Effect of carnosine synthesis precursors in the diet on jejunal metabolomic profiling and biochemical compounds in slow-growing Korat chicken

The slow-growing Korat chicken (KR) has been developed to provide an alternative breed for smallholder farmers in Thailand. Carnosine enrichment in the meat can distinguish KR from other chicken breeds. Therefore, our aim was to investigate the effect of enriched carnosine synthesis, obtained by the β-alanine and L-histidine precursor supplementation in the diet, on changes to metabolomic profiles and biochemical compounds in slow-growing KR jejunum tissue. Four hundred 21-day-old female KR chickens were divided into 4 experimental groups: a group with a basal diet, a group with a basal diet supplemented with 1.0% β-alanine, 0.5% L-histidine, and a mix of 1.0% β-alanine and 0.5% L-histidine. The feeding trial lasted 70 d. Ten randomly selected chickens from each group were slaughtered. Metabolic profiles were analyzed using proton nuclear magnetic resonance spectroscopy. In total, 28 metabolites were identified. Significant changes in the concentrations of these metabolites were detected between the groups. Partial least squares discriminant analysis was used to distinguish the metabolites between the experimental groups. Based on the discovered metabolites, 34 potential metabolic pathways showed differentiation between groups, and 8 pathways (with impact values higher than 0.05, P < 0.05, and FDR < 0.05) were affected by metabolite content. In addition, biochemical changes were monitored using synchrotron radiation-based Fourier transform infrared microspectroscopy. Supplementation of β-alanine alone in the diet increased the β-sheets and decreased the α-helix content in the amide I region, and supplementation of L-histidine alone in the diet also increased the β-sheets. Furthermore, the relationship between metabolite contents and biochemical compounds were confirmed using principal component analysis (PCA). Results from the PCA indicated that β-alanine and L-histidine precursor group was highly positively correlated with amide I, amide II, creatine, tyrosine, valine, isoleucine, and aspartate. These findings can help to understand the relationships and patterns between the spectral and metabolic processes related to carnosine synthesis.

Initiative on Avian Primordial Germ Cell Cryobanking in Thailand

Background: Biobanking the reproductive tissues or cells of animals preserves the genetic and reproductive ability of the species in long-term storage and promotes sharing of reproductive materials. In avian species, the primordial germ cell (PGC) is one of the most promising reproductive cells to be preserved in biobanks, due to self-renewal properties and direct access to the germ line mediated by PGC transfer. Methods: To conserve the genetic resource of local chicken breeds that are of conservation importance, we systematically isolated two types of pregonadal PGCs from chicken embryos-circulating and tissue PGCs. PGCs of individual embryos were separately isolated, cultured, and cryopreserved. Characteristics of cultured PGCs are described and evaluated. Results: The efficiency of PGC isolation from individual embryos was 98.9% (660/667). In most cases, both matching circulating and tissue PGC lines were isolated from the same embryo (68.2%, 450/660), whereas the remaining lines were from a single source, being either tissue (30.6%, 202/660) or circulating (1.2%, 8/660). Efficient PGC isolation and proliferation can be expected in cultures of circulating PGCs (68.7% and 64.3%, respectively) and tissue PGCs (97.8% and 80.7%, respectively). Following cryopreservation, recovered cells sustained PGC identities including expression of chicken vasa homolog and deleted in azoospermia-like proteins and migration ability to recipient embryonic gonads. Culture conditions equally supported proliferation of circulating and tissue PGCs from both sexes. Combining tissue PGC culture in the regimen prevented 30.3% loss of PGC cultures in the case where circulating PGC culture was ineffective. Cultured circulating and tissue PGCs were similar in morphology, but optimal culture characteristics were different. Conclusion: We applied the approach of PGC isolation from blood and tissue origins on a wide scale and demonstrated its efficiency for biobanking chicken PGCs. The workflow can be operated effectively almost year-round in a tropical climate. It was also described in ample and practical details, which are suitable for adoption or optimization in other conditions.

