Beef-on-dairy: Meat quality of veal and prediction of intramuscular fat using the Q-FOM™ Beef camera at the 5th-6th thoracic vertebra

This study aims to describe the meat quality of young Holstein (HOL) beef-on-dairy heifers and bulls sired by Angus (ANG, n = 109), Charolais (CHA, n = 101) and Danish Blue (DBL, n = 127), and to investigate the performance of the handheld vision-based Q-FOM™ Beef camera in predicting the intramuscular fat concentration (IMF%) in M. longissimus thoracis from carcasses quartered at the 5th-6th thoracic vertebra. The results showed significant differences between crossbreeds and sexes on carcass characteristics and meat quality. DBL × HOL had the highest EUROP conformation scores, whereas ANG × HOL had darker meat with higher IMF% (3.52%) compared to CHA × HOL (2.99%) and DBL × HOL (2.51%). Bulls had higher EUROP conformation scores than heifers, and heifers had higher IMF% (3.70%) than bulls (2.31%). These findings indicate the potential for producing high-quality meat from beef-on-dairy heifers and ANG bulls. The IMF% prediction model for Q-FOM performed well with R2 = 0.91 and root mean squared error of cross validation, RMSECV = 1.33%. The performance of the prediction model on the beef-on-dairy veal subsample ranging from 0.9 to 7.4% IMF had lower accuracy (R2 = 0.48) and the prediction error (RMSEveal) was 1.00%. When grouping beef-on-dairy veal carcasses into three IMF% classes (2.5% IMF bins), 62.6% of the carcasses were accurately predicted. Furthermore, Q-FOM IMF% predictions and chemically determined IMF% were similar for each combination of sex and crossbreed, revealing a potential of Q-FOM IMF% predictions to be used in breeding, when aiming for higher meat quality.

Satellite cells sourced from bull calves and dairy cows differs in proliferative and myogenic capacity - Implications for cultivated meat

Cultivated meat produced with primary muscle satellite cells (SCs) will need a continuous supply of isolated cell material from relevant animal donors. Factors such as age, sex, and breed, along with the sustainability and availability of donor animals, could determine the most appropriate donor type for an efficient production. In this study, we focus on the proliferation and differentiation of bovine SCs isolated from bull calf and dairy cow muscle samples. The proliferative performance of bull calf SCs was significantly better than SCs from dairy cows, however a dynamic differentiation assay revealed that the degree of fusion and formation of myotubes were similar between donor types. Furthermore, the proliferation of SCs from both donor types was enhanced using an in-house developed serum-free media compared to 10% FBS, which also delayed myogenic differentiation and increased final cell population density. Using gene chip transcriptomics, we identified several differentially expressed genes between the two donor types, which could help explain the observed cellular differences. This data also revealed a high biological variance between the three replicate animals within donor type, which seemed to be decreased when using our in-house serum-free media. With the use of the powerful imaging modalities of Cytation 5, we developed a novel high contrast brightfield-enabled label-free myotube quantification method along with a more efficient end-point fusion analysis using Phalloidin-staining. The results give new insights into the bovine SC biology and potential use of bull calves and dairy cows as relevant donor animals for cultivated beef cell sourcing. The newly developed differentiation assays will further enhance future research within the field of cultivated meat and SC biology.

A simple and robust serum-free media for the proliferation of muscle cells

Cultivated meat production requires an efficient, robust and highly optimized serum-free cell culture media for the needed upscaling of muscle cell expansion. Existing formulations of serum-free media are complex, expensive and have not been optimized for muscle cells. Thus, we undertook this work to develop a simple and robust serum-free media for the proliferation of bovine satellite cells (SCs) through Design of Experiment (DOE) and Response Surface Methodology (RSM) using precise and high-throughput image-based cytometry. Proliferative attributes were investigated with transcriptomics and long-term performance was validated using multiple live assays. Here we formulated a media based on three highly optimized components; FGF2 (2 ng/mL), fetuin (600 µg/mL) and BSA (75 µg/mL) which together with an insulin-transferrin-selenium (1x) supplement, sustained the proliferation of bovine SCs, porcine SCs and murine C2C12 muscle cells. Remarkably, cells cultured in our media named Tri-basal 2.0+ performed better than cell cultured in 10% FBS, with respect to proliferation. Hence, the optimized Tri-basal 2.0+ enhanced serum-free cell attachment and long-term proliferation, providing an alternative solution to the use of FBS in the production of cultivated meat.

