This research was funded by FAPESP (grants 2023/05002-3; 2023/02662-2 and 2024/09871-9), CAPES (Finance code 001), CNPq (304158/2022-4), and by PROPE (IEPe-RC grant number 149) of School of Veterinary Medicine and Animal Science, S&#227;o Paulo State University.

All procedures with animals complied with the ethical research standards established by the Animal Use Ethics Committee (CEUA) of the &#34;Universidade Estadual Paulista J&#250;lio de Mesquita Filho&#34; - UNESP Botucatu Campus, under protocol 0171/2018.
1. Experimental animals
<ol>
	<li>Finish 30 Nellore bulls (Bos indicus) and 30 F1 Angus-Nellore bulls (Bos taurus &#215; Bos indicus), aged 20-24 months, in a feedlot. House both groups of animals in collective pens measuring 5 m x 6 m with a concrete floor and equipped with shell-type water troughs, accommodating up to five animals per pen. Ensure that all animals belong to the same management group (born and raised on the same farm) and are submitted to the same feedlot period. 
	NOTE: In this study, the Nellore bulls had an average initial body weight of 370.7 kg while the F1 Angus-Nellore bulls had an average initial body weight of 380.8 &#177; 17 kg.</li>
	<li>Feedlot diet
	<ol>
		<li>Ensure that the finishing diet is comprised of 11.3% roughage (Tifton hay and sugarcane bagasse) and 88.7% concentrates (ground dry corn grain, soybean meal, corn wet distillers&#39; grains, dry corn gluten feed, and mineral core). Feed the animals for 120 days and provide the diets ad libitum twice a day (at 10:00 a.m. and 04:00 p.m.).</li>
	</ol>
	</li>
	<li>Slaughter
	<ol>
		<li>Register the final body weight (BWf) at the end of the experimental period. Process all animals at a nearby slaughterhouse, adhering to standard inspection procedures. Prior to slaughter, ensure that the animals undergo a minimum 16 h fast, abstaining from both feed and water. 
		NOTE: F1 Angus-Nellore bulls exhibited a final body weight of 615.09 &#177; 57.53 kg, while Nellore bulls had a weight of 545.47 &#177; 11.45 kg.</li>
	</ol>
	</li>
	<li>Evaluation of carcass traits
	<ol>
		<li>Weigh the beef carcasses initially and then subject them to a cooling period at 2-4 &#176;C for 48 h. Measurements include hot carcass weight (HCW), rib eye area (REA), and backfat thickness (BFT) at the 12th/13th rib interface, as recommended13. Determine the REA using the grid method with a small grid (18 cm x 13 cm) and measure the BFT in millimeters using a caliper.
		<ol>
			<li>Measure the REA in each carcass by using a reticulated grid (the same as used in the USDA Yield Grade classification system), divided into 1 cm&#178; squares with one dot in the middle. Add all squares within the ribeye tracing perimeter and those along the contour of the tracing passing through the middle dot.</li>
			<li>Measure the BFT at a specific position on the assessment site anywhere between the 12th/13th ribs. To determine this position, measure the length of the rib eye; then, starting at the medial border &#34;A&#34;, determine a point three quarters of the way along the rib eye and halfway across &#34;B&#34;. Take a caliper through this point and at right angles to the specified rib to the interface between the subcutaneous fat and intermuscular fat. Measure the subcutaneous fat by placing the caliper at a right angle to the line of the subcutaneous fat, from the interface point (Supplemental Figure S1).</li>
		</ol>
		</li>
	</ol>
	</li>
	<li>Sampling
	<ol>
		<li>Sample Longissimus thoracis (LT) from the left half-carcass (portion of &#177; 12.0 cm of meat), between the 11th and 13th ribs in the cranial direction. In the laboratory, section the meat samples into steaks of 2.54 cm.</li>
	</ol>
	</li>
	<li>Aging
	<ol>
		<li>Assess the meat quality traits after a 14 day wet-aging period at a temperature of 0-2 &#176;C in a biological oxygen demand (BOD) incubator. Use steaks of 2.54 cm thickness for the analysis of meat color, pH, intramuscular fat, purge loss, water-holding capacity, objective tenderness, and cooking losses. Pack the steaks separately in plastic bags for high vacuum and low oxygen permeability and after the aging time is reached, keep them frozen at -20 &#176;C until the time of analysis. Thaw the beef samples at 4 &#176;C for 24 h and expose them to oxygen for 30 min at 4 &#176;C (blooming time).</li>
	</ol>
	</li>
</ol>
2. Meat pH
<ol>
	<li>Measure the pH of the meat using a digital pH gauge equipped with a penetration probe. Calibrate it with pH 4.0 and 7.0 buffers at a room temperature of 25 &#176;C. Measure the meat pH at three locations of the LT muscle sample. Manually record the data readings and subsequently export the datasheet; calculate the average of the three readings for meat pH.</li>
