Dark , Firm And Dry Research Articles

Sequential window acquisition of all theoretical mass spectra (SWATH-MS) as an emerging proteomics approach for the discovery of dark-cutting beef biomarkers

Recent advances in “omics” technologies have enabled the identification of new beef quality biomarkers and have also allowed for the early detection of quality defects such as dark-cutting beef, also known as DFD (dark, firm, and dry) beef. However, most of the studies conducted were carried out on a small number of animals and mostly applied gel-based proteomics. The present study proposes for the first time a Sequential Window Acquisition of All Theoretical Mass Spectra (SWATH-MS) proteomics approach to characterize and comprehensively quantify the post-mortem muscle proteome of DFD (pH24 ≥ 6.2) and CONTROL (5.4 ≤ pH24 ≤ 5.6) beef samples within the largest database of DFD/CONTROL beef samples to date (26 pairs of the Longissimus thoracis muscle samples of young bulls from Asturiana de los Valles breed, n = 52). The pairwise comparison yielded 35 proteins that significantly differed in their abundances between the DFD and CONTROL samples. Chemometrics methods using both PLS-DA and OPLS-DA revealed 31 and 36 proteins with VIP > 2.0, respectively. The combination of different statistical methods these being Volcano plot, PLS-DA and OPLS-DA allowed us to propose 16 proteins as good candidate biomarkers of DFD beef. These proteins are associated with interconnected biochemical pathways related to energy metabolism (DHRS7B and CYB5R3), binding and signaling (RABGGTA, MIA3, BPIFA2B, CAP2, APOBEC2, UBE2V1, KIR2DL1), muscle contraction, structure and associated proteins (DMD, PFN2), proteolysis, hydrolases, and activity regulation (AGT, C4A, GLB1, CAND2), and calcium homeostasis (ANXA6). These results evidenced the potential of SWATH-MS and chemometrics to accurately identify novel biomarkers for meat quality defects, providing a deeper understanding of the molecular mechanisms underlying dark-cutting beef condition.

Role of the endoplasmic reticulum in the search for early biomarkers of meat quality

Defects in meat quality such as dark, firm and dry (DFD) beef have been related to high levels of oxidative stress that produce cellular alterations that may affect to the process of meat quality acquisition. Despite the important role of endoplasmic reticulum (ER) in the cellular response to oxidative stress, its function in the muscle-to-meat conversion process has not yet been studied. In this study, differences in muscular antioxidant defense and the unfolded protein response (UPR) of the ER in CONTROL (normal pH24) and dark, firm, and dry (DFD, pH24 ≥ 6.2) beef at 24 h post-mortem were analyzed to understand the changes in the muscle-to-meat conversion process related to meat quality defects. DFD meat showed poor quality, lower antioxidant activity (P < 0.05) and higher UPR activation (P < 0.05), which indicates higher oxidative stress what could partly explain the occurrence of meat quality defects. Therefore, the biomarkers of these cellular processes (IRE1α, ATF6α, and p-eIF2α) are putative biomarkers of meat quality.

A survey of broiler breast meat quality in the retail market of Quebec

In this study, 206 breast fillets were purchased from grocery stores in the province of Quebec and evaluated for the presence of different quality defects. Of these fillets, 48.5% showed breast muscle myopathies (BMM), 19.4% showed pale, soft, and exudative (PSE), and 6.8% showed dark, firm, and dry (DFD) attributes. BMM were equally present ( P &gt; 0.05) in fillets of economical, commercial, and high-quality brands, while PSE-like fillets were more present in economical brands ( P &lt; 0.0001). The combined effect of BMM and DFD induced significantly higher counts of Salmonella ( P = 0.03) and Enterobacteriaceae ( P = 0.03) in myopathic than in unaffected fillets. These quality defects also altered the nutritional quality of breast meat: BMM-affected fillets had greater fat content ( P &lt; 0.0001) and DFD fillets had lower protein content ( P = 0.041) than normal fillets. The technological quality was only slightly impacted by BMM, while PSE-like fillets had higher cooking loss ( P = 0.009) and a tougher texture after cooking ( P &lt; 0.0001) than DFD fillets. For the first time, this study confirmed the presence of multiple quality issues in the Quebec poultry supply chain, and provided valuable data to support future research efforts.

