Phenotypic and genetic correlations of pork myoglobin content with meat colour and other traits in an eight breed-crossed heterogeneous population

Meat colour is one of the most important meat quality traits affecting consumption desire. Genetic improvement for meat colour traits is not so easy because pigs can be phenotyped only after slaughter. Besides the parameters from the optical instrument, other indexes that reflect the material basis of meat colour should be measured accurately and used in the genomic analysis. Myoglobin (Mb) is the main chemical component determining meat colour. However, to what extent the Mb content contributes to meat colour, and whether it can be used as a trait for pig breeding to improve meat colour, and the correlations of Mb content with complex porcine traits are largely unknown. To address these questions, we measured the muscle Mb content in 624 pigs from the 7th generation of a specially designed eight breed-crossed pig heterogeneous population, evaluated its phenotypic and genetic correlations with longissimus thoracis colour score at 24 h after slaughter. More than that, we also systematically phenotyped more than 100 traits on these animals to evaluate the potential correlations between muscle Mb content and economically important traits. Our results showed that the average muscle Mb content in the 624 pigs was 1.00 mg/g, ranging from 0.51 to 2.17 mg/g. We found that higher Mb content usually correlated with favourable meat colour, higher marbling score, less moisture content, and less drip loss. Genetic correlation analysis between muscle Mb content and 101 traits measured in this study shows that Mb content is also significantly correlated with 31 traits, including marbling, shear force, firmness, and juiciness. To our knowledge, this is one of the largest studies about the correlations of muscle Mb content with as many as 100 various traits in a large-scale genetically diversified population. Our results showed that the Mb content could be a selection parameter for the genetic improvement of meat colour. The selection for higher Mb content will also benefit marbling, shear force, firmness, and overall liking but might not affect the growth, carcass, and fat deposition traits.     

Association of HSL gene E1-c.276C>T and E8-c.51C>T mutation with economical traits of Chinese Simmental cattle

Hormone-sensitive lipase (HSL) is responsible for the decomposition of triglycerides in adipose tissue to release free fatty acids, and it is a key rate-limiting enzyme in the regulation of adipose tissue deposition and decomposition. The objective of this study was to evaluate the association between novel SNPs in the coding region of bovine HSL gene and carcass and meat quality traits of Chinese Simmental-cross steers. Two novel SNPs were genotyped and the 47 traits of carcass and meat quality traits were measured in the population studied. Statistical analysis revealed that the SNPs of HSL gene were associated with the carcass and meat quality traits. The individuals with TT genotypes of E1-276C>T showed significant higher dressing percentage, net meat rate, hind legs circumference, fat coverage rate, mesenteric fat and kidney fat (p < 0.05). E8-51C>T (P17S) also showed a significant association with the pH of beef and fatty acids content in Chinese Simmental cattle (p < 0.01). Our findings indicated that polymorphisms in HSL might be one of important genetic factors that influence carcass yield and meat quality in beef cattle, and it may be a useful marker for meat quality traits in future marker-assisted selection programs in beef cattle breeding and production.     

Does a single adjustment in the meat standards Australia beef grading model cater for different hormonal growth promotant formulations?

