Effects of selection for ultrasound intramuscular fat percentage in Angus bulls on carcass traits of progeny

Angus bulls (n = 20) from three pure-bred herds in Georgia were acquired to determine the impact of selecting sires based on phenotypic yearling ultrasound intramuscular fat percentage (UIMF) or UIMF EPD on marbling score of steer progeny. Each year in each herd, pairs of bulls were selected to create large differences based on their age adjusted phenotypic yearling UIMF measurements. The average UIMF, weighted by number of progeny per sire, was 3.75% (SD = 1.10%) and 1.70% (SD = 0.53%) for high UIMF (HU) and low UIMF (LU) bulls, respectively. All available ultrasound measurements collected in the purebred co-operator herds were combined with other ultrasound records collected by the American Angus Association for the computation of genetic values for ultrasound fat thickness, ribeye area, and intramuscular fat percentage. Each year bulls were randomly mated to 14 to 30 commercial Angus females. Carcass weight, fat thickness at the 12th rib, ribeye area at the 12th rib, marbling score, yield grade, and quality-grade measurements were collected on 188 steer progeny. Carcass data were linearly adjusted to 480 d of age at slaughter. Steer progeny sired by HU bulls had higher age-adjusted marbling score and quality grade (P < 0.05), and smaller age-adjusted ribeye area (P < 0.05) than steer progeny sired by LU bulls. No significant differences between phenotypic UIMF lines were found for age-adjusted fat thickness (P = 0.84) and yield grade (P = 0.33) in the steer progeny. The regression of age-adjusted carcass marbling score and quality grade of the steer progeny on ultrasound intramuscular fat percentage EPD of the sires produced highly significant regression coefficients of 90.50 and 49.20, respectively. Thus, yearling Angus bulls selected for high-phenotypic UIMF and UIMF EPD can be expected to produce steer progeny with significantly higher amounts of marbling and quality grade. It also appears that marbling can be increased without corresponding increases in external fat thickness and yield grade.     

Prediction of fat percentage within marbling score on beef longissimus muscle using 3 different fat determination methods

Consumers are concerned with fat consumption from meat products, and the ability to determine fat has changed with recent technological advances. The objective of this study was to predict fat percentage within marbling scores and compare 3 fat analysis procedures. Steaks (n = 119) were selected by USDA grading system using an E + V Vision Grading camera at a commercial beef plant during 1 d. Two samples per carcass were cut from the 13th rib, both sides, and transported to the University of Missouri meat laboratory. The sample from the right side of the carcass was allotted to Warner-Bratzler shear force, and the sample from the left side, which was graded by the camera, was allotted to fat extraction. Warner-Bratzler shear force samples were cut into 2.54-cm steaks and aged for 14 d. Steaks allotted to fat extraction were trimmed of all external fat and twice ground using 8- and 4-mm grinding plates. The finely ground beef was then split into its allotted fat-extraction methods. The 3 methods used in fat extraction were 2:1 chloroform/methanol (Folch), ether-extractable fat (ether), and microwave drying and nuclear magnetic resonance (CEM). Warner-Bratzler shear force values were not different between marbling scores (P > 0.05). Regardless of fat extraction method, fat percentage increased as marbling score increased (P < 0.05). All regression equations for fat percentage, regardless of extraction method, were linear. Prediction equation for fat percentage using CEM was -3.46 + 0.016 (marbling score), R(2) of 0.824 (P < 0.0001). Prediction equation for fat percentage using ether was -3.08 + 0.017 (marbling score), R(2) of 0.859 (P < 0.0001). Prediction equation for fat percentage using Folch was -3.42 + 0.019 (marbling score), R(2) of 0.816 (P < 0.0001). When the CEM, Folch, and ether methods were compared, CEM and Folch regression lines had different slopes (P < 0.05). The slope of the regression line for ether was not different (P > 0.05) from CEM or Folch. Overall, ether is the most accurate method based on the R(2) value, but CEM is environmentally safe and the fastest method for determining total crude fat percentage.     

