Development of breast muscle and meat quality in Arbor Acres broilers, Jingxing 100 crossbred chickens and Beijing fatty chickens

Physico-chemical properties of natural actomyosin from breast and thigh meat of fast- and slow-growing chicken: a comparative study

Physico-chemical behaviors of natural actomyosin (NAM) from slow-growing Korat chicken (KC) breast and thigh at low (0.2 M) and high (0.6 M) NaCl concentrations were evaluated and compared to those from their corresponding muscles in fast-growing broiler chicken (BC). NAM from KC breast and thigh meat showed higher solubility than their corresponding in BC (p < 0.05). Breast NAM from both chickens showed the highest solubility at 0.4 M NaCl, while thigh NAMs showed the highest solubility at 0.8 M (p < 0.05). SDS-PAGE revealed higher protein extractability for breast NAMs at low ionic strength, regardless of breed and structural protein, particularly troponin, appeared to vary within muscle and breed. NAM from KC showed higher Ca2+-ATPase activity, surface hydrophobicity, but lower total sulfhydryl groups content (p < 0.05). Particle size of NAM solutions varied with ionic strength, in which KC-NAM showed larger size than at lower ionic strength, while BC-NAM appeared to be greater at higher ionic strength. NAM from KC breast showed higher thermal stability as higher initial (T0) and maximum (Tmax) denaturation temperatures of 48.4 and 54.8°C, respectively, recorded by microdifferential scanning calorimetry. The KC-NAM, particularly from breast, exhibited lower turbidity within 40-50°C, while turbidity increased in BC samples at low ionic strength when heated at 60°C. Dynamic rheology revealed different storage modulus (G') depending on breed, muscle type and ionic strength. Breast BC-NAM formed more elastic gel with higher end point G' at 80°C (Ge'; p < 0.05). Ionic strength showed reverse effects on different breeds as a stronger Ge' value achieved in KC- NAM at low ionic strength, while high ionic strength induced stronger gel in BC samples. Aggregation of NAMs began at lower temperatures at higher ionic strength and actin dissociation probably occurred in breast NAM from KC as observed by a drop of G' at around 70°C. The results of this study revealed differences between NAM of the two breeds, by which higher gel elasticity are expected in KC at lower ionic strength.

Research note: differential heterosis of spent laying hens' carcass characteristics and meat quality in reciprocal crosses between White Leghorn and Beijing-You chickens

Hybridization is used extensively in commercial layer production. However, heterosis for carcass performance and meat quality of spent laying hens remains unclear, especially under the trend of extended laying cycles. In this study, indigenous Beijing-You chickens (Y) and elite White Leghorn layers (W) were selected to generate purebreds (WW and YY) and reciprocal crosses (WY and YW). Data on traits including carcass compositions, meat quality, and main nutrients for breast muscle were collected when chickens were fed to 100 wk of age. Results showed that body weight (BW) and dressed weight for WY and YW with positive heterosis were significantly higher than WW (P < 0.05). YW had the heaviest breast and thigh of 232.28 g and 278.48 g, respectively. The abdominal fat weight for WY and YW were greatly higher than that for WW (P > 0.05). The yields of carcass compositions, including the dressed yield, half eviscerated yield, eviscerated yield, breast yield and thigh yield, did not differ among the four genetic groups (P > 0.05), except for the yield of abdominal fat. The largest heterosis differences appeared in breast weight (12.26% in YW vs. -0.46% in WY) and abdominal fat yield (15.26% in YW vs. 24.55% in WY). Although BW for crossbreds were similar, the specific parts of the carcass between them were different. For meat quality, WY had negative heterosis (P < 0.05) with the lowest lightness and yellowness, whereas YW had the completely opposite trend. Neither pH1h nor pH24h values had differences among purebreds and reciprocal crossbreds (P > 0.05). The drip loss and cooking loss were 4.01%-4.77% and 15.59%-21.31% respectively among the four genetic groups. The main nutrients of breast, including moisture, crude protein, intramuscular fat and unsaturated fatty acid, did not differ for purebreds and crossbreds (P > 0.05), except for saturated fatty acid. In general, the crossbreds even at the later laying period still showed divergent heterosis on carcass performance and meat characteristics. In view of the heterosis, Beijing-You chickens can be used as the sire line in the crossbreeding to improve carcass compositions of spent hens.

Analysis of carcass traits, meat quality, amino acid and fatty acid profiles between different duck lines

To investigate the effect of genetic selection on meat quality in ducks, twenty of each fast growth ducks (LCA) and slow growth ducks (LCC) selected from F6 generation of Cherry Valley ducks (♂) x Liancheng white ducks (♀) were analyzed for carcass characteristics, meat quality (physicochemical and textural characteristics), amino acid and fatty acid profiles at 7 wk. Results showed that live body weight, slaughter weight, eviscerated yield and abdominal fat percentage of LCA were significantly higher than those in LCC ducks (P < 0.01). Moreover, the average area and diameter of myofiber were larger in LCA than LCC ducks (P < 0.01). The breast and thigh muscles of LCA exhibited significantly lower water holding capacity and thermal loss compared with LCC ducks (P < 0.01). In addition, the content of nonessential amino acids (Glu, Asp, and Arg) in breast muscles and Asp, Ser, Thr, and Met in thigh muscles was higher in LCC than LCA ducks (P < 0.05). The proportion of polyunsaturated fatty acids (PUFA) in breast muscles of LCC was higher than LCA ducks (P < 0.05). However, the content of saturated fatty acids (SFA) in breast and thigh muscles of LCA was higher compared with LCC ducks (P < 0.05). The proportion of monounsaturated fatty acids (MUFA) in thigh muscles was significantly higher in LCC compared with LCA ducks (P < 0.01). Finally, multiple traits were evaluated by applying principal component analysis (PCA) and the results indicated that PUFA and SFA in breast muscles of LCA played important roles in meat quality, followed by Warner-Bratzler shear force (WBSF) and MUFA. However, water holding capacity (WHC) had a dominant effect in meat quality of thigh muscles in both LCA and LCC ducks.

A large-scale comparison of the meat quality characteristics of different chicken breeds in South China

Meat quality traits are essential for producing high-quality broilers, but the genetic improvement has been limited by the complexity of measurement methods and the numerous traits involved. To systematically understand the meat quality characteristics of different broiler breeds, this study collected data on slaughter performance, skin color, fat deposition, and meat quality traits of 434 broilers from 12 different breeds in South China. The results showed that there was no significant difference in the live weight and slaughter weight of various broiler breeds at their respective market ages. Commercial broiler breeds such as Xiaobai and Huangma chickens had higher breast muscle and leg muscle rates. The skin and abdominal fat of Huangma chickens cultivated in the consumer market in South China exhibited significantly higher levels of yellowness compared to other varieties. Concerning fat traits, we observed that Wenchang chickens exhibited a strong ability to fat deposition, while the younger breeds showed lower fat deposition. Additionally, there were significant positive correlations found among different traits, including traits related to weight, traits related to fat, and skin color of different parts. Hierarchical clustering analysis revealed that fast-growing and large broiler Xiaobai chickens formed a distinct cluster based on carcass characteristics, skin color, and meat quality traits. Principal component analysis (PCA) was used to extract multiple principal components as substitutes for complex meat quality indicators, establishing a chicken meat quality evaluation model to differentiate between different breeds of chickens. At the same time, we identified 46, 22, and 20 SNP loci and their adjacent genes that were significantly associated with muscle mass traits, fat deposition, and skin color through genome-wide association studies (GWAS). The above results are helpful for systematically understanding the differences and characteristics of meat quality traits among different breeds.