</ol>
3. Intramuscular fat
NOTE: Intramuscular fat (IMF) content was determined using near infrared (NIR) spectroscopy14 and by gravimetric method15.
<ol>
	<li>Remove the subcutaneous fat from the LT muscle using a scalpel. Then, grind and homogenize the steak for 5 min using a mixer, incorporating approximately 180 g of the sample. Place the sample in a cup, position it inside the sample chamber, and perform subscanning of various zones of the test sample by rotating the sample cup; merge the zones for the final result.</li>
	<li>Take three readings for each sample. After homogenization, place the samples in the plate for subsequent reading. Set the apparatus to NIR transmission, with a moving grating monochromator scanning the region from 850 nm to 1050 nm.</li>
	<li>Export the data sheet and then calculate the average three reading for the IMF. Express the results as a percentage, using the formula: [(IMF average &#247; sample weight) &#215; 100].</li>
	<li>Combine homogenize the LT muscle samples (3.0 g) with a chloroform/methanol methanol/chloroform (2:1) solution for 2 min and subject them to centrifugation (700 &#215; g; 10 min; 20 &#176;C) to segregate the hydrophilic (upper), solid (middle), and hydrophobic (lower) phases.</li>
	<li>Filter the hydrophobic phase obtained post centrifugation using a filter paper on a funnel with slight suction. Transfer the filtrate (bottom phase; lipids in chloroform) to a flask labeled as lipid phase and transfer at least 5 mm of filtrate to a preweighed beaker flask after letting it stand for a few minutes. Then, record the volume of the chloroform layer (at least 150 mL) and aspirate the alcoholic layer.
	<ol>
		<li>Homogenize 100 g aliquots of the sample of fresh or frozen tissue for 2 min with a mixture of 100 mL of chloroform and 200 mL of methanol. Add 100 mL of chloroform to the mixture, blend for 30 s, add 100 mL of distilled water, and blend for another 30 s.</li>
		<li>Filter the homogenate through filter paper on a funnel with slight suction. Apply pressure with the bottom of a beaker when the residue becomes dry to ensure maximum recovery of solvent.</li>
		<li>Transfer the filtrate to a 500 mL graduated cylinder and let it stand for a few minutes to allow separation and clarification. Record the volume of the chloroform layer (at least 150 mL) and aspirate the alcoholic layer.</li>
		<li>Be sure to completely remove the top layer; the chloroform layer contains the purified lipid. For quantitative lipid extraction, recover the lipid trapped in the tissue residue by blending the residue and filter paper with 100 mL of chloroform.</li>
		<li>Filter the mixture through the funnel and rinse the blender jar and residue with a total of 50 mL of chloroform. Mix this filtrate with the original filtrate before removing the alcoholic layer. 
		NOTE: Filtration is typically rapid; apply pressure with the bottom of a beaker on the dry residue to ensure maximum recovery of solvent.</li>
	</ol>
	</li>
	<li>Dry the samples in an oven, cool them in a desiccator for at least 24 h, place them in an oven at 110 &#176;C until complete solvent evaporation, further cool them in a desiccator overnight, and finally reweigh them.</li>
	<li>Determine the IMF content by calculating the difference between the initial and final weights of the beaker.</li>
</ol>
4. Meat color
<ol>
	<li>Calibrate the device using a black and a white standard plate. Place the white calibration plate near the middle of the plate. When doing a calibration, use the area near the middle of the plate. Calibration is complete after the lamp flashes three times.</li>
	<li>Take measurements after 30 min at 4 &#176;C (blooming time). Obtain color readings from three different locations on the LT muscle sample, carefully avoiding connective tissue and fat.</li>
	<li>At room temperature (20 &#176;C), compute an average from these measurements, as recommended16.</li>
</ol>
5. Water losses
<ol>
	<li>Assess purge loss (PL) for all samples. Determine the PL of beef loin sections by measuring the variance between the initial weight before freezing and the final weight after freezing/thawing. 
	NOTE: Do not evaluate the PL of never-frozen control beef loins.</li>
	<li>Gauge the water-holding capacity (WHC) by the weight difference of a meat sample (approximately 1.0 g) before and after being subjected to a pressure of 10 kg for 5 min17.</li>
</ol>
6. Objective meat tenderness
NOTE: The measurement of Warner-Bratzler shear force (WBSF) was conducted as described18,19.
<ol>
