Utilizing genomic tools in breeding programs accelerates genetic progress, particularly for difficult/expensive to measure traits such as meat colour. This study aimed to estimate genetic parameters and identify genomic regions and candidate genes associated with meat colour traits in Canadian crossbred beef cattle. Heritability estimates for lightness ( L* ), chroma ( c* ), and hue angle ( Hu) were 0.44, 0.20, and 0.57, respectively. L* and Hu were highly phenotypically (0.86) and genetically (0.98) correlated. The genome-wide association revealed a total of 30, 24, and 25 SNP windows explaining >0.5% additive genetic variance for L*, c*, and Hu, respectively. These SNP windows collectively explained >20% of the genetic variance for the three meat colour traits. The genes GNPDA2, CALCRL, CALM1, KIT, PRKN, and PRKAA2 are the most promising candidates associated with L*, TEX37, ADAMTS9, PRKACB, TTLL7, TFAM, AGT, ACAT2, and PPP1R3C with c*, and MMP2, AKR1B1, AKR1B10, and CYP7A1 with Hu. These candidate genes are mainly involved in energy metabolism pathways, among which the most important are glucose, fatty, and lipid metabolism.

Genetic parameters were estimated for objective and subjective traits assessed after 3 and 29 days aging in meat samples of 1154 commercial beef cattle. Meat attributes [Warner-Bratzler shear force (WBSF), intramuscular fat (IMF), and pH] and sensory traits [flavor intensity (FI), off-flavor (OF), connective tissue (CT), overall tenderness (OT), sustained juiciness (SJ), and overall palatability (OP)] were available. The animal mixed model used included additive genetic and residual effects as random effects, contemporary group as fixed effect and genomic breed composition and slaughter age as covariates. Genetic parameters were estimated using airemlf90 software and single-step genomic BLUP. Heritability estimates for OT (3 and 29 d), OP (3 d) and OF (29 d) were of moderate magnitude ranging from 0.18 ± 0.07 to 0.31 ± 0.07. Heritabilities were negligible or of low magnitude for all other sensory traits with values ranging from 0.03 ± 0.05 to 0.14 ± 0.07. Among objectively measured traits, the estimate of heritability for meat pH was moderate at day 3 (0.20 ± 0.08) and negligible at 29 (0.00 ± 0.05). For IMF and WBSF the heritability estimates were 0.43 ± 0.09 and 0.54 ± 0.09, and 0.22 ± 0.07 and 0.19 ± 0.07 for day 3 and 29, respectively. Genetic correlations between days for each sensory trait tended to be of high and positive magnitude ranging from 0.54 ± 0.60 to 0.99 ± 0.28. Genetic and phenotypic correlations of subjectively assessed traits were consistent in direction and magnitude with WBSF (negative) and IMF (positive) suggesting that genetic selection based on objectively measured traits can be used for meat quality improvement and to increase consumer satisfaction. In addition, selection can be implemented using sensory traits collected after 3 days of aging.

The application of two computer vision systems (CVS) was evaluated to predict primal and retail cut composition in youthful beef carcasses. Left carcass sides from a total of 634 animals were broken down into primal cuts, scanned using dual-energy x-ray absorptiometry for the prediction of tissue composition and fabricated into retail cuts. Cold carcass camera (CCC) images led to higher R2 values than hot carcass camera (HCC) images. The CVS coefficients of prediction for the primal cut weights ranged from 0.61 to 0.97. For the primal cut tissue composition predictions, R2 values ranged from 0.09 for Brisket HCC bone prediction to 0.82 for Chuck CCC fat prediction. Retail cut weight estimations had similar R2 values, ranging from 0.10 for IMPS 112 (Ribeye roll-denuded ribeye) to 0.99 for IMPS 113C (semi-boneless chuck) both using CCC. The results suggest the feasibility of CVS technologies to predict beef primal and retail cuts weights together with tissue composition, and yield percentages.

This study used 1076 crossbred steers to evaluate the effects of calf-fed and yearling-fed beef production systems, implant strategies (with and without implants), and their interactions on the primal tissue composition (lean and fat components) of individual primal cuts using complete carcass dissection data. The results indicate that production system × implant interactions affected loin and rib primal weight percentages as well as marbling (p < 0.05) but did not affect the dissectible lean and fat contents of the individual primal cut (p > 0.05). Implants increased lean and decreased fat tissue contents of primal cut; however, the production system only affected lean content in the loin (p < 0.05) and fat content in the loin, round, and rib (p < 0.05). Redundancy analysis revealed a strong association between Angus breed percentage and marbling, as well as between Simmental breed percentage and multiple primal lean traits. Response surface regression models explained less variability in the tissue composition traits in calf-fed compared with yearling-fed animals, suggesting the need for further exploration using genomic studies.