Recombinant production of growth factors for application in cell culture

Culturing eukaryotic cells has widespread applications in research and industry, including the emerging field of cell-cultured meat production colloquially referred to as “cellular agriculture”. These applications are often restricted by the high cost of growth medium necessary for cell growth. Mitogenic protein growth factors (GFs) are essential components of growth medium and account for upwards of 90% of the total costs. Here, we present a set of expression constructs and a simplified protocol for recombinant production of functionally active GFs, including FGF2, IGF1, PDGF-BB, and TGF-β1 in Escherichia coli. Using this E. coli expression system, we produced soluble GF orthologs from species including bovine, chicken, and salmon. Bioactivity analysis revealed orthologs with improved performance compared to commercially available alternatives. We estimated that the production cost of GFs using our methodology will significantly reduce the cost of cell culture medium, facilitating low-cost protocols tailored for cultured meat production and tissue engineering.

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Developed methodology for low-cost production of soluble, bioactive GFs

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Purified GFs were active on NIH-3T3 and bovine satellite cells

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Some GF orthologs outperformed commercially sourced GFs

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Production of GFs using these methods can foster significant cost savings

Collagen, intramuscular fat and proteolysis affect Warner-Bratzler shear-force of muscles from Bos taurus breed types differently at weaning, after backgrounding on pasture, and after feedlotting

Context The texture of beef is highly important for the eating experience, and there is a continued interest in understanding the biochemical basis for the variation in texture between cattle and their meat cuts in order to improve and minimise variation in tenderness due to production and processing factors. Aims The present study aimed to investigate the impact of characteristics of meat on Warner-Bratzler shear-force (WBSF) as an indicator of texture of beef as affected by breed type, age/feeding phase, and muscle. Methods Seventy-five steers of three breed types (Angus, Hereford and Wagyu × Angus) were slaughtered after weaning 6 months old (n = 15), after backgrounding 17 months old (n = 30) and after feedlotting 25 months old (n = 30). At slaughter three muscles (M. supraspinatus, M. semitendinosus and M. longissimus lumborum) were sampled from each steer, and pH, intramuscular fat and collagen content, sarcomere length, and proteolysis (desmin degradation) were measured and used to explain the variation in WBSF after 7 and 14 days of aging. Key results Meat from Hereford and Angus steers had higher WBSF after 7 days of aging compared with Wagyu × Angus steers, but after 14 days of aging there was only a difference between Hereford and Wagyu × Angus in the M. supraspinatus and M. semitendinosus. The WBSF of the young weaned steers and steers slaughtered after backgrounding were dependent on the degree of proteolysis in the muscles, whereas for steers slaughtered after feedlotting the content of collagen was more important for the WBSF. The amount of intramuscular fat had a significant impact on the differences in WBSF within the specific muscle studied. In contrast to the general dogma that WBSF increase with age, WBSF decreased in M. semitendinosus and M. longissimus lumborum from the weaned 6-month-old steers to the 25-month-old steers finished in feed-lot, whereas in M. supraspinatus the older feed-lot finished steers had a higher WBSF. Conclusion The factors contributing to the Warner-Bratzler shear force of beef depends on the age/feeding phase of the animal and the muscle and less on the breed type. Implications Optimisation of texture in beef through breeding and production should address different traits dependent on the age/feeding phase of the slaughter animal.

Supplementation of sows with L-Arginine during gestating and lactation affects muscle traits of offspring related with postnatal growth and meat quality: From conception to consumption

This study investigated the effect of dietary inclusion of 25 g/day of _L-Arginine (n = 7) or iso‑nitrogenous amounts of alanine (n = 6) from d 30 of gestation to d 28 of lactation of sows on performance, muscle traits and meat quality in offspring. From each litter, heaviest and smallest littermate of both sexes were reared from d 28 and slaughtered at d 140 in accordance with a 2³factorial design. A response to _L-Arginine were obtained on small females where _L-Arginine increased birth weight, however this effect disappeared at weaning. _L-Arginine increased daily gain by 7% and increased the cross-sectional area of the M. semitendinosus in small females by 14%, suggesting an increased lean ratio. Mechanistic studies showed firstly, that small female littermates had increased number of muscle fibres (myogenesis) after _L-Arginine treatment (11%) and secondly increased total DNA (12%) as a consequence of satellite cell proliferation. Traits describing tenderness seem to be affected by _L-Arginine but further studies are needed.