Growth performance, meat quality, strength of jejunum and leg bones of both sexes Cherry Valley ducks fed with zeolite

Zeolite, as a natural mineral, could be a good additive for ducks, in line with pro-environmental trends. The study aimed to evaluate zeolite additives in feed for broiler ducks of both sexes on production results, meat quality, and the strength of the jejunum, tibia, and femur. The experiment used 200 Cherry Valley ducks, divided into a control group of males (CM) and females (CF) and an experimental group of males (ZM) and females (ZF). In the control groups, a commercial diet was used. In the experimental groups, 1% zeolite was added. The ZM group demonstrated higher body weight and weight gain than the CM group. Zeolite reduced the feed conversion ratio. A higher liver weight was found in the experimental group (ZM). Notably, zeolite influenced the weight of male pectoral muscles. Higher water loss in the pectoral muscles and higher protein content in the leg muscles were found in the same group. Females had a higher weight of neck and wings with skin. Female pectoral muscles had lower protein and water content. Zeolite in feed at a 1% level for broiler ducks could be recommended as a natural additive that positively affects the ducks' production results concerning good quality meat.

Developmental Characteristics of Skeletal Muscle during the Embryonic Stage in Chinese Yellow Quail (Coturnix japonica)

The quail is an important research model, and the demand for quail meat has been increasing in recent years; therefore, it is worthwhile investigating the development of embryonic skeletal muscle and the expression patterns of regulatory genes. In this study, the expression of MyoD and Pax7 in the breast muscle (m. pectoralis major) and leg muscle (m. biceps femoris) of quail embryos on days 10 through 17 were determined using qRT-PCR. Paraffin sections of embryonic muscle were analyzed to characterize changes over time. Results showed that MyoD and Pax7 were expressed in both breast and leg muscles and played a significant role in embryonic muscle development. Compared to breast muscle, leg muscle grew faster and had greater weight and myofiber size. The findings suggested that embryonic day 12 (E12) may be a key point for muscle development. Correlation analysis showed that MyoD expression was significantly negatively correlated with muscle and embryo weight, whereas Pax7 gene expression had no significant correlation with these characteristics. These fundamental results provide a theoretical basis for understanding the characteristics and transition points of skeletal muscle development in quail embryos and an important reference for farmers raising quail from eggs.

Integrative metabolomic and transcriptomic analysis reveals difference in glucose and lipid metabolism in the longissimus muscle of Luchuan and Duroc pigs

Luchuan pig, an obese indigenous Chinese porcine breed, has a desirable meat quality and reproductive capacity. Duroc, a traditional western breed, shows a faster growth rate, high feed efficiency and high lean meat rate. Given the unique features these two porcine breeds have, it is of interest to investigate the underlying molecular mechanisms behind their distinctive nature. In this study, the metabolic and transcriptomic profiles of longissimus dorsi muscle from Duroc and Luchuan pigs were compared. A total of 609 metabolites were identified, 77 of which were significantly decreased in Luchuan compared to Duroc, and 71 of which were significantly elevated. Most differentially accumulated metabolites (DAMs) upregulated in Luchuan were glycerophospholipids, fatty acids, oxidized lipids, alcohols, and amines, while metabolites downregulated in Luchuan were mostly amino acids, organic acids and nucleic acids, bile acids and hormones. From our RNA-sequencing (RNA-seq) data we identified a total of 3638 differentially expressed genes (DEGs), 1802 upregulated and 1836 downregulated in Luchuan skeletal muscle compared to Duroc. Combined multivariate and pathway enrichment analyses of metabolome and transcriptome results revealed that many of the DEGs and DAMs are associated with critical energy metabolic pathways, especially those related to glucose and lipid metabolism. We examined the expression of important DEGs in two pathways, AMP-activated protein kinase (AMPK) signaling pathway and fructose and mannose metabolism, using Real-Time Quantitative Reverse Transcription PCR (qRT-PCR). Genes related to glucose uptake, glycolysis, glycogen synthesis, fatty acid synthesis (PFKFB1, PFKFB4, MPI, TPI1, GYS1, SLC2A4, FASN, IRS1, ULK1) are more activated in Luchuan, while genes related to fatty acid oxidation, cholesterol synthesis (CPT1A, HMGCR, FOXO3) are more suppressed. Energy utilization can be a decisive factor to the distinctive metabolic, physiological and nutritional characteristics in skeletal muscle of the two breeds we studied. Our research may facilitate future porcine breeding projects and can be used to reveal the potential molecular basis of differences in complex traits between various breeds.

Determination of metabolisable and net energy contents of corn fed to Arbor Acres broilers and Beijing You chickens

This study was done to compare the energy and nutrient utilisation of corn in Arbor Acres (AA) broilers and Beijing You (BJY) chickens. BJY chickens with the same age as AA broilers were named BJY1 chickens, and with the same body weight as AA broilers were named BJY2 chickens. Three groups of broilers (36 male AA broilers, 72 male BJY1 chickens, and 36 male BJY2 chickens), 2 treatments per group, 6 replicates per treatment, 3 chickens or 6 chickens per replicate. During each period, birds were fed in chambers for 11 days, including 5 days for adaptation to the feed, 3 days for excreta and gas data collection and another 3 days for fasting were recorded. Results showed that the fasting heat production (FHP) of AA, BJY1 and BJY2 chickens gradually stabilised after fasting for 72 h, the FHP of AA, BJY1 and BJY2 chickens were 486.54, 536.22 and 548.90 KJ/kg BW^0.70 /day respectively. AA broilers had significantly lower (p < 0.01) apparent total tract digestibility (ATTD) of starch in corn than that of BJY1 and BJY2 chickens, whereas there were no significant differences (p > 0.05) observed in ATTD of dry matter, crude protein, ether extract and crude fibre. The apparent metabolisable energy (AME) values of corn in AA, BJY1 and BJY2 chickens were 16.18, 16.81, and 16.39 MJ/kg dry matter (DM) and the corresponding nitrogen-corrected AME (AMEn) values were 15.71, 16.38 and 15.99 MJ/kg DM respectively. The net energy (NE) values of corn in AA, BJY1 and BJY2 chickens were 12.03, 12.28 and 11.97 MJ/kg DM respectively. In conclusion, BJY chickens had a higher maintenance energy requirement than that of AA broilers, and AA broilers of the same age and weight as BJY chickens showed no significant differences in AME, AMEn and NE values of corn.

Genome-wide association studies demonstrate the genes associated with perimysial thickness in ducks

The thickness of the perimysium has an essential effect on the tenderness of the meat. However, the genetic basis underlying perimysial thickness has not been determined. The objective of this study was to explore the quantitative trait loci (QTL) that influence perimysial thickness in an F₂ segregating population generated by Mallard × Pekin duck using the genome-wide association study (GWAS) method. Two QTL identified in chromosomes 27 and 13 displayed significant associations with perimysial thickness traits at the genome-wide level. The strongest association was the QTL located in chromosome 27, and this region had an effect on perimysial thickness and contained a promising candidate gene MAGI3 (Membrane-associated guanylate kinase, WW and PDZ domain containing 3). Meanwhile, association analysis showed that the top SNP within the MAGI3 gene was also associated with intramuscular fat content traits, which showed that perimysial thickness was positively correlated with intramuscular fat content. The second strongest association was the QTL region of chromosome 13. SUCLG2 (Succinate-CoA ligase GDP-forming subunit beta) is proximal to the top SNP and stood out as another candidate gene. Furthermore, the Transposase-Accessible Chromatin using Sequencing result showed that some key transcription factors (MYF5, MYOD1, KLF11) related to muscle development or energy metabolism might bind to the open regions of MAGI3 and SUCLG2. By analyzing the expression of different genotypes of the candidate gene, we speculate that different genotypes of MAGI3 may have an effect on breast muscle development, and then affect the thickness of the perimysium. This study maps two major genes of the duck breast muscle perimysial thickness trait, which helps to characterize muscle development and contributes to the genetic improvement of meat yield and quality in livestock.