This study evaluated whether different colour intensities of ribeye steaks from dark-cutting (B4 grade) beef carcasses (Dark-B4DK/Moderate-B4MD) were similar in appearance and eating quality to steaks from normal (N) carcasses of lower marbling grades (AA or A) as assessed by consumers. The B4MDAAA and B4DK/MDAA had similar raw appearance and eating quality to N carcasses with a one quality downgrade for marbling (P > 0.1), potentially supporting a B4MDAAA and B4DK/MDAA re-class to NAA and NA grades, respectively. Cooked B4DKAAA steaks had greater juiciness and tenderness acceptability (P < 0.01) and similar appearance, flavour and overall acceptability and purchase intent compared to NAA steaks (P > 0.1). However, consumers perceived greater marbling and lower colour acceptability (P < 0.01) in raw B4DKAAA compared to NAA steaks, lowering the purchase intent scores of B4DKAAA steaks (P < 0.01). These results suggest merit for continuing a B4DKAAA segregated grade, unless the superior eating quality of B4DKAAA could offset its poorer raw appearance through consumer education or modified atmosphere packaging.

This study determined the potential of computer vision systems, namely the whole-side carcass camera (HCC) compared to the rib-eye camera (CCC) and dual energy X-ray absorptiometry (DXA) technology to predict primal and carcass composition of cull cows. The predictability (R2) of the HCC was similar to the CCC for total fat, but higher for lean (24.0%) and bone (61.6%). Subcutaneous fat (SQ), body cavity fat, and retail cut yield (RCY) estimations showed a difference of 6.2% between both CVS. The total lean meat yield (LMY) estimate was 22.4% better for CCC than for HCC. The combination of HCC and CCC resulted in a similar prediction of total fat, SQ, and intermuscular fat, and improved predictions of total lean and bone compared to HCC/CCC. Furthermore, a 25.3% improvement was observed for LMY and RCY estimations. DXA predictions showed improvements in R2 values of 26.0% and 25.6% compared to the HCC alone or the HCC + CCC combined, respectively. These results suggest the feasibility of using HCC for predicting primal and carcass composition. This is an important finding for slaughter systems, such as those used for mature cattle in North America that do not routinely knife rib carcasses, which prevents the use of CCC.

Intramuscular Ehrlich Chromogen (EC) and pyridinoline (Pyr) concentrations in the gluteus medius (GM) and semitendinosus (ST) from crossbred Angus calf(n = 14) and yearling-fed (n = 14) steer and mature cow (MC, n = 12) carcasses were related to collagen and intramuscular connective tissue (IMCT) thermal stability and peak Warner-Bratzler shear force (WBSF). In both muscles, Pyr density was greater in MC, while EC concentrations were comparable in calfand yearling-fed steer muscles and lowest in MC muscles. Thermal denaturation temperature and enthalpy of IMCT were highest in both muscles when from MC, although only total collagen was correlated with WBSF in calf fed-yearling fed steer data. Results confirmed that EC concentration contributed to collagen thermal stability in steer muscles, but decreased it in MC muscles, while Pyr was consistently associated with collagen thermal stability.

Carcass attributes of steers were examined for influences of selection for residual feed intake (RFI), and exposure to different levels of prenatal nutrition. Heifers characterized for RFI corrected for backfat were mated to bulls with genetic potential for either High-RFI or Low-RFI, such that the progeny were expected to be H/H or L/L RFI (sire/dam). Pregnant heifers were assigned to a low diet (Ldiet; 0.40 kg/d ADG), or moderate diet (Mdiet; 0.57 kg/d ADG), from 30 to 150 days of gestation, after which all heifers were managed similarly. Steer offspring (n = 23) were also managed similarly until slaughter. Dressing percentage of steers from H-RFI dams/sires exposed to Ldiet during gestation was lower than all other groups (P = 0.02). Marbling was greater for steers from H-RFI parents, as was fat content of longissimus thoracis et lumborum and triceps brachii (P ≤ 0.02). Results suggest that parental selection for RFI and prenatal maternal diet can influence carcass characteristics of progeny.