Use of Near-Infrared Spectroscopy to Discriminate DFD Beef and Predict Meat Quality Traits in Autochthonous Breeds.

The potential of near-infrared reflectance spectroscopy (NIRS) to discriminate Normal and DFD (dark, firm, and dry) beef and predict quality traits in 129 Longissimus thoracis (LT) samples from three Spanish purebreeds, Asturiana de los Valles (AV; n = 50), Rubia Gallega (RG; n = 37), and Retinta (RE; n = 42) was assessed. The results obtained by partial least squares-discriminant analysis (PLS-DA) indicated successful discrimination between Normal and DFD samples of meat from AV and RG (with sensitivity over 93% for both and specificity of 100 and 72%, respectively), while RE and total sample sets showed poorer results. Soft independent modelling of class analogies (SIMCA) showed 100% sensitivity for DFD meat in total, AV, RG, and RE sample sets and over 90% specificity for AV, RG, and RE, while it was very low for the total sample set (19.8%). NIRS quantitative models by partial least squares regression (PLSR) allowed reliable prediction of color parameters (CIE L*, a*, b*, hue, chroma). Results from qualitative and quantitative assays are interesting in terms of early decision making in the meat production chain to avoid economic losses and food waste.

Rearing Performance and Carcass Composition of Broiler Chickens Fed Rations Containing Guar Meal at Graded Levels

This study aimed to evaluate how different percentages of guar meal in feed rations for broiler chickens affect their rearing performance and carcass composition. The experiment was conducted in a group of one hundred sixty Ross 308 broilers randomly allocated to four equinumerous groups (K, G4, G8 and G12). The birds were reared over 42 days with the application of three feeding periods: starter (days 1–21), grower (days 22–35) and finisher (days 36–42). All the feed rations were prepared using maize meal, soybean meal, oil and mineral and vitamin additives. An experimental factor was the share of guar meal in feed rations: group K—0%, G4—4%, G8—8% and G12—12%. It was demonstrated that a higher percentage (8% or 12%) of guar meal in the feed rations had a negative effect on the chickens’ weight gain and feed intake. The birds receiving feed rations supplemented with guar meal featured higher feed conversion levels than those fed rations in which soybean meal was the only protein-rich component (p ≤ 0.05). Birds fed rations with the highest percentage (12%) of guar meal showed a significant decrease in chilled carcass weight and dressing percentage compared with other chickens. A higher percentage (8% or 12%) of guar meal in feed rations had an adverse effect on the birds’ muscularity. In addition, it was demonstrated that their meat was DFD (dark, firm and dry; pH1 &gt; 6.4), but from a dietary point of view, it contained the smallest amount of intramuscular fat. To sum up, 4% of guar meal should be recommended in broiler chicken feeding to ensure their satisfactory rearing performance and carcass composition, including the physico-chemical properties of their muscles.

Effects of Rumen-Protected Creatine Pyruvate on Meat Quality, Hepatic Gluconeogenesis, and Muscle Energy Metabolism of Long-Distance Transported Beef Cattle