Long-stranded non-coding RNAs temporal-specific expression profiles reveal longissimus dorsi muscle development and intramuscular fat deposition in Tianzhu white yak

The process of muscle development and intramuscular fat (IMF) deposition is quite complex and controlled by both mRNAs and ncRNAs. Long-stranded non-coding RNAs (LncRNAs) are involved in various biological processes in mammals while also playing a critical role in muscle development and fat deposition. In the present study, RNA-Seq was used to comprehensively study the expression of lncRNAs and mRNAs during muscle development and intramuscular fat deposition in postnatal Tianzhu white yaks at three stages, including 6 mo of age (calve, n = 6), 30 mo of age (young cattle, n = 6) and 54 mo of age (adult cattle, n = 6). The results indicated that a total of 2,101 lncRNAs and 20,855 mRNAs were screened across the three stages, of which the numbers of differential expression (DE) lncRNAs and DE mRNAs were 289 and 1,339, respectively, and DE lncRNAs were divided into eight different expression patterns based on expression trends. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that some DE mRNAs overlapped with target genes of lncRNAs, such as NEDD4L, SCN3B, AGT, HDAC4, DES, MYH14, KLF15 (muscle development), ACACB, PCK2, LIPE, PIK3R1, PNPLA2, and MGLL (intramuscular fat deposition). These DE mRNAs were significantly enriched in critical muscle development and IMF deposition-related pathways and GO terms, such as AMPK signaling pathway, PI3K-Akt signaling pathway, PPAR signaling pathway, etc. In addition, lncRNA-mRNA co-expression network analysis revealed that six lncRNAs (MSTRG.20152.2, MSTRG.20152.3, XR_001351700.1, MSTRG.8190.1, MSTRG.4827.1, and MSTRG.11486.1) may play a major role in Tianzhu white yak muscle development and lipidosis deposition. Therefore, this study enriches the database of yak lncRNAs and could help to further explore the functions and roles of lncRNAs in different stages of muscle development and intramuscular fat deposition in the Tianzhu white yak.

Evaluation of dietary metabolizable energy concentrations on meat quality and lipid metabolism-related gene expression in yellow-feathered chickens

This study evaluated the effects of different dietary metabolizable energy (ME) concentrations on the meat quality, carcass traits, volatile flavour and lipid metabolism-related gene expression levels in yellow-feathered chickens. In total, 600 Huxu female chickens aged 90 days were randomly assigned to six dietary treatments, each with 10 replicates of 10 birds. During the finisher phase, the birds were fed diets containing 2880 (low), 2940, 3000, 3060, 3120 and 3180 (high) kcal ME/kg. The results showed that the average daily gain of chickens increased as the dietary ME concentration increased, while the feed to gain improved (p < 0.05), and the intramuscular fat content of breast muscle increased (p < 0.05). The energy concentration had no effect on the breast muscle pH (45 min and 24 h), colour parameter (L*) or percentage of drip loss (p > 0.05), but the shear force values decreased significantly (p < 0.05). The diameter and area of the breast muscle fiber decreased and the muscle fibre density increased as the dietary ME concentration increased (p < 0.05). The highest ME concentration (3180 kcal) increased the percentages of aldehydes (hexanal, heptanal, 2,4-nonadienal, octanal, nonanal and 2-decenal), alcohols (2-nonen-1-ol, trans-2-undecen-1-ol, 7-hexadecenal, 2-hexyl-1-decanoal and n-nonadecanol-1,3,7,11-trimethyl-1-dodecanol), alkanes (2,6-dimethyl-heptadecane) and carboxylic acids (9-hexadecenoic acid), but reduced the percentages of octadecanal, octadecane, heneicosane and tetradecanal (p < 0.05). In addition, the mRNA gene expression levels of fatty acid-binding protein 3 and apolipoprotein B were significantly upregulated in the liver, whereas that of cholesteryl ester transfer protein was significantly downregulated. In conclusion, increasing the ME diet to 3180 kcal/kg significantly improved the quality and flavour of the meat from yellow-feathered broilers. our finding may help poultry producers to improve the taste of meat by regulating genes related to lipid metabolism, thereby achieving the flavour and taste characteristics preferred by consumers.

Comparison of meat quality and glycolysis potential of two hybrid pigs in three-way hybrid model

With the improvement of consumers' requirements for pork quality, the method of crossbreeding with excellent local pig breeds to improve meat quality is popular. Saba pig has high reproduction rate, good meat quality and high utilization rate of roughage, but its excellent characteristics have not been fully developed and utilized. To promote the development and utilization of Saba pigs and production of high-quality pork, the meat quality traits and glycolysis potential of Duroc × (Landrace × Yorkshire) (DLY), Berkshire × (Duroc × Saba) (BDS), and Duroc × (Berkshire × Saba) (DBS) three-way crossbred pigs were compared. The results showed that DLY had the highest live weight, carcass weight, lean meat percentage, drip loss, glycolysis potential, muscle diameter, and relative mRNA expression levels of type IIb muscle fibers as well as the lowest ultimate pH (p < 0.05). The lightness value of DBS was the highest (p < 0.05). Among the three crossbred pigs, myristic, arachidic, palmitoleic, and eicosenoic acids were the highest in BDS. These results indicated that the carcass traits of local crossbred pigs were worse than those of DLY pigs, but meat quality was markedly higher, with BDS showing the best meat quality.

Effect of aerobic and modified atmosphere packaging on quality characteristics of chicken leg meat at refrigerated storage

The demand for chicken meat is continuously increasing in the consumer market. Increasing the shelf-life of chicken meat with modern packaging technology in the supply chain is necessary. Hence research was undertaken to study the effect of aerobic packaging (AP) and modified atmosphere packaging (MAP) on the quality and shelf-life of chicken meat. The chicken leg meat (CLM) was stored under refrigerated storage (4 ± 1°C) in aerobic and modified atmosphere packaging (MAP20 = 20%O₂ + 30%CO₂ + 50%N₂, MAP10 = 10%O₂ + 40%CO₂ + 50%N₂, MAP0 = 0%O₂ + 20%CO₂ + 80%N₂) conditions and evaluated for quality attributes. The results have indicated that MAP of chicken leg meat significantly increased the headspace carbon dioxide, Warner-Bratzler shear force value, standard plate count, color, and odor but decreased the TBARS value, headspace oxygen, and nitrogen when compared with AP. The pH, myoglobin forms, meat pigment, heme iron, CIELAB color space (L*, a*, b*), yeast and mold count, appearance, and sliminess were not affected significantly by AP and MAP. It is concluded that under refrigerated storage conditions, MAP extends the shelf-life of chicken leg meat up to 15 d compared to only 6 d for aerobic packaging.

•

Modified atmosphere packaging (MAP) significantly (P < 0.05) increases headspace carbon dioxide, Warner-Bratzler shear force, standard plate count, appearance, color, and odor of chicken leg meat.

•

Aerobic packaging (AP) significantly (P < 0.05) decreases the pH, total meat pigment, and heme iron in chicken leg meat.

•

Low oxygen, high carbon dioxide MAP (0–20%O₂ + 20–40%CO₂ + 50–80%N2) can increase the shelf-life by 100 to 150% in chicken leg meat under refrigeration storage.