Heating temperatures affect meat quality and vibrational spectroscopic properties of slow- and fast-growing chickens

This study determined the effect of water bath cooking (70°C and 90°C for 40 min) and the extreme heat treatment by an autoclave (121°C for 40 min) on the quality of breast meat of a fast-growing chicken, commercial broiler (CB), and slow-growing chickens, Korat chicken (KC), and Thai native chicken (NC) (Leung Hang Khao), by vibrational spectroscopic techniques, including synchrotron radiation-based Fourier transform infrared (SR-FTIR) microspectroscopy and Fourier transform Raman (FT-Raman) spectroscopy. Taste-enhancing compounds, including inosine-5'-monophosphate (IMP) and guanosine-5'-monophosphate (GMP), were better retained in cooked KC and NC meats than in cooked CB meat (P < 0.05). The high heat treatment at 121°C depleted the amount of insoluble collagen in all breeds (P < 0.05). Shear force values of slow-growing chicken meat were not affected by high heating temperatures (P > 0.05). In addition, the high heat treatment increased protein carbonyl (P < 0.05), while no effect on in vitro protein digestibility (P > 0.05). SR-FTIR microspectroscopy performed better in differentiating the meat quality of different chicken breeds, whereas FT-Raman spectroscopy clearly revealed differences in meat qualities induced by heating temperature. Based on principal component analysis (PCA), distinct characteristics of chicken meat cooked at 70°C were high water-holding capacity, lightness (L*), moisture content, and predominant α-helix structure, correlating with Raman spectra at 3,217 cm^-1 (O-H stretching of water) and 1,651 cm^-1 (amide I; α-helix). The high heating temperature at 90°C and 121°C exposed protein structure to a greater extent, as evidenced by an increase in β-sheets, which was well correlated with the Raman spectra at 2,968 and 2,893 cm^-1 (C-H stretching), tryptophan (880 cm^-1), tyrosine (858 cm^-1), and 1,042, 1,020, and 990 cm^-1 (C-C stretching; β-sheet). SR-FTIR and FT-Raman spectroscopy show potential for differentiation of chicken meat quality with respect to breeds and cooking temperatures. The marked differences in wavenumbers would be beneficial as markers for determining the quality of cooked meats from slow- and fast-growing chickens.

Thigh muscle metabolic response is linked to feed efficiency and meat characteristics in slow-growing chicken

The Korat chicken (KR) is a slow-growing Thai chicken breed with relatively poor feed efficiency (FE) but very tasty meat with high protein and low fat contents, and a unique texture. To enhance the competitiveness of KR, its FE should be improved. However, selecting for FE has an unknown effect on meat characteristics. Thus, understanding the genetic basis underlying FE traits and meat characteristics is needed. In this study, 75 male KR birds were raised up to 10 wk of age. For each bird, the feed conversion ratio (FCR), residual feed intake (RFI), and physicochemical properties, flavor precursors, and biological compounds in the thigh meat were evaluated. At 10 wk of age, thigh muscle samples from 6 birds (3 with high FCR and 3 with low FCR values) were selected, and their proteomes were investigated using a label-free proteomic method. Weighted gene coexpression network analysis (WGCNA) was used to screen the key protein modules and pathways. The WGCNA results revealed that FE and meat characteristics significantly correlated with the same protein module. However, the correlation was unfavorable; improving FE may result in a decrease in meat quality through the alteration in biological processes including glycolysis/gluconeogenesis, metabolic pathway, carbon metabolism, biosynthesis of amino acids, pyruvate metabolism, and protein processing in the endoplasmic reticulum. The hub proteins of the significant module (TNNT1, TNNT3, TNNI2, TNNC2, MYLPF, MYH10, GADPH, PGK1, LDHA, and GPI) were also identified to be associated with energy metabolism, and muscle growth and development. Given that the same proteins and pathways are present in FE and meat characteristics but in opposite directions, selection practices for KR should simultaneously consider both trait groups to maintain the high meat quality of KR while improving FE.