Pre-slaughter long-distance transport resulted in a rapid depletion of muscle glycogen and led to a higher rate of dark, firm and dry (DFD) meat. Therefore, enhancing muscle glycogen reserves is critical for beef cattle prior to transportation. Creatine pyruvate (CrPyr) can provide simultaneous pyruvate and creatine and both are proven to promote the glycogen reserves. This study aimed to investigate the effects of transport treatment and dietary supplementation of rumen-protected (RP)-CrPyr on the meat quality, muscle energy metabolism, and hepatic gluconeogenesis of beef cattle. Twenty 18 month-old male Simmental crossbred cattle (659 ± 16 kg) were allotted 4 treatments based on a 2 × 2 factorial arrangement with two RP-CrPyr levels (140 g/d or 0 g/d) and two transport treatments (12 h or 5 min): ST_CrPyr0, ST_CrPyr140, LT_CrPyr0 and LT_CrPyr140. Three cattle per group were slaughtered after 30 days of feeding. The interaction of transport and RP-CrPyr had a significant effect on the muscle pH45 min, redness, glycogen content, GP, and AMP level (P &amp;lt; 0.05). Compared with short-distance transport, long-distance transport increased the muscle pH45 min value, redness, yellowness, drip loss, creatine level (P &amp;lt; 0.05), decreased muscle glycogen content, glycolytic potential (GP), and liver glucose amount (P &amp;lt; 0.05). Supplementation of RP-CrPyr decreased the activities of creatine kinase and lactate dehydrogenase in serum, muscle pH24 h value, redness, yellowness, lactate content, AMP level, and AMP/ATP (P &amp;lt; 0.05), increased the muscle glycogen content, GP, hexokinase activity, ATP and ADP levels, and ATP/ADP, liver pyruvate and glucose contents, activity of pyruvate carboxylase in the liver of cattle than those in the nonsupplemented treatments (P &amp;lt; 0.05). These results indicated that dietary RP-CrPyr supplementation might be favorable to improve meat quality and regulatory capacity of energy metabolism of beef cattle suffering long-distance transport followed with recovery treatment by increasing muscle glycogen storage, energy supply, and hepatic gluconeogenesis.

Meat quality, biosecurity, and animal welfare: consequences of an inefficient inspection

In livestock, biosecurity, animal welfare and meat quality have a synergetic effect on the final product. To meet minimal safety and humane production, it is necessary to consider biosecurity risks and procedures to mitigate animal welfare problems. Following guidelines to achieve it, the meat quality improves consequently. Here we tested two parameters regarding the meat quality of beef cattle to understand how the poor inspection affects the quality of the final product. Therefore, 12 samples of the longissimus dorsi muscle were evaluated from different butcheries, using fresh meat recently received by the supplier. There were no sanitary inspection records related to the sampled meat. The results showed a large percentage of PSE (pale, soft, and exudative) and DFD (dark, firm, and dry) meats. Given the pH and color values, it is concluded that the slaughtering was not carried out properly. Hence, technological defects in the meat were observed, making it inappropriate for consumption. We concluded that inefficient pre-slaughter handling is compromising animal welfare, increasing the biosecurity risk, and impairing the quality of the final product. We argue that these problems not only decrease the sustainability of livestock systems, but also compromises human health. Currently, livestock plays an important role in global environmental concerns, such as climate change, land degradation, water pollution and biodiversity loss. Then, it is needed to reduce the waste of such products.

Effect of pre-slaughter beef cattle handling on welfare and beef quality in Ambo and Guder markets and abattoirs, Oromia Regional State, Ethiopia

Improper beef cattle handling could affect welfare and meat quality. The effect of beef cattle handling during transportation and in the lairage on the animal welfare and beef quality was studied in relation to Guder and Ambo markets and abattoirs. Data were collected from 200 respondents using a semi-structured questionnaire. For laboratory analysis, animals were randomly assigned into three groups: Group I - trekked from the nearest places (≤30 km), Group II - trekked farthest places (&gt;30 km), and Group III - transported using vehicles (&gt;50 km). One-hundred pooled beef swab samples were collected from the flank, brisket, and rump to determine aerobic bacterial load and another 100 beef samples to assess pH values. Descriptive statistics, independent t-test, and ANOVA were used for analysis. The result of the study indicated that trekking was the major means of transportation (72%). The majority of animal handlers (92%) did not allow animals to feed, water, and rest during trekking. Beef cattle were overcrowded and beaten during vehicle transport. About 47% of the beef samples were abnormal of which the majority were DFD (dark, firm and dry) beef and DFD beef with spoilage. The pH of meat was significantly affected by the distance traveled before slaughter using both trekking and vehicle transportation (t= -3.5, p=0.001). Therefore, it is concluded that there was poor handling and stressful situation of beef cattle before slaughtering, which negatively affected the welfare and beef quality. Hence, pertinent proclamations, regulations, and delivery of animal welfare awareness training for different stakeholders are urgently needed.