Bioactive peptides in beef: Endogenous generation through postmortem aging

The present research was performed to investigate endogenous release of bioactive peptides in beef during postmortem aging times (1, 10 and 20days). Gradually decreased Warner-Bratzler shear force (WBSF) values of longissimus thoracis (LT) and semitendinosus (ST) muscles were observed and the degradation of structural proteins and collagen led to release of low-molecular weight (<3kDa) peptides. These peptides exhibited 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity, ACE- and renin-inhibitory activities. The peptide sequences were identified by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS). In silico analysis (PeptideRanker and BIOPEP) of their bioactivity potentials demonstrated peptides with the predicted bioactivity scores (>0.8) as well as collagen peptides with bioactivity scores (0.6-0.8). The present findings provide insights on development of healthy beef through postmortem aging at 4°C.

Novel aspects of health promoting compounds in meat

Meat is an integral part of the human diet. Besides essential amino acids and nutritive factors of high quality and availability, meat provides often overlooked components of importance for human health. These are amino acids and bioactive compounds that may be very important in i) preventing muscle wasting diseases, such as in sarcopenia, ii) reducing food and caloric intake to prevent metabolic syndrome, iii) blood pressure homeostasis via ACE-inhibitory components from connective tissue, and iv) maintaining functional gut environment through meat-derived nucleotides and nucleosides. In addition, meat could be an important source of phytanic acid, conjugated linoleic acids and antioxidants. Further, it becomes increasingly apparent that design of in vitro meat will be possible, and that this development may lead to improved health benefits from commercially viable and sustainable meat products.

Influence of feeding intensity, grazing and finishing feeding on meat and eating quality of young bulls and the relationship between muscle fibre characteristics, fibre fragmentation and meat tenderness

Forty-one autumn-born Friesian bull calves were allocated to two production systems (Extensive='E'and Intensive='I'). In the E-system, animals were loose-housed and fed a roughage-based diet from October to May, followed by a grazing period from May to October. Ten animals were slaughtered directly from pasture in October [360 kg body weight (BW)] and 11 after a 10-week finishing period in tie-stalls (460 kg). The E-bulls were compared with intensively-fed tie-stall-housed young bulls (I) slaughtered at comparable weights (360 kg, n=11 and 460 kg, n=9). The myofibril fragmentation index (MFI) was measured 24 h post mortem in semitendinosus (ST), longissimus dorsi (LD), and supraspinatus (SU) muscles, and meat quality characteristics and sensory evaluation of LD were performed on aged meat. Intramuscular fat content was lower (P<0.001) in all three muscles of E- compared with I-bulls. MFI of ST and LD was lower in E-bulls compared with I-bulls, but only at 360 kg. In contrast, MFI of SU was higher in E- compared with I-bulls at 360 kg. In E- compared with I-bulls, shear force value of ST was higher (P<0.003) at 360 kg, but not at 460 kg. Panel scores for tenderness, taste and juiciness were all lower (P<0.006 to 0.001) and remarks for off-flavour higher in E- compared with I-bulls, the effects being most pronounced at 360 kg. A 10-week finishing period improved all meat and eating quality characteristics of E-bulls. In LD, the correlation between MFI and tenderness was 0.79 (P<0.001), which indicates a potential of MFI as an early predictor of tenderness.

