Longissimus Lumborum Muscle Research Articles

Comparison of muscle fiber characteristics and meat quality between newborn and adult Haimen goats

Goat meat is popular with consumers for its rich nutritional content. Muscle fiber characteristics have been shown to play a crucial role in determining the quantity and quality of meat. However, little is known about the temporal changes in muscle fiber characteristics and meat quality during growth in goats. In this study, muscle fiber type, fiber diameter, fiber cross-sectional area (CSA), glycolytic potential (GP), meat pH, and meat color were analyzed in the gastrocnemius (GAS), gluteus medius (GM), biceps brachii (BB), longissimus lumborum (LL) muscles from newborn (NHMG) and adult (AHMG) Haimen goats. The distribution of type I and type Π fiber in goats is not consistent across the four muscles and undergoes alterations with age. The diameter and CSA of the muscle fibers were similar among the four NHMG muscles. However, in AHMG, the LL muscle had the largest fiber in terms of both diameter and CSA, followed by BB, GM, and GAS muscles. Moreover, the CSA of type Π fibers was higher than that of type I fibers in both NHMG and AHMG. GP values ranged from 90 to 140 umol/g across the muscle and no significant differences were observed. AHMG had a higher pH level and a* value, but lower L* and b* values than NHMG. Overall, our findings enhance our understanding of the changes in muscle fiber type and meat quality during the growth in Haimen goats and provide a basis for future research on the development and transformation of muscle fibers in goats.

Canola meal as a supplement for grass-fed beef cattle: Effects on growth rates, carcase and meat quality, and consumer sensory evaluations

The current study examined the growth rates, carcase characteristics, meat quality, and consumer sensory evaluation of the longissimus lumborum muscle (striploin) from steers that were supplemented with either canola meal or grain-based pellets. Forty Angus and Hereford × Angus steers received one of these two supplements with ad libitum lucerne hay for 60 d prior to slaughter. Average daily weight gain was not affected by dietary treatment; however, hot standard carcase weight was significantly lower for steers offered canola meal compared with steers on the grain-based pellets. Dietary treatment did not affect the carcase characteristics, meat quality traits, and consumer sensory evaluation, irrespective of ageing periods. Therefore, canola meal can be used as an approved Pasturefed Cattle Assurance System (PCAS) supplement on moderate dry quality forages without negatively affecting carcase and meat quality traits.

Influence of Sex on Meat and Fat Quality from Heavy Alentejano Pigs Finished Outdoors on Commercial and High Fiber Diets.

This work aimed to examine the effects of sex on meat and fat quality traits from thirty Portuguese Alentejano (AL) pigs reared in outdoor conditions. These pigs were divided into three groups and fed ad libitum. From ~40 to 130 kg LW, castrated (C group) and intact animals (I and IExp) consumed commercial diets. Until slaughter (~160 kg), C and I pigs remained on commercial diets, and IExp changed to a more sustainable experimental diet with locally produced pulses and byproducts. Samples were collected from the Longissimus lumborum (LL), Psoas major (PM), and dorsal subcutaneous fat (DSF). At ~160 kg, the PM muscle of intact pigs presented lower intramuscular fat content than that of C pigs, while total collagen was higher. Additionally, PM myoglobin was lower and lightness (L*) was higher in intact pigs. Regarding DSF, moisture and total protein contents were higher and total lipids were lower in intact than in castrated pigs, while color parameters were not significantly different. Finally, antioxidant capacity measured in the LL muscle showed an overall lower value in intact pigs. However, lipid oxidation values were not significantly different between the experimental groups and only increased with storage time. Outdoor-reared intact AL pigs produced leaner and less saturated pork and fat compared to castrated ones. Despite the lower antioxidant activity observed in the LL muscles of intact pigs, the lipid oxidative stability of cooked meat was not different among the experimental groups.