	<li>Position samples on a grid attached to a glass refractory and cook them in an industrial electric oven until reaching a final temperature of 71 &#176;C. After cooking, cool, weigh, and refrigerate the samples at 4 &#176;C for 24 h.</li>
	<li>Determine cooking losses (CL) using the formula <img alt="Equation 1" src="/files/ftp_upload/66764/66764eq01.jpg" style="margin: auto;" />.
	<ol>
		<li>Determine drip loss by weighing the refractory before and after cooking the sample. To this end, place the samples on a grid over a glass refractory to allow drainage of meat juices and fat during cooking.</li>
		<li>Determine evaporation loss by weighing only the sample before and after cooking.</li>
		<li>Record raw and cooked weights and calculate the percentage of DL as the weight of drip after cooking divided by the weight of the thawed meat sample.</li>
		<li>Calculate the evaporation loss percentage (EVP) using the formula [100 - (weight after cooking) &#247; raw weight &#215; 100].</li>
	</ol>
	</li>
	<li>For the determination of WBSF, section eight cores with a diameter of 1.27 cm using a texture analyzer, equipped with a 3.07 mm Warner-Bratzler Shear Force blade and a V-shaped (60&#176; angle) cutting edge.
	<ol>
		<li>Report the results as the average of six values per sample, in kilograms (kg), after excluding the low and high extremes19.</li>
	</ol>
	</li>
</ol>
7. Biochemical assay
NOTE: Postmortem proteolysis was assessed by estimating the myofibril fragmentation index (MFI), following the original procedure outlined by Culler et al.20 and adapted for Bos indicus cattle by Borges et al.21.
<ol>
	<li>Homogenize fragments of approximately 3 g of LT samples (fat-stripped muscle tissue and connective tissue) in a buffer solution containing 100 mM potassium chloride, 20 mM potassium phosphate at pH 7, 1 mM ethylenediaminetetraacetic acid (EDTA), 1 mM magnesium chloride, and 1 mM sodium azide at 2 &#176;C, followed by centrifugation (1,000 &#215; g for 15 min at 4 &#176;C).
	<ol>
		<li>Resuspend the sediment in 10 volumes (v/w) of isolating medium using a stir rod, then sediment it again at 1,000 &#215; g for 15 min and decant the supernatant.</li>
		<li>Resuspend the sediment in 2.5 volumes (v/w) of isolating medium and separate the connective tissue and debris by passing it through a polyethylene strainer (18 mesh). Use an additional 2.5 volumes (v/w) to allow the myofibrils to pass through the strainer.</li>
		<li>Determine the protein concentration of the suspension of myofibrils using the biuret method of Gornall et al.22. Dilute an aliquot of the myofibril suspension with isolating medium to a protein concentration of 0.5 &#177; 0.05 mg/mL.</li>
		<li>Immediately measure the absorbance of this suspension at 540 nm. Determine MFI using spectrophotometry at 540 nm. Multiply the absorbance by 200 to obtain the MFI for each sample (and report it as an index without a measurement unit).</li>
	</ol>
	</li>
</ol>
8. Molecular biology assay
NOTE: For the analysis of myosin heavy chain (MyHC), the most abundant protein in bovine skeletal muscle, LT samples from both groups were processed following the protocol described in the literature23,24.
<ol>
	<li>Achieve electrophoretic separation using a gradient SDS-PAGE gel (7-10%) and a 4% stacking gel. Apply 25 &#181;L of each sample to the gel and run it at 70 V, 28 mA, and 4 &#176;C for 1 h, followed by a run at 180 V, 12 mA, and 4 &#176;C for 29 h.</li>
	<li>Employ two different buffers in the runs: the upper gel buffer comprising glycine, Tris(hydroxymethyl)aminomethane base, sodium dodecyl sulfate (SDS), and distilled water, while the lower gel buffer is identical to the upper buffer, with the addition of mercaptoethanol.</li>
	<li>Stain the gels with Coomassie Blue and capture images using appropriate software.</li>
	<li>Identify MyHC isoforms (MyHC-I, MyHC-IIa, MyHC-IIx/d) based on their molecular weights (223.900, 224.243, and 223.875 kDa, respectively). Conduct semi-quantitative analysis by densitometry of the bands corresponding to each isoform, utilizing appropriate software.</li>
	<li>Employ Rat soleus and Extensor digitorum longus (EDL) muscle as positive controls to classify MyHC isoforms, reserving one well in each gel for loading 40 &#181;L of the processed sample.</li>
	<li>For all data, perform the analysis of variance (ANOVA) by the F test, using the following model: 
	Yij = &#181; + ti + &#400;ij 
	where Yij is the observed value of the experimental unit referring to treatment i in repetition j; &#181; is the general effect of the mean; t is the treatment effect (genetic group), and&#160;&#949; is the experimental error.</li>
	<li>Compare the means by using the Student&#39;s t-test and adopt P-value &#60; 0.05 as the critical probability.</li>
</ol>

