Genetic parameters for concentrations of minerals in longissimus muscle and their associations with palatability traits in Angus cattle

Trace mineral concentrations and accretion rates in the empty body and body tissues of growing Fleckvieh (German Simmental) bulls

This research project aimed to generate basic data for specifying the trace mineral requirements of Fleckvieh (German Simmental) bulls. Hence, the concentrations of the trace minerals iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) in the empty-body and body tissue fractions of growing Fleckvieh bulls slaughtered at 120-780 kg live weight were determined. Results were used to calculate trace mineral accretion rates. Fe and Zn represented the largest shares in the animals' bodies. The Zn accretion increased, while Mn accretion steadily declined during cattle growth. Fe accretion attained a maximum at 400 kg live weight. Cu accretion declined until 600 kg live weight and then increased slightly afterwards. The provided data may be used to adjust the recommendations with respect to the trace mineral requirements of growing Fleckvieh bulls.

Content and gain of macro minerals in the empty body and body tissues of growing bulls

This research aimed to generate basic data for specifying the macro mineral requirements of beef bulls. Hence, the contents of the macro minerals calcium, phosphorus, sodium, potassium, sulfur, and magnesium in the empty body and body tissue fractions of growing Fleckvieh (German Simmental) bulls with 120-780 kg live weight were determined. Results were used to calculate mineral gain rates in bulls within a wide weight range from 100 to 800 kg live weight. Calcium and phosphorus represented the largest shares in the animals' bodies. Body mineral content changed during animal growth due to progressing bone mineralization and increasing amounts of fat in all body tissues. Peak mineral gain rates were observed for calcium, phosphorus, and magnesium during the 200-400 kg live weight range. The gain rates of sodium, potassium, and sulfur declined steadily during cattle growth. The provided data allow to adjust the existing values of net mineral requirements of growing Fleckvieh bulls within the factorial requirement calculation method.

Vascular Rinsing and Chilling Carcasses Improves Meat Quality and Food Safety: A Review

Rinse & Chill^® technology (RCT) entails rinsing the vasculature using a chilled isotonic solution (3°C; 98.5% water and a blend of dextrose, maltose, and sodium phosphates) to rinse out the residual blood from the carcass. Infusion of pre-chilled solutions into intact animal carcasses immediately upon exsanguination is advantageous in terms of lowering the internal muscle temperature and accelerating chilling. This technology is primarily used for purposes of effective blood removal, favorable pH decline, and efficient carcass chilling, all of which improve meat quality and safety. Although RCT solution contains some substrates, the pre-rigor muscle is still physiologically active at the time of early postmortem and vascular rinsing. Consequently, these substrates are fully metabolized by the muscle, leaving no detectable residues in meat. The technology has been commercially approved and in continuous use since 2000 in the United States and since 1997 in Australia. As of January 2022, 23 plants have implemented RCT among the 5 countries (Australia, US, Canada, New Zealand, and Japan) that have evaluated and approved RCT. All plants are operating under sound Sanitation Standard Operation Procedures (SSOP) and a sound Hazard Analysis Critical Control Point (HACCP) program. No food safety issues have been reported associated with the use of this technology. RCT has been adapted by the meat industry to improve product safety and meat quality while improving economic performance. Therefore, this review summarizes highlights of how RCT technically works on a variety of animal types (beef, bison, pork, and lamb).

Physical and biochemical mechanisms associated with beef carcass vascular rinsing effects on meat quality: a review

Carcass vascular rinsing and chilling involves infusing a chilled isotonic solution (98.5% water and a blend of mono- and di-saccharides and phosphates) into the vasculature immediately upon exsanguination. Primary purposes of carcass vascular rinsing are to (1) effectively remove residual blood from the carcass; (2) lower internal muscle temperature rapidly; and (3) optimize pH decline by effective delivery of glycolytic substrates in the rinse solution. Previous studies have revealed that the beef carcass vascular rinsing early postmortem positively affects meat quality, product shelf-life, and food safety. Thus, the objective of this review is to provide a more comprehensive understanding of the physical and biochemical mechanisms associated with beef carcass vascular rinsing, focusing on the relationship between quality attributes (CIE L*, a*, b*; chemical states of myoglobin; oxygen consumption and sarcomere length) and muscle metabolic response to various substrate solutions (Rinse & Chill^®, fructose, sodium phosphate, and dipotassium phosphate) that stimulate or inhibit the rate of glycolysis early postmortem. In addition, this review discusses the absence of metabolite residues (phosphorus, sodium, and glucose) related to the application of the chilled isotonic solution. This review primarily focuses on beef and as such extending the understanding of the mechanisms and meat quality effects discussed to other species associated with vascular rinsing, in particular pork, may be limited.