Transcriptomic analysis reveals diverse expression patterns underlying the fiber diameter of oxidative and glycolytic skeletal muscles in steers

Skeletal muscles consist of heterogeneous fibers with various contractile and metabolic properties that affect meat quality. The size of muscle fibers contributes to muscle mass and myopathy. Thus, improved understanding of the expression patterns underlying fiber size might open possibilities to change them using genetic methods. The aim of this study was to reveal transcriptomic landscapes of one oxidative (Psoas major) and three glycolytic (Longissimus lumborum, Triceps brachii, and Semimembranosus) muscles. Principal component analysis (PCA) showed significant differences in gene expression among the four muscles. Specifically, 2777 differentially expressed genes (DEGs) were detected between six pairwise comparisons of the four muscles. Weighted gene co-expression network analysis (WGCNA) identified six modules, which were significantly associated with muscle fiber diameter. We also identified 23 candidate genes, and enrichment analysis showed that biosynthesis of amino acids (bta01230), sarcomere (GO:0030017), and regulation of actin cytoskeleton (bta04810) overlapped in DEGs and WGCNA. Nineteen of these genes (e.g., EEF1A2, FARSB, and PINK1) have been reported to promote or inhibit muscle growth and development. Our findings contribute to the understanding of fiber size differences among oxidative and glycolytic muscles, which may provide a basis for breeding to improve meat yield.

Rapid assessment of the quality attributes of beef musculus longissimus lumborum during chilled storage using fluorescence spectra excited at 340 nm

The use of fluorescence spectra with 340 nm excitation was investigated for rapid evaluation of the quality attributes of beef musculus longissimus lumborum during chilled storage. The quality indices monitored were the Warner–Bratzler shear force, water-holding capacity (cooking loss and purge loss), pH, and color (L*, a*, and b*). The fluorescence characteristics of nicotinamide adenine dinucleotide (NADH) and porphyrin were highly correlated with these indices. A comprehensive and effective indicator was established by principal component analysis to reduce multicollinearity between each beef quality index. Quantitative models for prediction of the quality of beef were built using the partial least squares algorithm. The comprehensive indicator model provided satisfactory results with the Rc2 and Rp2 were 0.912 and 0.903, the RMSEC and RMSEP were 0.488 and 0.581. Therefore, this method could be used for a reliable assessment of beef quality during chilled storage.

Effect of low-dose blanched Saccharina latissima in finishing bulls’ diets on carcass and meat quality traits

Nutritional and bioactive compounds present in seaweeds make them suitable supplements or feed ingredients in livestock diets. This study assessed the effect of blanched seaweed (Saccharina latissima) as a supplement in finishing bulls’ diets on carcass traits and the quality of the longissimus lumborum (LL) and semimembranosus (SM) muscles. A concentration of 0.8% dry matter of blanched S. latissima in bulls’ diets was the maximum amount allowed, owing to iodine and arsenic thresholds in animal feed. Nineteen Limousin crossbreed bulls were randomly assigned to two groups, fed a control (CD, n = 9) diet or a test diet supplemented with blanched seaweed (SW, n = 10), and fed for 48 days pre slaughter. The carcasses from the bulls finished on a seaweed-supplemented diet were heavier (p < 0.05) than those in the control group, while levels of conformation and fatness were similar between the groups (p > 0.05). The pH was lower (p < 0.05) in the LL of CD-fed animals in early post mortem than in the LL of SW-fed animals, whereas no differences (p > 0.05) were found in the ultimate pH. The meat from the bulls fed both diets had a similar (p > 0.05) drip loss and shear force at days 7 and 14. The cooking loss at day 7 was not affected (p > 0.05) by diet, whereas on day 14 the cooking loss was greater (p < 0.05) for SW than for CD meat. Warmed-over flavor and shear force were muscle dependent and lower (p < 0.05) for LL than SM. Seaweed supplementation in finishing bulls’ diets had no clear effect on color changes (L*, a*, and b* values) during chilled storage, although reduced b* values (p < 0.05) suggest an improved color stability of meat from SW- compared with CD-fed animals. The iodine content was higher (p < 0.05) in the SW meat than in the CD meat, even when using the low seaweed supplementation level requested by the authorities. A small increase of arsenic in the meat with seaweed supplementation has no implications on human health. Cost-efficient processing methods for the further reduction of iodine and arsenic are needed to increase the utilization of seaweed as a feed additive/ingredient and attain a clear effect on meat quality.