Assessing Meat Quality Traits in Bos indicus and Crossbred Bulls

The authors have nothing to disclose. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

During carcass evaluation, it is crucial to accurately measure growth and quality traits following a 48 h cooling period to obtain consistent and comparable data. The two biological models exhibited divergent carcass traits, particularly HCW, REA, and BFT, which are consistent with findings reported in other studies. The average HCW of Nellore bulls aligns with Brazilian market preferences, which prioritize greater meat production per animal unit with less fat content25. Conversely, crossbred catt...

Brazil has the largest commercial cattle herd globally, numbering approximately 220 million animals and ranking as the second-largest meat producer, yielding over 9 million metric tons of carcass equivalent annually1. The beef cattle production sector significantly contributes to the national agricultural system, with total annual sales surpassing R$ 55 billion. Since 2004, Brazil has been a key player in the global meat trade, exporting to over 180 countries, which represents ~50% of the world meat trade2.
Meat tenderness stands out as the paramount quality attribute influencing consumer satisfaction and meat consumption3.&#160;By employing biochemical and objective methods to measure meat tenderness, researchers aim to provide valuable insights into factors such as animal genetics, processing techniques, and storage conditions, ultimately enhancing the quality and consistency of meat products for consumers. Such information is useful because meat tenderness has gained increased importance in consumer decision-making during purchases. Moreover, meat tenderness assessment provides valuable information for quality control in meat production and processing industries. By consistently monitoring tenderness, producers can ensure that meat products meet desired standards and specifications. In this context, Brazilian beef cattle producers are progressively embracing intensive feedlot systems with crossbred animals to enhance capital turnover. This system accounts for about 10% tons of carcass produced annually in Brazil4,5.
The escalating demand for improved meat quality by consumers has prompted beef cattle producers to crossbreed with European breeds, primarily Aberdeen Angus6. This strategy aims to produce F1 Angus-Nellore hybrids, known for superior performance, desirable carcass traits, and enhanced meat quality compared to pure zebu animals7,8. In the tropical regions of Brazil, it is common practice to utilize non-castrated animals (bulls) of advanced maturity in finishing farms, potentially compromising meat quality attributes such as color, marbling, and tenderness. Notably, a survey reveals that 95% of animals finished in Brazilian feedlots are males, with 73% being Nellore, followed by 22% crossbred animals and 5% other genotypes9,10.