Omega-3 meat enrichment and L-FABP, PPARA, and LPL genes expression are modified by the level and period of tuna oil supplementation in slow-growing chickens

This study proposes a strategy to manipulate the fatty acid (FA) content in slow-growing Korat chicken (KRC) meat using tuna oil (TO). To determine the optimal level and feeding period of TO supplementation, we conducted a study investigating the effects of dietary TO levels and feeding periods on meat quality, omega-3 polyunsaturated fatty acid (n-3 PUFA) composition, and gene expression related to FA metabolism in KRC breast meat. At 3 wk of age, 700 mixed-sex KRC were assigned to seven augmented factorial treatments with a completely randomized design, each consisting of four replicate pens containing 25 chickens per pen. The control group received a corn-soybean-based diet with 4.5% rice bran oil (RBO), while varying amounts of TO (1.5%, 3.0%, or 4.5%) replaced a portion of the RBO content in the experimental diets. The chickens were fed these diets for 3 and 6 wk, respectively, before being slaughtered at 9 wk. Our results indicated no significant interactions between TO levels and feeding periods on the growth performance or meat quality of KRC (P > 0.05). However, the liver fatty acid-binding protein gene (L-FABP, also known as FABP1), responsible for FA transport and accumulation, showed significantly higher expression in the chickens supplemented with 4.5% TO (P < 0.05). The chickens supplemented with 4.5% TO for a longer period (3 to 9 wk of age) exhibited the lowest levels of n-6 PUFA and n-6 to n-3 ratio, along with the highest levels of eicosapentaenoic acid, docosahexaenoic acid, and n-3 PUFA in the breast meat (P < 0.05). However, even a short period of supplementation with 4.5% TO (6 to 9 wk of age) was adequate to enrich slow-growing chicken meat with high levels of n-3 PUFA, as recommended previously. Our findings indicated that even a short period of tuna oil supplementation could lead to desirable levels of omega-3 enrichment in slow-growing chicken meat. This finding has practical implications for the poultry industry, providing insights into optimal supplementation strategies for achieving desired FA profiles without adversely affecting growth performance or meat quality.

L-arginine alters myogenic genes expression but does not affect breast muscle characteristics by in ovo feeding technique in slow-growing chickens

In ovo feeding (IOF) of nutrients is a viable method for increasing muscle mass through hyperplasia and hypertrophy. The objective of this study was to evaluate the effects of IOF of L-arginine (Arg) on breast muscle weight, muscle morphology, amino acid profile, and gene expression of muscle development in slow-growing chickens. Four hundred eighty fertilized eggs were randomly divided into two groups: the first group was the non-injected control group, and the second group was the Arg group, injected with 1% Arg (0.5 mL) into the amnion on day 18 of incubation. After hatching, 160 birds from each group were randomly divided into four replicates of 40 birds each. This experiment lasted for 63 days. The results showed that IOF of Arg did not affect (P > 0.05) breast muscle weight, muscle morphology, and mRNA expression of mammalian target of rapamycin (mTOR) signaling pathway in slow-growing chickens. However, the amino acid profile of breast muscle was altered (P < 0.05) on the day of hatching (DOH), day 21 (D21), and day 42 (D42) post-hatch, respectively. Myogenic factor 5 (Myf5) mRNA expression was upregulated (P < 0.05) on D21 post-hatch. Myogenic regulator 4 (MRF4) mRNA expression was increased (P < 0.05) on DOH. And myogenin (MyoG) was increased (P < 0.05) on DOH and D21 post-hatch, in the Arg group compared to the control group. Overall, IOF of 1% Arg improved the expression of myogenic genes but did not influence muscle morphology and BMW. These results indicate that in ovo Arg dosage (0.5 mL/egg) has no adverse effect on breast muscle development of slow-growing chickens.

Phenotypic correlations between feed efficiency, growth, and meat quality of slow-growing chickens

