Is the hepatic metabolism of glucose and linoleic acid influenced by species in overfed ducks?

There are genetic differences in the hepatic glucose and linoleic acid metabolisms between Muscovy and Pekin ducks ad libitum-fed. To understand the effect of overfeeding on the hepatic metabolisms in these two species of ducks, we compared the different pathways of glucose and linoleic acid reaching the liver of Muscovy (Cairina moschata) (n = 6) and Pekin (Anas platyrhynchos) (n = 6) ducks overfed for 1 week and sacrificed 2–4 h after their last meal by using the ex vivo method of liver slices incubated for 16 h with [U-¹⁴C]-glucose, [1-¹⁴C]-linoleic acid and [³⁵S]-methionine added to the survival medium. The glucose was the main precursor of triacylglycerol synthesis in the liver of these two species and its hepatic metabolism was similar between species. The hepatic uptake of linoleic acid was 1.7-fold higher (P = 0.020) in the Muscovy duck than in the Pekin duck leading to a 1.9-fold higher (P = 0.017) esterification of this fatty acid in the liver of the Muscovy duck than in that of the Pekin duck. Finally, both species after 1 week of overfeeding exhibited the same capacity to secrete VLDL remaining insufficient to avoid hepatic steatosis.     

Effect of feed consumption levels on growth performance and carcass composition during the force-feeding period in foie gras production of male Mule ducks

In order to avoid excess feed consumption during the force-feeding period in foie gras production, a dose-response experiment with seven feed consumption levels (450, 540, 630, 720, 810, 900, 990 g/day per bird) was conducted to evaluate the effects of feed consumption levels on growth performance and carcass composition of male Mule ducks from 91 to 102 days of age. One-day-old Mule ducklings (sterile and artificial hybrid of male Albatre Muscovy duck and female Pekin duck were fed a two-phase commercial diets for ad libitum intake from hatching to 91 days of age, followed by graded feeding levels of a corn diet by force-feeding from 91 to 102 days of age. Fifty-six 91-day-old male Mule ducks with similar BW were randomly assigned to seven treatments, with eight birds per treatment. Birds were housed in individual pens. At 102 days of age, final BW was measured and BW gain and feed conversion ratio of ducks from each treatment were calculated from day 91 to 102, and then all ducks were slaughtered to evaluate the yields of skin with subcutaneous fat, abdominal fat, breast meat (including pectoralis major and pectoralis minor), leg meat (including thigh and drum stick), and liver. Significant differences in BW gain, total liver weight and liver relative weight were observed among the treatments (P<0.001). According to the broken-line regression analysis, the optimal feed consumption levels of male Mule ducks from 91 to 102 days of age for maximum BW gain, total liver weight and liver relative weight were 217, 227 and 216 g feed/kg BW^0.75·per day, respectively.     

Genome-wide association studies demonstrate that TASP1 contributes to increased muscle fiber diameter

Muscle fiber diameter is an economically important trait because it affects meat yield and quality. However, the genetic basis underlying muscle fiber diameter has not been determined. In this study, we collected THREE muscular histological phenotypes in 479 ducks from an F₂ segregating population generated by mallard × Pekin duck crosses. We performed genome-wide association studies (GWAS) and identified a quantitative trait locus (QTL) significantly associated with muscle fiber diameter on chromosome 3. Then, we discovered the selection signatures using the fixation index among 40 mallards and 30 Pekin ducks in this QTL region. Furthermore, we characterized the recombination event in this QTL region and identified a 6-kb block located on TASP1 that was significantly associated with muscle fiber diameter. Finally, five SNPs were screened as potential causative mutations within the 6-kb block. In conclusion, we demonstrated that TASP1 contributes to an increase in muscle fiber diameter, which helps to characterize muscle development and contributes to the genetic improvement of meat yield and quality in livestock.Subject terms: Genome-wide association studies, Gene expression     

Identification and characterization of genes related to the development of breast muscles in Pekin duck