Effects of Silage Type and Feeding Intensity on Carcass Traits and Meat Quality of Finishing Holstein-Friesian Bulls.

The study aimed at evaluating the influence of silage type (grass silage-GS, and maize silage-MS) and energy level in the feed portion on animals' performance, carcass value and the quality of Holstein-Friesian bull meat. The animals were reared using intensive (I) feeding, 1.02 feed units for meat production (UFV)/kg dry matter (DM), and semi-intensive (SI) feeding, 0.94 UFV/kg DM. Thirty-two HF bulls with an average live weight of 530 kg were assigned to four feeding groups. The proportions (g/kg DM) of feed in the diets were as follows: group GS-I, GS 500, concentrate 500; group GS-SI, GS 700, concentrate 300; group MS-I, MS 500, concentrate 500; and group MS-SI, MS 700, concentrate 300. After 4 months of the finishing phase, bulls were slaughtered and samples of the longissimus lumborum muscle were collected. The silage type did not affect performance, carcass value or meat quality. However, in the intensive feeding, a 33% increase (p < 0.01) in daily weight gain and a reduction in the feed conversion ratio compared to semi-intensive feeding were noted. The carcasses of bulls fed intensively received higher scores for conformation and fatness than the carcasses of bulls fed semi-intensively. The meat of I group bulls had a higher intramuscular fat content and received higher juiciness, tenderness, taste and overall acceptability scores.

Effects of dietary methionine supplementation from different sources on growth performance and meat quality of barrows and gilts

Methionine is indispensable for growth and meat formation in pigs. However, it is still unclear that increasing dietary sulphur-containing amino acid (SAA) levels using different methionine sources affects the growth performance and meat quality of barrows and gilts. To investigate this, 144 pigs (half barrows and half gilts) were fed the control (100% SAA, CON), DL-Methionine (125% SAA, DL-Met)-supplemented, or OH-Methionine (125% SAA, OH-Met)-supplemented diets during the 11–110 kg period. The results showed that plasma methionine levels varied among treatments during the experimental phase, with increased plasma methionine levels observed following increased SAA consumption during the 25–45 kg period. In contrast, pigs fed the DL-Met diet had lower plasma methionine levels than those fed the CON diet (95–110 kg). Additionally, gilts fed the DL-Met or OH-Met diets showed decreased drip loss in longissimus lumborum muscle (LM) compared to CON-fed gilts. OH-Met-fed gilts had higher pH45min values than those fed the CON or DL-Met diets, whereas OH-Met-fed barrows had higher L45min values than those fed the CON or DL-Met diets. Moreover, increased consumption of SAA, regardless of the methionine source, tended to decrease the shear force of the LM in pigs. In conclusion, this study indicates that increasing dietary levels of SAA (+25%) appeared to improve the meat quality of gilts by decreasing drip loss and increasing meat tenderness.

Matrix metalloproteinase- 9 may contribute to collagen structure modification during postmortem aging of beef