Influence of Genotype and Slaughter Age on the Content of Selected Minerals and Fatty Acids in the Longissimus Thoracis Muscle of Crossbred Bulls

Simple Summary

In some European countries, including Poland, beef production is based mostly on dairy cattle herds. Beef quality can be improved by the commercial crossbreeding of dairy cows with beef bulls. The offspring are characterized by higher fattening performance and more desirable carcass characteristics. The experiment was performed on 72 bulls produced by crossing Polish Holstein-Friesian (PHF) cows with bulls of three most popular beef breeds: Hereford (HH), Limousin (LM), and Charolais (CH), to determine the effects of genotype and age at slaughter on the content of selected minerals (K, Na, Mg, Zn, and Fe) and fatty acid profile in beef. The meat of PHF × LM crosses had a lower content of K and Mg, compared with the remaining crossbred bulls. The Fe content per kg of meat was higher in bulls slaughtered at 21 months of age than in those slaughtered at 15 months of age. The best sire breed for crossing with dairy cows cannot be clearly indicated based on the present findings. However, the results of this study suggest that bulls should be slaughtered at 21 months of age to achieve the optimal values of most analyzed traits and parameters, in particular the fatty acid profile.

Abstract

The aim of this study was to determine the effects of genotype and slaughter age on the mineral content and fatty acid profile of beef. The experiment was performed on 72 crossbred bulls produced by crossing Polish Holstein-Friesian (PHF) cows with bulls of three beef breeds: Hereford (HH), Limousin (LM), and Charolais (CH), slaughtered at 15, 18, and 21 months of age. Samples of the longissimus thoracis muscle were collected to determine their mineral (potassium—K, sodium—Na, magnesium—Mg, zinc—Zn, and iron—Fe) and fatty acid composition. The meat of PHF × LM crosses had a lower (p ≤ 0.01) content of K and Mg, compared with the remaining crossbred bulls. The Fe content per kg of meat was 4 mg higher (p ≤ 0.01) in bulls slaughtered at 21 months of age than in those slaughtered at 15 months of age. The content of monounsaturated fatty acids (MUFAs) in intramuscular fat was 2.77% higher in bulls slaughtered at 21 months of age than in those slaughtered at 15 months of age. The n-6/n-3 polyunsaturated fatty acids (PUFA) ratio did not exceed 4.0, and it was most desirable in PHF × LM crosses (2.84) and in the oldest bulls (2.92).

Genetic regulators of mineral amount in Nelore cattle muscle predicted by a new co-expression and regulatory impact factor approach

Mineral contents in bovine muscle can affect meat quality, growth, health, and reproductive traits. To better understand the genetic basis of this phenotype in Nelore (Bos indicus) cattle, we analysed genome-wide mRNA and miRNA expression data from 114 muscle samples. The analysis implemented a new application for two complementary algorithms: the partial correlation and information theory (PCIT) and the regulatory impact factor (RIF), in which we included the estimated genomic breeding values (GEBVs) for the phenotypes additionally to the expression levels, originally proposed for these methods. We used PCIT to determine putative regulatory relationships based on significant associations between gene expression and GEBVs for each mineral amount. Then, RIF was adopted to determine the regulatory impact of genes and miRNAs expression over the GEBVs for the mineral amounts. We also investigated over-represented pathways, as well as pieces of evidences from previous studies carried in the same population and in the literature, to determine regulatory genes for the mineral amounts. For example, NOX1 expression level was positively correlated to Zinc and has been described as Zinc-regulated in humans. Based on our approach, we were able to identify genes, miRNAs and pathways not yet described as underlying mineral amount. The results support the hypothesis that extracellular matrix interactions are the core regulator of mineral amount in muscle cells. Putative regulators described here add information to this hypothesis, expanding the knowledge on molecular relationships between gene expression and minerals.