This paper investigated whether a single Hormonal Growth Promotant (HGP) adjustment in the Meat Standards Australia (MSA) beef grading model adequately predicted consumer eating quality of beef from cattle treated with different HGP formulations. This paper used consumer sensory data from two experiments. In experiment one, a total of 300 steers were allocated to three treatments; control (CON-100-F), 100 day oestradiol only HGP (OES-100-F), or a combination of trenbolone acetate and oestradiol HGP (TBA+OES-100-F) and finished in a feedlot for 73 days. In experiment two, a total of 200 steers were allocated either control or 400 day oestradiol only HGP treatments and finished on pasture for 389 days. Steers were slaughtered by finishing regime and carcass traits recorded. The anterior and posterior portions of the m. longissimus lumborum (LL-A and LL-P, respectively) and m. gluteus medius (GM) were collected and aged for five or 35 days. Grilled meat samples were scored for tenderness, juiciness, liking of flavour and overall acceptability using untrained consumers. Sensory scores were weighted by 0.3. 0.1, 0.3 and 0.3, respectively and summed to calculate a meat quality (MQ4) score. Residual MQ4 scores were calculated (observed MQ4 minus the predicted MQ4 score). The MSA model accounts for varied impacts of different HGPs on eating quality through a single HGP adjustment, and indirect impacts on carcass traits. For the majority of the HGP treatment samples, the residual MQ4 scores were not different to zero (5/18), or were positive i.e. the MSA model under-predicted these samples (11/18). Under-prediction was predominately for 35 day aged (7/9) and GM HGP treatment samples (6/6) and was considered low, with the majority less than ±5 MQ4 units. Under-prediction could be considered as advantageous through providing an additional safeguard to protect the interests of the consumers, rather than if the model had over-predicted and resulted in a more negative eating quality experience than expected. Some over-prediction was observed in the CON-100-F and TBA+OES-100-F treatment samples, which may be due to factors such as genetic variation and/or production environment. Minimal bias was observed when residual MQ4 was regressed against predicted MQ4 for the range of feeding regimes, muscles, ageing periods and treatment groups. This study showed that a single HGP adjustment in the MSA beef grading model, combined with the indirect effects of the different HGP formulations on carcass traits, provided a reasonable prediction of meat eating quality for different HGP formulations.     

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

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

Deciphering signature of selection affecting beef quality traits in Angus cattle

Artificial selection towards a desired phenotype/trait has modified the genomes of livestock dramatically that generated breeds that greatly differ in morphology, production and environmental adaptation traits. Angus cattle are among the famous cattle breeds developed for superior beef quality. This paper aimed at exploring genomic regions under selection in Angus cattle that are associated with meat quality traits and other associated phenotypes. The whole genome of 10 Angus cattle was compared with 11 Hanwoo (A-H) and 9 Jersey (A-J) cattle breeds using a cross-population composite likelihood ratio (XP-CLR) statistical method. The top 1% of the empirical distribution was taken as significant and annotated using UMD3.1. As a result, 255 and 210 genes were revealed under selection from A–H and A–J comparisons, respectively. The WebGestalt gene ontology analysis resulted in sixteen (A–H) and five (A–J) significantly enriched KEGG pathways. Several pathways associated with meat quality traits (insulin signaling, type II diabetes mellitus pathway, focal adhesion pathway, and ECM-receptor interaction), and feeding efficiency (olfactory transduction, tight junction, and metabolic pathways) were enriched. Genes affecting beef quality traits (e.g., FABP3, FTO, DGAT2, ACS, ACAA2, CPE, TNNI1), stature and body size (e.g., PLAG1, LYN, CHCHD7, RPS20), fertility and dystocia (e.g., ESR1, RPS20, PPP2R1A, GHRL, PLAG1), feeding efficiency (e.g., PIK3CD, DNAJC28, DNAJC3, GHRL, PLAG1), coat color (e.g., MC1-R) and genetic disorders (e.g., ITGB6, PLAG1) were found to be under positive selection in Angus cattle. The study identified genes and pathways that are related to meat quality traits and other phenotypes of Angus cattle. The findings in this study, after validation using additional or independent dataset, will provide useful information for the study of Angus cattle in particular and beef cattle in general.     

Improved tenderness of beef from bulls supplemented with active dry yeast is related to matrix metalloproteinases and reduced oxidative stress