Matrix metalloproteinases (MMPs) are responsible for the turnover of intramuscular connective tissue in live animals. We hypothesize that MMPs may play a role in postmortem aging of beef muscles for the degradation of connective tissues. Four different experiments were performed to: 1) characterize MMP activity during postmortem aging of beef; 2) determine if the native beef MMP can contribute to connective tissue degradation in a simulated standard industry postmortem aging condition; 3) explore approaches to improve the native beef MMP activity and 4) characterize MMP activity in beef from cattle supplemented with supranutritional level of Zn. In experiment 1, MMP was active throughout the entire aging periods (3, 21, 42 and 63 d) for beef muscles Longissimus lumborum, Gluteus medius and Gastrocnemius, and the unknown MMP responsible for the collagen degradation was identified as MMP-9 by Western Blot. In experiment 2 and 3, MMP-9 activity was noticeable in the gels after 42 d of storage in the cooler. Moreover, the addition of ZnCl2 in the model system significantly increased MMP-9 activity when compared to the control (P < 0.01). In experiment 4, Longissimus thoracis from animals supplemented with a supranutritional Zn level had increased Zn availability and MMP-9 activity than those from animals fed with a control diet (P < 0.05). Further research is needed better understand MMP-9 mechanism during postmortem aging of meat. With a better understanding of MMP-9 in the aging process, the beef industry can provide better connective tissue management strategies for lower-quality beef cuts.

Effects of different forage proportions in fermented total mixed ration on muscle fatty acid profile and rumen microbiota in lambs.

The objectives of this study were to evaluate the effects of different forage proportions in the fermented total mixed ration (FTMR) on growth performance, muscle fatty acid profile, and rumen microbiota of lambs. Thirty 6-month-old small tail Han sheep × Ujumqin lambs with initial body weight (BW) of 27.8 ± 0.90 kg were selected for the test and divided into two groups of 15 sheep in each treatment (three pens per treatment and five lambs per pen) according to the principle of homogeneity. Two isoenergetic and isonitrogenous diets were formulated according to the NRC. The diet treatments were designed as (1) OH treatment containing 25% alfalfa hay and 35% oat hay, and (2) AH treatment containing 35% alfalfa hay with 25% oat hay. The forage-to-concentrate ratio for both diets was 65: 35 (DM basis). Three replicates were randomly selected from each treatment to determine growth performance, fatty acid profile and rumen bacterial communities in lambs. Results revealed no statistically significant (p > 0.05) differences in dry matter intake and average daily gain between the two diet groups. Cholesterol and intramuscular fat were significantly (p > 0.05) higher in the AH group, while no statistically significant difference (p > 0.05) was found in pH24 value. The muscle fatty acid compositions of lambs were obviously (p < 0.05) influenced by the diet treatments. Compared with the OH group, the C16:1, C17:0, and C20:3n6 contents were higher (p < 0.05) in the AH group, whereas the content of C18:1n9c, C20:1, C18:3n3, and C22:6n3 was obviously (p < 0.05) increased in the OH group. The monounsaturated fatty acid (MUFA) contents were significantly higher in the OH group, whereas no significant differences (p > 0.05) were detected in saturated fatty acid (SFA) and polyunsaturated fatty acid (PUFA) contents among the two diet treatments. Bacterial composition was generally separated into two clusters based on principal coordinate analysis, and the OH group had a higher Shannon index. The relative abundance at the genes level of the Rikenellaceae_RC9_gut_group was obviously (p < 0.05) increased in the AH group and the relative abundances of Prevotella_1, Fibrobacter, and Bacteroidales_UCG_001_unclassified were obviously (p < 0.05) enriched in the OH group. Integrated correlation analysis also underscored a possible link between the muscle fatty acid compositions and significantly altered rumen microbiota. Overall, oat-based roughage in FTMR could promote a beneficial lipid pattern in the Longissimus lumborum muscles of lambs. These findings provide a potential insight into diet effects on fatty acid profile and the rumen microbiome of lambs, which may help make decisions regarding feeding.