Cross talk between mineral metabolism and meat quality: a systems biology overview

Meat quality has an inherent complexity because of the multiple interrelated causative factors and layers of feedback regulation. Understanding the key factors and their interactions has been challenging, despite the availability of remarkable high-throughput tools and techniques that have provided insights on muscle metabolism and the genetic basis of meat quality. Likewise, we have deepened our knowledge about mineral metabolism and its role in cell functioning. Regardless of these facts, complex traits like mineral content and meat quality have been studied under reductionist approaches. However, as these phenotypes arise from complex interactions among different biological layers (genome, transcriptome, proteome, epigenome, etc.), along with environmental effects, a holistic view and systemic-level understanding of the genetic basis of complex phenotypes are in demand. Based on the state of the art, we addressed some of the questions regarding the interdependence of meat quality traits and mineral content. Furthermore, we sought to highlight potential regulatory mechanisms arising from the genes, miRNAs, and mineral interactions, as well as the pathways modulated by this interplay affecting muscle, mineral metabolism, and meat quality. By answering these questions, we did not intend to give an exhaustive review but to identify the key biological points, the challenges, and benefits of integrative genomic approaches.

Muscle transcriptome analysis reveals genes and metabolic pathways related to mineral concentration in Bos indicus

Mineral content affects the biological processes underlying beef quality. Muscle mineral concentration depends not only on intake-outtake balance and muscle type, but also on age, environment, breed, and genetic factors. To unveil the genetic factors involved in muscle mineral concentration, we applied a pairwise differential gene expression analysis in groups of Nelore steers genetically divergent for nine different mineral concentrations. Here, based on significant expression differences between contrasting groups, we presented candidate genes for the genetic regulation of mineral concentration in muscle. Functional enrichment and protein-protein interaction network analyses were carried out to search for gene regulatory processes concerning each mineral. The core genetic regulation for all minerals studied, except Zn, seems to rest on interactions between components of the extracellular matrix. Regulation of adipogenesis-related pathways was also significant in our results. Antagonistic patterns of gene expression for fatty acid metabolism-related genes may explain the Cu and Zn antagonistic effect on fatty acid accumulation. Our results shed light on the role of these minerals on cell function.

Identifying labelling and marketing advantages of nutrients in minced beef meat: A case study

In 2006, the European Commission approved nutrition and health claim regulations of foods to stimulate healthier choices. To document how commercial, minced beef meat complied with regulations, meat samples from 72 carcasses were analysed. These samples were a source of niacin (B3), pyridoxine (B6), phosphorus and iron (cow meat only), and a rich source of protein, monounsaturated fat, vitamin B12 and zinc. A potential exists for establishing beef meat as a source of vitamin K, iron and selenium. The meat's nutrient relevance for young women when ingesting 150 g of raw beef mince/day was estimated. Increased levels of riboflavin (B2), pantothenic acid (B5), iron and selenium beyond presently observed, would better support this group's recommended nutrient intake. If the bioactivity of 25-OH-vitamin D3 could be used in calculations, vitamin D3 in the minced meat would add positively to the intake of vitamin D3 that was 49% of the recommended intake.

Fatty acid profile, mineral content, and palatability of beef from a multibreed Angus-Brahman population

Consumers demand meat that is both healthy and palatable, 2 attributes of meat that are affected by lipid content. Many cattle in the southern United States are Bos indicus influenced, as this improves the ability to survive and thrive in these subtropical regions. However, these animals tend to have leaner carcasses and less marbled meat products. Thus, the objective of this study was to examine the effect of percent Brahman genetics on carcass characteristics, palatability, fatty acids profile, and minerals content in LM of steers from a multibreed population ranging from 100% Angus to 100% Brahman. Breed effect was significant for birth weight (P = 0.0003), weaning weight (P < 0.0001), HCW (P < 0.0001), dressing percentage (P = 0.0008), ribeye area (P = 0.002), quality grade (P < 0.0001), and marbling score (P < 0.0001), and all these traits except dressing percentage decreased as the percentage of Brahman increased. Among palatability traits, breed group had a significant effect only on tenderness (TEND) and connective tissue (CT) scores (P < 0.0001). Least squares means decreased from Angus (5.75 ± 0.13 TEND score and 6.29 ± 0.14 CT score, respectively) to Brahman (4.84 ± 0.10 TEND score and 5.49 ± 0.11 CT score, respectively) as indicated by a significant linear effect. Breed group significantly affected the percentage of several individual fatty acids, saturated fatty acids (SFA), and polyunsaturated fatty acids (PUFA), but not monounsaturated fatty acids (MUFA). The 100% Angus group had the highest percentage of SFA at 49.92%, which was significantly higher (P < 0.05) than the SFA percentage in the 50%, 75%, and 100% Brahman breed groups. Brangus animals also had an increased SFA percentage compared with the 100% Brahman animals (P < 0.05). No significant effect was identified for the concentration of PUFA across the 6 breed groups (P = 0.14). Least squares means decreased from 100% Angus to 100% Brahman for concentration of total fat, SFA, and MUFA (g/mg meat). The concentration of magnesium (P < 0.0001), phosphorus (P = 0.06), and potassium (P = 0.06) increased as the percentage of Brahman increased. Our study shows that breed has a significant effect on the fatty acid profile of beef. Cattle with high Brahman percentage, which are characterized by lower marbled meat, will present a more favorable healthfulness profile with reduced content of SFA and MUFA but the same content of PUFA as purebred Angus animals.