Pekin Duck is world-famous for its fast growth, but its breast muscle development is later and breast muscle content is lower compared with other muscular ducks. Therefore, it is very important to discover the genetic mechanism between breast muscle development and relative gene expression in Pekin duck. In current study, the genes which have relationships with breast muscle development were identified by suppression subtractive hybridization. A total of 403 positive clones were sequenced and 257 unigenes were obtained. The expression of 23 genes were analyzed in the breast muscle of 2-, 4-, 6-, 8- week old Pekin ducks. The results showed that unknown clone A233, C83 and C99 showed descending tendency as age increased; KBTBD10, HSPA8, MYL1, ZFP622, MARCH4, Nexilin, FABP4 and MUSTN1 had high expression levels at 6 weeks old; WAC, NT5C3, HSP90AA1, MRPL33, KLF6, TSNAX, CDC42EP3, HSPA4, TRAK1, NR2F2, HAUS1 and IGF1 had high expression levels at 8 weeks and showed ascending tendency as age increased. Expression of these 23 genes were also analyzed in breast muscle, leg muscle, heart, kidney, liver, muscular stomach and sebum cutaneum in 4-8-week old Pekin duck and results showed that most of these genes had high expression in breast muscle, leg muscle and heart.     

鸡肉肌苷酸和肌内脂肪等肉品风味性状遗传参数的估计

对鸡肉肌苷酸（Inosine-5¢-Monophosphate,IMP）和肌内脂肪（Intramuscular fat,IMF）等重要肉品风味性状的遗传参数进行了估计,旨在从遗传理论上为确定鸡肉风味品质性状的选育方法提供依据。采用MTDFREML方法对1069只90日龄北京油鸡公鸡的相关性状的遗传力和遗传相关进行了估计,结果表明,胸肌IMP和IMF含量属中等偏低遗传力性状（h2=0.23,0.10）,腹脂重(AFW)、胸肌重(BMY)、胸肌率(BMR)、腿肌重(LMY)、体重(BW)、鸡冠重(CW)和鸡冠率(CWP)的遗传力较高（h2=0.56～0.79）,腹脂率(AFP)、腿肌率(LMR)、睾丸重(TW)和睾丸率(TWP)等性状的遗传力分别为0.24、0.32、0.39和0.35。IMP与胸肌率、腿肌率和尾脂厚呈较低度的表型正相关,与其他性状无明显表型相关;IMF与体重、腹脂率、尾脂厚和脂带宽呈一定程度的表型正相关（rP=0.11～0.33）。IMP与体重和鸡冠率呈中等以上程度的遗传负相关（rA=-0.38,-0.62）,与胸肌率呈较高水平的遗传正相关（rA=0.57）;IMF与体重和腹脂重则呈高度遗传正相关（rA=0.7 5,0.66）,与腹脂率和鸡冠率呈中等水平遗传正相关（rA=0.32,0.40）;IMP与IMF之间呈中低水平的遗传正相关（rA =0.27）。据此推断,可以利用家系法对IMP和IMF含量进行选择提高。     

Meat quality traits and fatty acid composition of breast muscles from ducks fed with yellow lupin

The protein sources in feed have a huge impact on good-quality and -quantity meat traits. Yellow lupin (YL) seeds have a similar level of protein as soybean meal (SBM). The most popular is SBM that is genetically modified (GMO). During this age, the consumer market requires non-GMO products. Yellow lupin used as a high-protein substitute for SBM in feed has an effect on the quality of meat from broiler ducks. The aim of the study was to analyse and compare meat quality traits in breast and leg muscles as well as fatty acid (FA) composition in breast muscles from ducks fed mixtures containing YL as an alternative to SBM. Two hundred 1-day-old Cherry Valley ducks were kept in pens on litter in two equal dietary groups, four replications with 25 birds per group. The control group (1) received balanced feed containing SBM. The treatment group (2) received balanced feed containing YL. The feed provided to both groups contained 55% of concentrate and 45% of wheat. Birds received feed and water ad libitum and were reared for 8 weeks. After that, 16 ducks (eight from each group) of BW close to the mean for the whole group were slaughtered. Plucked and gutted carcasses were analysed in a laboratory for quality parameters. Meat was analysed for pH, colour, water-holding capacity and drip loss. Samples of breast muscles were analysed for the content of cholesterol, collagen, intramuscular fat and FA composition. The proposed feed mixture containing YL had no impact on meat traits, content of muscles or fat in duck carcasses (P > 0.05). The values of lightness (L*) and yellowness (b*) and collagen content in breast muscles were significantly higher (P < 0.05) in group 2 (YL). A lower ability to retain water, that is, higher water-holding capacity (percentage of water lost from meat) (P < 0.05), was found for leg muscles from group 2 (YL). The content of C16:0, C18:0, C20:4 n-6, C22:4 n-6, C22:5 n-3, total content of saturated fatty acids (SFA), values of atherogenic index and thrombogenic index were significantly lower (P < 0.05) in group 2 (YL) than in group 1 (SBM). The content of C18:2 n-6 and the polyunsaturated fatty acids-to-SFA ratio (P/S) were significantly higher (P < 0.05) in ducks fed the diet with the inclusion of YL. Diets with YL could be proposed as a partial substitute for SBM in duck-rearing.     