Compensatory growth response as a strategy to enhance tenderness in entire male and female pork M. longissimus thoracis

The effects of restrictive feeding strategies aimed at promoting a compensatory growth response were investigated with respect to tenderness improvement in pork M. longissimus thoracis. Compensatory growth response is defined by increased weight in pigs fed ad libitum after a period with restricted feeding compared to pigs fed ad libitum the entire fattening period. Specifically, the aim was to study the sensory textural characteristics after female and entire male pigs have been exposed to restrictions in either energy, protein or both in specific growth periods. It was found that textural differences were caused by feeding strategies and not related to variation in intramuscular fat, which did not vary significantly between genders. The female pigs demonstrated compensatory growth response and the texture was significantly (P<0.001) improved by low dietary level of energy from day 50 to 90 and normal dietary level of protein during the entire feeding period. For the entire male pigs, low level of protein in the late feeding period significantly (P<0.05) improved the texture. Also, low level of protein and normal level of energy in the early feeding period resulted in improved tenderness. However, these texture improvements were deemed not to be an effect of compensatory growth since the entire male pigs did not compensate for the feeding restriction in the early feeding period. The tenderness enhancement for the entire male pigs compromised the production results in terms of 7-15% lower carcass weight.

An assessment of extraction and assay techniques for quantification of calpain and calpastatin from small tissue samples

Our objective was to evaluate whether small (biopsy-sized) samples could be used to measure calpain and calpastatin activities in skeletal muscle. The accuracy of different separation and assay methods for the quantification of calpains and calpastatin from small (1.0 and 0.2 g) skeletal muscle samples was tested. In Exp. 1, the LM was removed from six lambs, and a 50-g subsample was processed using the reference method (DEAE-Sephacel chromatography and casein assay). Subsamples (1.0 and 0.2 g) also were processed using the two-step separation (1 mL DEAE-Sephacel and bulk elution using 200 and 400 mM NaCl) and heated calpastatin methods; in both cases, fractions were assayed with Bodipy-labeled and [14C]-labeled casein microassays. Finally, casein zymography was used to separate and quantify the calpain proteases from 1.0-and 0.2-g samples. The values obtained after processing the 50-g sample using the reference method were judged most accurate, and the alternative approaches were compared with these. For each extraction and assay approach, we considered: 1) the effect of the sample size on the mean activity; 2) increased or decreased variation of data; and 3) the correlation relative to the reference method. Where possible, we compared the ratio of calpain to calpastatin activities determined using the alternative approaches with the ratios found using the reference method. These methodologies were further investigated in Exp. 2, where single homogenates from different tissues (heart, spleen, lung, and muscle) were assayed using the alternative approaches. Experiment 1 established that most of the approaches suffered from poor correlations and/or unacceptable variation. By using a large, homogenous sample in Exp. 2, however, we determined that this error was not due to the methodologies themselves. Therefore, the unacceptable variation found in Exp. 1 resulted from the small sample size, and we recommend that large tissue samples (e.g., 50 g) should be used for calpain and calpastatin activity measurements in skeletal muscle instead of small tissue biopsies (e.g., 0.2 and 1.0 g).

Compensatory growth improves meat tenderness in gilts but not in barrows

Compensatory growth is a phenomenon observed in pigs given free access to feed following a period of restricted feeding that results in increased growth rates. Compensatory growth is believed to increase protein turnover and thereby the proteolytic potential at the time of slaughter, leading to faster tenderization rates of meat. Nine litters of three gilts and three barrows were allocated within litter and gender to three dietary treatment groups. Pigs had ad libitum access to feed from d 28 to slaughter at d 140 (ALA) or were restricted to 69% ad libitum from d 28 to d 80 or 90, and then given ad libitum access to the diet until slaughter at d 140 (RA80 and RA90, respectively). Pigs in the RA80 and RA90 treatment groups had a 9.7% higher (P < or = 0.001) fractional growth rate in the second feeding period than those in the ALA group. Growth rate was correlated to the activity of m-calpain (r = 0.37; P < or = 0.01), beta-glucuronidase (r = 0.48; P < or = 0.001), and cathepsins B (r = 0.47; P < or = 0.001) and B+L (r = 0.31; P < or = 0.04). The LM of RA80-gilts received higher tenderness scores than the LM of ALA gilts, but tenderness scores were similar among barrows regardless of treatment (gender x treatment; P = 0.02). Conversely, tenderness scores were higher for the biceps femoris of ALA barrows than either ALA gilts or RA90 barrows (gender x treatment; P = 0.02). Desmin and troponin-T degradation, as well as myofibrillar fragmentation index, of the LM were not (P > or = 0.24) affected by treatment. No dietary treatment effects were observed on the activities of mu-calpain (P = 0.15), m-calpain (P = 0.74), or calpastatin (P = 0.91) at slaughter. The cathepsin inhibitors, cystatins, tended to be increased (P = 0.06) in RA80 and RA90 pigs. Sarcomere length was longer (P = 0.003) in the LM of gilts than barrows. Barrows in the RA80 group had lower i.m. fat concentrations than ALA; however, no differences were found in the LM of gilts (gender x treatment; P = 0.03). The underlying hypothesis that compensatory growth leads to an increased proteolytic potential at the time of slaughter could not be verified in this study.

