chickens were characterised by increased carcase fatness and an increased lipid level in thigh meat. 3. In both breast and thigh meat, the percentage of monounsaturated fatty acids was increased and the percentage of polyunsaturated fatty acids was decreased. However, these effects did not affect sensory characteristics of meat particularly those of roasted breast fillets containing very low lipid level by comparison with thigh meat. 4. Finally, in our study, high carcase fatness was related to high intermuscular fatness affecting the nutritional characteristics of meat but not its sensory attributes.

Chantier qualité GA; International audience; To explore the mechanisms leading to excessive adiposity in chicken, we investigated the regulation of fatty acid oxidation depending on genotype-related body fatness and diet composition. mRNA expression and/or activity of proteins involved in mitochondrial energy metabolism were measured in liver and gastrocnemius muscle of genetically lean or fat chickens reared on a low-fat/high-protein diet or an isoenergetic high-fat/low-protein diet (HF/LP). Muscle expressions of the muscle isoform of carnitine-paimitoyltransferase 1 (M-CPT1) and PPAR beta/delta were higher in fat than in lean chickens. This was also observed in liver, although only with the HF/LP diet for M-CPTI. This could stimulate mitochondrial fatty add oxidation in fat chickens. Up-regulations of liver and muscle CPT-1 hepatic isoform, and muscle cytochrome-c-oxidase mRNA expressions, and of beta-hydroxyacyl-CoA-dehydrogenase activities suggest higher fatty acid utilization with the HF/LP diet. PPAR beta/delta and PGC-1 alpha could control fatty acid oxidation in muscle and liver, respectively. Regulation of avian uncoupling protein (avUCP) mRNA was tissue-dependent. Predominantly expressed in muscle, it was stimulated in fat and in HF/LP-fed chickens, where it could be associated to the special need in muscle anti-oxidant pathways of fatter animals. In liver it was lower in fat than in lean chickens, and its potential function remains to be clarified.

International audience; In mammals, carnitine palmitoyltransferase 1 (CPT1) is a rate limiting enzyme of fatty acid oxidation. Two isoforms are present. We characterized a full-length cDNA sequence encoding chicken liver L-CPT1 isoform and a partial cDNA sequence encoding chicken muscle MCPT1 isoform. CPT1 messengers showed the expected tissue specificity. M-CPT1 messenger and CPT1 activity were higher in oxidative than in glycolytic muscle. Expression of both isoforms was assessed in various tissues of genetically fat or lean chickens. Fasting considerably increased L-CPT1 mRNA expression and β-hydroxyacyl CoA dehydrogenase (HAD) activity in the liver of fat or lean chickens. Unexpectedly, fasting did not increase M-CPT1 mRNA levels nor HAD activity in muscles of either chicken genotype. It however increased succinyl-CoA:3-ketoacid CoA transferase (SCOT) mRNA expression (an enzyme related to ketone body utilization) in oxidative muscle. SCOT messenger was slightly more abundant in oxidative muscle of lean chickens but not in glycolytic muscle. In conclusion, the regulation of fatty acid oxidation is probably not impaired in fat chicken. The absence of fasting stimulation of M-CPT1 mRNA expression, which is at variance with the situation observed in mammals, suggests that during fasting, chicken muscles preferentially use ketone bodies as fuel, at least in the short term

The effects of age (from 1 day post-hatch to 98 days of age) and feeding levels (feed restriction followed by overfeeding v. ad libitum feeding) on lipid deposition in breast muscle (quantity and quality, localisation) of mule ducks were determined in relation to muscle energy metabolism (glycolytic and oxidative), plasma levels of lipids, glucose and insulin, and muscle capacity for lipid uptake (characterised by lipoprotein lipase (LPL) activity). Two periods were defined for age effects on intramuscular lipids in breast muscle: 2 1 to 42 days of age when lipids (mainly phospholipids and cholesterol provided by egg yolk) stored in the adipocytes during embryonic life were transferred to the muscle fibres and used for growth and energy requirements, 2 42 to 98 days of age when the muscle again stored lipids (mainly triglycerides provided by liver lipogenesis), first in fibres and then in adipocytes. Plasma glucose and insulin levels were not affected by age. Plasma levels of lipids and LPL activity in breast muscle were high at 1 and 14 days of age and then decreased, remaining stable until 98 days of age. Energy metabolism activity in the breast muscle (mainly glycolytic activity) increased with age. Feed restriction, corresponding to 79% of ad libitum intake, applied between 42 and 75 days of age only resulted in decreases in plasma insulin concentration and total lipid content of breast muscle, mainly affecting triglyceride and mono-unsaturated fatty acid (MUFA) levels. Overfeeding increased plasma levels of insulin and lipids while glycaemia remained stable. LPL activity and total lipid levels increased in breast muscle, mainly induced by deposition of triglycerides and MUFA occurring particularly during the 2nd week of this period. Glycolytic energy metabolism decreased. In response to age or feeding levels, muscle lipid levels and composition reflect plasma lipid levels and composition and high muscle lipid levels stimulate oxidative energy metabolism.