Quality Characterization of Different Parts of Broiler and Ligor Hybrid Chickens

The quality characterization of different parts of male and female Ligor hybrid chickens was investigated and compared with those of commercial broiler. Genotypes, muscle types, and sex had effects on the composition, physicochemical, and textural properties of chicken samples. Ligor hybrid chicken contained higher percentages of protein, moisture, ash, and collagen content but lower fat content than those of commercial broiler (p < 0.05), except in the case of breast, where no significant difference in moisture and ash was observed (p ≥ 0.05). The pH in breast meat of both chickens was lower than that of thigh meat. The color (L*, a*, and b*) values of male and female chickens were not significantly different, except for the L* value of broiler chicken, which was higher in female chickens than in male chickens. Higher cooking loss and shear force were found in male Ligor hybrid chicken. A similar protein pattern was observed for the protein from the same muscle type, irrespective of sex and genotype tested. It was observed that Ligor hybrid chicken contained higher glutamic acid and aspartic acid than commercial broilers. Therefore, Ligor hybrid chicken is a promising new source of nutrition, which can be beneficial for consumers.

Evaluation of lipid sources and emulsifier addition on fat digestion of yellow-feathered broilers

This study evaluated the effect of an emulsifier on the energetic values of lipids fed to yellow-feathered chickens and established prediction equations for the metabolizable energy (ME) of lipids fed with and without an emulsifier. One hundred and ninety-two Chinese yellow-feathered roosters (Wen's Yellow A; initial BW = 2.37 ± 0.33 kg) were individually weighed, divided into 4 body weight blocks, and randomly assigned within block to the 16 dietary treatments with replicates of 3 roosters. The diets consisted of a corn basal diet or the basal diet supplemented with 8% of corn oil (CO), soybean oil (SO), cottonseed oil (CSO), rice bran oil (RBO), palm oil (PO), modified palm oil (MPO), or lard was evaluated with or without an emulsifier (0.02% of diet) in an 8×2 factorial arrangement. Diets were fed for 8 d, with 4 d for adaptation to diets and another 4 d for excreta collection. There was interaction between lipid sources and emulsifier on ME (apparent ME and N-corrected apparent ME) of the lipids (P < 0.05). Addition of 0.02% emulsifier had no effect on the ME of CO, SO, PO or lard, but reduced the ME of CSO (P < 0.05) and MPO (P < 0.05), and tended to increase the ME of RBO (0.05 ≤ P < 0.10). There was a quadratic relationship between ME and concentration of stearic (C18:0) (P < 0.05) or linoleic acid (C18:2) (0.05 ≤ P < 0.10), and a linear function between ME and concentration of oleic acid (C18:1) or monounsaturated fatty acids (P < 0.05) in diets without emulsifier. The ME of lipids could be predicted by the concentration of C18:0 with C18:1 or with MUFA without an emulsifier. With an emulsifier, the ME concentration was affected linearly by the concentration of myristic acid (C14:0), palmitic acid (C16:0), C18:2, polyunsaturated fatty acids, unsaturated fatty acids, saturated fatty acids, and the ratio of unsaturated to saturated fatty acids (P < 0.05). Prediction equations for the ME of lipid were established on the content of C18:0, C16:0, C14:0, SFA, and U:S. These results indicated that the ME of RBO is positively affected by emulsifiers, but the ME of CSO and MPO declines with emulsifiers. These inconsistent results may be influenced by the relationship between ME and concentration of fatty acid across sources of dietary lipids.

Role of steroid growth promoter on growth performance and meat quality traits in broiler

Growth promoters are added with broiler feed to boost the overall feed efficiency and growth rate. The current study investigated the effect of dexamethasone (DEX)—a commonly used growth promoter—on the broiler growth rate, meat quality, and muscle biology. Four homogenous groups (20 chicks/group) of broiler one-day-old chicks were fed commercial broiler feed where the treatment groups received 3, 5, and 7 mg/kg of DEX with their diet for 28 d. Feed consumption and body weight were monitored on a daily basis. Muscle samples were collected on 7, 14, 21, and 28 d of the experiment to investigate meat quality and muscular biology. The residue of DEX in meat was detected using thin-layer chromatography. We observed that DEX had substantially decreased (P < 0.05) feed intake, feed efficiency, and overall weight gain in the broiler. While the weight of breast and thigh meat was decreased, the relative meat weight (meat/body weight) was increased significantly in chicks fed DEX. Simultaneously, body fat decreased while the percentage of fat increased significantly (P < 0.05) in the DEX groups. Contrariwise, DEX improved the investigated meat quality parameters with the potential threat of accumulation of DEX residue in the meat at a high dose (7 mg/kg). We also observed that DEX significantly increased the number of myofibers and decreased the cross-sectional area of myofibers. Based on these findings, we conclude that DEX reduces feed intake, feed efficiency, and growth rate, but might improve meat quality with a potential risk of residual DEX accumulation if fed at a high dose.

Integrative ATAC-seq and RNA-seq Analysis of the Longissimus Muscle of Luchuan and Duroc Pigs

Luchuan pig is a typical obese pig breed in China, and the diameter and area of its longissimus dorsi muscle fibers are significantly smaller than those of Duroc (lean) pig. Skeletal muscle fiber characteristics are related to meat quality of livestock. There is a significant correlation between the quality of different breeds of pork and the characteristics of muscle fiber, which is an important factor affecting the quality of pork. The diameter and area of muscle fibers are related to muscle growth and development. Therefore, we used the assay for transposase-accessible chromatin using sequencing (ATAC-seq) and RNA sequencing (RNA-seq) analysis to investigate the potential mechanism underlying the difference in skeletal muscle growth and development between the two types of pigs. First, transposase-accessible chromatin was analyzed to map the landscape of open chromatin regions and transcription factor binding sites. We identified several transcription factors that potentially affected muscle growth and development, including TFAP4, MAX, NHLH1, FRX5, and TGIF1. We also found that transcription factors with basic helix-loop-helix structures had a preference for binding to genes involved in muscle development. Then, by integrating ATAC-seq and RNA-seq, we found that the Wnt signaling pathway, the mTOR signaling pathway, and other classical pathways regulate skeletal muscle development. In addition, some pathways that might regulate skeletal muscle growth, such as parathyroid hormone synthesis, secretion, and action, synthesis and degradation of ketone bodies, and the thyroid hormone signaling pathway, which were significantly enriched. After further study, we identified a number of candidate genes (ASNS, CARNS1, G0S2, PPP1R14C, and SH3BP5) that might be associated with muscle development. We also found that the differential regulation of chromatin openness at the level of some genes was contrary to the differential regulation at the level of transcription, suggesting that transcription factors and transcriptional repressors may be involved in the regulation of gene expression. Our study provided an in-depth understanding of the mechanism behind the differences in muscle fibers from two species of pig and provided an important foundation for further research on improving the quality of pork.

Evaluation of Meat from Native Chickens: Analysis of Biochemical Components, Fatty Acids, Antioxidant Dipeptides, and Microstructure at Two Slaughter Ages

This study examined biochemical components, fatty acids, antioxidant dipeptides, and muscle fiber density of breast and thigh muscles from Korean new native chicken strains (A and B) at two slaughter ages, compared with white semi-broiler (W) or broilers. The pH values were different by chicken breed. The new native strains had the lowest fat content in the breast at 12 wk (p<0.05). Regardless of the muscles, A and B at 12 wk had higher levels of arachidonic acid (ARA; C20:4), docosahexaenoic acid (DHA; C22:6), and nervonic acid (C24:1) than broilers (p<0.05). A similar result was observed for the polyunsaturated fatty acids (PUFAs) and polyunsaturated and saturated fatty acids ratio (P/S) content in the breast. Irrespective of the muscles, A and B enriched with omega-3 fatty acids had a lower ω-6/ω-3 PUFA ratio than broilers (p<0.05) at 12 wk. Of the antioxidant di-peptides, the anserine contents were highest in A and B than in the W or broilers (p<0.05), regardless of the muscles and slaughter ages. Furthermore, the breast meat from A and B contained a higher muscle fiber density for both slaughter ages than the W and broilers (p<0.05). Based on these findings, even if the commercial birds (broilers or W) are raised under the similar environmental conditions as A and B, the new native chicken strains have distinct meat quality attributes, particularly higher ARA and DHA levels, lower ω-6/ω-3 PUFA ratio, and higher anserine contents.