Supplementing diets with active dry yeast (ADY, Saccharomyces cerevisiae) improves the carcass quality grade of beef cattle and the tenderness of beef. The relevant mechanisms have not been fully elucidated, but may be related to the effect of ADY on oxidative stress and the activity of matrix metalloproteinases (MMPs). To provide further insight into these mechanisms, this study evaluated the influence of ADY supplementation on growth performance, carcass traits, meat quality, concentrations of MMPs in serum (MMP-2, MMP-9 and MMP-13), oxidative stress indices and antioxidant capacity indices in beef cattle. Forty-six crossbred Simmental × Yanbian bulls (～18 months of age, BW 436 ± 35 kg) participated in a 145-day finishing trial. ADY supplementation significantly improved marbling deposition, intramuscular fat content, and beef tenderness (P < 0.05); altered individual fatty acid proportions in the beef and increased saturated fatty acids while decreasing polyunsaturated fatty acids (P < 0.05); significantly decreased the abundance of reactive oxygen species in serum and meat; significantly increased the level of superoxide dismutase in meat (P < 0.05); tended to increase the level of catalase (P = 0.075) in serum and glutathione reductase (P = 0.066) in meat; and increased the secretion of MMPs. The improvement of beef tenderness following ADY supplementation of finishing bulls is related to the effects of ADY on the secretion of MMPs and the lowering of oxidative stress.     

Genome-enabled prediction of meat and carcass traits using Bayesian regression,single-step genomic best linear unbiased prediction and blending methods in Nelore cattle

Several methods have been used for genome-enabled prediction (or genomic selection) of complex traits, for example, multiple regression models describing a target trait with a linear function of a set of genetic markers. Genomic selection studies have been focused mostly on single-trait analyses. However, most profitability traits are genetically correlated, and an increase in prediction accuracy of genomic breeding values for genetically correlated traits is expected when using multiple-trait models. Thus, this study was carried out to assess the accuracy of genomic prediction for carcass and meat quality traits in Nelore cattle, using single- and multiple-trait approaches. The study considered 15 780, 15 784, 15 742 and 526 records of rib eye area (REA, cm²), back fat thickness (BF, mm), rump fat (RF, mm) and Warner–Bratzler shear force (WBSF, kg), respectively, in Nelore cattle, from the Nelore Brazil Breeding Program. Animals were genotyped with a low-density single nucleotide polymorphism (SNP) panel and subsequently imputed to arrays with 54 and 777 k SNPs. Four Bayesian specifications of genomic regression models, namely, Bayes A, Bayes B, Bayes Cπ and Bayesian Ridge Regression; blending methods, BLUP; and single-step genomic best linear unbiased prediction (ssGBLUP) methods were compared in terms of prediction accuracy using a fivefold cross-validation. Estimates of heritability ranged from 0.20 to 0.35 and from 0.21 to 0.46 for RF and WBSF on single- and multiple-trait analyses, respectively. Prediction accuracies for REA, BF, RF and WBSF were all similar using the different specifications of regression models. In addition, this study has shown the impact of genomic information upon genetic evaluations in beef cattle using the multiple-trait model, which was also advantageous compared to the single-trait model because it accounted for the selection process using multiple traits at the same time. The advantage of multi-trait analyses is attributed to the consideration of correlations and genetic influences between the traits, in addition to the non-random association of alleles.     

Whole genome association study identifies regions of the bovine genome and biological pathways involved in carcass trait performance in Holstein-Friesian cattle

Background

Four traits related to carcass performance have been identified as economically important in beef production: carcass weight, carcass fat, carcass conformation of progeny and cull cow carcass weight. Although Holstein-Friesian cattle are primarily utilized for milk production, they are also an important source of meat for beef production and export. Because of this, there is great interest in understanding the underlying genomic structure influencing these traits. Several genome-wide association studies have identified regions of the bovine genome associated with growth or carcass traits, however, little is known about the mechanisms or underlying biological pathways involved. This study aims to detect regions of the bovine genome associated with carcass performance traits (employing a panel of 54,001 SNPs) using measures of genetic merit (as predicted transmitting abilities) for 5,705 Irish Holstein-Friesian animals. Candidate genes and biological pathways were then identified for each trait under investigation.

Results

Following adjustment for false discovery (q-value < 0.05), 479 quantitative trait loci (QTL) were associated with at least one of the four carcass traits using a single SNP regression approach. Using a Bayesian approach, 46 QTL were associated (posterior probability > 0.5) with at least one of the four traits. In total, 557 unique bovine genes, which mapped to 426 human orthologs, were within 500kbs of QTL found associated with a trait using the Bayesian approach. Using this information, 24 significantly over-represented pathways were identified across all traits. The most significantly over-represented biological pathway was the peroxisome proliferator-activated receptor (PPAR) signaling pathway.