Understanding the biochemical mechanisms underlying meat tenderness is crucial for improving meat quality. One key aspect is postmortem proteolysis, which affects the structural integrity of muscle fibers11. The myofibril fragmentation index (MFI) is a widely used biochemical assay that quantifies the extent of myofibril degradation, providing insights into the tenderness of meat12. The MFI method involves measuring the fragmentation of myofibrillar proteins, which directly correlates with meat tenderness. This assay complements traditional meat quality assessments and offers a deeper understanding of the biochemical processes that contribute to variations in meat tenderness.
In this context, the present study investigated the skeletal muscle of Bos indicus versus crossbred (Bos taurus &#215; Bos indicus) bulls finished in feedlot, aiming to explain differences in meat quality traits.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Acetone</td>
			<td>Merk, Darmstadt, Germany</td>
			<td>CAS 67-64-1 | 100014</td>
			<td>solutions used for the electrophoretic separations</td>
		</tr>
		<tr>
			<td>Anti-MYH-1 Antibody</td>
			<td>Merk, Darmstadt, Germany</td>
			<td>MABT846</td>
			<td>Rat soleus</td>
		</tr>
		<tr>
			<td>Anti-Myosin antibody</td>
			<td>Abcam, Massachusetts, United States</td>
			<td>ab37484</td>
			<td>Myosin heavy chain</td>
		</tr>
		<tr>
			<td>Anti-Myosin-2 (MYH2) Antibody</td>
			<td>Merk, Darmstadt, Germany</td>
			<td>MABT840</td>
			<td>Extensor digitorum longus (EDL)</td>
		</tr>
		<tr>
			<td>Biological oxygen demand (BOD) incubator</td>
			<td>TECNAL, S&#227;o Paulo, Brazil</td>
			<td>TE-371/240L</td>
			<td>Meat aging</td>
		</tr>
		<tr>
			<td>Chloroform; absolute analytical reagent</td>
			<td>Sigma-Aldrich, Missouri, United States</td>
			<td>67-66-3</td>
			<td>Intramuscular fat</td>
		</tr>
		<tr>
			<td>CIELab system</td>
			<td>Konica Minolta Sensing, Tokyo, Japan</td>
			<td>CR-400 colorimeter</td>
			<td>Meat color</td>
		</tr>
		<tr>
			<td>Coomassie Blue</td>
			<td>Sigma-Aldrich, Missouri, United States</td>
			<td>C.I. 42655)</td>
			<td>Myosin heavy chain</td>
		</tr>
		<tr>
			<td>Electric oven</td>
			<td>Ven&#226;ncio Aires, Rio Grande do Sul, Brazil</td>
			<td></td>
			<td>Meat tenderness</td>
		</tr>
		<tr>
			<td>Ethanol</td>
			<td>Merk, Darmstadt, Germany</td>
			<td>64-17-5</td>
			<td>solutions used for the electrophoretic separations</td>
		</tr>
		<tr>
			<td>Ethylenediaminetetraacetic acid</td>
			<td>Sigma-Aldrich, Missouri, United States</td>
			<td>60-00-4</td>
			<td>Post-mortem proteolysis</td>
		</tr>
		<tr>
			<td>Glass flasks</td>
			<td>Sigma-Aldrich, Missouri, United States</td>
			<td></td>
			<td>solutions used for the electrophoretic separations</td>
		</tr>
		<tr>
			<td>Glycine</td>
			<td>Sigma-Aldrich, Missouri, United States</td>
			<td>G6761</td>
			<td>Myosin heavy chain</td>
		</tr>
		<tr>
			<td>Infrared spectroscopy - FoodScan</td>