Effect of marketable age on proximate composition and nutritional profile of breast meat from Cherry Valley broiler ducks

Marketable age is an important determinant of meat quality. Cherry Valley duck (SM3 medium) is the most efficient Pekin-type duck and is the most widely farmed breed globally. However, whether marketable age determines the meat quality of Cherry Valley ducks is not well documented. The objective of this study was to investigate the effect of marketable age on the proximate composition and nutritional profile of breast meat from Cherry Valley broiler ducks. Ducks at 28, 38, 42, and 45 days old were selected and slaughtered, and their proximate composition, cholesterol and essential mineral compositions, and amino acids and fatty acid profile of breast meat lipid were determined. The results showed higher protein content and lower intramuscular fat content were observed in the 38-day-old ducks than in the 28-day-old birds (P < 0.05). Additionally, 38-day-old ducks contained higher Fe and Mg contents (P < 0.05), whereas 28-day-old birds had higher Zn and Ca contents (P < 0.05). The essential amino acid content in 38-day-old was about 95.29 g/kg, higher than that in 28-day-old birds (P < 0.05). The contents of C20:5 n-3, omega-6 polyunsaturated fatty acids, and polyunsaturated fatty acids were the highest in 38-day-old birds (P < 0.05), whereas the content of C20:4 n-6, DHA (C22:6 n-3), and saturated fatty acids in 28-day-old birds was the lowest (P < 0.05). Finally, a comprehensive evaluation model of multiple traits was developed by applying principal component analysis, and the meat nutrition of 38-day-old ducks was identified as the optimal. Taken together, the meat of 38-day-old ducks had an advantage in proximate composition, minerals content, essential amino acids, and fatty acids, and 38 d might be recommended as an appropriate marketable age to provide duck meat of high nutrition value.

Promising Role of Growth Hormone-Boosting Peptide in Regulating the Expression of Muscle-Specific Genes and Related MicroRNAs in Broiler Chickens

Appropriate skeletal muscle development in poultry is positively related to increasing its meat production. Synthetic peptides with growth hormone-boosting properties can intensify the effects of endogenous growth hormones. However, their effects on the mRNA and miRNA expression profiles that control muscle development post-hatching in broiler chicks is unclear. Thus, we evaluated the possible effects of synthetic growth hormone-boosting peptide (GHBP) inclusion on a chicken's growth rate, skeletal muscle development-related genes and myomiRs, serum biochemical parameters, and myofiber characteristics. A total of 400 one-day-old broiler chicks were divided into four groups supplied with GHBP at the levels of 0, 100, 200 and 300 μg/kg for 7 days post-hatching. The results showed that the highest levels of serum IGF-1 and GH at d 20 and d 38 post-hatching were found in the 200 μg/kg GHBP group. Targeted gene expression analysis in skeletal muscle revealed that the GHBP effect was more prominent at d 20 post-hatching. The maximum muscle development in the 200 μg/kg GHBP group was fostered by the upregulation of IGF-1, mTOR, myoD, and myogenin and the downregulation of myostatin and the Pax-3 and -7 genes compared to the control group. In parallel, muscle-specific myomiR analysis described upregulation of miR-27b and miR-499 and down-regulation of miR-1a, miR-133a, miR-133b, and miR-206 in both the 200 and 300 μg/kg GHBP groups. This was reflected in the weight gain of birds, which was increased by 17.3 and 11.2% in the 200 and 300 μg/kg GHBP groups, respectively, when compared with the control group. Moreover, the maximum improvement in the feed conversion ratio was achieved in the 200 μg/kg GHBP group. The myogenic effects of GHBP were also confirmed via studying myofiber characteristics, wherein the largest myofiber sizes and areas were achieved in the 200 μg/kg GHBP group. Overall, our findings indicated that administration of 200 μg/kg GHBP for broiler chicks could accelerate their muscle development by positively regulating muscle-specific mRNA and myomiR expression and reinforcing myofiber growth.

Effect of muscle fiber characteristics on meat quality in fast- and slow-growing ducks

This study evaluated the effects of muscle fiber characteristics on meat quality traits in 45 female fast- and slow-growing ducks. Three duck breeds at typical market ages were selected and slaughtered, including fast-growing ducks (Cherry Valley duck) and slow-growing ducks (Small-sized Beijing duck and Liancheng White duck). M. pectoralis major (PM), m. soleus (SOL), m. gastrocnemius (GAS) and m. extensor digitorum longus (EDL) were used to assess muscle fiber characteristics as well as meat quality properties. The results showed that the fiber compositions in PM, GAS, and EDL muscles only consisted of fast-twitch fibers irrespective of the breeds, while a low percentage of slow-twitch fibers were observed in slow-growing ducks (17.03% and 29.14%). The significant clear differences of fiber diameter, fiber density and fiber cross-sectional area (CSA) was observed among three duck breeds. Small-sized Beijing ducks had the highest diameter and cross-sectional fiber area coupled with a dramatically lowest fiber density when compared to other 2 breeds both in breast and leg muscles. In addition, the meat quality traits such as moisture content, release water, and intramuscular fat content were significantly affected by the breeds. Slow-growing ducks, especially Liancheng White ducks, exhibited higher release water, intramuscular fat content, as well as lower moisture content (P < 0.05) compared to the fast-growing ducks. The lower pH_{24 h} value and shear force tended to be present in breast of Liancheng White ducks (P < 0.05). The higher protein content and collagen content were detected in breast of Liancheng White ducks and the leg muscle of Small-sized Beijing ducks (P < 0.05), respectively. Finally, the correlation coefficients between muscle fiber characteristics and meat quality showed that the diameter, density and CSA of fibers had a moderate or significant correlation with pH, shear force value, moisture content, and protein content of meat in fast-growing ducks. In slow-growing ducks, muscle fiber characteristics had a moderate or significant correlation with pH, shear force value, release water, protein content, and intramuscular fat content of meat. These results indicated that muscle fiber characteristics is a useful parameter to explain in parts the variation of meat quality including pH, shear force value, and protein content of meat, both in slow-growing ducks and fast-growing ducks.

Effect of housing system and feed restriction on meat quality of medium-growing chickens