Bovine quantitative trait loci analysis for growth, carcass, and meat quality traits in an F2 population from a cross between Japanese Black and Limousin

A genome-wide scan for QTL affecting economically important traits in beef production was performed using an F(2) resource family from a Japanese Black x Limousin cross, where 186 F(2) animals were measured for growth, carcass, and meat-quality traits. All family members were genotyped for 313 informative microsatellite markers that spanned 2,382 cM of bovine autosomes. The centromeric region of BTA2 contained significant QTL (i.e., exceeding the genome-wide 5% threshold) for 5 carcass grading traits [LM area, beef marbling standards (BMS) number, luster, quality grade, and firmness), 8 computer image analysis (CIA) traits [LM lean area, ratio of fat area (RFA) to LM area, LM area, RFA to musculus (M.) trapezius area, M. trapezius lean area, M. semispinalis lean area, RFA to M. semispinalis area, and RFA to M. semispinalis capitis area], and 5 meat quality traits (contents of CP, crude fat, moisture, C16:1, and C18:2 of LM). A significant QTL for withers height was detected at 80.3 cM on BTA5. We detected significant QTL for the C14:0 content in backfat and C14:0 and C14:1 content in intermuscular fat around the 62.3 to 71.0 cM region on BTA19 and for C14:0, C14:1, C18:1, and C16:0 content and ratio of total unsaturated fatty acid content to total SFA content in intramuscular fat at 2 different regions on BTA19 (41.1 cM for C14:1 and 62.3 cM for the other 4 traits). Overall, we identified 9 significant QTL regions controlling 27 traits with genome-wide significance of 5%; of these, 22 traits exceeded the 1% genome-wide threshold. Some of the QTL affecting meat quality traits detected in this study might be the same QTL as previously reported. The QTL we identified need to be validated in commercial Japanese Black cattle populations.     

Evaluation of performance characteristics in a diallel among Simmental, Limousin, Polled Hereford and Brahman beef cattle. II. Carcass traits

Evaluations of steer and heifer progeny from a diallel mating design of Simmental, Limousin, Polled Hereford and Brahman beef cattle over 5 yr are presented. Traits evaluated included final weight, hot carcass weight, ribeye area, 12th rib fat thickness, marbling score, yield grade, dressing percentage and percentage of kidney, pelvic and heart fat. Progeny of Simmental sires were heavier at slaughter than those with Brahman sires (P less than .05), but no differences were found for carcass weight. Dressing percentage was higher for Limousin crosses compared with progeny of other sire breeds (P less than .05). Similar results were found for dam breeds, except that progeny of Limousin dams had heavier carcasses with a higher dressing percentage (P less than .05) than Brahman crosses. Crosses of Limousin and Simmental had larger ribeye areas (P less than .05) compared with calves of the other breeds. Progeny of Polled Hereford dams had higher marbling scores and were fatter than progeny of dams of other breeds (P less than .05). Heterosis estimates were significant for all Brahman crosses for final weight, carcass weight and ribeye area, but these contrasts were negligible for other traits. Estimates of general combining ability were positive and significant for Simmental for final weight, carcass weight, ribeye area and marbling score and were significant and negative for Limousin for final weight, fat thickness and yield grade. Maternal values were generally small.     

Predicting carcass composition of beef cattle using ultrasound technology.