Importance of breed aptitude (beef or dairy) in determining trace element concentrations in bovine muscles

The aim of this study was to determine the concentrations of various trace elements in muscles with different oxidative/glycolytic profiles (cardiac [CA]; diaphragm [DI], as oxidative; trapezius [TR], as intermediate oxidative/glycolytic; and semimembranosus [SM], as glycolytic muscle) of ten dairy-aptitude (Holstein-Friesian, HF), ten beef-aptitude (Galician Blonde, GB) and ten cross-breed (GBxHF) calves. The type of muscle was a highly significant factor in relation to the concentrations of all elements, whereas breed was only significant for Fe, Mn and Zn in the SM muscle. The concentrations of the main trace elements (Cu, Fe, Se and Zn) were significantly lower in GB and GBxHF than in HF, that were mainly associated with differences in the oxidative/glycolytic profile, probably due to the muscular hypertrophy characteristic of heavily muscled breeds. The pattern of distribution was similar in all breeds, with significantly higher concentrations in the CA muscle, followed by the DI; trace element concentrations in the SM and TR muscles were very similar.

Relationships between mineral concentrations and physicochemical characteristics in the Longissimus thoracis muscle of Japanese Black cattle

The relationship between mineral concentrations, and the relationship of mineral concentrations with physicochemical characteristics in muscles were investigated using the Longissimus thoracis (LT) muscle of 44 Japanese Black steers. We determined moisture content, fat content, meat color, fatty acid composition and mineral concentrations in the LT muscle. Magnesium (Mg), potassium (K) and zinc (Zn) concentrations had negative correlations with fat content, but sodium (Na), manganese (Mn), copper (Cu) and molybdenum (Mo) concentrations were not correlated with fat content. The concentrations of Mg, Mn, Fe, Cu and Zn largely and positively contributed to the first principal component of mineral concentrations. Because the red muscle was rich in these minerals compared to the white muscle, the variation of these minerals probably results from the abundance of red fibers in the LT muscle. The concentration of K was positively correlated with moisture content but Na concentration was not related to moisture content, suggesting that the intracellular fluid volume can largely affect moisture content. The results of the present experiment suggest that mineral concentrations reflect some traits such as not only fat content but also the composition of myofiber type and the intracellular fluid volume in the LT muscle of Japanese Black cattle.

Iron Content Affects Lipogenic Gene Expression in the Muscle of Nelore Beef Cattle

Iron (Fe) is an essential mineral for metabolism and plays a central role in a range of biochemical processes. Therefore, this study aimed to identify differentially expressed (DE) genes and metabolic pathways in Longissimus dorsi (LD) muscle from cattle with divergent iron content, as well as to investigate the likely role of these DE genes in biological processes underlying beef quality parameters. Samples for RNA extraction for sequencing and iron, copper, manganese, and zinc determination were collected from LD muscles at slaughter. Eight Nelore steers, with extreme genomic estimated breeding values for iron content (Fe-GEBV), were selected from a reference population of 373 animals. From the 49 annotated DE genes (FDR<0.05) found between the two groups, 18 were up-regulated and 31 down-regulated for the animals in the low Fe-GEBV group. The functional enrichment analyses identified several biological processes, such as lipid transport and metabolism, and cell growth. Lipid metabolism was the main pathway observed in the analysis of metabolic and canonical signaling pathways for the genes identified as DE, including the genes FASN, FABP4, and THRSP, which are functional candidates for beef quality, suggesting reduced lipogenic activities with lower iron content. Our results indicate metabolic pathways that are partially influenced by iron, contributing to a better understanding of its participation in skeletal muscle physiology.