We evaluated the effects of genotype (Muscovy, Pekin and their crossbreed hinny and mule ducks) and feeding levels (overfeeding between 12 and 14 weeks of age vs ad libitum feeding) on energy metabolism and lipid deposition in breast muscle of ducks. Samples of breast muscle (Pectoralis major) were collected at 14 weeks of age from 8 birds per group. Overfeeding induced an accumulation of lipids in breast muscle (1.5- to 1.7-fold, depending on genotype) mainly induced by triglyceride deposition. It also induced a considerable increase in the amounts (expressed as g/100 g of tissue) of saturated and mono-unsaturated fatty acids (SFA, MUFA), while the amounts of poly-unsaturated fatty acids (PUFA) remained unchanged in hinny and Muscovy ducks or slightly increased in Pekin and mule ducks. In breast muscle, overfeeding decreased the activity of the main enzymes involved in lipogenesis from glucose (glucose-6-phosphate dehydrogenase, G6PDH, malic enzyme, ME, acetyl CoA carboxylase, ACX). Lipoprotein lipase (LPL) activity in Pectoralis major muscle was also significantly decreased (− 21%). The ability of muscle tissues to catabolize long-chain fatty acids, as assessed by β-hydroxyacyl CoA dehydrogenase (HAD) activity, was increased in Pectoralis major muscle, as was cytochrome- c oxidase (COX) activity. Hybrid and Pekin ducks exhibited higher levels of ACX and LPL activity in Pectoralis major muscle than Muscovy ducks, suggesting a greater ability to synthesise lipids in situ , and to take up circulating lipids. Total lipid content in breast muscle of hybrid and Pekin ducks was higher than in that of Muscovy ducks. In hybrid and Pekin ducks, lipid composition of breast muscle was characterized by higher amounts of triglycerides, SFA and MUFA than in Muscovy ducks. Finally, oxidative metabolism was greater in Pectoralis major muscles of hybrid and Pekin ducks than in Muscovy ducks, suggesting an adaptative strategy of muscle energy metabolism according to lipid level.

This study was conducted to evaluate the effects of genotype (Muscovy, Pekin and their crossbred hinny and mule ducks) and overfeeding (14 days from 12 weeks of age) on the quantity and quality of lipid deposition in adipose and muscle tissue in ducks. Samples of muscles (Pectoralis major and Iliotibialis superficialis) and abdominal fat were collected at 14 weeks of age to determine lipid levels, lipid classes and fatty acid composition. By comparison with the other genotypes, Pekin ducks exhibited higher amounts of abdominal fat and higher lipid levels in muscles (+105 and +120% in P. major and Iliotibialis superficialis, respectively) by comparison with Muscovy ducks. By comparison with other genotypes, Muscovy ducks exhibited the lowest triglyceride and phospholipid levels in muscles and Pekin ducks the highest levels. Muscovy ducks also showed the lowest cholesterol levels in I. Superficialis muscles. Muscovy ducks exhibited the highest levels of saturated fatty acids (SFA) and poly-unsaturated fatty acids (PUFA) in muscle and adipose tissues and the lowest levels of mono-unsaturated fatty acids (MUFA), and Pekin ducks exhibited the reverse. For all these parameters, the crossbred ducks always presented intermediate values. Overfeeding induced an accumulation of lipids in adipose and muscle tissues (1.2- to 1.7- fold, depending on muscle type and genotype). This increase was higher in P. major than in I. superficialis muscles. The increase in the amount of abdominal fat was 1.7- to 3.1-fold, depending on genotype. This increase in lipid levels in peripheral tissues was mainly induced by triglyceride deposition. Finally, it induced a considerable increase in proportions of MUFA (particularly oleic acid) (expressed as % of total fatty acids) at the expense of PUFA (particularly arachidonic acid) and SFA. However, the amounts (expressed as g per 100 g of tissue) of SFA and MUFA increased in tissues while the amounts of PUFA remained unchanged in muscles and decreased in abdominal fat. The quantity and quality of fat deposition in peripheral tissues depends on the liver's ability to synthesise and also to export lipids. lipids / fatty acids / meat / muscles / ducks

We evaluated the effects of genotype (Muscovy, Pekin and their crossbreed hinny and mule ducks) and feeding levels (overfeeding between 12 and 14 weeks of age vs ad libitum feeding) on liver ability for lipogenesis and lipid secretion in ducks. Samples of liver and blood were collected at 14 weeks of age from 8 birds per group. Plasma levels of insulin was considerably increased in overfed ducks (1.9-fold), stimulating the hepatic activity of the main enzymes involved in lipogenesis from glucose (glucokinase, GK, glucose-6-phosphate dehydrogenase, G6PDH, malic enzyme, ME, acetyl CoA carboxylase, ACX), while cytochrome-c oxidase (COX) activity, indicating overall oxidation ability of energy-yielding substrates, remained unchanged. Plasma levels of triglycerides, phospholipids and total cholesterol were therefore increased (1.9, 3.7, 1.6 and 1.6-fold, respectively). Glycaemia also significantly increased (+8%). Pekin ducks exhibited higher levels of GK and G6PDH activity in the liver than Muscovy ducks, suggesting a greater ability to use glucose consistent with their lower glycaemia. Muscovy ducks had greater ACX activity, suggesting greater ability to synthesise lipids. However, plasma lipid levels were much higher in Pekin ducks than in Muscovy ducks, suggesting a greater ability to export lipids from the liver. Values for the different criteria measured in this study were intermediate or similar in hinny and mule ducks to those of parental species. The high values for GK, G6PDH, ME and ACX activity in hybrid ducks enabled them to produce heavy fatty livers with the same chemical and lipid composition as Muscovy ducks and characterised by high amounts of triglycerides (around 96% of total lipids), and saturated and mono-unsaturated fatty acids.