We evaluated 20 slaughtered cattle with ultrasound before hide removal to predict fat thickness and ribeye area at the 12th rib for possible use in carcass composition prediction. Carcasses were fabricated into boneless subprimals that were trimmed progressively from 2.54 to 1.27 to .64 cm maximum fat trim levels. Stepwise regression was used to indicate the relative importance of variables in a model designed to estimate the percentage of boneless subprimals from the carcass at different external fat trim levels. Variables included those obtained on the slaughter floor (ultrasound fat thickness and ribeye area; estimated percentage of kidney, pelvic, and heart [KPH] fat; and warm carcass weight) and those obtained from carcasses following 24 h in the chill cooler (actual fat thickness, actual ribeye area, estimated percentage of KPH fat, warm carcass weight, and marbling score). At all different subprimal trim levels, percentage KPH was the first variable to enter the model. In the models using measures taken on the slaughter floor, ultrasound fat thickness was the only other variable to enter the model. Ultrasound fat thickness increased R2 and decreased residual standard deviation (RSD) in models predicting subprimals at 2.54-cm maximum fat trim; however, at 1.27- and .64-cm trim levels, R2 and RSD increased. Models using the same two variables (except actual fat instead of ultrasound) in the cooler were similar to those using data from the slaughter floor. However, as more cooler measurement variables entered the models, R2 increased and RSD decreased, explaining a greater amount of the variation in the equation. Ultrasonic evaluation on the slaughter floor may be of limited application compared with the greater accuracy found in chilled carcass assessment.     

Whole-genome QTL scan for ultrasound and carcass merit traits in beef cattle using Bayesian shrinkage method

Fine mapping of quantitative trait loci (QTL) for 16 ultrasound measurements and carcass merit traits that were collected from 418 hybrid steers was conducted using 1207 SNP markers covering the entire genome. These SNP markers were evaluated using a Bayesian shrinkage estimation method and the empirical critical significant thresholds (α = 0.05 and α = 0.01) were determined by permutation based on 3500 permuted datasets for each trait to control the genome-wide type I error rates. The analyses identified a total of 105 QTLs (p < 0.05) for seven ultrasound measure traits including ultrasound backfat, ultrasound marbling and ultrasound ribeye area and 113 QTLs for seven carcass merit traits of carcass weight, grade fat, average backfat, ribeye area, lean meat yield, marbling and yield grade. Proportion of phenotypic variance accounted for by a single QTL ranged from 0.06% for mean ultrasound backfat to 4.83% for carcass marbling (CMAR) score, while proportion of the phenotypic variance accounted for by all significant (p < 0.05) QTL identified for a single trait ranged from 4.54% for carcass weight to 23.87% for CMAR.     

Growth implants reduced tenderness of steaks from steers and heifers with different genetic potentials for growth and marbling

The objective of this study was to evaluate the effect of growth implants on the carcass characteristics and tenderness of steers and heifers with different genetic potentials for growth, lean meat yield production, and marbling. Two experiments were conducted. Experiment 1 evaluated Angus steers sired by bulls with high EPD for retail product yield or marbling. Implant treatment was imposed randomly within sire groups. Loins (Institutional Meat Purchasing Specifications 180) were collected from each carcass and cut into three 2.54-cm steaks aged for 7, 14 and 21 d to evaluate tenderness. The second experiment evaluated steers and heifers of British and Continental breed descent. Steers and heifers were slaughtered after 120 d on feed. Loin sections were collected, and one 2.54-cm steak aged 7 d was used for tenderness analysis. When implants were used in Angus steers, HCW and LM area increased, whereas internal fat and marbling decreased (P < 0.01). In Angus steers, sire type did not affect shear force values of steaks; however, implant use significantly increased shear force values (P < 0.01). Carcasses from cattle of Continental breed descent were significantly heavier than carcasses of British breed descent with larger LM area, slightly less fat, and a reduced yield grade (P < 0.01). Also, steer carcasses were heavier than heifer carcasses with larger LM (P < 0.05), but no effect of sex on fat depth, internal fat, yield grade or marbling was observed. No significant interactions were seen between growth implant and breed or between growth implant and sex for shear force values. Shear force values were significantly less for steaks from steers and heifers of British decent compared with steers and heifers of Continental descent (P < 0.01). Steaks from implanted steers and heifers had significantly (P < 0.01) greater shear force values than steaks from steers and heifers not implanted. Use of growth implants in growing cattle resulted in significantly heavier carcass weights, larger LM area, and reduced internal fat. However, implant use also reduced the amount of marbling along with contributing to reduced tenderness. Complicating the tenderness issue is the increased shear force values reported for heifers as well as steers of Continental breed descent. Use of implants may contribute to tenderness variability because of different animal responses to implants.     