			<td>Foss NIRSystems, Madson, United States</td>
			<td>FoodScan&#8482; 2</td>
			<td>Intramuscular fat</td>
		</tr>
		<tr>
			<td>Magnesium chloride</td>
			<td>Sigma-Aldrich, Missouri, United States</td>
			<td>&#160;7786-30-3</td>
			<td>Post-mortem proteolysis</td>
		</tr>
		<tr>
			<td>Mercaptoetanol</td>
			<td>Sigma-Aldrich, Missouri, United States</td>
			<td>M6250</td>
			<td>Myosin heavy chain</td>
		</tr>
		<tr>
			<td>Methanol, absolute analytical reagent</td>
			<td>Sigma-Aldrich, Missouri, United States</td>
			<td>67-56-1</td>
			<td>Intramuscular fat</td>
		</tr>
		<tr>
			<td>pH meter</td>
			<td>LineLab, S&#227;o Paulo, Brazil</td>
			<td>AKLA 71980</td>
			<td>Meat pH</td>
		</tr>
		<tr>
			<td>PlusOne 2-D Quant Kit</td>
			<td>GE Healthcare Product</td>
			<td>Code 80-6483-56</td>
			<td>Post-mortem proteolysis</td>
		</tr>
		<tr>
			<td>Polypropylene</td>
			<td>Sigma-Aldrich, Missouri, United States</td>
			<td></td>
			<td>solutions used for the electrophoretic separations</td>
		</tr>
		<tr>
			<td>Potassium chloride</td>
			<td>Sigma-Aldrich, Missouri, United States</td>
			<td>7447-40-7</td>
			<td>Post-mortem proteolysis</td>
		</tr>
		<tr>
			<td>Potassium phosphate</td>
			<td>Sigma-Aldrich, Missouri, United States</td>
			<td>P0662</td>
			<td>Post-mortem proteolysis</td>
		</tr>
		<tr>
			<td>R software</td>
			<td>Vienna, Austria</td>
			<td>version 3.6.2</td>
			<td>Data analysis</td>
		</tr>
		<tr>
			<td>Sodium azide</td>
			<td>Sigma-Aldrich, Missouri, United States</td>
			<td>26628-22-8</td>
			<td>Post-mortem proteolysis</td>
		</tr>
		<tr>
			<td>Sodium dodecyl sulfate&#160;(SDS)</td>
			<td>Sigma-Aldrich, Missouri, United States</td>
			<td>822050</td>
			<td>Myosin heavy chain</td>
		</tr>
		<tr>
			<td>Spectrophotometer</td>
			<td>Perkin Elmer, Shelton, United States</td>
			<td>Perkin Elmer 
			Lambda 25 UV/Vis</td>
			<td>Post-mortem proteolysis</td>
		</tr>
		<tr>
			<td>Statistical Analysis System</td>
			<td>SAS, Cary, North Carolina, United States</td>
			<td>version 9.1,</td>
			<td>Data analysis</td>
		</tr>
		<tr>
			<td>Texture Analyzer</td>
			<td>AMETEK Brookfield, Massachusetts, United 
			States</td>
			<td>CTX</td>
			<td>Meat tenderness</td>
		</tr>
		<tr>
			<td>Tris(hydroxymethyl)aminomethane</td>
			<td>Sigma-Aldrich, Missouri, United States</td>
			<td>77-86-1</td>
			<td>Myosin heavy chain</td>
		</tr>
		<tr>
			<td>Ultrafreezer</td>
			<td>Indrel Scientific, Londrina, Paran&#225;, Brazil.</td>
			<td>INDREL IULT 335 D - LCD</td>
			<td>Sample storage</td>
		</tr>
		<tr>
			<td>Ultrapure water</td>
			<td colspan="2">Elga PURELAB Ultra Ionic system</td>
			<td>solutions used for the electrophoretic separations</td>
		</tr>
		<tr>
			<td>Ultra-Turrax high shear mixer</td>
			<td>Marconi &#8211; MA102/E, Piracicaba, S&#227;o Paulo, Brazil</td>
			<td></td>
			<td>Post-mortem proteolysis</td>
		</tr>
	</tbody>
</table>