1. Korat (KR) chicken is a new meat-type chicken breed established with the purpose of developing Small and Micro Community Enterprise Production. This slow-growing chicken has been recognised for its good texture and flavour, but its low feed efficiency is associated with high cost of production which can hamper the development of local production. This has highlighted the importance of studying the trade-off between feed efficiency and meat quality in KR chicken.2. This study investigated the phenotypic correlations between feed efficiency, growth performance, and meat quality in KR chicken. Individual body weight and feed intake were recorded weekly for 75 male KR chickens for the calculation of feed conversion ratio (FCR) and residual feed intake (RFI). The growth curve was modelled by Gompertz function and meat quality evaluated at 10 weeks of age, through the measurement of pH (pH_u), water-holding capacity (WHC) and drip loss (DL) in breast and thigh muscle.3. Faster growth rate at young age appeared favourable, regarding feed efficiency, since a moderate negative correlation was found between FCR and initial growth rate. Chickens with a higher initial growth and maturation rates were characterised by lower water-holding capacity in meat. This was not associated with acidic meat, since a higher speed of growth (especially in the first weeks) was positively associated with final pH in breast meat. Relationships between RFI and meat quality traits appeared to be weak. While better FCR could be achieved by increased initial growth rate, this seemed to negatively impact water-holding capacity of the meat.4. RFI appeared as an interesting alternative as a compromise between FCR and meat quality.

Comparative proteomics revealed duodenal metabolic function associated with feed efficiency in slow-growing chicken

The Korat chicken (KR), developed in Thailand, is a slow-growing breed developed as an alternative breed for Thai chicken producers. The growing interest in slow-growing chicken meat, due to its unique taste, distinct texture, health benefits, and higher broiler welfare have led to higher market demand for KR. However, its low feed efficiency (FE) has a significant negative impact on farm profitability. Understanding the molecular mechanism regulating FE allows for designing a suitable selection program and contributing to breeding more efficient chicken for poultry production. Thus, the objective of our study was to investigate the proteome differences and possible pathways associated with FE in male KR using a label-free quantitative proteomic approach. Seventy-five KR males were individually evaluated for FE, and duodenum samples from 6 animals (3 high-FE and 3 low-FE chickens) were collected at 10 wk of age for differential abundant proteins (DAPs), protein networks, functional enrichment, and pathway analyses. In this study, we found 40 DAPs significantly associated with FE pathways, including glycolysis/gluconeogenesis, peroxisome, oxidative phosphorylation, tight junction, and cysteine and methionine metabolism. Thus, variations in observed DAPs or genes related to DAPs could be interesting biomarker candidates for selection for higher feed utilization efficiency in chicken.

Biomolecules, Fatty Acids, Meat Quality, and Growth Performance of Slow-Growing Chickens in an Organic Raising System

This study was to determine the effect of the organic raising system (OR) on growth performance, meat quality, and physicochemical properties of slow-growing chickens. Three hundred and sixty (one-day-old) Korat chickens (KRC) were randomly assigned to control (CO) and OR groups. The groups comprised six replicates of thirty chickens each. The chickens were housed in indoor pens (5 birds/m2), wherein those in OR had free access to Ruzi pasture (1 bird/4 m2) from d 21 to d 84 of age. In the CO group, chickens were fed with a mixed feed derived from commercial feedstuffs, while those in the OR group were fed with mixed feed derived from organic feedstuffs. The results revealed a lower feed intake (p < 0.0001) and feed conversion ratio (p = 0.004) in the OR. The OR increased total collagen, protein, shear force, color of skin and meat, and decreased abdominal fat (p < 0.05). The OR improved fatty acid with increased DHA, n-3 PUFA, and decreased the ratio of n-6 to n-3 PUFA in KRC meat (p < 0.05). The synchrotron radiation-based Fourier transform infrared spectroscopy and correlation loading analyses confirmed these results. In conclusion, our results proved that OR could improve growth performance and meat quality and suggested the raising system be adopted commercially. In addition, the observed differences in biochemical molecules could also serve as markers for monitoring meat quality.

Influences of L-Arginine In Ovo Feeding on the Hatchability, Growth Performance, Antioxidant Capacity, and Meat Quality of Slow-Growing Chickens

Simple Summary

The nutrition and health status of the embryo in the hatching process directly influence the hatchability and chicken performance post-hatch in poultry production. The in ovo feeding (IOF) technique provides a viable way to improve the embryonic development and chicken performance post-hatch. Thus, the hypothesis of this study was that supplementing L-arginine (Arg) into embryos could positively affect the hatchability, growth performance, antioxidant capacity, and meat quality of slow-growing chickens. The results of this study demonstrate that IOF of Arg positively affected the antioxidant capacity of the breast muscle in the starter period, and there was no effect on the hatchability, growth performance, carcass traits, and meat quality. Overall, our findings suggest that IOF of Arg may have beneficial effects on chicken health without compromising the hatchability, subsequent growth, and meat quality.