The aim of the study was to evaluate the differences in meat quality of 420 Hubbard JA757 cockerels in relation to the housing system (litter and mobile box) and level of mixed feed (ad libitum [AL], reducing the level by 20% [R20] and 30% [R30]). Three groups of chickens were housed in litter boxes for the entire fattening period (stocking density: 0.094 m²/bird). The other 3 groups were housed in litter boxes until 28 d of age and then relocated into mobile boxes (stocking density: 0.154 m²/bird) on pasture until the end of the experiment at 57 d of age. Restricted groups received a reduced diet level from 29th to 57th d of age. Feed mixture restriction increased the pasture vegetation intake of chickens from 2.63 to 3.50 (R20) and 3.94 g of dry matter/bird/d (R30). Restriction adversely affected the dressing percentage (P < 0.001) and breast yield (P < 0.001), while the leg yield (P < 0.001) was increased with increasing restriction levels. Meat of chickens housed in mobile boxes on a pasture showed lower cooking loss (P < 0.001) and higher redness and yellowness values in the skin (P = 0.030 and P = 0.026; respectively) and meat (P = 0.008 and P < 0.001; respectively). The fragile meat after cooking was observed in chickens reared on litter (P = 0.001). As the level of restriction increased, the number of muscle fibres (P = 0.001) increased, and their cross-sectional area (P = 0.001) and diameter (P = 0.002) decreased. The highest contents of lutein (P = 0.002) and zeaxanthin (P = 0.006) in breast muscle were found in chickens housed in mobile boxes and fed 80% and 70% AL. However, the concentrations of α- and γ-tocopherol (P = 0.006 and P = 0.003) were negatively affected by feed restriction. A 30% reduction in feed level in outdoor housed chickens led to a decrease in oxidative stability (P = 0.024). Feed restriction (R20) in chickens housed in mobile boxes significantly increased the n3 fatty acids content (P = 0.002) and h/H index (P = 0.005) and reduced the n6/n3 ratio (P < 0.001) and atherogenic (P < 0.001) and thrombogenic index (P = 0.003), which possess a health benefits for human. In addition, restriction of mixed feed decreased cholesterol content in breast meat (P = 0.042). It might be concluded that, in terms of meat quality, cereal diet restriction of 20% in medium-growing cockerels housed in mobile boxes on a pasture is beneficial. The higher level of restriction does not lead to further improvement in meat quality indicators.

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.

Effects of Stocking and Transport Conditions on Physicochemical Properties of Meat and Acute-Phase Proteins in Cattle

This study's objective was to evaluate the effects of distance and stocking density on physicochemical properties and oxidative stability of meat and acute-phase proteins in Brahman crossbred cattle transported by road under hot and humid tropical conditions. Sixty Brahman crossbred heifers were subjected to road transport from a cattle feedlot farm located in Universiti Putra Malaysia (UPM), Serdang, to a commercial ruminant abattoir in Shah Alam, Selangor. Animals were assigned to long and short distances and high, medium, and low stocking densities. The results revealed that the intensity of response significantly increased in meat samples from animals subjected to long-distance transportation and higher stocking density. Alpha-1-acid glycoprotein and serum amyloid-A values increased considerably and were different from the baseline values recorded at preload. In conclusion, the current results revealed that the color, pH, shear force values, water holding capacity (WHC), glycogen level, and malondilaldehyde assay (MDA) concentrations in meat and acute-phase proteins (APP) were affected by both distances and stocking densities, as evidenced by the significant changes recorded from the parameters above.

Effects of Soy Protein Concentrate in Starter Phase Diet on Growth Performance, Blood Biochemical Indices, Carcass Traits, Immune Organ Indices and Meat Quality of Broilers

Soybean meal (SBM) is high in antinutritional factors (ANFs), which is not conducive to the starter growth of broilers. The purpose of this study was to investigate the effects of soy protein concentrate (SPC) in starter diet on growth performance, carcass traits, meat quality, immune organ indices and blood biochemical indices of broilers. A total of 384 1-day-old Arbor Acres (AA) male broilers (46.05 ± 0.37 g) with similar body weight were randomly divided into 4 groups with 8 replicates in each group and 12 broilers in each replicate. The experiment was divided into three phases: in starter phase (1-10 d), birds were fed a corn-SBM-based basal mash diet (control) and the basal diet was supplemented with SPC at 4% (SPC4), 8% (SPC8), 12% (SPC12). In the grower phase (11-21 d) and the finisher phase (22-42 d), the birds in all four treatment groups were fed the same diets. The results showed that the body weight was significantly increased in the SPC8 and SPC12 groups of broilers at 10 d and 42 d (p < 0.05). The average daily gain was significantly increased in the SPC12 group of broilers at 1-10 d and 1-42 d (p < 0.05). The average daily feed intake was significantly increased in the SPC8 and SPC12 groups of broilers at 1-10 d (p < 0.05). The feed conversion rates at 1-42 d (p = 0.055) tended to decline in the SPC12 group. The carcass yield and the thymus indices were significantly increased in the SPC12 group of broilers at 42 d (p < 0.05). Alanine aminotransferase (ALT)/ aspartate aminotransferase (AST) tended to decline in SPC12 group at 10 d (p = 0.055) and total protein (TP) tended to increase in the SPC12 group at 42 d (p = 0.080). The contents of total cholesterol (T-CHO) and high-density lipoprotein (HDL) were significantly elevated in the SPC12 group of broilers at 42 d (p < 0.05). In conclusion, dietary inclusion of 12% SPC as a starter diet can be recommended due to the positive effects on broilers.

Changes in the gut microbiota mediate the differential regulatory effects of two glucose oxidases produced by Aspergillus niger and Penicillium amagasakiense on the meat quality and growth performance of broilers

BACKGROUND

Glucose oxidase (GOD), an aerobic dehydrogenase, has been used as an antibiotic substitute in feed. A study was conducted to evaluate the differential effects of 2 different GODs fermented by Aspergillus niger or Penicillium amagasakiense on caecal microbiota and to further illuminate the potential roles of changes in the gut microbiota in regulating the growth performance and meat quality of broiler chickens.

RESULTS

A total of 420 one-day-old healthy Arbor Acres broilers were randomly assigned to 4 treatments: the control group, the antibiotic growth promoter (AGP) supplementation group, and the GOD-A and GOD-P (GODs produced by A. niger and P. amagasakiense, respectively) groups. As a result, supplementation with GOD produced by P. amagasakiense could significantly improve the average daily weight gain and average daily feed intake of broilers before 21 days of age by significantly increasing the enzymatic activities of jejunal amylase and those of ileal amylase, chymotrypsin, and lipase in 21-day-old broilers and could increase the enzymatic activities of duodenal amylase, jejunal amylase and lipase, and ileal chymotrypsin and lipase in 42-day-old broilers. Meanwhile, compared with AGP treatment, supplementation with GOD produced by P. amagasakiense significantly decreased the L value of 21-day-old broilers and the ΔpH and L* value of 42-day-old broilers, while supplementation with GOD produced by A. niger significantly increased the pH_24 h value of 21-day-old and 42-day-old broilers by reducing plasma malondialdehyde content. By using 16S rRNA sequencing, we found that the beneficial bacteria and microbiota in broilers were not disturbed but were improved by GOD supplementation compared with ADP treatment, including the genera Eubacterium and Christensenella and the species uncultured_Eubacterium_sp, Clostridium_asparagiforme, and uncultured_Christensenella_sp, which were positively related to the improved intestinal digestive enzymatic activities, growth performance, and meat quality of broilers.

CONCLUSION

The altered gut microbiota induced by supplementation with glucose oxidase produced by P. amagasakiense mediate better regulatory effects on the meat quality and growth performance of broilers than that induced by supplementation with glucose oxidase produced by A. niger.

Comparison of carcass and meat quality traits between lean and fat Pekin ducks

OBJECTIVE

According to market demand, meat duck breeding mainly includes 2 breeding directions: lean Pekin duck (LPD) and fat Pekin duck (FPD). The aim of the present study was to compare carcass and meat quality traits between 2 strains, and to provide basic data for guidelines of processing and meat quality improvement.

METHODS

A total of 62 female Pekin ducks (32 LPDs and 30 FPDs) were slaughtered at the age of 42 days. The live body weight and carcass traits were measured and calculated. Physical properties of breast muscle were determined by texture analyzer and muscle fibers were measured by paraffin sections. The content of inosine monophosphate (IMP), intramuscular fat (IMF) and fatty acids composition were measured by high-performance liquid chromatography, Soxhlet extraction method and automated gas chromatography respectively.