Conclusions

A large number of genomic regions putatively associated with bovine carcass traits were detected using two different statistical approaches. Notably, several significant associations were detected in close proximity to genes with a known role in animal growth such as glucagon and leptin. Several biological pathways, including PPAR signaling, were shown to be involved in various aspects of bovine carcass performance. These core genes and biological processes may form the foundation for further investigation to identify causative mutations involved in each trait. Results reported here support previous findings suggesting conservation of key biological processes involved in growth and metabolism.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-837) contains supplementary material, which is available to authorized users.     

Impact of a high-fibre diet on genetic parameters of production traits in growing pigs

The use of diets with increased fibre content from alternative feedstuffs less digestible for pigs is a solution considered to limit the impact of increased feed costs on pig production. This study aimed at determining the impact of an alternative diet on genetic parameters for growth, feed efficiency, carcass composition and meat quality traits. A total of 783 Large White pigs were fed a high-fibre (HF) diet and 880 of their sibs were fed a conventional (CO) cereal-based diet. Individual daily feed intake, average daily gain, feed conversion ratio and residual feed intake were recorded as well as lean meat percentage (LMP), carcass yield (CY) and meat quality traits. Pigs fed the CO diet had better performances for growth and feed efficiency than pigs fed the HF diet. They also had lower LMP and higher CY. In addition, pigs fed the CO diet had lower loin percentage and ham percentage and higher backfat percentage. No differences were observed in meat quality traits between diets, except for a* and b* values. For all traits, the genetic variances and heritability were not different between diets. Genetic correlations for traits between diets ranged between 0.80 ± 0.13 and 0.99 ± not estimable, and none were significantly different from 0.99, except for LMP. Thus, traits in both diets were considered as mainly affected by similar sets of genes in the two diets. A genetic correlation lower than 0.80 would justify redesigning the breeding scheme; however, some genetic correlations did not differ significantly from 0.80 either. Therefore, larger populations are needed for a more definitive answer regarding the design of the breeding scheme. To further evaluate selection strategies, a production index was computed within diets for the 29 sires with estimated breeding value reliability higher than 0.35. The rank correlation between indices estimated in the CO and in the HF diet was 0.72. Altogether, we concluded that limited interaction between feed and genetics could be evidenced, and based on these results there is no need to change pig selection schemes to adapt to the future increased use of alternative feedstuffs in production farms.     

Non-destructive evaluation of carcass and ham traits and meat quality assessment applied to early and late immunocastrated Iberian pigs

Castration is a common practice in Iberian pigs due to their advanced age and high weight at slaughter. Immunocastration (IC) is an alternative to surgical castration that influences carcass and cut fatness. These traits need to be evaluated in vivo and postmortem. The aims of the present work were (a) to determine the relationship between ham composition measured with computed tomography (CT) and in vivo ultrasound (US) and carcass fat thickness measurements, (b) to apply these technologies to early (EIP) and late (LIP) immunocastrated Iberian pigs in order to evaluate carcass fatness and ham tissue composition and (c) to assess meat quality on these animals and to find the relationships between meat quality traits (namely, intramuscular fat (IMF)) and fat depot thicknesses. For this purpose, 20 purebred Iberian pigs were immunocastrated with three doses of Improvac ®, at either 4.5, 5.5 and 9 or 11, 12 and 14 months of age (EIP or LIP; respectively; n = 10 each) and slaughtered at 17 months of age. Fat depots were evaluated in vivo by US, in carcass with a ruler and in hams by CT. Carcass and cut yields, loin meat quality and loin acceptability by consumers were determined. Also, IMF was determined in the loin and three muscles of the ham. Carcass weight was 14.9 kg heavier in EIP vs LIP, and loin backfat thickness (US- and ruler-measured) was also greater in EIP. Similarly, CT-evaluated ham bone and fat contents were greater and smaller for EIP vs LIP, respectively. Loin and ham IMF were also greater in EIP, but the other meat quality parameters were similar. The acceptability of meat by consumers was high and it did not differ between IC protocols. Correlations between several fat depots measured with the different technologies were high. In conclusion, all these technologies allowed fat depot measurements, which were highly correlated despite being obtained at different anatomical locations.     