The single nucleotide polymorphisms of the chicken myostatin gene are associated with skeletal muscle and adipose growth

Myostatin, a new member of the TGF-ß superfamily, is predominantly expressed in skeletal muscle cells and functions as a negative regulator of skeletal muscle growth in animals. Recently, we have reported three single nucleotide polymorphisms (SNPs) in the chicken myostatin gene. Herein, we investigate the association of those SNPs with the production traits in a F₂ chicken line derived from Broilers crossing to Silky with the least square analysis. The results show that the BB and AA genotypes are strongly associated with abdominal fat weight (AFW), abdominal fat percentage (AFP), and birth weight (BW) (P < 0.05). Breast muscle percentage (BMP) of the AA type is higher than that of the AB type. The breast muscle weight and breast muscle percentages of F₂ individuals have significant difference between CC and DD genotypes (P < 0.05). Breast muscle weight (BMW) of EF birds is higher than that of EE birds (P < 0.05). In this report, we present the first genetic evidence to show that chicken myostatin not only plays an important role in controlling skeletal muscle growth and differentiation, but also may be involved in regulation of adipose growth in chicken.     

Insulin effect on lipogenesis and fat distribution in three genotypes of ducks during overfeeding

In waterfowl, the response to overfeeding differs from one genotype to the other. Pekin ducks generally store lipids in the peripheral tissues while Muscovy and mule ducks promote hepatic lipid storage. A possible reason for these various susceptibilities to hepatic steatosis could be a difference in insulin sensitivity. We suggest a resistance to insulin in Pekin ducks. In the present work we investigate the action of insulin on glucose and lipid metabolisms for the three overfed genotypes. Regardless of the kind of genotype, all ducks appear to be sensitive to insulin: their glycemia is lower when the animals are treated with insulin. Insulin-treated Muscovy and Pekin ducks present a lower increase in total body weight (? 16.5% for Muscovy; ? 8.3% for Pekin); and a significantly lower liver weight than the controls (? 9.6% and ? 18.3%). The percentage of total lipids in the liver is higher in the controls than in the insulin-treated Pekin and mule ducks (respectively ? 40.4% and ? 34.7%), which means a decreased hepatic lipogenesis. Pekin ducks present a higher pectoral muscle weight when the individuals are insulin-treated (+ 9.7%). Lipoprotein lipase (LPL) activity appears to be significantly higher in insulin-treated Pekin and Muscovy ducks (1.39 and 3.38 times greater than controls). Insulin-treated mule ducks present a decrease of muscle and abdominal lipid storage compared to controls (? 11.6% and ? 13.8%). In this experiment, exogenous insulin has induced an increase of lipid oxidation and has led to a less favorable use and storage of dietary glucose. The hypothesis of insulin-resistance of Pekin ducks is not verified.     

Influence of lipoprotein-lipase activity on plasma triacylglycerol concentration and lipid storage in three genotypes of ducks

The lipoprotein-lipase (LPL) hydrolyses the triacylglycerols (TG) secreted by the liver and, thus, allows the storage of lipids onto the extrahepatic tissues. The LPL activity has been studied by injection of LPL antibodies in three genotypes of ducks (Muscovy (Cairina moschat), Pekin (Anas plathyrhynchos) and Mule (hybrids of male Muscovy ducks and female Pekin ducks)) under overfeeding condition. The results show a similar weight gain between injected and control animals. A higher liver steatosis is observed in Mule ducks (616 ± 18 g; 8.79% of body mass (BW)) and Muscovy ducks (514 ± 13 g; 7.05% BW) compared to Pekin ducks (353 ± 21 g; 5.89% BW, p < 0.05). Pekin ducks showed a much marked extrahepatic fattening of abdominal and subcutaneous adipose tissues. The LPL activity was evaluated by comparing the evolution of the plasma TG concentrations after injections of saline (control animals) or injections of specific LPL-antibodies. Inhibition of LPL activity performed by intravenous injections of LPL-antibodies showed a spectacular increase in the plasma TG concentrations in the three genotypes. That increase was considerably higher in Pekin ducks (98 ± 10 g/L) compared to Muscovy ducks (35 ± 2 g/L, p < 0.01) and Mule ducks (30 ± 4 g/L, p < 0.01). Those data suggest that a high export of lipids synthesized in liver and a high LPL activity occur in overfed Pekin ducks, which can favour the extrahepatic fattening to the detriment of the liver steatosis, and conversely in overfed Muscovy and Mule ducks.     