Relationship of fatty acid composition to intramuscular fat content in beef from crossbred Wagyu cattle.

The deposition of i.m. fat, or marbling, in cattle is recognized as a desirable carcass trait in North American beef grading schemes. In order to investigate the relationship between degree of marbling and fatty acid composition of whole bovine muscle, we extracted the total lipid from pars costalis diaphragmatis (PCD) (n = 23) and longissimus (n = 36) muscles from Wagyu crossbred cattle that were assigned Canadian Grading Agency marbling scores ranging from 1 to 8 on an inverse 10-point scale (i.e., a score of 1 indicated "very abundant" marbling and a score of 10 would be assigned to a carcass "devoid" of marbling). Fatty acid methyl esters (FAME) of the total lipid and triacylglycerol fractions were resolved and quantified through GLC. Marbling scores were negatively associated with total lipid from both PCD (r = -.57, P < .01) and longissimus (r = -.80, P < .001). Differences between PCD and longissimus were found for almost all FAME studied from both lipid fractions, but no differences (P > .05) were seen when the monounsaturated:saturated fatty acid (MUFA/SFA) ratios were compared. Heifers had higher (P < .05) oleic acid content and lower (P < .05) palmitic acid content in lipid extracted from both muscles, resulting in higher (P < .05) MUFA/SFA ratios than those for steers. The relative amount of myristic acid increased as the lipid content (total lipid and triacylglycerol) increased in either longissimus (r values from .48 to .55; n = 36; P < .01) or PCD muscles (r from .67 to .76; n = 23; P < .001). The relative amount of linoleic acid (cis-9, cis-12 isomer) from total lipid was negatively associated with all chemical measurements of lipid from the longissimus (r from -.52 to -.64; n = 36; P < .001) and PCD muscles (r from -.75 to -.85; n = 23; P < .001). This association was not significant (P > .1) for either muscle when linoleic acid from the triacylglycerol fraction was examined, suggesting the negative association between this fatty acid and lipid content was due to a dilution of membrane phospholipids with increasing triacylglycerol. Indices of fatty acid elongase activity, calculated from FAME data, implicated the balance between this enzyme activity and fatty acid synthase as a source of variation between animals displaying various degrees of marbling and worthy of further investigation to better understand the process of marbling fat deposition in beef cattle.     

Carcass characteristics of Hanwoo (Korean cattle) from different sex conditions, raising altitudes and slaughter seasons

This study was carried out to investigate the carcass characteristics of Hanwoo (Korean cattle) from different sex conditions, raising altitudes and slaughter seasons. The total number of cattle used in this study was 3608 heads which comprised of 1336 bulls and 1660 steers. The data was analyzed according to sex condition (bull and steer), raising altitude (low: 0–100 m and high: 700–800 m) and slaughter season (spring, summer, autumn and winter). At 24 h post-slaughter, the carcasses were weighed and evaluated for carcass traits according to the Korean carcass grading standard by an official grader. Carcass weight, ribeye area, yield index and grade, and meat color, firmness and maturity scores of carcass from bulls were significantly higher (P < 0.001) than those from steers. Inversely, the backfat thickness, marbling score and quality grade of carcass from steers were significantly higher (P < 0.001) than those from bulls. The maturity score of carcass from a high area was significantly higher (P < 0.01) than that from a low area. The ribeye area of carcass from summer was significantly smaller (P < 0.05) than that from other seasons. The maturity score of carcass from the summer season was highest among that from other seasons and the lowest was that from the winter season. Marbling score and carcass quality grade from the winter season were highest among those from other seasons and the lowest were those from the autumn season. There were no significant interactions between sex condition and raising altitude on carcass traits except the ribeye area. There were significant interactions between sex condition and slaughter season on marbling score and carcass quality grade. There were no significant interactions between raising altitude and slaughter season on all of the carcass traits. There were significant interactions among sex condition, raising altitude and slaughter season on meat color score. It was concluded that sex condition affected muscle and fat depositions on the carcass, raising altitude affected maturity and slaughter season affected ribeye area, maturity and marbling.     