Abstract

The aim of this study was to evaluate the effects of in ovo feeding (IOF) of L-arginine (Arg) on the hatchability, growth performance, antioxidant capacity, and meat quality of slow-growing chickens. A total of 480 eggs were randomly divided into a non-injected control group (NC group) and a 1% Arg-injected group (Arg group). On day 18 of incubation, 0.5 mL of Arg solution was injected into the embryonic amnion in the Arg group. Upon hatching, 160 mixed-sex chickens were randomly assigned to two groups, with four replicates per group. This experiment lasted for 63 days. The results showed that the hatchability, growth performance, carcass traits, and meat quality were not significantly different (p > 0.05) between the two groups. However, the malondialdehyde (MDA) content was lower (p < 0.05), and the glutathione (GSH) level was higher (p < 0.05) on day of hatching in the Arg group. The total antioxidant capacity (T-AOC) activity was increased (p < 0.05) on day 21 post-hatch in the Arg group compared to that in the NC group. In conclusion, IOF of Arg increased the antioxidant capacity of the breast muscle in the starter period, which may have a positive effect on health status of slow-growing chickens post-hatch.

Effects of β-alanine and L-histidine supplementation on carnosine contents in and quality and secondary structure of proteins in slow-growing Korat chicken meat

Carnosine enrichment of slow-growing Korat chicken (KRC) meat helps differentiate KRC from mainstream chicken. We aimed to investigate the effects of β-alanine and L-histidine supplementation on the carnosine synthesis in and quality and secondary structure of proteins in slow-growing KRC meat. Four hundred 21-day-old female KRC were used, and a completely randomized design was applied. The chickens were divided into 4 experimental groups: basal diet (A), basal diet supplemented with 1.0% β-alanine (B), 0.5% L-histidine (C), and 1.0% β-alanine combined with 0.5% L-histidine (D). Each group consisted of 5 replicates (20 chickens per replicate). On d 70, 2 chickens per replicate were slaughtered, and the levels of carnosine, anserine, and thiobarbituric acid reactive substances were analyzed. Biochemical changes were monitored using synchrotron radiation-based Fourier transform infrared microspectroscopy; 5 chickens per replicate were slaughtered, and the meat quality was analyzed. Statistical analysis was performed using ANOVA and principal component analysis (PCA). Group D chickens exhibited the highest carnosine meat content, followed by those in groups B and C. However, amino acid supplementation did not affect anserine content and growth performance. Higher carnosine levels correlated with increasing pH_{45 min} and decreasing drip loss, cooking loss, shear force, and lipid oxidation. PCA revealed that supplementation with only β-alanine or L-histidine was related to increased content of β-sheets, β-turns, and aliphatic bending groups and decreased content of α-helix groups. This study is the first to report such findings in slow-growing chicken. Our findings suggest that KRC can synthesize the highest carnosine levels after both β-alanine and L-histidine supplementation. Higher carnosine contents do not adversely affect meat quality, improve meat texture, and alter the secondary structures of proteins. The molecular mechanism underlying carnosine synthesis in chickens needs further study to better understand and reveal markers that facilitate the development of nutrient selection programs.

RNA Profiles of the Korat Chicken Breast Muscle with Increased Carnosine Content Produced through Dietary Supplementation with β-Alanine or L-Histidine

Simple Summary

Carnosine is a bioactive food component with several potential health benefits for humans due to its physiological functions. Dietary supplementation with β-alanine or L-histidine can increase the carnosine content of skeletal muscles in chickens. Dietary supplementation with β-alanine or L-histidine has produced a slow-growing chicken variety with high carnosine content in the breast meat; however, the supplementation with L-histidine alone softens the meat toughness, which may affect consumers’ willingness to buy the meat. Gene expression is a key factor that influences meat quality. Understanding the molecular mechanisms that affect carnosine content and meat toughness would allow the production of more value-added slow-growing chickens. We compared global gene expression in chicken breast muscles with differing carnosine contents and meat toughness produced through dietary supplementation with β-alanine or L-histidine. We identified differentially expressed genes involved in regulating myosin, collagen, intramuscular fat, and calpain—factors that may affect meat tenderness. Pathway enrichment analysis indicated that the insulin-related and adipocytokine signaling pathways were altered by dietary supplementation with β-alanine or L-histidine. These data will be useful for future studies on carnosine content and meat toughness in slow-growing chickens.