Dark-cutting beef: A brief review and an integromics meta-analysis at the proteome level to decipher the underlying pathways

Comprehensive characterization of the post-mortem muscle proteome defines a fundamental goal in meat proteomics. During the last decade, proteomics tools have been applied in the field of foodomics to help decipher factors underpinning meat quality variations and to enlighten us, through data-driven methods, on the underlying mechanisms leading to meat quality defects such as dark-cutting meat known also as dark, firm and dry (DFD) meat. In cattle, several proteomics studies have focused on the extent to which changes in the post-mortem muscle proteome relate to dark-cutting beef development. The present data-mining study firstly reviews proteomics studies which investigated dark-cutting beef, and secondly, gathers the protein biomarkers that differ between dark-cutting versus beef with normal-pH in a unique repertoire. A list of 130 proteins from eight eligible studies was curated and mined through bioinformatics for Gene Ontology annotations, molecular pathways enrichments, secretome analysis and biological pathways comparisons to normal beef color from a previous meta-analysis. The major biological pathways underpinning dark-cutting beef at the proteome level have been described and deeply discussed in this integromics study.

Welfare and meat quality of lambs

Recently, in many parts of the world, greater importance has been given to lamb meat as well as to the intensive production of lamb and sheep, due to demand for this type of meat at affordable prices. In Serbia, similar to most European countries, the structure of total sheep meat production comprises about 70% lamb meat and 30% sheep meat. This study assessed resource-based measures on 11 dairy sheep farms and investigated, in a total of 30 lambs, the effects of sex, the presence of bruises and pneumonia in carcasses, and carcass and meat quality. Carcass (carcass length, thigh length, croup width, subcutaneous fat thickness, presence of bruises) and meat quality (pH, temperature, drip, thawing and cooking losses, color, and meat quality classes) traits were measured post mortem. The most common deficiencies on farms were high stocking density, poor hygienic conditions, dirty drinkers, and lack of outdoor access. Regarding sex differences, higher prevalences of carcass bruises and severe pneumonia were recorded in male lambs. Meat pH (pH45min), sensory color score, and prevalence of dark, firm and dry (DFD) meat were higher in lambs with carcass bruises. The occurrence of quality defects (DFD meat) was higher in lambs with severe pneumonia. It can be concluded that it is necessary to improve the welfare conditions on the lamb farms and pre-slaughter conditions in order to achieve better lamb meat quality.

Fasting Finisher Pigs before Slaughter Influences Pork Safety, Pork Quality and Animal Welfare.

Simple SummaryFasting prior to slaughter is an accepted best management practice in pork production worldwide. Often, fasting time is confounded with the resting time at the slaughterhouse. In practice, fasting is sometimes only applied from the departure from the farm to the slaughterhouse. When implemented correctly with attention to the local factors, pre-slaughter fasting can improve animal welfare, pathogen risk and carcass hygiene. This review aims to describe the impact of fasting pigs before slaughter.The final phase in pork production is the transport of finisher pigs to the slaughterhouse. Fasting is one of the parameters that influence the stress coping ability of the pigs during transport and lairage. When implemented correctly with attention to the local factors, pre-slaughter fasting can improve animal welfare, pathogen risk and carcass hygiene. The length of pre-slaughter feed withdrawal time is important to the success of the production practice. In practice, a fasting time before slaughter between 12 and 18 h enhances pork safety, pork quality, and animal welfare. This means that communication between producer and slaughterhouse is essential when planning the fasting and lairage times to avoid carcass and technological pork quality problems (such as pale, soft, and exudative (PSE) meat or dark, firm and dry (DFD) meat).