不同部位西门塔尔牛肉理化品质分析及烤制加工适宜性的研究

[目的]研究不同部位西门塔尔牛肉原料肉的理化品质,评价烤制加工后的食用品质和感官品质。[方法]选取体重为550 kg左右的西门塔尔肉牛10头,屠宰分割后取不同部位牛肉（里脊、外脊、前腿、后腿、眼肉、米龙）。4 ℃排酸72 h后,采用常规方法测定不同部位牛肉的蛋白质含量、脂肪含量、水分含量、pH值以及色泽指标,并对大理石花纹等级进行评分;220 ℃烤制10 min后,对不同部位牛肉进行剪切力和加工损失率测定,并对感官品质指标进行评价。[结果]不同部位牛肉的脂肪含量、大理石花纹评分、L^*值、a^*值、剪切力、色泽评分、嫩度评分、多汁性评分、香气评分和总体可接受性评分差异显著（P<0.05或P<0.01）,不同部位牛肉中的蛋白质含量、水分含量、pH值、b^*值、加工损失率、滋味评分差异不显著（P>0.05）。眼肉中脂肪含量最高（P<0.01）,前腿、后腿脂肪含量相同,均为最低（P<0.01）;眼肉、外脊的大理石花纹评分显著（P<0.01）高于其他部位;眼肉、外脊的L^*值显著（P<0.05）高于其他部位,里脊、后腿的L^*值显著（P<0.05）低于其他部位;外脊和眼肉的a^*值显著（P<0.01）低于其他部位;眼肉、外脊的剪切力显著（P<0.01）低于其他部位;眼肉的总体可接受性评分显著（P<0.05）高于其他部位,前腿、后腿和米龙的总体可接受性评分相同,均为最低（P<0.05）。[结论]外脊、眼肉的肌内脂肪含量高于其他部位,烤制后产品的嫩度、滋味及总体可接受性较好。眼肉和外脊是西门塔尔牛肉中最适宜加工烤制产品的部位。     

Fat depot‐specific effects of body fat distribution and adipocyte size on intramuscular fat accumulation in Wagyu cattle

Ectopic fats have been recognized as a new risk factor for metabolic syndrome. In obese humans, ectopic fat accumulations are affected by body fat distribution. Intramuscular adipose tissue is categorized as one of the ectopic fats. Japanese black cattle (Wagyu) are characterized by the ability to accumulate high amounts of intramuscular adipose tissue. In Japan, the marbling level is indicated by the beef marbling standard number (BMS No.), which reflects the intramuscular fat content of longissimus muscle. We hypothesized that the intramuscular fat accumulation is affected by the body fat distribution in Wagyu cattle. In this study, we showed that the BMS No. was not correlated with the subcutaneous and visceral adipocyte diameter. In contrast, the BMS No. was positively correlated with intramuscular adipocyte diameter. These results indicate that the intramuscular adipocyte diameter of Wagyu is hypertrophied with an increase in the intramuscular fat accumulation. In addition, we showed that the BMS No. was positively correlated with the subcutaneous fat percentage. In contrast, the BMS No. was negatively correlated with the visceral fat percentage. These results indicate that highly marbled Wagyu cattle have a higher percentage of subcutaneous fat and a lower percentage of visceral fat.     

