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1.
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.  相似文献   

2.
Carcass (n = 854) and longissimus thoracis palatability (n = 802) traits from F1 steers obtained from mating Hereford, Angus, and MARC III cows to Hereford or Angus (HA), Tuli (Tu), Boran (Bo), Brahman (Br), Piedmontese (Pm), or Belgian Blue (BB) sires were compared. Data were adjusted to constant age (444 d), carcass weight (333 kg), fat thickness (1.0 cm), fat trim percentage (21%), and marbling (Small00) end points. Results presented in this abstract are for age-constant data. Carcasses from BB- and HA-sired steers were heaviest (P < 0.05) and carcasses from Bo- and Tu-sired steers were lightest (P < 0.05). Adjusted fat thickness was greatest (P < 0.05) on carcasses from HA-sired steers and least (P < 0.05) on carcasses from BB- and Pm-sired steers. Numerical USDA yield grades were lowest (P < 0.05) for carcasses from Pm- and BB-sired steers and highest (P < 0.05) for carcasses from HA- and Br-sired steers. Marbling scores were highest (P < 0.05) for carcasses from HA- and Tu-sired steers and lowest (P < 0.05) for carcasses from Br-, BB-, and Pm-sired steers. Longissimus thoracis from carcasses of HA-, Pm-, and Tu-sired steers had the lowest (P < 0.05) 14-d postmortem Warner-Bratzler shear force values. Carcasses from HA-sired steers had longissimus thoracis with the highest (P < 0.05) tenderness ratings at 7 d postmortem. Longissimus thoracis from carcasses of Br- and Bo-sired steers had the highest (P < 0.05) Warner-Bratzler shear forces and the lowest (P < 0.05) tenderness ratings at 7 d postmortem. Adjustment of traits to various slaughter end points resulted in some changes in sire breed differences for carcass traits but had little effect on palatability traits. Carcasses from BB- and Pm-sired steers provided the most desirable combination of yield grade and longissimus palatability, but carcasses from HA-cross steers provided the most desirable combination of quality grade and longissimus palatability. Tuli, a breed shown to be heat-tolerant, had longissimus tenderness similar to that of the non-heat-tolerant breeds and more tender longissimus than the heat-tolerant breeds in this study.  相似文献   

3.
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.  相似文献   

4.
Carcasses of 342 steers of known genetic backgrounds from four fundamentally different growth types were developed either on pasture or feedlot regimens to study differences in carcass traits. Growth types were large framed-late maturing (LL), intermediate framed-intermediate maturing (II), intermediate framed-early maturing (IE), and small framed-early maturing (SE). Five calves from each growth type were assigned to each regimen in each year of a 9-yr study. Eighteen steers were removed from the study because of accident or illness. Data collected were preslaughter shrunk BW (SBW); hot carcass weight (HCW); chilled carcass weight (CCW); dressing percentage (DRESS); fat thickness at the 12th and 13th-rib interface (FAT); percentage kidney, pelvic, and heart fat (KPH); longissimus muscle area (LMA); marbling score (MARB); quality grade (QG); and yield grade (YG). Differences in carcass traits reflected genetic differences among growth types. The LL steers had heavier BW, HCW, and CCW and larger LMA (P < .05) than steers of other growth types, regardless of development regimen. Among pasture-developed steer carcasses, IE and SE steers had higher (P < .05) MARB and QG than either LL or II steers. Carcasses of large framed-late maturing steers had the lowest (P < .05) MARB and QG of the growth types. Carcasses of the II, IE, and SE steers had a higher (P < .05) numerical value for YG than carcasses of the LL steers. Among the carcasses of the feedlot-developed steers, IE and SE steers had the highest (P < .05) MARB and QG. Carcasses from the IE and SE steers were fatter (P < .05) than those from LL or II steers. Carcasses of the LL steers had the lowest percentage of KPH of growth types developed in the feedlot. No difference was observed in KPH for carcasses of II, IE, and SE steers. The LL steer carcasses had the lowest numerical value for YG of all growth types. These data indicate that variation existed among carcass traits for the four growth types and that carcass traits influenced by fatness were greater and more attainable in the feedlot-developed steers using current methods of evaluation.  相似文献   