Evaluation of pH in swine carcasses regarding on the trasport distance of the animals: a case study

The PSE (Pale, Soft and Exudative) swine meat is an anomaly that produces great economic losses in the swine industry and products because proteins lose their functionality, affecting the ability of water retention, binding, and emulsification of meat. Due to the importance of quality control of carcasses, the determination of the pH parameter is necessary to perform the classification of the product in: normal; PSE; and DFD (Dark, Firm, and Dry). In this sense, the purpose of the work was to perform the evaluation of pH values after 45 minutes of bleeding (pH45) and function of the distance from farms to a slaughterhouse and calculate the indicator of Meat PSE in swine carcasses. The experiment was carried out in a large plant, under the supervision of the Federal Inspection Service (SIF). A total of 725 carcasses were used, separated into lots and the transport distance from the farms to the slaughterhouse ranged from 25 to 427 km. For the evaluation of the incidence of PSE, pH45 was measured by a direct method, and the management of pre-slaughter animals was standardized for all lots, except for rest time. The animals transported for shorter distances (25 and 65 km) presented 11% indicative of PSE meat, a fact that shows that the stress response is higher when the animals are subjected to short transport distances compared to longer distances (320, 340, and 427 km).

Prediction of quality traits and grades of intact chicken breast fillets by hyperspectral imaging

ABSTRACT 1. In this study, hyperspectral imaging was evaluated for its usefulness to predict quality traits and grading of intact chicken breast fillets. 2. Lightness of colour (L*) and pH of the fillets were measured as quality traits, and samples were then selected and graded to three different quality categories, i.e., dark, firm and dry (DFD), normal (NORM), and pale, soft and exudative (PSE) based on these two quality traits. Based on the prediction performance of full wavelength partial least square regression (PLSR) models, the spectral range of visible and near-infrared (Vis-NIR) was more suitable for the evaluation of quality traits and grading than the range of near-infrared (NIR). Key wavelengths of each quality trait and grade value were selected by the regression coefficient (RC) method. 3. The new key wavelength PLSR models showed good predictive performances (Rp = 0.85 and RMSEp = 2.18 for L*, Rp = 0.84, and RMSEp = 0.13 for pH, and Rp = 0.80 and RMSEp = 0.44 for quality grading). The classification accuracy for grades was 85.71% (calibration set) and 81.82% (prediction set), respectively. Finally, distribution maps showed that quality traits and grades of samples were able to be visualised. 4. These results suggested that hyperspectral imaging has the potential for quality prediction of fresh chicken meat.

Impacts of heat stress on meat quality and strategies for amelioration: a review.

During the summer, high ambient temperature and humidity cause economic loss to the global livestock industry via reduced livestock productivity and increased mortality. The problem of heat stress (HS) is likely to be exacerbated by global warming and climate change. Recent research has shown that HS not only leads to physiological and metabolic perturbations in live animals but can also affect carcass and meat quality characteristics plausibly by altering the rate and extent of postmortem muscle glycolysis and resultant pH. However, these impacts of HS are not consistent across species. Higher incidence of pale soft and exudative (PSE) meat has been reported in poultry. On the contrary, higher incidence of high ultimate pH and dark firm and dry (DFD) meat or no impacts of HS have been reported in sheep and cattle. With the limited data on HS impacts on meat quality of ruminants, it is difficult to explain the exact mechanisms driving these variable impacts. However, it is hypothesized that the severity and duration of HS may lead to variable impacts due to lack of opportunity to adapdate to acute heat exposure. Longer HS exposure may allow ruminants to adapdate to heat and may not record any negative impacts on meat quality. This paper reviews the recent research on impacts of HS on meat quality characteristics and identify the key areas of further research required to better understand these negative impacts to develop strategies for amelioration. In addition, some mitigation strategies of HS have also been discussed which include both managemental and nutritional interventions.