Genome‐wide association studies reveal genetic loci associated with plasma cholinesterase activity in ducks

Plasma cholinesterase (PCHE) activity is an important auxiliary test in human clinical medicine. It can distinguish liver diseases from non‐liver diseases and help detect organophosphorus poisoning. Animal experiments have confirmed that PCHE activity is associated with obesity and hypertension and changes with physiological changes in an animal's body. The objective of this study was to locate the genetic loci responsible for PCHE activity variation in ducks. PCHE activity of Pekin duck × mallard F2 ducks at 3 and 8 weeks of age were analyzed, and genome‐wide association studies were conducted. A region of about 1.5 Mb (21.8–23.3 Mb) on duck chromosome 9 was found to be associated with PCHE activity at both 3 and 8 weeks of age. The top SNP, g.22643979C>T in the butyrylcholinesterase (BCHE) gene, was most highly associated with PCHE activity at 3 weeks (?logP = 21.45) and 8 weeks (?logP = 27.60) of age. For the top SNP, the strong associations of CC and CT genotypes with low PCHE activity and the TT genotype with high PCHE activity indicates the dominant inheritance of low PCHE activity. Problems with block inheritance or linkage exist in this region. This study supports that BCHE is a functional gene for determining PCHE levels in ducks and that the genetic variations around this gene can cause phenotypic variations of PCHE activity.     

Effects of heat stress on antioxidant defense system,inflammatory injury,and heat shock proteins of Muscovy and Pekin ducks: evidence for differential thermal sensitivities

Rising temperatures are severely affecting the mortality, laying performance, and meat quality of duck. Our aim was to investigate the effect of acute heat stress on the expression of heat shock proteins (HSPs: HSP90, 70, 60, 40, and 10) and inflammatory factors (nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2)) and antioxidant enzyme activity (superoxide dismutase (SOD), malondialdehybe (MDA), catalase (CAT), total antioxidant capacity (T-AOC)) in livers of ducks and to compare the thermal tolerance of Pekin and Muscovy ducks exposed to acute heat stress. Ducks were exposed to heat at 39 ± 0.5 °C for 1 h and then returned to 20 °C for 1 h followed by a 3-h recovery period. The liver and other tissues were collected from each individual for analysis. The mRNA levels of HSPs (70, 60, and 40) increased in both species, except for HSP10, which was upregulated in Muscovy ducks and had no difference in Pekin ducks after heat stress. Simultaneously, the mRNA level of HSP90 decreased in the stress group in both species. Morphological analysis indicated that heat stress induced tissue injury in both species, and the liver of Pekin ducks was severely damaged. The activities of several antioxidant enzymes increased in Muscovy duck liver, but decreased in Pekin duck. The mRNA levels of inflammatory factors were increased after heat stress in both duck species. These results suggested that heat stress could influence HSPs, inflammatory factors expression, and the activities of antioxidant enzymes. Moreover, the differential response to heat stress indicated that the Muscovy duck has a better thermal tolerance than does the Pekin duck.     

Meat eating and nutritional quality of lambs sired by high and low muscle density rams