exploring the longissimus muscle: unraveling its correlation with meat quality in bos indicus and crossbred bulls

This study investigated muscle tissue in Bos indicus and crossbred bulls to explain differences in meat quality traits. Carcass traits, meat quality parameters, and biochemical and molecular investigations of myofibrillar proteins are described. Methods for evaluating pH, intramuscular fat (IMF), meat color (L*, a*, b*), water losses, tenderness, and molecular biology assays have been outlined. Specific procedures detailing calibration, sample preparation, and data analysis for each method are described. These include techniques such as infrared spectroscopy for IMF content, objective tenderness assessment, and electrophoretic separation of MyHC isoforms.
Color parameters were highlighted as potential tools for predicting beef tenderness, a crucial quality trait influencing consumer decisions. The study employed the Warner-Bratzler shear force (WBSF) method, revealing values of 4.68 and 4.23 kg for Nellore and Angus-Nellore (P &#60; 0.01), respectively. Total cooking losses and biochemical analyses, including myofibril fragmentation index (MFI), provided insights into tenderness variations. Muscle fiber types, particularly myosin heavy chain (MyHC) isoforms, were investigated, with a notable absence of MyHC-IIb isoform in the studied Zebu animals. The relationship between MyHC-I and meat tenderness revealed divergent findings in the literature, highlighting the complexity of this association. Overall, the study provides comprehensive insights into the factors influencing meat quality in Bos indicus and crossbred (Bos taurus &#215; Bos indicus) bulls, offering valuable information for the beef industry.

Author Spotlight: Improving Beef Cattle Nutrition and Production with a Focus on Feed Efficiency and Meat Quality Traits Through Advanced Biochemical and Molecular Assays

Exploring the Longissimus Muscle: Unraveling its Correlation with Meat Quality in Bos indicus and Crossbred Bulls

Our research involves improving beef cattle nutrition and production, with a significant focus on feed efficiency and meat quality traits. Recently, we have investigated several feed efficiency index of cattle. For example, the residual feed intake, to understand their impact on carcass and meat quality traits.We applied biochemical and molecular assays, including proteomics, lipidomics, and metabolomic approach, to investigate beef cattle nutrition strategy, particularly in feedlot diets. Besides, we also aim to explain the difference in meat quality traits between cattle breeds and sex class. The last years, our findings explored the muscle tissue proteome of beef cattle, which allow us to a better understand of our nutritional strategy used in the livestock production systems.Our lab will focus on omic related analytic technologies and bioinformatics to identify proteins related to growth and meat quality traits of livestock species, since they are the main constituents of muscle tissue and also they're responsible for regulation of the main metabolic pathways.

Table 1 displays the carcass traits of the two genetic groups investigated in this study. Notably, differences were identified (P &#60; 0.01) in HCW, REA, and BFT, with crossbred animals exhibiting greater values, suggesting a heterosis effect.
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Variable&#185;</td>
			<td>Nellore</td>
			<td>F1 Angus x Nellore</td>
			<td>SEM</td>
			<td>P-value</td>
		</tr>
		<tr>
			<td...

We investigated skeletal muscle tissue in Bos indicus and crossbred bulls to explain differences in meat quality traits. Warner-Bratzler shear force (WBSF) was found to range from 4.7 kg to 4.2 kg. Myosin heavy chain isoforms revealed differences between animals, and myofibril fragmentation index provided further insights into tenderness (WBSF) variations.

This study investigated muscle tissue in Bos indicus and crossbred bulls to explain differences in meat quality traits. Carcass traits, meat quality ...

exploring-longissimus-muscle-unraveling-its-correlation-with-meat

Research

JoVE Journal

Biology

288 Views.  São Paulo State University, Botucatu (São Paulo). Our research involves improving beef cattle nutrition and production, with a significant focus on feed efficiency and meat quality traits. Recently, we have investigated several feed efficiency index of cattle. For example, the residual feed intake, to understand their impact on carcass and meat quality traits.We applied biochemical and molecular assays, including proteomics, lipidomics, and metabolomic approach, to investigate beef cattle nutrition strategy, particularly in feedlot di...