Evaluating RNA quality and transcriptomic profile of beef muscle over time post-mortem may provide insight into RNA degradation and underlying biological and functional mechanisms that accompany biochemical changes occurring post-mortem during transformation of muscle to meat. RNA was extracted from longissimus thoracis (LT) sampled from British Continental crossbred heifer carcasses (n = 7) stored at 4°C in an abattoir drip cooler at 5 time points post-mortem, i.e., 45 min (0 h), 6 h, 24 h, 48 h, and 72 h. Following RNA-Sequencing, processed reads were aligned to the ARS-UCD1.2 bovine genome assembly. Subsequent differential expression (DE) analysis identified from 51 to 1434 upregulated and 27 to 2256 downregulated DE genes at individual time points compared to time 0 h, showing a trend for increasing counts of both upregulated and downregulated genes over time. Gene ontology and biological pathway term enrichment analyses on sets of DE genes revealed several processes and their timelines of activation/deactivation that accompanied or were involved with muscle transformation to meat. Although the quality of RNA in refrigerated LT remained high for several days post-mortem, the expression levels of several known biomarker genes for meat quality began to change from 24 h onwards. Therefore, to ensure accuracy of predictions on meat quality traits based on the expression levels of those biomarker genes in refrigerated beef muscle tissue, it is crucial that those expression measurements be made on RNA sampled within 24 h post-mortem. The present study also highlighted the need for more research on the roles of mitochondrial genes and non-coding genes in orchestrating muscle tissue processes after death, and how pre-mortem immune status might influence post-mortem meat quality.

Consumption of red meat contributes to the intake of many essential nutrients in the human diet including protein, essential fatty acids, and several vitamins and trace minerals, with high iron content, particularly in meats with high myoglobin content. Demand for red meat continues to increase worldwide, particularly in developing countries where food nutrient density is a concern. Dietary and genetic manipulation of livestock can influence the nutritional value of meat products, providing opportunities to enhance the nutritional value of meat. Studies have demonstrated that changes in livestock nutrition and breeding strategies can alter the nutritional value of red meat. Traditional breeding strategies, such as genetic selection, have influenced multiple carcass and meat quality attributes relevant to the nutritional value of meat including muscle and fat deposition. However, limited studies have combined both genetic and nutritional approaches. Future studies aiming to manipulate the composition of fresh meat should aim to balance potential impacts on product quality and consumer perception. Furthermore, the rapidly emerging fields of phenomics, nutrigenomics, and integrative approaches, such as livestock precision farming and systems biology, may help better understand the opportunities to improve the nutritional value of meat under both experimental and commercial conditions.

This study evaluated the relationship among palatability attributes, volatile compounds, and fatty acid (FA) profiles in meat from barley, corn, and blended (50:50, barley and corn) grain-fed steers. Multiple correspondence analysis with three dimensions (Dim) explained 62.2% of the total variability among samples. The Dim 1 and 2 (53.3%) separated pure from blended grain-fed beef samples. Blended grain beef was linked to a number of volatiles including (E,E)-2,4-decadienal, hexanal, 1-octen-3-ol, and 2,3-octanedione. In addition, blended grain-fed beef was linked to fat-like and rancid flavors, stale-cardboard, metallic, cruciferous, and fat-like aroma descriptors, and negative categories for flavor intensity (FI), off-flavor, and tenderness. A possible combination of linoleic and linolenic acids in the blended diet, lower rumen pH, and incomplete biohydrogenation of blended grain-fed polyunsaturates could have increased (p ≤ 0.05) long-chain n-6 fatty acids (LCFA) in blended grain-fed beef, leading to more accumulation of FA oxidation products in the blended than in barley and corn grain-fed meat samples. The Dim 3 (8.9%) allowed corn separation from barley grain beef. Barley grain-fed beef was mainly linked to alkanes and beef positive FI, whereas corn grain-fed beef was associated with pyrazines, in addition to aldehydes related to n-6 LCFA oxidation.

Effects of residual feed intake (RFI) and genetic group on growth, carcass, and meat quality characteristics of bovine longissimus lumborum (LL), triceps brachii (TB), semimembranosus (SM), and gluteus medius (GM) muscles were investigated using 72 purebred Angus, purebred Charolais, and Angus crossbred steers (n = 24 per genetic group) classified as either high (inefficient) or low (efficient) RFI (n = 12 high and low RFI steers within genetic group). There was no RFI effect (P > 0.05) on growth, carcass, and meat quality measurements except high RFI steers had the highest dry matter intake (P < 0.05), and low RFI TB was rated as having reduced beef flavour intensity and sustained juiciness (P < 0.05). Purebred Angus and Charolais LL and GM had lower shear force values (P < 0.05) than Angus crossbreds and ageing reduced mean shear force values except in TB. For TB, SM, and GM, Angus crossbred steers had the highest mean beef flavour intensity scores, and Charolais SM and TB were less tender than those of Angus crossbred (P < 0.05). Overall, RFI did not influence most meat quality traits; therefore, low RFI animals may contribute to reducing feed costs or environmental impact without compromising meat quality and palatability.