Serum metabolomic fingerprints of lambs fed chitosan and its association with performance and meat quality traits

Chitosan (CHI) is a natural biopolymer with antimicrobial, anti-inflammatory, antioxidant and digestive modulatory effects, which can be used in the ruminant diet to replace antibiotics. The aim of this study was to evaluate the effects of CHI on lamb growth traits, nutrients digestibility, muscle and fatty deposition, meat fatty acid (FA) profile, meat quality traits and serum metabolome. Thirty 30-month-old male lambs, half Suffolk and half Dorper, with an average BW of 21.65 ± 0.86 kg, were fed in a feedlot system for a total of 70 days. The lambs were separated into two groups according to the diet: the control (CON) group which received the basal diet and the CHI group which received the basal diet with the addition of CHI as 2 g/kg of DM in the diet. Lambs supplemented with CHI had a greater (P< 0.05) final BW, DM intake, final body metabolic weight (P< 0.05) and lower residual feed intake than the CON group. Animals fed CHI had a greater (P< 0.05) starch digestibility at 14 and 28 days, average daily gain at 14, 42 and 56 days, greater feed efficiency at 28 days and feed conversation at 14 and 42 days in feedlot. Most of the carcass traits were not affected (P> 0.05) by the treatment; however, the CHI supplementation improved (P< 0.05) dressing and longissimus muscle area. The treatments had no effect (P> 0.05) on the meat colour and other quality measurements. Meat from the CHI-fed lambs had a greater concentration (P< 0.05) of oleic-cis-9 acid, linoleic acid, linolenic-trans-6 acid, arachidonic acid and eicosapentaenoic acid. According to the variable importance in projection score, the most important metabolites to differentiate between the CON and the CHI group were hippurate, acetate, hypoxanthine, arginine, malonate, creatine, choline, myo-inositol, 2-oxoglutarate, alanine, glycerol, carnosine, histidine, glutamate and 3-hydroxyisobutyrate. Similarly, fold change (FC) analysis highlighted succinate (FC = 1.53), arginine (FC = 1.51), hippurate (FC = 0.68), myo-inositol (FC = 1.48), hypoxanthine (FC = 1.45), acetate (FC = 0.73) and malonate (FC = 1.35) as metabolites significantly different between groups. In conclusion, the present data showed that CHI changes the muscle metabolism improving muscle mass deposition, the lamb’s performance and carcass dressing. In addition, CHI led to an alteration in the FA metabolism, changes in the meat FA profile and improvements in meat quality.     

Genome-wide association study reveals a quantitative trait locus and two candidate genes on Sus scrofa chromosome 5 affecting intramuscular fat content in Suhuai pigs

Intramuscular fat content (IFC) is an essential quantitative trait of meat, affecting multiple meat quality indicators. A certain amount of IFC could not only improve the sensory score of pork but also increase the flavour, tenderness, juiciness and shelf-life. To dissect the genetic determinants of IFC, two methods, including genome-wide efficient mixed-model analysis (GEMMA) and linkage disequilibrium adjusted kinships (LDAKs), were used to carry out genome-wide association studies for IFC in Suhuai pig population. A total of 14 and 18 significant single nucleotide polymorphisms (SNPs) were identified by GEMMA and LDAK, respectively. The results of these two methods were highly consistent and all 14 significant SNPs in GEMMA were detected by LDAK. Seven of the 18 SNPs reached the genome-wide significance level (P < 9.85E−07) while 11 cases reached the suggestive significance level (P < 1.77E−05). These significant SNPs were mainly distributed on Sus scrofa chromosome (SSC) 5, 3, and 7. Moreover, one locus resides in a 2.27 Mb (71.37–73.64 Mb) region on SSC5 harbouring 13 significant SNPs associated with IFC, and the lead SNP (rs81302978) also locates in this region. Linkage disequilibrium (LD) analysis showed that there were four pairs of complete LD (r² = 1) among these 13 SNPs, and the remaining 9 SNPs with incomplete LD (r² ≠ 1) were selected for subsequent analyses of IFC. Association analyses showed that 7 out of 9 SNPs were significantly associated with IFC (P < 0.05) in 330 Suhuai pigs, and the other 2 SNPs tended to reach a significant association level with IFC (P < 0.1). The phenotypic variance explained (PVE) range of these 9 SNPs was 0.92–3.55%. Meanwhile, the lead SNP was also significantly associated (rs81302978) with IFC (P < 0.05) in 378 commercial hybrid pigs (Pietrain × Duroc) × (Landrace × Yorkshire) (PDLY), and the PVE was 1.38%. Besides, two lipid metabolism-relevant candidate genes, the leucine rich repeat kinase 2 (LRRK2) and PDZ domain containing ring finger 4 (PDZRN4) were identified in the 2.27 Mb region on SSC5. In conclusion, our results may provide a set of markers useful for genetic improvement of IFC in pigs and will advance the genome selection process of IFC on pig breeding programmes.     