Flavor Development of Individually Vacuum-Packaged Beef Steaks During Extended Wet Aging

The objective of the study was to determine the effect of extended aging on the flavor development of various muscles, individually stored in vacuum rollstock packaging. Strip loins, paired tenderloins, and top sirloin butts (n=48) from USDA Low Choice carcasses (Small00 to Small100 marbling score, n=16). Subprimals were wet-aged in the absence of light for 28 d postmortem before fabrication into 2.54 cm steaks representing the longissimus lumborum (LL), psoas major (PM), and gluteus medius (GM). Steaks were individually packaged in vacuum rollstock packaging and assigned to an additional aging time of 28, 35, 42, 49, or 56 d. Cut steaks (n=240/test) were designated to trained descriptive panel analysis or volatile compound analysis. No interactions occurred for trained sensory analysis, but a main effect of days of age (P≤0.033) showed the greatest effect on negatively associated attributes, including liver-like, oxidized, fishy, bitter, and sour, after 42 d of aging. A main effect of muscle type also occurred (P≤0.040) for flavor attributes, in which GM and PM samples scored higher in off-flavor attributes compared with LL samples, including flavors such as liver-like, oxidized, and sour. An interaction between muscle type and days of age occurred for 2-pentyl-furan (P=0.021). One compound—3 hydroxy-2 butanone—was affected by muscle type (P=0.009). However, most compounds were affected by days of age (P≤0.046), in which compounds related to off-flavors increased in concentrations the most after 49 d. Additionally, discriminant function analyses were performed, suggesting the most effective aging time for individual steaks to be under 49 d when considering loadings for volatile compounds and flavor attributes corresponding with days of age. Overall, these data suggest individual packaging of GM, LL, and PM muscles is most optimal for up to 42 or49 d of age without a large impact from the presence of off-flavors, thus providing food service establishments the opportunity to individually package beef steaks for an extended period while maintaining consumer satisfaction through optimal flavor.

A Comparative Study on the Adipogenic and Myogenic Capacity of Muscle Satellite Cells, and Meat Quality Characteristics between Hanwoo and Vietnamese Yellow Steers.

Myogenesis and adipogenesis are the important processes determining the muscle growth and fat accumulation livestock, which ultimately affecting their meat quality. Hanwoo is a popular breed and its meat has been exported to other countries. The objective of this study was to compare the myogenesis and adipogenesis properties in satellite cells, and meat quality between Hanwoo and Vietnamese yellow cattle (VYC). Same 28-months old Hanwoo (body weight: 728±45 kg) and VYC (body weight: 285±36 kg) steers (n=10 per breed) were used. Immediately after slaughter, tissue samples were collected from longissimus lumborum (LL) muscles for satellite cells isolation and assays. After 24 h post-mortem, LL muscles from left carcass sides were collected for meat quality analysis. Under the same in vitro culture condition, the proliferation rate was higher in Hanwoo compared to VYC (p<0.05). Fusion index was almost 3 times greater in Hanwoo (42.17%), compared with VYC (14.93%; p<0.05). The expressions of myogenesis (myogenic factor 5, myogenic differentiation 1, myogenin, and myogenic factor 6)- and adipogenesis (peroxisome proliferator-activated receptor gamma)-regulating genes, and triglyceride content were higher in Hanwoo, compared with VYC (p<0.05). Hanwoo beef had a higher intramuscular fat and total monounsaturated fatty acids contents than VYC beef (p<0.05). Whilst, VYC meat had a higher CIE a* and total polyunsaturated fatty acids content (p<0.05). Overall, there was a significant difference in the in vitro culture characteristics and genes expression of satellite cells, and meat quality between the Hanwoo and VYC.

Differences in toughness and aging potential of longissimus lumborum muscles between Hanwoo cow, bull and steer.