Genetic correlations between live yearling bull and steer carcass traits adjusted to different slaughter end points. 2. Carcass fat partitioning

Partial carcass dissection data from 1,031 finished crossbred beef steers were used to calculate heritabilities and genetic correlations among subcutaneous, intermuscular, and body cavity fat percentage and marbling score adjusted to slaughter age-, HCW-, fat depth-, and marbling score-constant endpoints. Genetic correlations were also calculated among these fat partitions with live growth and ultrasound traits evaluated in yearling beef bulls (n = 2,172) and steer carcass measurements. Heritabilities of the different fat partitions ranged from 0.22 (marbling score-constant body cavity fat) to 0.46 (HCW-constant marbling score). Genetic correlations between subcutaneous fat and intermuscular fat (rg = 0.16 to 0.32) and between intermuscular fat and body cavity fat (rg = 0.38 to 0.50) were more highly associated than subcutaneous fat and body cavity fat (rg = -0.08 to 0.05), indicating that fat depots are not under identical genetic control. Adjusting fat depots to different end points affected the magnitude but usually not the sign of the genetic correlations. Bull postweaning gain was associated with intermuscular (-0.24 to -0.35), body cavity (-0.24 to -0.29), and marbling fat (-0.24 to -0.39) in steers. Bull hip height was associated with body cavity (-0.20 to -0.29) and marbling fat (-0.20 to -0.47) in steers. Bull ultrasound fat depth was associated with subcutaneous (0.11 to 0.29), intermuscular (0.05 to 0.36), body cavity (0.27 to 0.49), and marbling fat (0.27 to 0.73) in steers. Bull ultrasound intramuscular fat percentage was associated with subcutaneous (-0.22 to -0.44) and intermuscular fat (-0.06 to 0.31) in steers. Bull ultrasound LM area was associated with body cavity (-0.25 to -0.31) and marbling fat (-0.25 to -0.30) in steers. Ultrasound LM width measurements were negatively correlated with subcutaneous fat (rg = -0.09 to -0.18), intermuscular fat (rg = -0.53 to -0.61), body cavity fat (rg = -0.63 to -0.69), and marbling score (rg = -0.75 to -0.87) at slaughter age-, HCW-, and fat depth-constant endpoints; correlations were generally lower at a marbling score-constant end point (rg = 0.07 to -0.49). Ultrasound indicator traits measured in seedstock may be useful in altering fat partitioning in commercial beef carcasses.     

Deposition and distribution of carcass fat for steers differing in frame size and muscle thickness

Yearling feeder steers (n = 324) representing nine frame size (Large, Medium, Small) x muscle thickness (No. 1, No. 2, No. 3) subclasses were serially slaughtered at 28-d intervals during a 140-d finishing period. Weights for total dissectible (TDF) and subcutaneous fat (SQ) from each of nine wholesale cuts were recorded. Resulting data were analyzed using allometry (Y = aXb and Y = aXb10cx) to characterize deposition patterns for fat and to determine effects of feeder cattle frame size (F) and muscle thickness (M) on relative fat deposition and distribution. Patterns of TDF and SQ deposition were similar among cuts. As the steers became fatter, relative proportions of TDF and SQ in the abdominal and dorsal regions of the carcass increased and relative proportions of fat in the distal regions decreased. There was a tendency for the growth impetus of TDF and SQ to shift from the ventral portions of the carcass toward the dorsal region of the carcass as fattening progressed. Despite significant among-class differences in allometric coefficients, relative proportions of TDF and SQ in the nine wholesale cuts were remarkably similar for all nine F x M subclasses when compared at a constant percentage of total carcass fat. At endpoints of either a constant fat thickness measurement or a constant USDA marbling score, subclass differences in fat distribution were negligible.     

The relationship of average backfat thickness of feedlot steers to performance and relative efficiency of fat and protein retention