ATP Sensitive Potassium Channels in the Skeletal Muscle Function: Involvement of the KCNJ11(Kir6.2) Gene in the Determination of Mechanical Warner Bratzer Shear Force

The ATP-sensitive K⁺-channels (KATP) are distributed in the tissues coupling metabolism with K⁺ ions efflux. KATP subunits are encoded by KCNJ8 (Kir6.1), KCNJ11 (Kir6.2), ABCC8 (SUR1), and ABCC9 (SUR2) genes, alternative RNA splicing give rise to SUR variants that confer distinct physiological properties on the channel. An high expression/activity of the sarco-KATP channel is observed in various rat fast-twitch muscles, characterized by elevated muscle strength, while a low expression/activity is observed in the slow-twitch muscles characterized by reduced strength and frailty. Down-regulation of the KATP subunits of fast-twitch fibers is found in conditions characterized by weakness and frailty. KCNJ11 gene knockout mice have reduced glycogen, lean phenotype, lower body fat, and weakness. KATP channel is also a sensor of muscle atrophy. The KCNJ11 gene is located on BTA15, close to a QTL for meat tenderness, it has also a role in glycogen storage, a key mechanism of the postmortem transformation of muscle into meat. The role of KCNJ11 gene in muscle function may underlie an effect of KCNJ11 genotypes on meat tenderness, as recently reported. The fiber phenotype and genotype are important in livestock production science. Quantitative traits including meat production and quality are influenced both by environment and genes. Molecular markers can play an important role in the genetic improvement of animals through breeding strategies. Many factors influence the muscle Warner-Bratzler shear force including breed, age, feeding, the biochemical, and functional parameters. The role of KCNJ11gene and related genes on muscle tenderness will be discussed in the present review.

Concentration of Potassium in Plasma, Erythrocytes, and Muscle Tissue in Cows with Decreased Feed Intake and Gastrointestinal Ileus

BACKGROUND

Healthy cows consume large amounts of potassium and a sudden loss in appetite can lead to hypokalemia. The routine method to evaluate potassium homeostasis is the measurement of the extracellular potassium in plasma or serum, but this does not provide information about the intracellular potassium pool.

HYPOTHESIS/OBJECTIVES

To evaluate potassium homeostasis by comparing the extracellular and intracellular potassium concentration in cows with reduced feed intake and gastrointestinal ileus.

ANIMALS

Twenty cows 1-3 days postpartum (group 1) and 20 cows with gastrointestinal ileus (group 2).

METHODS

Observational cross-sectional study. Plasma potassium was measured by using an ion-sensitive electrode. Intracellular potassium was measured in erythrocytes and muscle tissue (muscle biopsy) by using inductively coupled plasma optical emission spectroscopy.

RESULTS

Cows of group 1 did not have hypokalemia. Overall cows with gastrointestinal ileus were hypokalemic (mean ± SD, 2.9 mmol/L ± 0.78), but potassium concentration in erythrocytes and muscle tissue was not lower than in postpartum cows. Intracellular potassium in erythrocytes varied very widely; group 1: 3497-10735 mg/kg (5559 ± 2002 mg/kg), group 2: 4139-21678 mg/kg (7473 ± 4034 mg/kg). Potassium in muscle tissue did not differ between group 1 (3356 ± 735 mg/kg wet weight) and group 2 (3407 ± 1069 mg/kg wet weight). No association between extracellular and intracellular potassium concentrations was detected.

CONCLUSIONS AND CLINICAL IMPORTANCE

That measurement of plasma potassium concentration is not sufficient to evaluate potassium metabolism of cows.