Thirty Hanwoo cattle including bulls, cows, and steers (n = 10 each) were slaughtered and investigated for carcass traits (weight, meat color, fat color, yield index, maturity, marbling score, back-fat thickness, and firmness) and meat quality. The meat quality such as: pH, color, cooking loss, fatty acid, thiobarbituric acid reactive substance, warner-bratzler shear force, tensile tests, and texture profiles were analyzed on longissimus lumborum (LL) muscles of the carcasses at different aging times (3 d and 21 d). The results showed that steers and cows had higher back-fat thickness and marbling score, and a lower firmness (p < 0.001) than bulls. Bulls exhibited a lower meat quality indicating by higher cooking loss, thiobarbituric acid reactive substance content, warner-bratzler shear force and tensile test values (p < 0.01). Regarding the sensory property, the bull meat also had higher hardness, and lower tenderness, juiciness and flavor scores than the cow or steer meat (p < 0.01). Additionally, the bull meat had a higher polyunsaturated fatty acid and a lower monounsaturated fatty acid contents (p < 0.01). With increased aging time, the meat tenderness was improved in all the genders. Taken together, the present study demonstrated that the gender and aging time affected the carcass traits, fatty acid and sensory quality of beef. Postmortem aging could improve the meat tenderness of all genders especially bulls.

Cull Beef Cow from Southern Portugal: High Amount of n-3 PUFA

The goal of this research work was to characterize carcass, meat quality traits, proximate composition and lipid profile of cull beef cows reared in extensive systems across various seasons. Mature beef cows (n=65) with mean age of 14.12 years and culled from commercial farms were slaughtered in the Spring, Summer, Autumn and Winter, after a finishing period of about 4 weeks. The meat quality traits were analyzed at 7 d postmortem in Longissimus thoracis, Longissimus lumborum, Semimembranosus, Psoas major and Semitendinosus muscles. The highest carcass yield was obtained in Winter (P &lt;0.05), but the Intramuscular Fat (IMF) means were similar in the different seasons. The meat samples showed high average Warner-Bratzler shear forceWBSF (between 5.41-6.86kg), which may be considered as tough (according to the scale used), except for the Longissimus thoracis which showed intermediate average (5.13kg). However, Psoas major obtained the highest overall acceptance scores. Samples of meat from animals kept in extensive system, natural conditions of Southern Portugal, present high amounts of n-3 PUFA. In Autumn and Summer, portions of 100 g/day of meats with 4.03% and 4.25% of IMF with 1.12 and 2.20% of n-3 PUFA in total fatty acids, can provide between 72.96 and 143.31mg of n-3 PUFA or 31.99 and 61.21mg/d of EPA plus DHA, which corresponds to 12.47% and 24.48% of the requirements recommended by EFSA authorities (250mg/d of EPA plus DHA).

The Effect of Festulolium Silage-Based Diets on the Content of Tocopherols, β-Carotene and Retinol in Meat from Young Rams.

This study analyzed the chemical composition and the β-carotene, tocopherol and retinol content of meat (musculus longissimus lumborum, musculus gluteus maximus) from young rams fed different silage-based diets. The animals were divided into four groups depending on the type of silage in the feed ration (hybrid ryegrass, Festulolium cv. Becva, Festulolium cv. Felopa, Festulolium cv. Paulita). The concentrations of the examined lipophilic compounds were measured via high-performance liquid chromatography (HPLC). Animals fed a diet based on ryegrass silage had the highest intakes of α-, β-, γ- and δ-tocopherol and total tocopherols (p < 0.01). Muscles of rams fed Festulolium silage-based diets contained more tocopherols (p < 0.01) and retinol (p < 0.01 in m. g. maximus; p = 0.053 in m. l. lumborum) than the meat of animals receiving hybrid ryegrass-based diets. The highest amounts of tocopherols (p < 0.01) and retinol (p < 0.01 in m. g. maximus; p = 0.053 in m. l. lumborum) were found in meat from rams fed rations based on silage made from Festulolium cvs. Felopa and Paulita. The analysis revealed a positive correlation between the intake of tocopherols and the α-tocopherol content of meat (r = 0.99), as well as between the β-carotene intake and the retinol content of meat (r = 0.92 in m. l. lumborum; r = 0.91 in m. g. maximus).