5.
The present experiment was conducted to evaluate the ability of the U.S. Meat Animal Research Center's beef carcass image analysis system to predict calculated yield grade, longissimus muscle area, preliminary yield grade, adjusted preliminary yield grade, and marbling score under commercial beef processing conditions. In two commercial beef-processing facilities, image analysis was conducted on 800 carcasses on the beef-grading chain immediately after the conventional USDA beef quality and yield grades were applied. Carcasses were blocked by plant and observed calculated yield grade. The carcasses were then separated, with 400 carcasses assigned to a calibration data set that was used to develop regression equations, and the remaining 400 carcasses assigned to a prediction data set used to validate the regression equations. Prediction equations, which included image analysis variables and hot carcass weight, accounted for 90, 88, 90, 88, and 76% of the variation in calculated yield grade, longissimus muscle area, preliminary yield grade, adjusted preliminary yield grade, and marbling score, respectively, in the prediction data set. In comparison, the official USDA yield grade as applied by online graders accounted for 73% of the variation in calculated yield grade. The technology described herein could be used by the beef industry to more accurately determine beef yield grades; however, this system does not provide an accurate enough prediction of marbling score to be used without USDA grader interaction for USDA quality grading.  相似文献   

6.
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.  相似文献   

7.
Feedlot and carcass characteristics of 276 steers from five closed lines of Hereford cattle and reciprocal crosses among these lines were studied. The traits studied were initial weight, final weight, 224-d gain, days on test, hot carcass weight, marbling score, longissimus muscle area, fat thickness, yield grade, dressing percentage and shear force. Year of record was a significant source of variation for most traits. Age of dam was a significant source of variation for growth traits but not carcass traits. Line of sire affected initial weight, final weight, 224-d gain, days on test, marbling score and dressing percentage. Significant heterosis was observed only for hot carcass weight. Heterosis estimates were 1.9% for initial weight, 2.2% for final weight, 2.5% for 224-d gain, -2.1% for days on test, .6% for hot carcass weight, -.6% for marbling score, 0 for carcass grade, .6% for longissimus muscle area, 2.3% for backfat thickness, .9% for yield grade, -.9% for dressing percent and -10.9% for shear force. Initial age on test affected only hot carcass weight. Hot carcass weight, dressing percentage, marbling score, longissimus muscle area and fat thickness were affected by slaughter weight. Slaughter age affected dressing percent and marbling score.  相似文献   

8.
Left sides from 18 beef carcasses (9 steers and 9 heifers) were divided equally among three marbling groups (low = traces or slight; intermediate = small or modest; high = slightly abundant) and evaluated to determine the relationship between longissimus composition and the percentage each major muscle contributes to the weight of the beef carcass. The adductor (A), biceps femoris (BF), deep pectoral (DP), gluteal group (GL), infraspinatus (I), longissimus (L), psoas major (PM), rectus abdominis (RA), rectus femoris (RF), semimembranosus (SM), semitendinosus (ST), serratus ventralis (SV), spinalis (SP), supraspinatus (SU) and triceps brachii (TB) were removed, trimmed of external fat and weighed. Muscle weights were expressed as a percentage of hot carcass weight: A = .76%; BF = 3.30%; DP = 1.89%; GL = 1.81%; I = 1.10%; L = 3.35%; PM = .95%; RA = 1.12%; RF = .94%; SM = 2.35%; ST = 1.14%; SV = 2.26%; SP = .82%; SU = .69% and TB = 1.83%. The deep pectoral and triceps brachii were heavier (P less than .05) in steer carcasses than in heifer carcasses. No other significant sex effects were noted. Percentage of muscle tended to decrease with increasing marbling level; however, the linear regression of relative muscle weight on marbling level was significant for the BF, DP, PM, SM, SU and TB. Using marbling score or yield grade factors to predict the percentage of individual muscles in the carcass resulted in R/ values greater than .4 in 7 of the 15 muscles evaluated.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