RESULTS

The results showed that the bodyweight of LPDs was higher than that of FPDs. FPDs were significantly higher than LPDs in subcutaneous fat thickness, subcutaneous fat weight, subcutaneous fat percentage, abdominal fat percentage and abdominal fat shear force (p<0.01). LPDs were significantly higher than FPDs in breast muscle thickness, breast muscle weight, breast muscle rate and breast muscle shear force (p<0.01). The muscle fiber average area and fiber diameter of LPDs were significantly higher than those of FPDs (p<0.01). The muscle fiber density of LPDs was significantly lower than that of FPDs (p<0.01). The IMF of LPDs in the breast muscle was significantly higher than that in the FPDs (p<0.01). There was no significant difference between the 2 strains in IMP content (p>0.05). The polyunsaturated fatty acid content of LPDs was significantly higher than that of FPDs (p<0.01), and FPDs had higher saturated fatty acid and monounsaturated fatty acid levels (p<0.05).

CONCLUSION

Long-term breeding work resulted in vast differences between the two strains Pekin ducks. This study provides a reference for differences between LPD and FPD that manifest as a result of long-term selection.

Effects of Slaughter Age on Muscle Characteristics and Meat Quality Traits of Da-Heng Meat Type Birds

Simple Summary

The current work evaluated the breast muscle performance, meat quality traits, and myofiber characteristics of Da-Heng meat type birds with 60, 90, 120, 150, 180 days of age. Older chickens often presented a higher pH, lower drip loss, higher shear force, darker, and redder breast meat. The correlation coefficients showed that myofiber characteristics played an important role in breast pH values, drip loss, and meat color.

Abstract

Due to the increasing demand for producing chickens with high meat quality, there is a need to determine its mode of action on chicken meat quality traits across a wider age spectrum. In this study, five groups of 200 male Da-Heng meat type birds were reared until slaughter age of 60, 90, 120, 150, 180 days old and breast muscle performance, meat quality traits, and myofiber characteristics were evaluated. The larger body weight and breast weight of chicken are based on larger myofiber diameter and area, less myofiber density for the older birds than younger birds. There was an age effect on all meat quality traits of chicken breast muscle (p < 0.05). Older chickens often presented a higher pH, lower drip loss, higher shear force, darker, and redder breast meat. The correlation coefficients showed that myofiber characteristics played an important role in breast pH values, drip loss, and meat color (p < 0.05). Besides, significant correlations were also found between meat quality traits (p < 0.05). Further studies are needed to explore the biochemical character and potential molecular mechanism of chicken breast muscle to determine the factors that causes these age-related differences in meat quality in the current study.

Meat quality, fatty acid profile, and sensory attributes of spent laying hens fed expeller press canola meal or a conventional diet

This study evaluated the effects of feeding an expeller press canola meal (EPCM) supplement (20%) on the carcass, meat, and sensory quality characteristics of spent laying hens. Thirty EPCM-based and thirty conventionally (soybean based) fed Lohmann Brown-Elite spent laying hens were obtained from a commercial egg farm. Carcass, portions, physical quality, proximate composition, fatty acids, and sensory quality were determined. EPCM-fed hens had higher (P ≤ 0.05) drum yield, breast bone weights and percentages, but lower (P ≤ 0.05) thigh and breast meat yields. Conventionally fed hens had higher (P ≤ 0.05) thaw losses, skin yellowness (b*), Chroma values and breast fat content with lower (P ≤ 0.05) cooking losses, skin redness (a*) and hue angle values, as well as breast Warner-Bratzler shear force values (N) (15.43 ± 0.600 vs. 12.37 ± 0.411). Palmitic acid, stearic acid, heneicosanoic acid, palmitoleic acid, saturated fatty acids (SFA) (34.0 ± 0.56 vs. 38.7 ± 0.71), n-6:n-3 polyunsaturated fatty acids (PUFA) ratio (5.5 ± 0.13 vs. 7.2 ± 0.28), atherogenic index, thrombogenic index, delta-5 desaturase, elongase index, and thiosterase index were lower (P ≤ 0.05) for EPCM-fed hen breast meat. Myristic acid, lignoceric acid, nervonic acid, alpha-linolenic acid, docosahexaenoic acid (DHA), PUFA:SFA ratio (0.7 ± 0.05 vs. 0.9 ± 0.02), n-3 PUFA (3.4 ± 0.31 vs. 5.1 ± 0.17), hypocholesterolemic:Hypercholesterolaemic, stearoyl-CoA desaturase 16, and stearoyl-CoA desaturase 18 were higher (P ≤ 0.05) for EPCM-fed hen breast meat. Metallic flavor was decreased (P ≤ 0.05) for EPCM-fed hen breast meat. Generally, effects of EPCM supplementation were observed to have an effect on the carcass, physical quality, proximate composition, fatty acids, and health indices. The sensory profiles did not differ between EPCM and conventionally fed spent laying hen breast meat (except for metallic flavor). The EPCM improved the nutritional profile of spent laying hen meat with low intramuscular fat, low n-6:n-3 PUFA ratio, and favorable lipid health indices.

The Effect of Slaughter Age and the Diet in the Final Growth Phase of Poulards on Productivity and Meat Quality

The aim of the studies was to evaluate the effect of the diet in the final growth phase and slaughter age of poulards on productivity, dressing percentage, carcass colour and physicochemical properties of meat. The studies were conducted on 78 hybrids obtained by crossing Ross 308 broiler roosters with Rhode Island Red (R-11) dual-purpose laying hens (♂Ross 308 × ♀R-11). Birds were assigned to 3 groups: control group (K) fed starter, grower and finisher diets without addition of dairy products, experimental group S offered a finisher diet supplemented with 4% whey, and experimental group M receiving 4% milk powder supplement in the final growth phase. Spaying procedure was carried out at 8 weeks of age. Poulards were slaughtered at 18 and 20 weeks of age. The studies showed that by using hybrids of dual-purpose hens with broiler roosters for production of poulards, rearing period could be shortened to 18 weeks, and the obtained meat had comparable or even better quality traits compared with poulards slaughtered at 20 weeks of age. Supplementation of poulard diet with 4% whey or milk powder in the final growth phase had a beneficial effect mostly on improvement of sensory properties of meat. There were not many significant differences in meat quality between poulards fed the diet supplemented with milk and whey but instead there were differences between these groups and the control group fed the diet without these additives.

Effects of glucose oxidase on growth performance, gut function, and cecal microbiota of broiler chickens

A study was conducted to study the effects of glucose oxidase (GOD) supplement on the growth performance, gut function, and cecal microbiota in broiler chickens from 1 to 42 d, and further evaluate the use of GOD as an antibiotic substitution. A total of 525 1-d-old healthy Arbor Acres broilers were randomly assigned to five treatments, including control group, antibiotic growth promoters (AGP) supplement group, and three GOD supplement groups, with seven replicates per treatment and 15 birds per replicate. Growth performance, gut function including digestive ability and gut barrier, and cecal microbiota were determined. Compared with the control group, the increased daily body weight gain, improved meat quality, and enhanced digestive ability that indicated from the nutrients apparent digestibility and digestive enzymes were identified in GOD supplement groups, which could have a similar effect with the AGP supplement. The content of secreted immunoglobulin A and the transepithelial electrical resistance were also increased with the GOD supplement, which indicated an enhanced gut barrier. Additionally, 16S rRNA gene of cecal contents was sequenced by high-throughput sequencing. Sequencing data indicated that the Firmicutes phylum, Ruminococcaceae and Rikenellaceae families, Faecalibacterium genus, and F. prausnitzii species were significantly altered. Especially, combined with previous studies, our results indicated that the significantly increased F. prausnitzii, Ruminococcaceae, and Firmicutes could be involved in the effect of GOD on gut function and growth performance of broilers. Our results indicated that dietary GOD supplement could improve the growth performance of broilers in two main ways: by enhancing the digestive function of gut, which concluded from the improved nutrients apparent digestibility and digestive enzyme, and by increasing the abundance of beneficial bacterium, such as F. prausnitzii, Ruminococcaceae, and Firmicutes, which could be further served as an important regulator to improve the growth performance and the gut health.