Effect of Aging Methods and Ultrasonication Treatment on the Sensory Profile of Beef Longissimus lumborum Muscle

Tenderness is one of the most appreciated quality characteristics in beef by consumers. Meat aging is the most recognized natural methodology to improve tenderness in beef. The current study was designed to evaluate if ultrasonication was able to simulate (ultrasonication alone) or to grant an additional effect (aging plus ultrasonication) to two different aging methods (dry and wet) on the sensory profile of the beef Longissimus lumborum muscle. The two aging methods (dry and wet), or ultrasonication for 40 min (US), had no effect (p &gt; 0.05) in overall consumer acceptability. However, in terms of sensory attribute liking, the highest values (p &lt; 0.05) were observed in the ultrasonicated and wet-aged meat for 10 d and the dry-aged meat for 10 d, without difference between them (p &gt; 0.05). It is concluded that ultrasound offers the possibility to obtain tender meat without the cost and contamination risks implicated in the dry-aging method.

Fatty acid and amino acid profiles in muscle longissimus lumborum et thoracis of the indigenous Prestice Black-Pied pig breed in comparison with a commercial pig hybrid

The objective of the study was to analyse the fatty acid profile (FA) and amino acid profile (AA) in the musculus longissimus lumborum et thoracis (MLLT) in two contrast pig populations. The study was carried out on a total of 39 pigs (19 barrows and 20 gilts) of the indigenous Prestice Black-Pied Pig (PB) and 37 pigs (17 barrows and 20 gilts) of the three-breed commercial hybrid of Large White × Landrace × Large Whitesireline (CH). The pigs were kept in the same conditions of diet and management. The slaughter was carried out at the average weight of 95 kg. Sex of the evaluated pigs was also taken into account. The CH pigs showed lower contents of saturated FA (p < 0.01), monounsaturated FA (MUFA; p < 0.05) and a higher content of n-6 polyunsaturated FA (PUFA; p < 0.05), more favourable health indexes, expressed as lower values of atherogenic (p < 0.001), thrombogenic (p < 0.001) and saturation (saturated/unsaturated FA) index (p < 0.001) and positively higher values of hypocholesterolemic/hypercholesterolemic FA ratio (p < 0.01). The gilts showed lower content of MUFA (p < 0.05). Significant (p < 0.05) interaction effects between genotype and sex were recorded for the caprylic acid, capric acid, lauric acid, tridecylic acid, myristic acid, stearic acid, arachidic acid, α-linolenic and γ-linolenic acid (p < 0.01), with the highest content found in PB barrows. Differences in the AA profiles in the MLLT muscle were only minimal. The PB pigs showed higher proportion (p < 0.05) of threonine, isoleucine and aspartic acid. Higher proportions of threonine and valine were observed in barrows (p < 0.05). The results indicate that the evaluated populations of pigs are characterised by significantly different composition of FA. The health indexes suggest more favourable values in the meat of CH pigs.

Objective Meat Quality from Quality Grade and Backfat Thickness of Hanwoo Steers.

The objective of this study was to determine the effects of quality grade (QG), and back-fat thickness on the carcass traits and meat quality properties of Hanwoo steers. Fifty carcasses were sorted into two QG (QG 1+ and 1) and three back-fat thickness (<10 mm, 10 to 19 mm and ≥19 mm) groups. After investigating the carcass traits (rib eye, back-fat thickness, weight, color, yield index, maturity, marbling score, and texture), the longissimus lumborum muscles from the carcass groups were collected and analyzed for meat quality (pH, color, cooking loss, and moisture), texture profiles [Warner-Bratzler shear force (WBSF), and tensile tests], and fatty acid. Results showed that marbling score (p<0.001), moisture (p<0.05) and tensile tests values (p<0.05) had a significant differences between QG1+ and QG1. No differences in pH, color traits, cooking loss and WBSF values occurred between the QG groups. Regarding the back-fat thickness effect, we observed that the carcass weight, yield index (p<0.001), yield grade (p<0.001) and marbling score (p<0.05) had a significant differences among the back-fat thickness groups. Regarding the meat quality, moisture content and WBSF values (p<0.01) among the back-fat thickness groups. The back-fat thickness did not affect the pH, color, cooking loss and tensile tests. The QG and back-fat thickness did not affect the fatty acids contents (p>0.05). It may be concluded that the carcass traits and meat quality were significantly affected the QG and back-fat thickness.