Abstract

Korat chicken (KRC) is a slow-growing chicken bred in Thailand, whose meat exhibits a unique toughness. A previous study produced KRC breast meat containing high carnosine content through dietary supplementation with β-alanine or L-histidine; however, the KRC that were fed an L-histidine-supplemented diet produced meat that was significantly more tender. Herein, we performed RNA-Seq to identify candidate genes involved in the regulation of carnosine content and meat toughness. Total RNA was isolated from five female KRC breast muscles in each treatment group that KRC fed diets without supplementation, supplemented with β-alanine or L-histidine. Compared to the non-supplemented group, we identified 118 and 198 differentially expressed genes (DEGs) in the β-alanine or L-histidine supplementation groups, respectively. Genes potentially related to meat tenderness—i.e., those regulating myosin, collagen, intramuscular fat, and calpain—were upregulated (LOC107051274, ACSBG1, and CAPNS2) and downregulated (MYO7B, MYBPH, SERPINH1, and PGAM1). However, carnosine synthase gene was not identified. Functional enrichment analysis identified pathways affected by dietary supplementation, including the insulin signaling pathway (β-alanine supplementation) and the insulin resistance and adipocytokine signaling pathways (L-histidine supplementation). The FoxO signaling pathway was identified as a regulatory network for both supplementation groups. The identified genes can be used as molecular markers of meat tenderness in slow-growing chickens.

Association of growth hormone and insulin-like growth factor I genotype with body weight, dominance of body weight, and mRNA expression in Korat slow-growing chickens

Objective

Growth hormone (GH) and insulin-like growth factor I (IGF-I) play a critical role in animal growth rates. We aimed to investigate the effect of GH and IGF-I genotypes on body weight (BW), dominance, and gene expression in slow-growing chickens at different ages.

Methods

A total of 613 Korat chickens (KRs) were bred and divided into three groups by genotype – A1A1, A1A3, and A3A3 for GH and AA, AC, and CC for IGF-I. Chickens were weighed every two weeks, and liver and breast muscle tissues were collected at 10 weeks of age. Genetic parameters of KRs were estimated using ASReml software. The GH and IGF-I mRNA levels were measured by quantitative polymerase chain reaction. Significant differences between traits were analyzed using the generalized linear model.

Results

A significant effect of GH genotypes on BW was found at most ages, and the A1A1 genotype had the highest value of BW. Compared with the A3A3 genotype, the A1A1 and A1A3 genotypes showed a higher dominance effect at 0 and 2 weeks, and genotype A1A1 had the highest value of dominance at 8 weeks of age. A difference in GH mRNA levels between genotypes was detected in breast muscle at 6 weeks and in the liver tissue at 2 weeks. In the case of IGF-I gene, the AA genotype had the highest BW at the beginning of life. Significant differences in BW dominance were found at 2 weeks. However, IGF-I mRNA levels were not different among genotypes in both breast muscles and liver tissues.

Conclusion

Our results revealed that GH and IGF-I influence growth, but may not be involved in heterosis. GH can be used as a marker gene in selection programs for growth because the homozygous genotype (A1A1) had the highest BW at all ages. The IGF-I is not a useful marker gene for selection programs.

The significant influence of residual feed intake on flavor precursors and biomolecules in slow-growing Korat chicken meat

Objective

This study investigated the association between feed efficiency, physicochemical properties, flavor precursors and biomolecules in the thigh meat of Korat (KR) chickens.