Genetic parameters and genetic correlations among triacylglycerol and phospholipid fractions in Angus cattle

The objective of this study was to estimate genetic parameters for intramuscular fatty acids from triacylglycerol (TAG) and phospholipid (PL) fractions in beef LM tissue. Longissimus muscle samples were obtained from 1,833 Angus cattle to determine the intramuscular fatty acid composition for 31 lipids and lipid classes from TAG and PL fractions and were classified by structure into saturated (SFA), monounsaturated (MUFA), polyunsaturated (PUFA), omega-3 (n-3), and omega-6 (n-6) fatty acids. An atherogenic index (AI) was also determined as a measure of the unsaturated fatty acid to SFA ratio. Restricted maximum likelihood methods combined with pedigree data were used to estimate variance components with the WOMBAT software package. Heritability estimates ranged from 0.00 to 0.63 for the major classes of fatty acids. Heritability estimates differed between the TAG and PL fractions, with higher estimates for TAG up to 0.64 and lower estimates for PL that ranged from 0.00 to 0.14. Phenotypic and genetic correlations among individual fatty acids were determined for the TAG fraction as well as among carcass traits, including rib eye area, numerical marbling score, yield grade, ether fat, and Warner-Bratzler shear force value. Strong negative or positive genetic correlations were observed among individual fatty acids in the TAG fraction, which ranged from -0.99 to 0.97 ( < 0.05). Moderate correlations between carcass traits and fatty acids from the TAG fraction ranged from -0.43 to 0.32 ( < 0.05). These results indicate that fatty acids prominent in beef tissues show significant genetic variation as well as genetic relationships with carcass traits.

Sire breed effect on beef longissimus mineral concentrations and their relationships with carcass and palatability traits

The objective of this study was to evaluate sire breed effect on mineral concentration in beef longissimus thoracis (LT) and investigate the correlations between beef mineral concentrations and carcass and palatability traits. Steer progeny (N=246) from the Germplasm Evaluation project-Cycle VIII were used in this study. In addition to carcass traits, LT was evaluated for mineral concentrations, Warner-Bratzler shear force, and palatability traits. A mixed linear model estimated breed effects on mineral concentrations. No significant sire breed (P≥0.43) or dam breed (P≥0.20) effects were identified for mineral concentrations. Pearson correlation coefficients were calculated among mineral concentrations, carcass, and sensory traits. Zinc concentration was positively correlated (P≤0.05) with total iron (r=0.14), heme iron (r=0.13), and magnesium (r=0.19). Significant (P<0.05) correlations were identified between non-heme or heme iron and most traits in this study. Magnesium concentration was correlated with all carcass and palatability traits.

Polymorphisms in calpastatin and mu-calpain genes are associated with beef iron content

The objective of this study was to assess the association of markers in the calpastatin and mu-calpain loci with iron in beef cattle muscle. The population consisted of 259 cross-bred steers from Beefmaster, Brangus, Bonsmara, Romosinuano, Hereford and Angus sires. Total iron and heme iron concentrations were measured. Markers in the calpastatin (referred to as CAST) and mu-calpain (referred to as CAPN4751) genes were used to assess their association with iron levels. The mean and standard error for iron and heme iron content in the population was 35.6 ± 1.3 μg and 27.1 ± 1.4 μg respectively. Significant associations (P < 0.01) of markers were observed for both iron and heme iron content. For CAST, animals with the CC genotype had higher levels of iron and heme iron in longissimus dorsi muscle. For CAPN4751, individuals with the TT genotype had higher concentrations of iron and heme iron than did animals with the CC and CT genotypes. Genotypes known to be associated with tougher meat were associated with higher levels of iron concentration.

Genetic parameters for meat quality traits of Australian lamb meat

Genetic parameters were estimated for a range of meat quality traits recorded on Australian lamb meat. Data were collected from Merino and crossbred progeny of Merino, terminal and maternal meat breed sires of the Information Nucleus programme. Lambs born between 2007 and 2010 (n=8968) were slaughtered, these being the progeny of 372 sires and 5309 dams. Meat quality traits were found generally to be of moderate heritability (estimates between 0.15 and 0.30 for measures of meat tenderness, meat colour, polyunsaturated fat content, mineral content and muscle oxidative capacity), with notable exceptions of intramuscular fat (0.48), ultimate pH (0.08) and fresh meat colour a* (0.08) and b* (0.10) values. Genetic correlations between hot carcass weight and the meat quality traits were low. The genetic correlation between intramuscular fat and shear force was high (-0.62). Several measures of meat quality (fresh meat redness, retail meat redness, retail oxy/met value and iron content) appear to have potential for inclusion in meat sheep breeding objectives.