Intramuscular fat (IMF) content affects eating and nutritional quality of lamb meat. Muscle density measured by computer tomography is an in vivo proxy measure of IMF content that affects eating and nutritional quality of lamb meat. Lambs sired by high muscle density (HMD) or low muscle density (LMD) rams, selected for slaughter on commercial criteria were measured for meat quality and nutritional traits. A restricted maximum likelihood model was used to compare lamb traits. Additionally, regression analysis of sire estimated breeding value (EBV) for muscle density was performed for each meat quality trait. Muscle density EBV had a negative regression with IMF content (P < 0.001). For each unit increase in muscle density EBV, there was a significant decrease in loin (− 1.69 mg/100 g fresh weight) and topside IMF (− 0.03 mg/100 g fresh weight). Muscle density EBV had a negative regression with grouped saturated and monounsaturated fatty acids concentration (and monounsaturated proportion P < 0.001). Muscle density EBV had a negative regression with loin sensory traits tenderness, juiciness and overall liking and many novel tenderness sensory traits measured (P < 0.05). Selecting for LMD EBV increased IMF content and favourable meat eating quality traits. In contrast, sire muscle density EBV had a positive regression with loin polyunsaturated:saturated fat ratio and grouped polyunsaturated proportion traits (including total polyunsaturated proportion, total omega-6 (n-6) and total omega-3 (n-3) fatty acids (P < 0.001). This is explained by the fact that as sire muscle density EBV increases, polyunsaturated fatty acid proportion increases and the proportion of saturated and monounsaturated fatty acid content decreases. Muscle density EBV had a positive regression with shear force and the novel toughness sensory traits (P < 0.05). Selection for HMD EBV's increased shear force and toughness traits, which is unfavourable for the consumer. Low muscle density sired meat had higher meat colour traits chroma/saturation (+ 0.64, SD 2.30, P = 0.012), redness (+ 0.52, SD 1.91, P = 0.012) and yellowness (+ 0.31, SD 1.49, P = 0.08) compared to HMD sired meat. Selection for LMD could be used within a breeding programme to increase IMF content and enhance both meat colour and improve eating quality parameters.     

The rearing system modulates biochemical and histological differences in loin and ham muscles between Basque and Large White pigs

Conventional pork production, based on highly selected breeds for growth efficiency and carcass leanness, is generally considered to decrease pork quality. In contrast, non-selected breeds produced in extensive systems are associated with high pork quality, which is generally attributed to higher intramuscular fat (IMF) content and less glycolytic muscle metabolism. The present study aimed to determine biochemical, histological and quality traits of loin and ham muscles of pigs from selected Large White (LW) and local French, non-selected Basque (B) breeds. Pigs were reared in a conventional indoor (C, slatted floor), alternative (A, indoor bedding and outdoor area) or extensive system (E, free range, B pigs only). A total of 100 castrated males were produced in 2 replicates, each containing 5 groups of 10 pigs based on breed and system: LWC, LWA, BC, BA and BE. The glycolytic longissimus muscle (LM) and semimembranosus muscle (SM), and the deep red (RSTM) and superficial white (WSTM) portions of semitendinosus muscle (STM) were studied at 145 kg BW. Overall, breed induced stronger effects on muscle traits than the rearing system, among which the E system induced greater changes. The lower muscle growth of B pigs was associated with fewer muscle fibers and a smaller cross-sectional area (CSA) of glycolytic fibers (P < 0.01). The SM was less glycolytic and more oxidative in B than in LW pigs (P < 0.001). The WSTM followed a similar trend, with a larger relative area of type I fibers in B pigs. In contrast, the LM and RSTM were more oxidative in LW pigs. B pigs had higher IMF content and ultimate pH in all muscles, along with lower glycolytic potential, less light and redder meat in the LM and SM (P < 0.001). Compared to the C system, the A system induced only a shift towards a more oxidative metabolism in the LM and a smaller fiber CSA in the RSTM of LW pigs (P < 0.05), without influencing pork quality traits. Compared to BC pigs, BE pigs had a more oxidative and less glycolytic muscle metabolism, along with higher ultimate pH, lower lightness and redder meat (P < 0.01), but similar IMF content. Overall, results indicate that influences of breed and rearing system on muscle properties depend on muscle type, and that IMF content and fiber-type composition are unrelated traits that can be modified independently by genetic or rearing factors.     

Quantitative trait loci analysis of a Duroc commercial population highlights differences in the genetic determination of meat quality traits at two different muscles

We performed a whole‐genome scan with 110 informative microsatellites in a commercial Duroc population for which growth, fatness, carcass and meat quality phenotypes were available. Importantly, meat quality traits were recorded in two different muscles, that is, gluteus medius (GM) and longissimus thoracis et lumborum (LTL), to find out whether these traits are determined by muscle‐specific genetic factors. At the whole‐population level, three genome‐wide QTL were identified for carcass weight (SSC7, 60 cM), meat redness (SSC13, 84 cM) and yellowness (SSC15, 108 cM). Within‐family analyses allowed us to detect genome‐wide significant QTL for muscle loin depth between the 3rd and 4th ribs (SSC15, 54 cM), backfat thickness (BFT) in vivo (SSC10, 58 cM), ham weight (SSC9, 69 cM), carcass weight (SSC7, 60 cM; SSC9, 68 cM), BFT on the last rib (SSC11, 48 cM) and GM redness (SSC8, 85 cM; SSC13, 84 cM). Interestingly, there was low positional concordance between meat quality QTL maps obtained for GM and LTL. As a matter of fact, the three genome‐wide significant QTL for colour traits (SSC8, SSC13 and SSC15) that we detected in our study were all GM specific. This result suggests that QTL effects might be modulated to a certain extent by genetic and environmental factors linked to muscle function and anatomical location.     