There have been many attempts to increase n-3 fatty acids (FA) in beef due to their health benefits and their presence in ruminant animals [1]. However, when polyunsaturated fatty acids are too abundant, oxidation can result in a shorter shelf life and negative flavours or off-flavours in cooked meat. Vahmani et al. [2] improved the profile of health favourable FA (n-3, vaccenic and rumenic) in beef by feeding co-extruded flaxseed (flaxseed, peas, and alfalfa) before alfalfa-grass hay. However, this beef enriched with healthful FA resulted in tougher steaks with lower beef flavour and greater off-flavour intensity, presenting a fishy offflavour to an extent that might be detectable by consumers [3]. The aim of this study was to characterize the volatile compounds responsible for the fishy off-flavour found in beef with health enhanced FA profiles.

Feeding ultra-high levels (5–10 × 106 IU/hd/d) of vitamin D3 (vitD3) prior to slaughter has been shown to enhance post-mortem proteolysis and improve beef tenderness. However, due to potential toxicity risks, these levels of vitD3 are not permitted in feed. The present study was designed to test whether long-term dietary supplementation of vitD3 at the maximum allowable level would improve beef tenderness. Forty Angus-cross heifers (469 ± 18 kg) were stratified by weight to 4 pens of 10 heifers, and pens were randomly allocated to one of two barely-grain based finishing diets: Control [NRC recommendation for vitD3 (275 IU /kg DM)] or high-vitD3 diet [maximum allowed vitD3 for beef cattle in Canada (3000 IU vitD3/kg DM)]. The heifers were fed ad libitum for 120 days, feed intake was recorded daily, and heifers were weighed every 28 days. At 72h post-mortem, four 2.5 cm steaks were removed from left longissimus lumborum of each carcass, vacuum packaged and aged at 2.5°C for 4d, 13d, 20d and 27d post-mortem. Steaks were then grilled to an internal temperature of 71 °C, and transferred to a 2°C cooler for 24 h. Warner–Bratzler shear force (WBSF) was determined on 6 cores (1.9 cm in diameter) from each steak perpendicular to the fiber grain (TA-XT Plus Texture Analyzer; Texture Technologies Corp., Hamilton, MA, USA). Data were analyzed using the PROC MIXED procedure of SAS. Daily dry matter intake (11.83 kg), final weight (609 kg), average daily gain (1.76 kg/d) and feed efficiency (0.14) did not differ (P >0.10) between heifers fed control or high-vitD3 diet. WBSF values were reduced (P<0.05) by increase in aging time, but were not affected by diet at any time during aging. In conclusion, supplementing diets with the maximum allowed amount of vitD3 over the finishing period does not improve tenderness of beef.

Dark-cutting is a youthful (under 30 months) carcass condition that is severely penalized within the Canadian grading system. Carcasses that ‘cut dark’ are assigned a grade of Canada B4 and their value is reduced by up to $0.50/lb, meaning that up to $300 in value can be lost per head if a carcass grades B4. According to the 2010/11 Beef Quality Audit, 2.5% of youthful cattle were dark cutters, while the Canadian Beef Grading Agency reported 1.28% in 2010/2011, suggesting the audit sample contained a higher percentage of dark cutters than the Canadian population as a whole. Assuming 1.28% of Canadian cattle are dark cutters, this represents a loss in value of up to over $1.2 million annually, depending on the level of discount.