Changes in the muscle proteome after compensatory growth in pigs

Sixteen female pigs (Duroc x Landrace x Large White) were divided into 2 groups, which had either free access to the diet (control group) or were feed-restricted from d 28 to 80 and then had free access to the diet (compensatory growth group). The sensory analysis showed that the pigs exhibiting compensatory growth produced meat with increased tenderness compared with control pigs (P < 0.05). To gain further knowledge of the influence of compensatory growth on meat tenderness, the sarcoplasmic protein fraction of muscle tissue was studied at the time of slaughter and 48 h postmortem using proteome analysis. At slaughter, 7 different proteins were found to be affected by compensatory growth: HSC70, HSP27, enolase 3, glycerol-3-phosphate dehydrogenase, aldehyde dehydrogenase E2, aldehyde dehydrogenase E3, and biphosphoglycerate mutase. The HSC70 and HSP27 both belong to the heat shock family and are known to play a role during muscle development. Hence, they may be affected by compensatory growth and increased protein turnover. Forty-eight hours after slaughter, 8 different proteins were found to be affected by compensatory growth: myosin light chain (MLC) II, MLC III, sulfite oxidase, chloride intracellular channel 1, 14-3-3 protein gamma, elongin B, and phosphohistidine phosphatase 14. The changes observed on MLC II and MLC III could be a consequence of enzymatic cleavage in the neck region of the globular myosin head domain that causes the release of MLC II and MLC III from the actomyosin complex. It has previously been hypothesized that compensatory growth results in an increased postmortem proteolysis; thus it was presumed that the intensity of some protein fragments would be affected by compensatory growth. However, the peptides that were found to be affected at 48 h postmortem were all full-length proteins. The 14-3-3 protein gamma has been proposed to play a role in the contraction of muscle during rigor and may thereby have an effect on meat tenderness. This study reveals some very interesting changes in the muscle proteome affected by compensatory growth, which may be useful in understanding the relationship among compensatory growth, protein turnover, and meat tenderness.

Proteome analysis of early post-mortem changes in two bovine muscle types:M. longissimus dorsi andM. semitendinosis

To study early post-mortem changes in muscle tissues from bull calves, cytosole proteins from two muscles: M. longissimus dorsi (LD) and M. semitendinosis (ST) at 0 and 24 h after slaughter were analysed by 2-DE. Principal component analysis (PCA) and rotation testing were used to analyse the protein patterns in the two muscles in order to select protein spots that were significantly different at the two time-points. Selected proteins were identified by MALDI-TOF/TOF. Five proteins, namely cofilin, lactoylglutathione lyase, substrate protein of mitochondrial ATP-dependent proteinase SP-22, HSP 27 and HSP20, were changed in both LD and ST muscles during post-mortem storage. Fifteen additional protein changes were observed in either LD or ST muscles, and some of these changes have not previously been observed to change during post-mortem storage of bovine muscles. Further studies will reveal the relevance of these biomarkers for meat quality.

A capillary electrophoresis method to study postmortem proteolysis in relation to pork tenderness

Identification of factors that determine meat tenderness is of high priority. The aim of this work was to develop a method that can detect indicators of proteolysis in meat early postmortem. The method was validated on pork samples. A procedure to detect differences of extractable lower molecular weight compounds after a prerigor freeze/thaw cycle of meat was developed using capillary electrophoresis. The procedure was able to separate 39 peaks in the electropherograms. Eight of the peaks were correlated (P < 0.1) to Warner-Bratzler shear forces 1 day postmortem (WB1). A multiple linear regression model explained 69% of the variation in WB1 using the areas of four peaks. Several of the peaks used in modeling WB1 were related to the at-slaughter activity of the calpain system. The results presented show that the developed method is able to detect indicators of proteolysis and tenderness at an early time point after slaughter. The method is a new tool intended for studies regarding the mechanisms of postmortem proteolysis and tenderization.