Evaluation of Beef Meat Quality at Slaughterhouse in Kendari City

. This study aims to find out whether DFD (Dark, Firm, and Dry) and PSE (Pale, Soft, and Exsudative) happen/ occur to Bali Cattle Carcas slayed in Anggoeya Animal Slaugtherhouse in Kendari City. This study is useful to give information about the meats’ DFD and PSE cases and carcas quality at Anggoeya Slaugtherhouse in Kendari City. The sample of this study are 6 bulls and 6 cows taken from slaugtherhouse in Kendari City. The obtained data was, then, analyzed descriptively based on the mean and deviation standard (χ ± SD).The variables observed in this studyincludes PH measurement for 1 – 6 hours after slashing, color, loss of mass, texture, hardness, and humidity. The meats were found to be around normal PH 5.55 – 5.73. Based on the color score AUS_MEAT Colour, the color of the meats were around the score of 4 – 5, loss of mass were around 30,64 – 43,28%. Based on panelist judgement, most of the meats texture were scored 3 or were in moderate level. Most of the meats’ elasticity were scored 3 or were rather soft, while most of the meats’ humidity were scored 3 or moderate (62.50%). On the meats produced by the Animals Slaugtherhouse in Kendari City, no changes to DFD (Dark, Firm, and Dry) or PSE (Pale, Soft and Exudative) was found.

PH Variability and its Relationship with Sarcomere Length and Free Calcium in Beef from Commercial Cattle in Puerto Rico

ObjectivesResearch conducted at the University of Puerto Rico noted that beef with elevated pH values (&gt; 5.86) resulted in more tender meat (P ≤ 0.05). It has been established that proteolytic degradation mechanisms can be influenced by pH and calcium concentration in muscle. Beef with pH values ≥ 5.86 is classified as Dark Firm and Dry (DFD) but there are negative implications associated with greater pH values. However, observations indicating increased tenderness with increased pH raise the question: can variations in pH be associated with differences in sarcomere length (SL) and free calcium concentration (FCC)? Therefore, the objectives of this project were to: (1) document pH distribution; (2) determine the incidence of DFD; and (3) evaluate the relationship between pH, SL, and FCC in commercial cattle harvested in Puerto Rico.Materials and MethodsLongissimus lumborum samples (n = 51) were obtained and background information was noted including number of permanent incisors (PI), type (Dairy or Beef), and gender. The pH values were used to categorize beef into the following groups: Low (≤ 5.40), Normal (5.41 to 5.59), High (5.60 to 5.85) and DFD (≥ 5.86). Meat was flash frozen, powdered, and placed on a microscope slide and a Helium-Neon laser was used to determine SL. A subset of samples was sent off and prepared at the University of Nebraska-Lincoln for FCC quantification (Ward Laboratories; Kearney, NE) with an inductively coupled plasma emission spectrometer (iCAP 6500 Radial; Thermo Electron, Cambridge, UK). All statistical analyses were conducted in SAS (9.4). The Proc FREQ was used to determine pH category distributions and incidence of DFD. The Proc GLIMMIX and Tukey adjustment (α = 0.05) were used to determine the effects of number of PI, type, and gender on pH category, SL and FCC. The Proc CORR was used to evaluate the relationship between pH category, SL and FCC.ResultsThe pH category distribution for the current samples was as follows: 3.92% Low, 41.18% Normal, 35.29% High and 19.61% DFD. The SL ranged from 1.69 to 1.46 mm with an average of 1.53 mm. The FCC ranged from 132.19 to 31.39 mM with an average of 64.23 mM. Longer sarcomeres were detected in cattle with eight and zero PI (1.57 and 1.56 mm, respectively); cattle with two and four PI had intermediate SL (1.53 and 1.52 mm, respectively), and cattle with six PI had the shortest sarcomeres (1.51 mm; P = 0.03). Dairy cattle had longer sarcomeres relative to beef cattle (1.56 vs. 1.52 mm; P = 0.02). Dairy cattle tended to have increased FCC relative to beef cattle (70.72 vs. 58.38 mM; P = 0.08). Also, FCC tended to be greater within the Normal and Low pH categories relative to the High and DFD categories (72.36 vs. 57.31 mM; P = 0.06). The SL and FCC had no relationship (P &gt; 0.05) within the Low, Normal and High pH categories. However, DFD beef had longer SL (0.78; P = 0.01), while having decreased FCC (–0.66; P = 0.04).ConclusionOver half (54.90%) of the beef samples analyzed fell into the High and DFD pH categories, with nearly 20% being classified as DFD. Although, a clear relationship was not established between SL and FCC within the Low, Normal or High pH categories, the results indicate that the increased pH in samples surpassing the DFD threshold correspond to longer sarcomeres and decreased free calcium.