Effects of genomic estimated breeding value and dietary energy to protein ratio on growth performance,carcass trait,and lipogenic gene expression in Hanwoo steer

“Genome-based precision feeding” is a concept that involves the application of customised diets to different genetic groups of cattle. We investigated the effects of the genomic estimated breeding value (gEBV) and dietary energy to protein ratio (DEP) on growth performance, carcass traits, and lipogenic gene expression in Hanwoo (Korean cattle) steers. Forty-four Hanwoo steers (BW = 636 kg, age = 26.9 months) were genotyped using the Illumina Bovine 50 K BeadChip. The gEBV was calculated using genomic best linear unbiased prediction. Animals were separated into high gEBV of marbling score or low-gMS groups based on the upper and lower 50% groupings of the reference population, respectively. Animals were assigned to one of four groups in a 2 × 2 factorial arrangement: high gMS/high DEP (0.084 MJ/g), high gMS/low DEP (0.079 MJ/g), low gMS/high DEP, and low gMS/low DEP. Steers were fed concentrate with a high or low DEP for 31 weeks. The BW tended to be higher (0.05 < P < 0.1) in the high-gMS groups compared to the low-gMS groups at 0, 4, 8, 12, and 20 weeks. The average daily gain (ADG) tended to be lower (P = 0.08) in the high-gMS group than in the low-gMS group. Final BW and measured carcass weight (CW) were positively correlated with the gEBV of carcass weight (gCW). The DEP did not affect ADG. Neither the gMS nor the DEP affected the MS and beef quality grade. The intramuscular fat (IMF) content in the longissimus thoracis (LT) tended to be higher (P = 0.08) in the high-gMS groups than in the low-gMS groups. The mRNA levels of lipogenic acetyl-CoA carboxylase and fatty acid binding protein 4 genes in the LT were higher (P < 0.05) in the high-gMS group than in the low-gMS group. Overall, the IMF content tended to be affected by the gMS, and the genetic potential (i.e., gMS) was associated with the functional activity of lipogenic gene expression. The gCW was associated with the measured BW and CW. The results demonstrated that the gMS and the gCW may be used as early prediction indexes for meat quality and growth potential of beef cattle.     

Genome-wide identification of quantitative trait loci for carcass composition and meat quality in a large-scale White Duroc × Chinese Erhualian resource population