Avian mitochondria respiration is not predicated solely on complex abundance and DNA content

Skeletal muscle is a collection of heterogenous muscle fiber types differing in their ability to contract and metabolize energy substrates. The relative proportion of each fiber type in muscle drive function, where oxidative muscles are more fatigue resistant and generally have greater amounts of mitochondria than more glycolytic muscles that have less mitochondria because of their reliance on glycolytic reactions for energy production. However, even highly glycolytic muscles, like the breast muscle of chickens have mitochondria. Yet, differences in mitochondrial characteristics across muscle types remain largely unknown.We compared glycolytic and oxidative muscles of two different species in an attempt to understand better the relationship between mitochondrial DNA (mtDNA) and protein abundance, and mitochondria function. Glycolytic muscles longissimus lumborum (LL) and the pectoralis major (PM) and oxidative muscles masseter (MS) and quadriceps femoris (QF) were collected from adult pigs and chickens, respectively. Greater mtDNA abundance (2 -ΔΔCT ) was noted in oxidative muscles of both species compared to their glycolytic counterparts ( P &lt; 0.01). However, when absolute mtDNA was estimated, porcine MS had more mtDNA than LL ( P &lt; 0.001), whereas both avian muscles were equivalent. Porcine MS muscle had greater succinate dehydrogenase (SDHA, P &lt; 0.05) and citrate synthase (CS, P &lt; 0.001) than LL, while avian QF muscle had greater CS ( P &lt; 0.001) and voltage dependent anion channel (VDAC, P &lt; 0.05) compared to PM muscle. Isolated mitochondria from the MS of pigs had more electron transport chain complex I (CI, P &lt; 0.010) and complex II (CII, P &lt; 0.05) than those isolated from the LL. Avian mitochondria had no differences in either electron transport chain complexes across muscle, but mitochondria from the PM had greater VDAC than those purified from the QF. Oxygen consumption rates (OCR) followed muscle type, where mitochondria from oxidative muscles consumed more oxygen than those of glycolytic muscle when stimulated with ADP ( P &lt; 0.05). These data show that porcine mtDNA abundance, mitochondrial protein abundance, and mitochondrial function is greater in oxidative muscle compared to glycolytic muscle, and that respiration is greater in mitochondria from more oxidative muscle. However, differences in the relative abundance of mtDNA and electron transport chain complexes were not evident in isolated mitochondria from the chicken, yet respired differently nonetheless suggesting mtDNA and protein may not be directly correlated to the overall function of mitochondria. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

L‐Arginine and l‐lysine can weaken the intermolecular interactions of main myofibrillar proteins: the roles in improving the tenderness of pork Longissimus lumborum muscle

SummaryThis work aims at investigating the mechanisms underlying the effects of l‐arginine and l‐lysine on the tenderness of pork Longissimus lumborum muscle. The results indicated that on day 7, L‐arginine and l‐lysine were able to decrease the shear force from 71.47 to 27.59 or 32.53 N, but raise the myofibrillar fragmentation index from 70.93 to 88.2 or 92.4, compared to the control. Additionally, l‐arginine inhibited the degradation of desmin, troponin‐T and titin; while l‐lysine inhibited the degradation of desmin, troponin‐T, titin and nebulin. l‐Arginine, especially l‐lysine alleviated the Z‐disc damage, while accelerated the M‐line damage. l‐Arginine and l‐lysine promoted the extraction of myosin, titin and some unidentified proteins, decreased ionic bonds but increased hydrophobic interactions. The results suggest that the weakening of the intermolecular interactions between main myofibrillar proteins by l‐arginine or l‐lysine may play crucial roles in improving meat tenderness. The finding may broaden the way to tenderise meat.