Study on the effect of CaMKKβ-mediated AMPK activation on the glycolysis and the quality of different altitude postmortem bovines longissimus muscle.

This study investigated the activity of adenosine monophosphate-activated protein kinase (AMPK), glycolysis, and meat quality index in three altitude bovines during postmortem aging process. Local cattle (altitude:1,500m), Gannan yak (3,000m), and Yushu yak (4,500m) postmortem Longissimus Dorsi (LD) muscle were used. Results indicated that CaCl2 significantly increased the AMPK activity by increasing the calcium-regulated protein kinase kinase (CaMKKβ) activity. Besides, AMPK activation enhanced the activity of lactate dehydrogenase (LDH) and Ca2+ -ATPase and accelerated the rate of muscle maturation during postmortem aging. Moreover, the expression of HIF-1, PRKAA2, and GLUT4 genes in high-altitude Yushu yak was higher than that of low-altitude bovines. CaCl2 activates AMPK by activating CaMKKβ cascade and accelerates postmortem glycolysis affecting the intramuscular environment, color, and muscle protein degradation to accelerate postmortem muscle maturation, suggesting that AMPK has essential effects on postmortem muscle glycolysis and quality, and can regulate muscle quality by regulating postmortem muscle AMPK activity. PRACTICAL APPLICATIONS: Insufficient postmortem glycolysis usually leads to DFD (dark, firm, and dry) meat. Beef have relatively high incidences of DFD meat, which has an unattractive dark color and causes significant loss to the meat industry. Therefore, AMPK, which can regulate postmortem glycolysis to affect meat quality, is a valid research target.

The first evidence of global meat phosphoproteome changes in response to pre-slaughter stress

BackgroundPre-slaughter stress (PSS) impairs animal welfare and meat quality. Dark, firm and dry (DFD) are terms used to designate poor quality meats induced by PSS. Protein phosphorylation can be a potentially significant mechanism to explain rapid and multiple physiological and biochemical changes linked to PSS-dependent muscle-to-meat conversion. However, the role of reversible phosphorylation in the response to PSS is still little known. In this study, we report a comparative phosphoproteomic analysis of DFD and normal meats at 24 h post-mortem from the longissimus thoracis (LT) bovine muscle of male calves of the Rubia Gallega breed. For this purpose, two-dimensional gel electrophoresis (2-DE), in-gel multiplex identification of phosphoproteins with PRO-Q Diamond phosphoprotein-specific stain, tandem (MALDI-TOF/TOF) mass spectrometry (MS), novel quantitative phosphoproteomic statistics and bioinformatic tools were used.ResultsNoticeable and statistically significant differences in the extent of protein phosphorylation were detected between sample groups at the qualitative and quantitative levels. Overall phosphorylation rates across significantly changed phosphoproteins were about three times higher in DFD than in normal meat. Significantly changed phosphoproteins involved a variable number of isoforms of 13 myofibrillar and sarcoplasmic nonredundant proteins. However, fast skeletal myosin light chain 2 followed by troponin T, F-actin-capping and small heat shock proteins showed the greatest phosphorylation change, and therefore they were the most important phosphoproteins underlying LT muscle conversion to DFD meat in the Rubia Gallega breed.ConclusionsThis is the first study reporting global meat phosphoproteome changes in response to PSS. The results show that reversible phosphorylation is a relevant mechanism underlying PSS response and downstream effects on meat quality. This research opens up novel horizons to unravel the complex molecular puzzle underlying muscle-to-meat conversion in response to PSS.