Carcass and meat quality traits are economically important in pigs. In this study, 17 carcass composition traits and 23 meat quality traits were recorded in 1028 F₂ animals from a White Duroc × Erhualian resource population. All pigs in this experimental population were genotyped for 194 informative markers covering the entire porcine genome. Seventy-seven genome-wide significant quantitative trait loci (QTL) for carcass traits and 68 for meat quality were mapped to 34 genomic regions. These results not only confirmed many previously reported QTL but also revealed novel regions associated with the measured traits. For carcass traits, the most prominent QTL was identified for carcass length and head weight at 57 cM on SSC7, which explained up to 50% of the phenotypic variance and had a 95% confidence interval of only 3 cM. Moreover, QTL for kidney and spleen weight and lengths of cervical vertebrae were reported for the first time in pigs. For meat quality traits, two significant QTL on SSC5 and X were identified for both intramuscular fat content and marbling score in the longissimus muscle, while three significant QTL on SSC1 and SSC9 were found exclusively for IMF. Both LM and the semimembranous muscle showed common QTL for colour score on SSC4, 5, 7, 8, 13 and X and discordant QTL on other chromosomes. White Duroc alleles at a majority of QTL detected were favourable for carcass composition, while favourable QTL alleles for meat quality originated from both White Duroc and Erhualian.     

Genetic and Phenotypic Correlations between Performance Traits with Meat Quality and Carcass Characteristics in Commercial Crossbred Pigs

Genetic correlations between performance traits with meat quality and carcass traits were estimated on 6,408 commercial crossbred pigs with performance traits recorded in production systems with 2,100 of them having meat quality and carcass measurements. Significant fixed effects (company, sex and batch), covariates (birth weight, cold carcass weight, and age), random effects (additive, litter and maternal) were fitted in the statistical models. A series of pairwise bivariate analyses were implemented in ASREML to estimate heritability, phenotypic, and genetic correlations between performance traits (n = 9) with meat quality (n = 25) and carcass (n = 19) traits. The animals had a pedigree compromised of 9,439 animals over 15 generations. Performance traits had low-to-moderate heritabilities (±SE), ranged from 0.07±0.13 to 0.45±0.07 for weaning weight, and ultrasound backfat depth, respectively. Genetic correlations between performance and carcass traits were moderate to high. The results indicate that: (a) selection for birth weight may increase drip loss, lightness of longissimus dorsi, and gluteus medius muscles but may reduce fat depth; (b) selection for nursery weight can be valuable for increasing both quantity and quality traits; (c) selection for increased daily gain may increase the carcass weight and most of the primal cuts. These findings suggest that deterioration of pork quality may have occurred over many generations through the selection for less backfat thickness, and feed efficiency, but selection for growth had no adverse effects on pork quality. Low-to-moderate heritabilities for performance traits indicate that they could be improved using traditional selection or genomic selection. The estimated genetic parameters for performance, carcass and meat quality traits may be incorporated into the breeding programs that emphasize product quality in these Canadian swine populations.     

Effects of dietary energy content and source using by-products on carcass and meat quality traits of cull ewes

In cull ewes, energy supply by time short periods can affect growth, carcass traits, and meat quality. The objective of this study was to evaluate the effect of biscuit bran (BB) and cashew nut bran (CNB) in diets with different total digestible nutrient (TDN) content on animal performance and carcass and meat traits of cull ewes. Twenty Morada Nova cull ewes, with the initial BW of 30.1 ± 3.56 kg, and three years of age were distributed in a completely randomized design into factorial scheme 2 × 2, with two energy sources (BB and CNB) × two levels of TDN. All diets were isoproteic with variations in TDN content increased by 10% (TDN10) and 25% (TDN25) above the recommended requirement for the study category, which was 66.0% TDN. The experimental period lasted 56 days, in which daily intake in relation to metabolic weight and weight performance of the animals was determined. The hot carcass, the cold carcass, commercial cuts, loin eye area, and subcutaneous fat thickness were measured, obtained, or calculated. A sample of the Longissimus lumborum (LL) muscle was used by determination of physical–chemical composition, sensory, and fatty acid (FA) profile analysis. The ANOVA was performed to access the effect of diet and energy level on the characteristics studied, and means were compared by the Turkey and Kruskal Wallis tests at 5% of probability. A higher daily gain weight was observed from TDN25 (P = 0.006). Among by-products, higher nutrient intakes were observed in animals fed with BB diets (P < 0.01), except for crude protein. The same patterns have been observed for live weight, reconstituted half-carcass, higher yield in fat thickness, and internal carcass length. Cashew nut bran produced darker colored meat (P = 0.017) and higher cooking weight loss (P = 0.008). Higher lipid content was observed in animals submitted to diets with CNB and TDN25 (P = 0.001). The internal length of the carcass was higher in animals fed with BB (P = 0.041). All diets did not effect on sensory characteristics (P > 0.05). Total digestible nutrient in 25% above recommended promotes higher weight gain and meat with higher lipid content and less weight loss by cooling. The inclusion of BB, compared to CNB, provides a higher weight of carcasses and better conformation, in addition to lower total lipid content with higher proportion for monounsaturated FAs in meat, providing more attractive features for the consumer market.     