Video: Author Spotlight: Improving Beef Cattle Nutrition and Production with a Focus on Feed Efficiency and Meat Quality Traits Through Advanced Biochemical and Molecular Assays

Comprehensive Evaluation of Carcass Traits and Meat Quality Parameters in Beef Cattle

To begin place the longissimus thoracis, or LT muscle, on the working platform. Measure the rib eye area in the 12th and 13th rib interface using a small grid with a dot in the middle. Sum all squares within the rib eye, tracing perimeter, and those along the contour, passing through the middle dot.To measure the back fat thickness, place the caliper at a right angle to the line of the subcutaneous fat from the interface point between the 12th and 13th ribs. Calibrate the pH meter probe with pH-4 and 7 buffers at room temperature. Measure the meat pH at three locations of the longissimus thoracis, or LT muscle.Manually record the data readings, export the data sheet, and calculate the average of the three readings. Homogenize the LT muscle in a methanol chloroform solution for two minutes. Centrifuge the muscle suspension at 700 G for 10 minutes at 20 degrees Celsius to segregate the hydrophilic, solid, and hydrophobic phases.Aspirate the alcoholic layer. Filter the homogenate through filter paper on a funnel with a slight suction. Apply pressure with the bottom of a beaker when the residue becomes dry.Transfer the filtrate to a 500 milliliter graduated cylinder and let it stand for a few minutes. Record the volume of the chloroform layer. Place the sample in an oven at 110 degrees Celsius until complete solvent evaporation.Then, cool the sample in a desiccator overnight. The next day, reweigh the beaker, and determine the intramuscular fat content by calculating the difference between the initial and final weights of the beaker. To calibrate the colorimeter, place the white calibration plate near the middle of the plate.Confirm the calibration once the lamp flashes three times. After 30 minutes of blooming at four degrees Celsius, obtain color readings from three different locations on the LT muscle. Compute the average from three measurements.To determine the purge loss of the beef loin section, measure the variance between the initial weight before freezing, the weight after freezing and thawing, and the final weight. To gauge the water-holding capacity, first, weigh the meat sample before subjecting it to a pressure of 10 kilograms for five minutes. Then, weigh the meat sample again and assess the water holding capacity by calculating the weight differences.Position LT muscles on a grid attached to a glass refractory, place the digital thermometer in the sample, and cook the muscles in an industrial electric oven until reaching a final temperature of 71 degrees Celsius. After cooling, weigh the sample, and refrigerate at four degrees Celsius for 24 hours. Use the given formula to calculate the cooking losses.To determine drip loss, weigh the refractory before cooking the sample. Place the samples on a grid over a glass refractory to allow drainage of meat juices and fat during cooking. After cooking, again, weigh the refractory.Weigh only the sample before and after cooking to determine evaporation loss. After recording raw and cooked weights, calculate the percentage of drip loss as the weight of drip after cooking, divided by the weight of the thawed meat sample. Calculate the evaporation loss percentage using the given formula.For the determination of Warner-Bratzler shear force, section eight cores using a texture analyzer equipped with a Warner-Bratzler blade and V-shaped cutting edge. After excluding the low and high extremes, report the results as the average of six values per sample. Homogenize three grams of LT muscles for 30 seconds in a potassium buffer at two degrees Celsius.Then, centrifuge the sample at 1000 G for 15 minutes at four degrees Celsius, and resuspend the pellet in 10 volumes of isolating medium using a stir rod. Again, centrifuge and resuspend the pellet in 2.5 volumes of isolating medium. Pass the suspension through a polyethylene strainer to separate the connective tissue and debris.Use an additional 2.5 volumes of isolating medium to allow the myofibrils to pass through the strainer. Next, dilute an aliquot of myofibril suspension with an isolating medium. Determine the protein concentration of the suspension of myofibrils using the biuret method.Immediately, measure the absorbance at 540 nanometers. Multiply the absorbance value by 200 to obtain the myofibrillar fragmentation index for each value. Significant differences in hot carcass weight, rib eye area, and back fat thickness were observed with crossbred animals showing higher values, indicating a heterosis effect.Meat quality traits comparisons showed no significant differences in meat pH, purge loss, extractable volume percentage, and cooking loss between Nellore and F1 Angus Nellore bulls. However, crossbred bulls had higher intramuscular fat, yellowness, water holding capacity, and myofibrillar fragmentation index. The meat of Nellore bulls showed reduced tenderness with higher Warner-Bratzular shear force and drip loss, indicating it is tougher than the meat of F1 Angus Nellore bulls.