9.
The objective of this study was to estimate parameters required for genetic evaluation of Simmental carcass merit using carcass and live animal data. Carcass weight, fat thickness, longissimus muscle area, and marbling score were available from 5,750 steers and 1,504 heifers sired by Simmental bulls. Additionally, yearling ultrasound measurements of fat thickness, longissimus muscle area, and estimated percentage of intramuscular fat were available on Simmental bulls (n = 3,409) and heifers (n = 1,503). An extended pedigree was used to construct the relationship matrix (n = 23,968) linking bulls and heifers with ultrasound data to steers and heifers with carcass data. All data were obtained from the American Simmental Association. No animal had both ultrasound and carcass data. Using an animal model and treating corresponding ultrasound and carcass traits separately, genetic parameters were estimated using restricted maximum likelihood. Heritability estimates for carcass traits were 0.48 +/- 0.06, 0.35 +/- 0.05, 0.46 +/- 0.05, and 0.54 +/- 0.05 for carcass weight, fat thickness, longissimus muscle area, and marbling score, respectively. Heritability estimates for bull (heifer) ultrasound traits were 0.53 +/- 0.07 (0.69 +/- 0.09), 0.37 +/- 0.06 (0.51 +/- 0.09), and 0.47 +/- 0.06 (0.52 +/- 0.09) for fat thickness, longissimus muscle area, and intramuscular fat percentage, respectively. Heritability of weight at scan was 0.47 +/- 0.05. Using a bivariate weight model including scan weight of bulls and heifers with carcass weight of slaughter animals, a genetic correlation of 0.77 +/- 0.10 was obtained. Models for fat thickness, longissimus muscle area, and marbling score were each trivariate, including ultrasound measurements on yearling bulls and heifers, and corresponding carcass traits of slaughter animals. Genetic correlations of carcass fat thickness with bull and heifer ultrasound fat were 0.79 +/- 0.13 and 0.83 +/- 0.12, respectively. Genetic correlations of carcass longissimus muscle area with bull and heifer ultrasound longissimus muscle area were 0.80 +/- 0.11 and 0.54 +/- 0.12, respectively. Genetic correlations of carcass marbling score with bull and heifer ultrasound intramuscular fat percentage were 0.74 +/- 0.11 and 0.69 +/- 0.13, respectively. These results provide the parameter estimates necessary for genetic evaluation of Simmental carcass merit using both data from steer and heifer carcasses, and their ultrasound indicators on yearling bulls and heifers.  相似文献   

10.
Steers from research crossbreeding projects (n = 406) were serially scanned using real-time ultrasound at 35-d intervals from reimplant time until slaughter. Cattle were evaluated for rump fat depth, longissimus muscle area (ULMA), 12th-rib fat thickness (UFAT), and percentage of intramuscular fat (IMF) to determine the ability of ultrasound to predict carcass composition at extended periods before slaughter. Additional background information on the cattle, such as live weight, ADG, breed of sire, breed of dam, implant, and frame score was also used. Carcass data were collected by trained personnel at "chain speed," and samples of the 12th-rib LM were taken for ether extract analysis. Simple correlation coefficients showed positive relationships (P < 0.01) between ultrasound measures taken less than 7 d before slaughter and carcass measures: ULMA and carcass LM area (CLMA, r = 0.66); UFAT and carcass 12th-rib fat thickness (CFAT, r = 0.74); and IMF and carcass numeric marbling score (r = 0.61). The same correlation coefficients for ultrasound measures taken 96 to 105 d before slaughter and carcass values (P < 0.01) were 0.52, 0.58, and 0.63, respectively. Steers were divided into source-verified and nonsource-verified groups based on the level of background information for each individual. Regression equations were developed for the carcass measurements; 46% of the variation could be explained for CLMA and 44% of CFAT at reimplant time, 46% of the variation in quality grade and 42% of the variation in yield grade could be explained. Significant predictors of quality grade were IMF (P < 0.001), natural log of 12th-rib fat thickness (LUFAT, P < 0.001), and ADG (P < 0.01), whereas LUFAT (P < 0.001), ULMA (P < 0.01), live weight (P < 0.001), hip height (P < 0.001), and frame score (P < 0.001) were significant predictors of yield grade. Regressions using ultrasound data taken 61 to 69 d before slaughter showed increasing R2. Live ultrasound measures at reimplant time are a viable tool for making decisions regarding future carcass composition.  相似文献   