Carcass and meat quality attributes of Malawi Zebu steers fed &lt;i&gt;Vachellia polyacantha&lt;/i&gt; leaves or &lt;i&gt;Adansonia digitata&lt;/i&gt; seed as alternative protein sources to &lt;i&gt;Glycine max&lt;/i&gt;

To enhance smallholder beef farmers’ capacity to cope with animal feed shortages, especially dietary protein induced by climate change, it is important to evaluate the feeding value of low-cost protein sources naturally available in the environment. The aim of the study was to evaluate carcass and meat quality of Malawi Zebu steers fed diets containing Adansonia digitata (baobab) seed meal or Vachellia polyacantha (white thorn tree) leaf meal as alternative protein sources to Glycine max (soybean) under feedlot conditions. Thirty Malawi Zebu steers (181 ± 21.4 kg body weight; 29 months old) were individually fed forage-based diets made up of rangeland hay and maize bran, with either baobab seed meal, Vachellia leaf meal or soybean meal as a protein source for 120 days. At the end of the feeding trial, animals were slaughtered and the longissimus thoracis et lumborum muscle sampled for meat quality analyses. Steers fed soybean and baobab diets had higher subcutaneous fat thickness, carcass weights than those fed the Vachellia diet. Meat from steers fed the Vachellia and baobab diets had higher ultimate pH and water-holding capacity, and lower drip and cooking losses than meat from steers fed the soybean diet. Feeding baobab and Vachellia diets produced beef with lower lightness (L*) values than the soybean diet, characteristic of dark, firm and dry (DFD) beef. Steers fed the baobab diet had the highest gross profits followed by those fed the Vachellia and soybean diets, respectively. Overall, feeding the baobab and Vachellia diets improved gross profit but produced DFD beef compared to the soybean diet.Keywords: beef cattle, baobab seed, soybean meal, smallholder production

PH measured 24 hours post mortem should not be regarded as ultimate pH in pork meat quality evaluation

The aim of this study was to compare the diagnostic values of two methods in pork meat quality evaluation, that is, Method I: pH1 and pH24 and Method II: electrical conductivity (EC 2 ) and pH 24 , which included pH 24 , and their modifications, that is, Method III: pH1 and pH48 and Method IV: EC 2 and pH 48 , which included pH 48 measurement. Five meat quality classes, namely reddish-pink, firm and non-exudative (RFN), high quality (HQ), pale, soft and exudative (PSE), dark, firm and dry (DFD) and acid meat (AM) were assessed in four even-numbered genetic groups of 40 fatteners each, namely (L×Y)×D-A, (L×Y)×D-B, (L×Y)×H and (L×Y)×(D×P). The change of diagnostic method and therefore pH time measurement from 24 hours to 48 hours post mortem caused a major increase in the percentage of acid meat (AM) that was diagnosed. Most differences were observed in (L×Y)×H fatteners, namely 77.5% between Methods I and III and 75% between Methods II and IV. This increase in AM frequency indicates that as a result of significant changes in the post-mortem metabolism that occur in the meat ageing process pH 48 should be regarded as ultimate pH (pHu). Keywords : Acid meat, fatteners, post-mortem muscle metabolism