Selection for growth and improved carcass merit has resulted in cattle that are variable in composition of gain during the finishing phase. This study assessed the relative performance among cattle with different levels of initial backfat thickness. It also exploited the ability to track carcass composition in the live animal with ultrasound estimates of backfat and marbling. A procedure was developed to partition and estimate relative efficiency of fat and protein gain. The trial periods were the last 43 or 50 d before slaughter and included 10 pens (average of 27 animals per pen) that ranged in average backfat thickness from 6.3 to 13.1 mm. There was no correlation (r2 = 0.0026) between average backfat thickness and G:F (g/kg of DMI). Correlations between average backfat thickness and ADG or DMI were also nearly zero (r2 = 0.0007 and 0.0042, respectively). Fat deposition from NEg was 3.98 times more efficient than protein deposition. Carcass backfat thickness was a poor predictor of carcass marbling score (r2 = 0.083), even though backfat thickness was an important predictor of the percentage of empty body fat (r2 = 0.807). The results indicate that a measure of backfat thickness on the live animal during the finishing phase is not an effective predictor of future feed efficiency. They also confirm that protein accretion is energetically expensive, and that using a single coefficient for predicting gain from NEg is valid regardless of whether gain is predominantly muscle or fat. These data document that there is little relationship between body composition and marbling score, which is contrary to models that assume a USDA quality grade target at a specified percent fat end point.     

Factors influencing intermuscular fat and other measures of beef chuck composition.

Carcasses from 59 steers produced from the mating of Braford, Simbrah, Senepol, and Simmental bulls to Brahman- and Romana Red-sired cows and Brahman bulls mated to Angus cows were used in this study. Effects of sire breed and feeding calves vs yearlings on fat depots in the chuck, when steers were fed to 1.0 cm external fat, were determined. Breed of sire and feeding calves vs yearlings had no effect (P greater than .05) on percentage of intermuscular fat. However, carcasses from Braford-sired steers had a higher (P less than .05) percentage of dissectable subcutaneous fat on the chuck than did those from other breed groups. Carcasses from Simmental-sired steers were superior (P less than .05) to those from Braford-sired steers in USDA yield grade and had a higher average marbling score (P less than .05) than the Simbrah-sired group. Estimated kidney, pelvic, and heart (KPH) fat was higher (P less than .05) in carcasses from Brahman-, Simbrah-, and Senepol-sired steers than in Braford-sired steers. Steers fed as calves had higher percentages (P less than .05) of KPH fat and major chuck muscles than did those fed as yearlings. The best single predictor of percentage of intermuscular fat within the chuck was adjusted fat over the ribeye (R2 = .46).     

Estimation of beef marbling in the Longissimus muscle with computer image analysis of ultrasonic pictures of the Iliocostalis muscle area

This study investigated an objective method for estimating beef marbling using ultrasonic images of the Iliocostalis muscle and the Lomgissimus muscle area sections. Thirty‐one Japanese Black cattle steers were used in this study. The end of the left side shoulder blade bone was scanned using an ultrasonic device. Ultrasonic images were captured of the Longissimus muscle area and that around the Iliocostalis muscle area. Twenty items were measured in the two images using computer image analysis software. The level of beef marbling was measured according to the Beef Marbling Standard (BMS) for carcass grading, and the percentage of ether‐extractable fat content in the Longissimus muscle (EE). The difference in the gray level between the Iliocostalis muscle and intermuscular fat (X10) was used to estimate the BMS and the EE, which were highly correlated (r² = 67.72% and 61.30%). An equation was developed using four parameters from the two ultrasonic images, which could estimate the BMS (r² = 85.88%). This equation could also estimate the EE (r² = 68.98%). The equations used to estimate beef marbling were based on one to four parameters that included X10. Thus, ultrasonic images of the Iliocostalis muscle area section are important for estimating beef marbling.     

Differences among Wagyu sires for USDA carcass traits and palatability attributes of cooked ribeye steaks

The objective of this experiment was to evaluate the effects of various Wagyu sires on carcass quality traits and palatability attributes of cooked ribeye steaks. Wagyu sires were used and grouped as Old (n = 6) or New (n = 2) sires, based on the chronological order in which they were imported into the United States. One hundred thirteen F1 heifer and steer calves sired by Wagyu bulls out of three different sources of cows were fed a backgrounding diet for 112 d consisting of an 80:20 ratio of roughage:concentrate then grazed on a mixture of orchardgrass and bluegrass pasture for 84 d and finished on a 10:90 ratio of roughage:concentrate diet for 231 d in a feedlot. Progeny from New sires had larger (P < .05) ribeye areas, higher (P < .05) marbling scores, and lower (P < .05) maturity scores than progeny from Old sires. Marbling was positively correlated (P < .05) to brightness (r = .56), texture (r = .60), and fat luster (r = .38). Progeny of New sires had lower shear force values (P < .05) than progeny of Old sires. These results indicate the superiority of New Wagyu sires to produce progeny with more marbling, lower shear force values, and larger ribeye areas than Old Wagyu sires. Furthermore, there are substantial differences between Wagyu sires for carcass quality traits and palatability attributes.     