11.
A survey of beef muscle color and pH   总被引：4，自引：0，他引：4  
The objectives of this study were to define a beef carcass population in terms of muscle color, ultimate pH, and electrical impedance; to determine the relationships among color, pH, and impedance and with other carcasses characteristics; and to determine the effect of packing plant, breed type, and sex class on these variables. One thousand beef carcasses were selected at three packing plants to match the breed type, sex class, marbling score, dark-cutting discount, overall maturity, carcass weight, and yield grade distributions reported for the U.S. beef carcass population by the 1995 National Beef Quality Audit. Data collected on these carcasses included USDA quality and yield grade data and measurements of muscle color (L*, a*, b*), muscle pH, and electrical impedance of the longissimus muscle. About one-half (53.1%) of the carcasses fell within a muscle pH range of 5.40 to 5.49, and 81.3% of the carcasses fell within a longissimus muscle pH range of 5.40 to 5.59. A longissimus muscle pH of 5.87 was the approximate cut-off between normal and dark-cutting carcasses. Frequency distributions indicated that L* values were normally distributed, whereas a* and b* values were abnormally distributed (skewed because of a longer tail for lower values, a tail corresponding with dark-cutting carcasses). Electrical impedance was highly variable among carcasses but was not highly related to any other variable measured. Color measurements (L*, a*, b*) were correlated (P < 0.05) with lean maturity score (-.58, -.31, and -.43, respectively) and with muscle pH (-.40, -.58, and -.56, respectively). In addition, fat thickness was correlated with muscle pH and color (P < 0.05). There was a threshold at approximately .76 cm fat thickness, below which carcasses had higher muscle pH values and lower colorimeter readings. Steer carcasses (L* = 39.62, a* = 25.20, and b* = 11.03) had slightly higher colorimeter readings (P < 0.05) than heifer carcasses (L* = 39.20, a* = 24.78, and b* = 10.80) even though muscle pH was not different between steer and heifer carcasses. Dairy-type carcasses (pH = 5.59, L* = 37.56, a* = 23.40, and b* = 9.68) had higher muscle pH values and lower colorimeter readings than either native-type (pH = 5.50, L* = 39.55, a* = 25.13, and b* = 11.00) or Brahman-type (pH = 5.46, L* = 39.75, a* = 25.17, and b* = 11.05) carcasses (P < 0.05).  相似文献   

12.
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.  相似文献   

13.
Carcass and growth measurements of finished crossbred steers (n = 843) and yearling ultrasound and growth measurements of purebred bulls (n = 5,654) of 11 breeds were analyzed to estimate genetic parameters. Multiple-trait restricted maximum likelihood (REML) was used to estimate heritabilities and genetic correlations between finished steer carcass measurements and yearling bull ultrasound measurements. Separate analyses were conducted to examine the effect of adjustment to three different end points: age, backfat thickness, and weight at measurement. Age-constant heritability estimates from finished steer measurements of hot carcass weight, carcass longissimus muscle area, carcass marbling score, carcass backfat, and average daily feedlot gain were 0.47, 0.45, 0.35, 0.41, and 0.30, respectively. Age-constant heritability estimates from yearling bull measurements of ultrasound longissimus muscle area, ultrasound percentage of intramuscular fat, ultrasound backfat, and average daily postweaning gain were 0.48, 0.23, 0.52, and 0.46, respectively. Similar estimates were found for backfat and weight-constant traits. Age-constant genetic correlation estimates between steer carcass longissimus muscle area and bull ultrasound longissimus muscle area, steer carcass backfat and bull ultrasound backfat, steer carcass marbling and bull ultrasound intramuscular fat, and steer average daily gain and bull average daily gain were 0.66, 0.88, 0.80, and 0.72, respectively. The strong, positive genetic correlation estimates between bull ultrasound measurements and corresponding steer carcass measurements suggest that genetic improvement for steer carcass traits can be achieved by using yearling bull ultrasound measurements as selection criteria.  相似文献   