Dietary-induced changes of muscle growth rate in pigs: effects on in vivo and postmortem muscle proteolysis and meat quality

The effects of various growth rates in pigs induced by four different feeding strategies on the activity of the calpain system and on postmortem (PM) muscle proteolysis and tenderness development were studied. An increased growth rate may be caused by an increased protein turnover, which results in up-regulated levels of proteolytic enzymes in vivo that, in turn, possibly will affect PM tenderness development. It can be hypothesized that increased proteolytic activity pre-slaughter will increase the PM tenderization rate. From postnatal d 28 to d 90 (phase 1) the pigs were divided into two groups, given either ad libitum (A) or restricted (R, 60% of ad libitum) access to feed. The two groups were then divided into two subgroups, given either restricted or ad libitum access to feed from d 91 to slaughter at d 165 (phase 2). Measurements of the activity of mu-calpain, m-calpain, and calpastatin; concentrations of total collagen and the percent of soluble collagen; and RNA, DNA, and elongation factor-2 where made at slaugther. Myofibrillar fragmentation index (MFI) was determined at slaughter and 24 h PM. Warner-Braztler shear force was determined 1 d and 4 d PM. Pigs fed restricted diets in phase 1 and fed ad libitum in phase 2 (RA pigs) had increased growth rates in the last phase compared to pigs fed ad libitum during both phase 1 and phase 2 (AA pigs). The increased growth rate (compensatory growth) was followed by an increased proteolytic potential (mu-calpain:calpastatin ratio), increased MFI values, and higher tenderization rates. There was a positive correlation between the activities of m-calpain and growth rates (r = 0.35, P = 0.03), and between RNA levels and growth rates (r = 0.43, P = 0.006). The proposed hypothesis is largely supported by the results. The activities of both mu- and m-calpain at slaughter were highest in fast-growing pigs. The calpain activity was highest in RA pigs, which in turn also had the fastest growth rates prior tslaughter among the four groups. This implies that the synthesis of these enzymes was up-regulated during the second feeding period to a larger extent in RA pigs. The proteolytic potential and the MFI values indicate that the up-regulated in vivo calpain activity had an effect on PM protein degradation, which also is supported by the higher tenderization rate in RA pigs.

Muscle glycogen stores and meat quality as affected by strategic finishing feeding of slaughter pigs

The aim of the present study was to investigate whether muscle glycogen stores in slaughter pigs could be decreased through strategic finishing feeding before slaughter. Moreover, preliminary meat quality traits were measured to see whether such a regulation of muscle glycogen stores affected ultimate pH, color, and tenderness in the meat. The strategic finishing feeding was carried out the last 3 wk prior to slaughter. Seven experimental groups with eight animals per group were fed diets low in digestible carbohydrates. A control group with four animals was fed a traditional grower-finishing diet. The muscle glycogen stores were reduced in longissimus muscle (LM) 11 to 26% at the time of slaughter in pigs that were fed the experimental diets compared with the control group. Meat quality measured as ultimate pH and color on LM muscle in half the pigs 24 h postmortem showed that ultimate pH in LM was not affected by the reduction in glycogen stores in the muscles from pigs fed any of the experimental diets. However, the meat from pigs fed the experimental diets was darker than the meat from pigs that were fed the control diet with two of the experimental diets, resulting in significantly lower L* values. Activities of key enzymes in the glycolytic pathway, glycogen phoshorylase a and b, phosphofructokinase, and the fatty acid oxidative pathway, beta-hydrozyacyl-CoA-dehydrogenase, were not affected by the strategic feeding. In contrast, the activity of the proteolytic enzyme calpain as well as its inhibitor calpastatin was influenced by the strategic feeding. Lower activity of mu-calpain and greater activity of calpastatin in the muscle samples from the strategically fed pigs indicate a lesser muscle protein degradation in the muscles compared with muscles of control animals. The present study showed that the muscle glycogen stores in slaughter pigs can be reduced at the time of slaughter through strategic finishing feeding with diets low in digestible carbohydrate without compromising growth rate.