International audience; Standard fast-growing (FG), 'label' slow-growing (SG), and medium growing (MG) chicken crosses were grown until their market ages: 6, 8 and 12 weeks, respectively. They were compared for carcass and muscle traits and meat processing ability. The breasts of 6wk-FG birds contained less protein, more fat and muscle fibres with larger diameters than those of 8wk-MG and 12wk-SG birds. The pH15 and pHu values of breast and thigh muscle were the highest in the 6wk-FG and the lowest in the 12wk-SG. The latter exhibited higher breast drip loss compared with the 6wk-FG. During processing, the highest curing-cooking yields were obtained with the breast and leg meat from 6wk-FG and the lowest with that from the 12wk-SG. As a consequence of their reduced water holding ability, the processed meat from the 12wk-SG exhibited the lowest moisture and the white cured-cooked meat showed the driest texture and the best slice cohesiveness. This study suggests that processing ability and processed product characteristics of breast and leg meats are greatly related to the chicken type of production, with fast growing birds being more adapted to further processing than slow growing ones in terms of profitability.; Qualité technologique de la viande de filet et de cuisse de poulets commerciaux à croissance rapide, intermédiaire ou lente. Des poulets issus d'une souche standard à croissance rapide (FG), d'une souche 'label' à croissance lente (SG), et d'un croisement à croissance intermédiaire (MG) ont été élevés jusqu'à leurs âges respectifs de commercialisation : 6 semaines pour les FG, 8 pour les MG et 12 pour les SG. Nous avons comparé leurs caractéristiques musculaires et la qualité technologique de leurs viandes. Les filets des poulets standards (FG) contenaient moins de protéines, plus de lipides et présentaient des fibres musculaires de diamètre plus large que les deux autres types de poulets (MG et SG). Les pH à 15 minutes et à 24 h post mortem des muscles du filet et de la cuisse étaient les plus élevés chez les animaux standards (FG) et les plus faibles chez les animaux de type 'label' (SG). Les filets de ces derniers présentaient par ailleurs des pertes par exsudation supérieures à celles des filets des poulets standards. Lors de la transformation par saumurage-cuisson, les rendements technologiques les plus élevés ont été obtenus pour la viande de filet et de cuisse des poulets standards et les rendements les plus faibles pour la viande des poulets de type label. Du fait de leur pertes en eau supérieures lors de la transformation par saumurage-cuisson, les produits élaborés à base de viande de poulets labels présentaient les teneurs en eau les plus faibles, et dans le cas des blancs de poulets, la texture en bouche la plus sèche et la meilleure tenue de tranche. Cette étude montre que l'aptitude à la transformation ainsi que la qualité des produits élaborés sont largement influencées par le type de poulet, la viande des poulets de type standard paraissant la plus adaptée, d'un point de vue économique, aux procédés de transformation par saumurage-cuisson.

International audience; We conducted a study to evaluate the effects of genotype (Muscovy, Pekin and their crossbred, hinny and mule) and overfeeding (14 days from 12 weeks of age) on lipid deposition in myofibres and intramuscular adipocytes of breast and thigh muscles of ducks. Birds of the four genotypes were also reared contemporaneously with a growing diet distributed ad libitum. Muscle samples (Pectoralis major and Sartorius) were collected at 14 weeks of age on 8 ducks per treatment. The muscle fibre typing, the total lipid and triglyceride contents in myofibres and the relative surface occupied by adipocytes on the cross-sectional area of the muscles were determined by histological and image analysis. Overfeeding induced a marked increase of body weight but had no significant effect on the muscle weight, the cross-sectional area (CSA) of myofibres and the muscle typology. In muscles, overfeeding induced a large accumulation of lipids, mainly in adipocytes whose relative surface increased 1.5 fold in P. major and 2.1 fold in Sartorius and an increase in triglyceride content of fast twitch oxydo-glycolytic and glycolytic fibres in P. major only (+ 37 and + 16% respectively). Genotype had no significant effect on the muscle typology. By comparison with the other genotypes, Muscovy ducks exhibited the highest body weight, the highest muscle weight which could partly be explained by the highest fibre CSA and the lowest intramuscular fat content in adipocytes and myofibres (only fast twitch oxydo-glycolytic fibres in P. major). We observed the reverse situation for the Pekin ducks. The crossbred ducks always presented intermediate values except for body weight.