14.
Postweaning growth, feed efficiency, and carcass traits were analyzed on 1,422 animals obtained by mating F1 cows to F1 (Belgian Blue x British breeds) or Charolais sires. Cows were obtained from mating Hereford, Angus, and MARC IIIHereford, 1/4 Angus, 1/4 Pinzgauer, and 1/4 Red Poll) dams to Hereford or Angus (British breeds), Tuli, Boran, Brahman, or Belgian Blue sires. Breed groups were fed in replicated pens and slaughtered serially in each of 2 yr. Postweaning average daily gain; live weight; hot carcass weight; fat depth; longissimus area; estimated kidney, pelvic, and heart fat (percentage); percentage Choice; marbling score; USDA yield grade; retail product yield (percentage); retail product weight; fat yield (percentage); fat weight; bone yield (percentage); and bone weight were analyzed in this population. Quadratic regressions of pen mean weight on days fed and of cumulative ME consumption on days fed were used to estimate gain, ME consumption and efficiency (Mcal of ME/kg of gain) over time (0 to 200 d on feed), and weight (300 to 550 kg) intervals. Maternal grandsire breed was significant (P < 0.01) for all traits. Maternal granddam breed (Hereford, Angus, or MARC III)was significant (P < 0.05) only for fat depth, USDA yield grade, retail product yield, fat yield, fat weight, and bone yield. Sire breed was significant (P < 0.05) for live weight, hot carcass weight, longissimus area, and bone weight. Sex class was a significant (P < 0.001) source of variation for all traits except for percentage Choice, marbling score, retail product yield, and fat yield. Interactions between maternal grandsire and sire breed were nonexistent. Sire and grandsire breed effects can be optimized by selection and use of appropriate crossbreeding systems.  相似文献   

15.
Two experiments were conducted to determine the effects of sex on carcass traits and cooked beef steak palatability. In Exp. 1, steers (n = 99), heifers (n = 51), and intravaginally spayed heifers (n = 46) were fed a high-energy diet for 161 d. No implants were administered, and heifers were not fed melengestrol acetate to suppress estrus. In Exp. 2, 60 steers and 60 intact heifers from the same ranch source used in Exp. 1 were fed in 2 locations (sites 1 and 2). All management factors were equal across experiments except that intact heifers were fed melengestrol acetate to suppress estrus in Exp. 2. Steers in Exp. 1 were 25 kg heavier (P < 0.01) in HCW than heifers at comparable (P = 0.39) carcass fat thickness. Spayed heifers (Exp. 1) had a 5.7% smaller (P < 0.05) LM area compared with steers and intact heifers, which were similar. In Exp. 2, there was no difference (P = 0.2) in carcass weight, and heifers had greater (P < 0.01) 12th rib fat thickness compared with steers. Calculated yield grades were similar (P = 0.21) among treatments in Exp. 1 and tended (P = 0.08) to be greater for heifers compared with steers in Exp. 2. In Exp. 1, USDA quality grades and marbling scores were lower (P < 0.01) for steers compared with intact and spayed heifers, which were similar. The effects of sex on tenderness were examined at a common level of fat-thickness and marbling by covariate analysis. Steaks from steers, compared with those from nonimplanted, intact heifers, in the 2 experiments combined were: (a) superior (P < 0.05) in 2 of 9 palatability assessments when subcutaneous fat thickness (at the 12th rib) was adjusted to a common level, and (b) superior (P < 0.05) in 6 of 9 palatability assessments when marbling score was adjusted to a common level. In Exp. 1, steaks from nonimplanted steers compared with those from nonimplanted spayed heifers were: (a) superior (P < 0.05) in 0 of 8 palatability assessments when subcutaneous fat thickness (at the 12th rib) was adjusted to a common level, and (b) superior (P < 0.05) in 3 of 8 palatability assessments when marbling score was adjusted to a common level. These findings suggest that sex should be added to the list of antemortem factors contributing to variation in cooked beef steak tenderness. However, more research is needed to precisely identify those factors contributing to the lower tenderness observed for steaks from heifer carcasses.  相似文献   