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

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

Growth curve,blood parameters and carcass traits of grass-fed Angus steers

The increasing demand for natural products is currently transforming the meat industry, making grass-fed and finished beef a valuable option for improving profits. However, the transformation of conventional operations to grass-fed systems comprises many modifications, such as logistical, technological, and financial that could be very complex and expensive, involving economic risk. Therefore, in this study, we analyzed the growth curve, critical economic traits, and carcass quality and finished characteristics over several consecutive years in closely related grass-fed and finished Angus steers, to reduce the genetic effect on the results. We found that grass-fed steers require around 188 additional days to reach the market weight (approx. 470 kg) and had approximately 70% less average daily gain compared to the grain-fed and finished steers. Regression analysis demonstrated an interaction between feed and age (P < 0.01); thus, individual regressions were fitted for each regimen style, obtaining almost perfect linear curves for both treatments, which could be straightforwardly used in practical situations due to its simplicity. Six of eight carcass traits were different between grain-fed and grass-fed and finished steers. Hot-carcass weight, dressing, back fat, and quality grade were superior in grain-fed individuals, contrarily to yield grade and ribeye area/carcass ratio, which were better in grass-fed and finished steers (P < 0.05).Interestingly, the meat tenderness was certainly low and similar in both treatments (P = 0.25), indicating the feasibility of producing tender meat with animals under a grass-fed diet. Nevertheless, according to the quality grade analysis, grain-fed carcasses were greater ranked compared to grass-fed bodies (P < 0.01), regardless of their same tenderness. The results will provide valuable information for better understanding beef cattle in grass-feeding finishing systems, especially from weaning to harvest. Additionally, the study will expand the knowledge about the quality of meat obtained from animals that received grass exclusively, becoming relevant information for economic evaluation and management decisions for grass-based cattle operations.     

Genome-Wide Association Study Identifies Loci and Candidate Genes for Body Composition and Meat Quality Traits in Beijing-You Chickens

Body composition and meat quality traits are important economic traits of chickens. The development of high-throughput genotyping platforms and relevant statistical methods have enabled genome-wide association studies in chickens. In order to identify molecular markers and candidate genes associated with body composition and meat quality traits, genome-wide association studies were conducted using the Illumina 60 K SNP Beadchip to genotype 724 Beijing-You chickens. For each bird, a total of 16 traits were measured, including carcass weight (CW), eviscerated weight (EW), dressing percentage, breast muscle weight (BrW) and percentage (BrP), thigh muscle weight and percentage, abdominal fat weight and percentage, dry matter and intramuscular fat contents of breast and thigh muscle, ultimate pH, and shear force of the pectoralis major muscle at 100 d of age. The SNPs that were significantly associated with the phenotypic traits were identified using both simple (GLM) and compressed mixed linear (MLM) models. For nine of ten body composition traits studied, SNPs showing genome wide significance (P<2.59E−6) have been identified. A consistent region on chicken (Gallus gallus) chromosome 4 (GGA4), including seven significant SNPs and four candidate genes (LCORL, LAP3, LDB2, TAPT1), were found to be associated with CW and EW. Another 0.65 Mb region on GGA3 for BrW and BrP was identified. After measuring the mRNA content in beast muscle for five genes located in this region, the changes in GJA1 expression were found to be consistent with that of breast muscle weight across development. It is highly possible that GJA1 is a functional gene for breast muscle development in chickens. For meat quality traits, several SNPs reaching suggestive association were identified and possible candidate genes with their functions were discussed.