中草药饲料添加剂对延边黄牛肉品质与风味物质的影响

【目的】试验旨在研究中草药饲料添加剂对延边黄牛不同部位牛肉营养成分、重金属及抗生素残留、风味物质含量的影响。【方法】选用100头健康且体重相近的27月龄延边黄牛,随机分为2组,每组50头。对照组饲喂基础饲粮,试验组在基础饲粮中添加0.2%中草药饲料添加剂。预试期10 d,正试期90 d。试验结束后,每组随机选择10头牛进行屠宰,取胸肉、眼肉、西冷、上脑和里脊5个部位肌肉样,测定牛肉中常规营养成分、剪切力、肉色、氨基酸、脂肪酸、重金属、抗生素、风味物质等指标。【结果】与对照组相比,饲粮中添加中草药饲料添加剂对牛肉常规营养成分粗蛋白质、粗脂肪、粗纤维、钙和磷含量均无显著影响(P>0.05),可以增加牛肉中总氨基酸含量及鲜味氨基酸、甜味氨基酸和苦味氨基酸的总含量,并提高牛肉中棕榈油酸和亚麻酸含量,但差异均不显著(P>0.05);试验组延边黄牛胸肉剪切力显著降低(P<0.05),眼肉和里脊部位的红度值显著提高(P<0.05),西冷、眼肉和胸肉中氮氧化合物和无机硫化物类等芳香化合物的含量均显著降低(P<0.05)。试验组与对照组牛肉中均未检测到重金属和抗生素残留。【...     

Computer image analysis of intramuscular adipocytes and marbling in the longissimus muscle of cattle

The deposition of fat in muscle, recognized by the consumer as marbling, is an important meat quality trait. The objective of the study was to provide additional insights into the quantitative extent of marbling by means of computer image analysis. Fifty-one F(2) generation German Holstein and Charolais crossbreed cattle, 18 mo of age, were used to determine relationships among marbling traits, adipocyte size, and the amount of adipose tissue in different depots. Differences were recorded among the size of i.m. adipocytes in different groups of marbling flecks, divided according to the location in the muscle cross-section and to the size of the marbling flecks. The results showed positive correlation between i.m. adipocyte size and the weight of s.c. fat, intestinal fat, omental fat, and perirenal fat (r = 0.50, 0.61, 0.70, and 0.63, respectively, P < 0.001). The i.m. adipocyte size was correlated with i.m. fat content, number of marbling flecks, proportion of marbling fleck area, and total length of marbling flecks (r = 0.71, 0.44, 0.62, and 0.55, respectively, P < 0.01). The number of marbling flecks was also correlated with i.m. fat content, proportion of marbling fleck area, and total length of marbling flecks (r = 0.58, 0.62, and 0.91, P < 0.01, respectively). The ventral marbling flecks had a 5-fold larger fleck area, 4-fold more adipocytes, and larger adipocytes (P < 0.001). Larger marbling flecks contained larger adipocytes (P < 0.001). Moreover, compared with the small marbling flecks, there was a 48-fold larger fleck area and 26-fold more adipocytes in the large marbling flecks. The results indicate that i.m. fat deposition increases concurrently with the other fat depots but is still independent. Furthermore, the i.m. fat is preferentially deposited in the ventral area of LM. Although the i.m. adipocyte size has an important effect on the traits of marbling flecks, cell number plays a greater role in i.m. fat deposition than cell size.