16.
Two hundred beef carcasses were randomly selected by dental classification (zero, two, four, six, or eight permanent incisors) from a population of 11,136 carcasses harvested by a large commercial beef processor. Warner-Bratzler shear force and trained sensory panel evaluations of longissimus thoracis steaks as well as cooking and carcass traits were evaluated for differences among dental classes. No differences in Warner-Bratzler shear force (P = 0.60), sensory panel evaluations (P = 0.64) for tenderness, or percentage of total cooking loss (P = 0.73) were found among the five dental classes. Longissimus muscle color, USDA marbling score, hot carcass weight, adjusted fat thickness, longissimus muscle area, and USDA yield grade did not differ among the five dental classes. A significant dental classification x sex interaction indicated that heifers advanced in skeletal and overall maturity at a much faster rate than steers. An increase of intramuscular fat was associated (P < 0.05) with decreased shear force (r = -0.31), whereas darkening of the lean (r = 0.16), advancing lean maturity (r = 0.21), and increased evaporative cooking loss (r = 0.39) were associated (P < 0.05) with increased shear force values. Warner-Bratzler shear force measurements were not related to sensory panel overall tenderness scores. Carcass traits accounted for a relatively small proportion of the variation in tenderness of longissimus steaks, and dental classification was not related to tenderness.  相似文献   

17.
Angus x Hereford steers (n = 48) similar in frame size and in muscle thickness were allotted to eight groups (n = 6) of similar mean live weight for serial slaughter at 28-d intervals (0 to 196 d). Except for d-0 steers, which served as grass-fed controls, all steers were fed a high-concentrate diet during the finishing period. Upon slaughter, one side of each carcass was trimmed of subcutaneous fat in the wholesale rib region. Postmortem longissimus muscle (LM) temperature was monitored for each side during the 24-h chilling period. After quality and yield grade data were collected, rib steaks were removed and aged (7 d) and sensory traits of the steaks were evaluated. Most carcass grade traits increased linearly (P less than .01) with days on feed, whereas most sensory panel variables and marbling increased curvilinearly (P less than .05). Generally, after 56 d on feed, carcasses chilled at slower rates (P less than .05) with increased days fed. Taste panel tenderness, amount of perceived connective tissue, and shear force values peaked at 112 d and were slightly less desirable for cattle fed longer than 112 d (quadratic term, P less than .01). Postmortem muscle temperature at 2.5 h was the chilling time most highly correlated with tenderness values among untrimmed sides. Correlations for shear force with 2.5-h LM temperature, marbling score, days fed, fat thickness, and carcass weight were -.63, -.61, -.56, -.55, and -.53, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

18.
Steers were generated from Angus (A), Beefmaster (BM), Brangus (BA), Gelbray (GB), and Simbrah (SB) sires mated to cows of their breed and to Brahman x Hereford F1 cows (except A) to characterize their carcass traits, composition, and palatability. The 290 steers (48 A, 48 BM, 36 BA, 31 GB, and 46 SB) were slaughtered at an equal fatness end point as determined by real-time ultrasound and visual evaluation. Angus steers had lighter (P < 0.01), more youthful (P < 0.01) carcasses with a higher (P < 0.05) quality grade, more (P < 0.01) fat thickness, and a larger (P < 0.01) longissimus area/100 kg than BM-, BA-, GB-, and SB-sired steers. Angus steers also had a lower (P < 0.01) specific gravity, a higher (P < 0.01) percentage fat and less (P < 0.05) lean in the 9th to 11th rib, and steaks aged for 10 d were more tender (P < 0.01) than steaks from Brahman-derivative sired steers. The BM- and BA-sired steers had lighter (P < 0.01), more youthful (P < 0.05) carcasses, and smaller (P < 0.01) longissimus area than GB- and SB-sired steers. The 9th to 11th rib section from the BM- and BA-sired steers had less lean and more bone (P < 0.01) than GB- and SB-sired steers. The BA-sired steers had more (P < 0.01) marbling and a higher (P < 0.05) quality grade than BM-sired steers. The SB-sired steers had heavier (P < 0.01) carcasses than the GB-sired steers. There were no differences in shear force for steaks aged for 3 d for any of the breed types, but with 10 d of aging, steaks from Angus steers were more tender, possibly indicating that steaks of Brahman-derivative breeds aged at a slower rate than those from Angus.  相似文献   