Methods

The feed intake and body weight of individual male KR chickens were recorded from 1 to 10 weeks old to calculate the individual residual feed intake (RFI) of 75 birds. At 10 weeks of age, chickens with the 10 highest (HRFI) and lowest RFI (LRFI) were slaughtered to provide thigh meat samples. The physicochemical properties (ultimate pH, water holding capacity [WHC], drip loss) and flavor precursors (guanosine monophosphate, inosine monophosphate (IMP), adenosine monophosphate and inosine) were analyzed conventionally, and Fourier transform infrared spectroscopy was used to identify the composition of biomolecules (lipids, ester lipids, amide I, amide II, amide III, and carbohydrates) and the secondary structure of the proteins. A group t-test was used to determine significant differences between mean values and principal component analysis to classify thigh meat samples into LRFI and HRFI KR chickens.

Results

The physicochemical properties of thigh meat samples from LRFI and HRFI KR chickens were not significantly different but the IMP content, ratios of lipid, lipid ester, protein (amide I, amide II) were significantly different (p<0.05). The correlation loading results showed that the LRFI group was correlated with high ratios of lipids, lipid esters, collagen content (amide III) and beta sheet protein (rg loading >0.5) while the HRFI group was positively correlated with protein (amide I, amide II), alpha helix protein, IMP content, carbohydrate, ultimate pH and WHC (rg loading >0.5).

Conclusion

The thigh meat from chickens with different RFI differed in physiochemical properties affecting meat texture, and in the contents of flavor precursors and biomolecules affecting the nutritional value of meat. This information can help animal breeders to make genetic improvements by taking more account of traits related to RFI.

Meat quality and Raman spectroscopic characterization of Korat hybrid chicken obtained from various rearing periods

Meat quality attributes vary with chicken age. Understanding the relationship between poultry age and the quality of the meat would be beneficial for efficient poultry farming to meet market needs. The Korat hybrid chicken (KC) is a new crossbred chicken whose meat quality is distinct from that of commercial broiler (CB) chickens and has not been well characterized. In this study, we characterized the physico-chemical properties of KC meat and correlate the findings with Raman spectral data. The protein content of KC breast and thigh meat increased with age. The pH of thigh meat decreased, while the water-holding capacity of breast meat increased as the age of the chickens increased. The amount of cholesterol in breast meat decreased as the rearing period was extended. Inosine 5′-monophosphate and guanosine 5′-monophosphate of breast meat decreased as KC grew older. The shear force values of meat from older birds increased concomitantly with an increase in total collagen. Principle component analysis revealed that the meat quality of CB was greatly different from that of KC meat. High shear force values of KC meat at 20 wk of age were well correlated with an increase in the β-sheet structure (amide I) and amide III of collagen. Raman spectra at 3,207 cm⁻¹ and relative α-helical content were negatively correlated with shear force values of KC breast meat. These could be used as markers to evaluate KC meat quality.

Association between Single Nucleotide Polymorphisms of the Major Histocompatibility Complex Class II Gene and Newcastle Disease Virus Titre and Body Weight in Leung Hang Khao Chickens

The aim of the present study was to investigate the effect of single nucleotide polymorphisms in the major histocompatibility complex (MHC) class II gene on resistance to Newcastle disease virus and body weight of the Thai indigenous chicken, Leung Hang Khao (Gallus gallus domesticus). Blood samples were collected for single nucleotide polymorphism analysis from 485 chickens. Polymerase chain reaction sequencing was used to classify single nucleotide polymorphisms of class II MHC. Body weights were measured at the ages of 3, 4, 5, and 7 months. Titres of Newcastle disease virus at 2 weeks to 7 months were determined and the correlation between body weight and titre was analysed. The association between single nucleotide polymorphisms and body weight and titre were analysed by a generalized linear model. Seven single nucleotide polymorphisms were identified: C125T, A126T, C209G, C242T, A243T, C244T, and A254T. Significant correlations between log titre and body weight were found at 2 and 4 weeks. Associations between single nucleotide polymorphisms and titre were found for C209G and A254T, and between all single nucleotide polymorphisms (except A243T) and body weight. The results showed that class II MHC is associated with both titre of Newcastle disease virus and body weight in Leung Hang Khao chickens. This is of concern because improved growth traits are the main goal of breeding selection. Moreover, the results suggested that MHC has a pleiotropic effect on the titre and growth performance. This mechanism should be investigated in a future study.