Carcass and meat quality characterization of indigenous and improved variety of chicken genotypes

A study was conducted to examine four genotypes of chicken for their carcass and meat quality characteristics. From each genotype, 20 birds were slaughtered at their respective age of maturity. Breast and thigh muscles were evaluated for meat quality characteristics. Transport loss and carcass weight were highest in the white commercial broiler (WBR) and lowest in Aseel (ASL) and Indbro Aseel (ASR). Dressing percentage ranged between 66.41 and 72.56 and was not significantly different among genotypes. The yield of various cut-up parts for different genotypic birds was significantly different (P < 0.05). Highest percent yield for breast (29.15), thigh (15.57), drumstick (13.82) and wings (18.44) were observed in WBR, rainbow rooster (RR), ASR and rainbow rooster Plus (RRP), respectively. Giblet % was highest in RR and meat:bone ratio of thigh portion was highest in WBR. Higher ultimate pH was recorded for RR, RRP, and WBR, and higher water-holding capacity was detected in ASL and ASR. Further, bound water was higher in RR, RRP, and WBR, and free water was maximum in ASL and ASR. A significant (P < 0.05) higher shear force was observed in ASL and higher muscle fiber diameter in WBR. Cooking yield did not differ significantly among genotypes. The breast meat from ASL showed significantly (P < 0.05) higher redness value and WBR showed the lower redness. Further, ASL and ASR meats were darker and red in color than broiler meat. Meat from two indigenous birds (ASL and ASR) had significantly (P < 0.05) lower fat content compared to broilers and other crosses. ASL gave a slightly firmer meat as liked by consumers. The sensory evaluation showed breast meat from RR birds and ASL birds had better flavor scores than other birds. These results indicated that meat of indigenous chickens (ASL and ASR) has some unique features over commercial fast-growing birds that would increase their demand by consumers who prefer chewy, low-fat chicken meat.

Sequencing and characterization of lncRNAs in the breast muscle of Gushi and Arbor Acres chickens

Chicken muscle quality is one of the most important factors determining the economic value of poultry, and muscle development and growth are affected by genetics, environment, and nutrition. However, little is known about the molecular regulatory mechanisms of long non-coding RNAs (lncRNAs) in chicken skeletal muscle development. Our study aimed to better understand muscle development in chickens and thereby improve meat quality. In this study, Ribo-Zero RNA-Seq was used to investigate differences in the expression profiles of muscle development related genes and associated pathways between Gushi (GS) and Arbor Acres (AA) chickens. We identified two muscle tissue specific expression lncRNAs. In addition, the target genes of these lncRNAs were significantly enriched in certain biological processes and molecular functions, as demonstrated by Gene Ontology (GO) analysis, and these target genes participate in five signaling pathway, as revealed by an analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. Taken together, these data suggest that different lncRNAs might be involved in regulating chicken muscle development and growth and provide new insight into the molecular mechanisms of lncRNAs.

Poultry Meat Quality in Relation to Muscle Growth and Muscle Fiber Characteristics

Variations in the definition of poultry meat quality exist because the quality traits are not solely based on intrinsic and extrinsic factors but also consumers’ preference. Appearance quality traits (AQT), eating quality traits (EQT), and reliance quality traits (RQT) are the major factors focused by the consumer before buying good quality of poultry meat. AQT and EQT of poultry meat are controlled by physical and biochemical characteristics of muscle fibers which can be categorized into a total number of fibers (TNF), cross-sectional area of fibers (CSAF), and fiber type composition (FTC). In poultry meat, it has been shown that muscle fiber properties play a key role in meat quality because numerous studies have reported the relationships between quality traits and fiber characteristics. Despite intensive research has been carried out to manipulate the muscle fiber to improve poultry meat quality, demand in a rapid growth of poultry muscle has correlated to the deterioration in the meat quality. The present paper reviews the definition of poultry meat quality, meat quality traits, and variations of meat quality. Also, this review presents recent knowledge underlying the relationship between poultry meat quality traits and muscle fiber characteristics.

Effects of caponization and ovariectomy on objective indices related to meat quality in chickens

Capons and ovariectomized chickens are birds that have been gonadectomized to improve the meat quality. This study investigated the effects of caponization and ovariectomy on physical, chemical, and fatty acid and amino acid profiles of meat from Beijing-You chickens (a Chinese local breed) at market age (17 wk). All birds (20 capons, 20 ovariectomized, and 40 controls) were reared under the same conditions. Breast muscle fiber diameter and area were significantly smaller and the fiber density was higher in capons and ovariectomized chickens than in controls (P < 0.05). Compared with controls, caponization and ovariectomy significantly decreased breast muscle shear values and redness (a*), as well as increased yellowness (b*), hue (H*), and chroma (C*) (P < 0.05). There was significantly more intramuscular fat (IMF) in capons than in controls (P < 0.05), and there was a tendency for more inosine-5΄-monophosphate (IMP) in capons than in controls (P = 0.10). The levels of IMF and IMP in ovariectomized chickens were significantly higher than those in controls (P < 0.05). Capons and ovariectomized chickens exhibited a significantly higher content of palmitic acid (C16:0), palmitoleic acid (C16:1) and oleic acid (C18:1), together with a lower content of stearic acid (C18:0), arachidonic acid (C20:4), and lignoceric acid (C24:0) compared to controls (P < 0.05). The total saturated, monounsaturated, and polyunsaturated fatty acids as well as amino acid composition were not affected by gonadectomy (P > 0.05). Overall, this study indicates that both caponization and ovariectomy likely improve the meat quality of the breast muscle based on the objective indices of IMF, appearance (color), texture, and minor change of the fatty acid profile; ovariectomy improves flavor-related indices.

Quality characteristics of broiler chicken meat from free-range and industrial poultry system for the consumers

ABSTRACT

The aim of this study was to determine and compare the quality parameters of broiler chicken meat from free-range and industrial poultry system. Proximate composition, color, pH, shear force, microbial quality and sensory characteristics were evaluated. Both free-range and industrial chicken meat presented PSE (pale, soft and exudative) anomaly (L* > 53). An inverse correlation between lightness, pH and shear force was observed. The free range broiler meat had higher yellow color (b* 11.56) and shear force (2.75 kgf) and lower red color (a* 1.65) and pH (5.75) in comparison to the industrial broiler meat, due intensive physical activity on growing phase and influence of the pre-slaughter stress on the rigor mortis. The thigh cut from free range broiler meat showed higher protein levels (18.00%), while to the thigh and drumstick cuts of industrial broiler meat showed higher total fat levels (3.4 and 5.0%, respectively). In general, each strain and chickens producing methods gave the peculiar characteristics to meat (chemical, physical, microbiological and sensorial).

GRAPHICAL ABSTRACT

Thai native chicken meat: an option to meet the demands for specific meat quality by certain groups of consumers; a review

Native chickens are slowly growing indigenous chicken (Gallus domesticus) breeds; many of them were developed from jungle fowl, which is found in every part of Asia. These breeds are disease resistant, easy adapting to tropical climates, and have a low mortality. In Thailand, a distinct sector of consumers prefers to eat meat from native chickens rather than that from broilers because it is more tasty and chewy. In addition, studies have shown that it has a low content of fat which may be helpful for people susceptible to coronary heart diseases. This review also compiles evidence for further indicators of a special meat quality such as more oxidative (Type I) muscle fibres, a higher collagen content (promoting the preferred chewiness), an elevated content of certain flavor-relevant compounds, as well as high ratio of polyunsaturated to saturated fatty acids.