19.
Real time ultrasound (RTU) measures of longissimus muscle area and fat depth were taken at 12 and 14 mo of age on composite bulls (n = 404) and heifers (n = 514). Carcass longissimus muscle area and fat depth, hot carcass weight, estimated percentage lean yield, marbling score, Warner-Bratzler shear force, and 7-rib dissectable seam fat and lean percentages were measured on steers (n = 235). Additive genetic variances for longissimus muscle area were 76 and 77% larger in bulls at 12 and 14 mo than the corresponding estimates for heifers. Heritability estimates for longissimus muscle area were 0.61 and 0.52 in bulls and 0.49 and 0.47 in heifers at 12 and 14 mo, respectively. The genetic correlations of longissimus muscle area of bulls vs heifers were 0.61 and 0.84 at 12 and 14 mo, respectively. Genetic correlations of longissimus muscle area measured in steer carcasses were 0.71 and 0.67 with the longissimus muscle areas in bulls and heifers at 12 mo and 0.73 and 0.79 at 14 mo. Heritability estimates for fat depth were 0.50 and 0.35 in bulls and 0.44 and 0.49 in heifers at 12 and 14 mo, respectively. The genetic correlation of fat depth in bulls vs heifers at 12 mo was 0.65 and was 0.49 at 14 mo. Genetic correlations of fat depth measured in bulls at 12 and 14 mo with fat depth measured in steers at slaughter were 0.23 and 0.21, and the corresponding correlations of between heifers and steers were 0.66 and 0.86, respectively. Live weights at 12 and 14 mo were genetically equivalent (r(g) = 0.98). Genetic correlations between live weights of bulls and heifers with hot carcass weight of the steers were also high (r(g) > 0.80). Longissimus muscle area measured using RTU was positively correlated with carcass measures of longissimus muscle area, estimated percentage lean yield, and percentage lean in a 7-rib section from steers. Measures of backfat obtained using RTU were positively correlated with fat depth and dissectable seam fat from the 7-rib section of steer carcasses. Genetic correlations between measures of backfat obtained using RTU and marbling were negative but low. These results indicate that longissimus muscle area and backfat may be under sufficiently different genetic control in bulls vs heifers to warrant being treated as separate traits in genetic evaluation models. Further, traits measured using RTU in potential replacement bulls and heifers at 12 and 14 mo of age may be considered different from the corresponding carcass traits of steers.  相似文献   

20.
Cattle (n = 995 steers and 757 heifers) were randomly selected from a commercial abattoir (Emporia, KS) to determine the relationships between USDA quality and yield grade characteristics and serum concentrations of leptin, IGF-I, and GH. Animals were randomly selected postexsanguination on the slaughter line on 4 occasions (March, May, August, and January). Blood was collected at exsanguination and transported to the University of Missouri for analysis. Sex and hide color were recorded. Carcass data included HCW, 12th-rib fat thickness, KPH, LM area, and marbling score, which were collected from each carcass approximately 24 h postmortem. Average serum leptin concentrations were greater (P = 0.008) for heifers (11.9 ng/mL) than steers (10.9 ng/mL). Heifers had lighter carcasses (331.9 vs. 352.2 kg, P < 0.001), greater 12th-rib fat measurements (1.3 vs. 1.1 cm, P < 0.001), greater KPH (2.5 vs. 2.4%, P < 0.001), and more marbling (Small(40) vs. Small(10), P < 0.001) than steers. Positive correlations (P < 0.01) existed between leptin concentration and marbling score (r = 0.28), 12th-rib fat depth (r = 0.37), KPH (r = 0.23), and USDA yield grade (r = 0.32). Negative correlations were found between leptin and IGF-I (r = -0.11; P < 0.001) and leptin and GH (r = -0.32; P < 0.001). Negative correlations (P < 0.01) were observed for IGF-I and KPH (r = -0.23) and marbling score (r = -0.20), whereas GH was most highly negatively correlated with KPH (r = -0.23; P < 0.001). Leptin concentration accounted for variation (P < 0.001) in a model separating least squares means across USDA quality grade, separating USDA standard (8.5 ng/mL), select (10.3 ng/mL), low choice (12.2 ng/mL), and upper 2/3 choice/prime (>12.9 ng/mL) carcasses. There was no difference (P = 0.31) observed in leptin concentrations between the upper 2/3 choice and prime carcasses (12.9 and 14.2 ng/mL, respectively). Relationships within endocrine profiles and between endocrine concentrations and carcass quality characteristics may prove to be a useful tool for the prediction of beef carcass composition.  相似文献   

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