To determine the effect of a needle-free injection device (NFID) on tissue damage and beef sub-primal quality, Angus steers were vaccinated and boostered subcutaneously using needle syringe (NS; n = 20) and the NFID (n=22). The primary vaccination occurred at 60 d of age (right side of the neck), and booster at 120 d after first vaccination (left side of the neck); respectively, both with a bovine viral diarrhea vaccine. The vaccination for both injection systems was on the anterior angle of the neck triangle zone. Infrared thermography (320 x 240 pixels) was performed on d 0, 2, 5 and 7 post-vaccination to measure skin temperature and assess skin reaction (SKINR). Steers were backgrounded in pasture, finished in a feedlot and slaughtered, when reaching a final BW of 605 kg, for further carcass visual tissue damage and histopathological evaluation. Visual inspection of the post-vaccination SKINR was performed 120 d after the last vaccination. The IRT measurement, skin temperatures at the injection site were higher in NS-vaccinated steers than NFID-vaccinated steers (P < 0.02). In both vaccinations occasions, NFID-steers had a greater proportion of SKINR compared to NS-steers (NFID ≥ 83 vs. NS 0%; P < 0.01).On carcasses, “suspected lesions” were identified in the subcutaneous and seam fat (~ 2.6 x 3.8 cm size; NFID = 6 and NS = 3). The core samples obtained from NFID and NS samples were confirmed to have ‘no vital lesion’ from histopathological examinations. Thus, further analysis of the shear force and the collagen content was not performed. In conclusion, the use of NFID technology does not cause tissue damage and can be used to eliminate the risk of broken needles.

The objective of this study was to identify the genomic regions associated with Warner-Bratzler shear force (WBSF) and sensory traits at 3 and 29 d ageing via genome wide association study. A total of 982 animals including 486 steers and 495 heifers with proportions of the main breeds including Angus (37%), Charolais (18 %) Hereford (10%), Limousin (11%) and Simental (8%) had actual and imputed high density genotypes (HD; n=414,469 SNPs). The association analyses were performed using linear mixed models implemented in GCTA software. The genomic heritability for tenderness and meat quality traits using the HD SNP were estimated using GVCBLUP software and ranged from 0.01 to 0.32 for sustained juiciness and WBSF at 3 d of aging, respectively. A total of 518 SNPs showed association (P < 0.00009) located with, or nearby (at ±100k base) 835 genes. Some of the detected associations were previously reported including CAPN1 which was found to be associated with tenderness at 29 din this dataset. The olfactory transduction pathway was the most significantly (P < 0.001) enriched pathway using the Database for Annotation, Visualization and Integrated Discovery (DAVID v6.8). In addition, the DAVID analyses suggested 36 and 23 genes involved in sensory perception of chemical stimulus (at 0.06 % false discovery rate; FDR) and sensory perception of smell, respectively, as the most significant (6% FDR) enriched mechanisms contributing to the genetic variation of meat quality and sensory traits in the current study. With availability of whole genome sequence genotypes, the associated genomic regions found in the current study will be investigated further in order to search for causal variants for meat tenderness and quality traits in the beef cattle.

Dual energy X-ray absorptiometry (DXA) was evaluated for its accuracy in predicting total lean, fat and bone in beef carcass sides and primal cuts. Left carcass sides (n = 316) were broken down into primal cuts, scanned using DXA and then dissected to fat, lean and bone. The DXA estimates for bone, lean and fat from the primals (n = 237) were used to calibrate partial least squares regression (PLSR) models for predicting tissue weights. Models were validated using 79 additional carcass sides, which were broken into primals, scanned using DXA, and subsequently dissected to fat, lean and bone. Models were highly accurate for predicting tissue weights for the entire carcass side (lean R-2 = 0.991, fat R-2 = 0.985 and bone R-2 = 0.941) and within most primal cuts. Results suggest DXA technology can be utilized to accurately predict carcass tissue composition for whole carcass sides and within most primals.

The eating quality and shear force of meat from mature beef carcasses graded within the Canadian grading system were compared with youthful carcasses. Eleven muscles were obtained from mature-graded carcasses with >50% ossification (D1, D2, D3, and D4; n = 84) and youthful carcasses with <50% ossification [over 30 mo (OTM); n = 18, and under 30 mo (UTM) of age; n = 18, based on dentition]; muscles were aged 14 d prior to sensory and shear force analysis. Many muscles from mature-graded carcasses were juicier than UTM, however, most were less tender (P < 0.05). Psoas major was tender, particularly in D1 and OTM carcasses where tenderness measures were not significantly different from UTM (P > 0.05). Shear force values from the infraspinatus of D1 and OTM carcasses were not different from UTM. Flavour intensity was higher in several muscles from D1, D2, and D4 carcasses (P < 0.05), whereas flavour intensity was lower in several muscles from D3 (P < 0.05). Changes to eating quality attributes differed among mature grades; therefore, processors could potentially use the information presented here as a guide for utilizing cuts which retain high eating quality and separating those requiring tenderness intervention to reach consumer acceptability.