Dietary arginine supplementation enhances antioxidative capacity and improves meat quality of finishing pigs

The present study was conducted to test the hypothesis that dietary arginine supplementation may improve meat quality of finishing pigs. Beginning at ~60 kg body weight, pigs were fed a corn- and soybean meal-based diet supplemented with 0, 0.5 or 1% l-arginine until they reached a body weight of ~110 kg. On the last day of the experiment, pigs were food-deprived for 16 h before blood samples were obtained for analysis of amino acids, insulin, and other metabolites. Immediately thereafter, pigs were slaughtered for determination of carcass composition, muscle biochemical parameters, and meat quality. The result showed that arginine did not affect pig growth performance or carcass traits. However, 1% arginine decreased drip loss of pork muscle at 48 h postmortem, while increasing intramuscular fat content (P < 0.05). Supplementing 0.5 or 1% arginine to the diet increased arginine concentration and decreased cortisol level in serum, while enhancing antioxidative capacity and glutathione peroxidase activity in serum (P < 0.05). Additionally, 1% arginine increased antioxidative capacity in skeletal muscle (P < 0.05). Furthermore, 0.5 or 1% arginine decreased the cortisol receptor mRNA level in muscle (P < 0.05). Collectively, these results indicate that supplemental arginine improved meat quality and attenuated oxidative stress of finishing pigs.     

Genetic mapping of quantitative trait loci affecting carcass and meat quality traits in Beijing ducks (Anas platyrhynchos)

Quantitative trait loci (QTL) for carcass and meat quality traits were detected in a sample of 224 progeny from four males in line VI and 12 females in line V of Beijing ducks. These lines were selected for high body weight at 42 days of age (line VI) or high egg production at 360 days of age (line V). Traits were weights of the carcass, head, neck, shanks, wings, legs, thighs, breast, heart, liver, crop, gizzard, abdominal fat (AFW) and skin fat, as well as fat thickness in the tail, and pH value, shear force, drip loss (DL) (%) and cooking loss (CL) (%) of the breast. Using a half-sib analysis with a multiple QTL model, linkage between the carcass and meat quality traits and 95 microsatellite markers was investigated. Eight genome-wide significant QTL for weight of crop, skin fat, liver, neck, shanks, wings, DL were detected on linkage groups CAU4 and CAU6. One genome-wide suggestive QTL and one chromosome-wide significant QTL for weight of breast were found on CAU1 and CAU4 respectively. Fifteen chromosome-wide suggestive QTL influencing weight of AFW, breast, crop, heart, carcass, thighs, liver, shanks, gizzard, fat thickness in tail, DL (%) and CL (%) were mapped on CAU2, CAU4, CAU5, CAU6, CAU7, CAU10 and CAU13. In addition, two linked QTL for weight of liver and DL (%) were located on CAU2 and CAU7 respectively. The detection of QTL in ducks is a step towards identification of genes influencing these traits and their use for genetic improvement in this species.     

The single nucleotide polymorphisms of the chicken myostatin gene are associated with skeletal muscle and adipose growth

Myostatin, a new member of the TGF-p superfamily, is predominantly expressed in skeletal muscle cells and functions as a negative regulator of skeletal muscle growth in animals. Recently, we have reported three single nucleotide polymorphisms (SNPs) in the chicken my-ostatin gene. Herein, we investigate the association of those SNPs with the production traits in a F2 chicken line derived from Broilers crossing to Silky with the least square analysis. The results show that the BB and AA genotypes are strongly associated with abdominal fat weight (AFW), abdominal fat percentage (AFP), and birth weight (BW) (P < 0.05). Breast muscle percentage (BMP) of the AA type is higher than that of the AB type. The breast muscle weight and breast muscle percentages of F2 individuals have significant difference between CC and DD genotypes (P< 0.05). Breast muscle weight (BMW) of EF birds is higher than that of EE birds (P< 0.05). In this report, we present the first genetic evidence to show that chicken myostatin not o