Effect of feeding regimen, breed and sex condition on carcass composition and feed efficiency

Eighty bulls and eighty steers representing four breed types (7/8 Angus. 7/8 Simmental, 7/8 Simmental × 7/8 Angus and 7/8 Simmental × 7/8 Hereford) were randomly assigned to two diets by sex class and breed type. Exotic breeds produced heavier, leaner, more muscular carcasses, with lower USDA quality grades and darker colored, coarser textured lean. Angus 9-10-11th rib composition showed that Angus tended to have less lean, more bone and the most fat when compared to the Simmental and Simmental crosses. Feeding the deferred diet resulted in carcasses with (P < 0·05) less fat, lower USDA quality grade, smaller ribeyes, more sensory panel detectable connective tissue, higher cooking losses and higher Instron shear values. Sex class caused differences (P < 0·05) in feed efficiency, carcass traits and sensory properties.     

Carcass characteristics and composition of Brahman, angus and Brahman x Angus steers fed for different times-on-feed

Twenty-five steers of each of three breedtypes (Angus, Brahman and F(1) Brahman x Angus) were sorted by frame size and muscle thickness, assigned to groups (five steers of each breedtype) to be fed for 0, 56, 112, 168 or 224 days, slaughtered and compared for various carcass traits. Steers of each breedtype had similar dressing percentages. Carcasses from all three breedtypes merited similar USDA quality and yield grades; breedtypes differences in quality grade were slight. Differences were found in the fat deposition patterns exhibited by the three breedtypes. Brahman steers tended to deposit more of their total fat as subcutaneous fat early in the feeding period. Angus steers had more (P < 0·05) seam fat as a percentage of carcass weight at all five feeding periods and more (P < 0·05) kidney, pelvic and heart fat at two of the five feeding periods than Brahman steers. Brahman steers had a higher percentage of their separable lean in the muscles of the round than did steers of the other breedtypes.     

Tenderness of major muscles from three breed-types of cattle at different times-on-feed

Seventy-five steers (9 to 12 months of age) of Angus (n = 25), Brahman (n = 25) and Brahman × Angus (n = 25) breed-types of known history were fed a high-energy diet and five steers from each breed-type were slaughtered after 0, 56, 112, 168 and 224 days on test. At seven days post mortem, the left side of each carcass was fabricated and eight major primals or subprimals were obtained. Steaks were removed from the shoulder clod, strip loin, tenderloin, top sirloin, knuckle, top round, bottom round and eye of round for Warner-Bratzler shear (WBS) determinations and from the strip loin and bottom round for sensory panel evaluations. Steaks from Angus and Brahman × Angus steers were generally more tender than steaks from Brahman steers. Tenderness of steaks from steers of the three breed-types responded to time-on-feed differently: (a) steaks from Brahman steers improved (P < 0·05) in tenderness with increasing time-on-feed for all muscles except the M. psoas major (tenderloin); (b) with the exception of the M. longissimus muscle (strip loin), the tenderness of steaks from Angus steers did not change (P > 0·05) as time-on-feed increased and (c) for the Brahman × Angus steers, five of the ten muscles studied improved (P < 0·05) in tenderness with increasing time-on-feed. 'Acceptable' tenderness (WBS values of less than 4·5 kg) for most of the muscles was achieved at feeding periods from 112 to 224 days for Brahman, from 0 to 56 days for Angus and from 56 to 168 days for Brahman × Angus.     

EFFECTS OF ELECTRICAL STIMULATION ON TALLOW SUPPLEMENTED STEER CARCASSES1

Forty-nine Angus and Angus X Hereford steers were slaughtered to determine the effects of time on feed, electrical stimulation and 4% tallow in the diet on the carcass and various chemical and physical characteristics of the lean. All cattle were backgrounded on winter annuals and small grain pastures for a period of 5 months. Following the backgrounding period, ten steers were slaughtered and the rest randomly assigned to 4 treatments. The treatments consisted of high grain or grain plus 4% tallow diets, fed for either 45 or 75 days. At slaughter, the left side of each carcass was ES. Rib-fat exhibited an increase in redness with a decrease in color intensity due to electrical stimulation (P< .05). Overall, ES decreased percentage purge loss while increasing percentage cook loss (P < .05). Electrical stimulation had no significant effect on percentage thaw loss and percentage cumulative weight loss of rib steaks. Rib steaks from 75 day grain fed carcasses exhibited the greatest improvements in palatability due to ES. Across treatments the effects of ES on taste panel traits were minimal, with time on feed and diet having a greater effect on observed sensory traits than ES.     

Singular and combined effects of electrical stimulation, post-mortem ageing and blade tenderisation on the palatability attributes of beef from young bulls

Thirty Santa Gertrudis bulls (approximately 15-18 months old) were slaughtered, dressed and split into siides. The right side of each carcass was electrically stimulated (ES) with seventeen impulses (1·8s impulse duration; 1·8s interval between impulses) of 550 V (AC) and 5 A while the left side served as a non-stimulated control (not-ES). At 24h post morten, USDA quality and yield grade data were obtained from each side. On the second day post mortem, all sides were fabricated and strip loins, top sirloin butts and ribeyes were obtained from each side for post-mortem ageing and blade tenderisation studies. Steaks were removed after a post-mortem ageing period of 4 or 18 days and before (not-BT) or after blade tenderisation (BT) for sensory panel evaluations or shear force determinations. ES sides had more youthful lean maturity (P < 0·0001), higher marbling (P < 0.·002), higher USDA quality grades (P < 0·0.0001) and finer-textured lean (P < 0·002) than did not-stimulated (not-ES) sides. ES significantly improved (P < 0·05) palatability traits in two of twenty-four comparisons; BT significantly improved palatability traits in twelve of twenty-four comparisons and 18-day post-mortem ageing significantly improved palatability traits in seven of twelve comparisons. No significant reductions (P < 0·05) in shear force values were observed for steaks from ES versus not-ES sides while significant reductions (P < 0·05) were observed for steaks from BT versus non-BT cuts (four of six comparisons) and for steaks from cuts aged for 18 versus 4 days (ten of twelve comparisons). BT and 18-day post-mortem ageing were more effective for increasing palatability or for decreasing shear force requirements than was ES; however, ES greatly improved lean colour of meat from bulls.     

Physical, chemical, histological and palatability characteristics of muscles from three breed-types of cattle at different times-on-feed

Forty-five steers (9-12 months of age) of Angus (n =15), Brahman (n = 15) and Brahman × Angus (n = 15) breed-types were fed a high-energy diet and then slaughtered after 0, 112 or 224 days of feeding. At 7 days post mortem, the M. longissimus and M. biceps femoris were removed from the left side of each carcass and steaks were obtained for determination of sensory panel ratings, Warner-Bratzler shear force, sarcomere length, collagen content and collagen solubility. Tenderness ratings of steaks from the M. longissimus and M. biceps femoris from Angus were generally higher than ratings for steaks from Brahman or Brahman × Angus steers. Steaks from Brahman × Angus received higher tenderness ratings than steaks from Brahman steers in only a few comparisons. The three breed-types of cattle responded to time-on-feed differently; Brahman cattle needed to have been fed longer than Angus cattle to produce equally tender beef. With increased time-on-feed, M. longissimus tenderness increased for all breed-types, but M. biceps femoris tenderness was not related to time-on-feed. Few significant differences were observed among breed-types and among time-on-feed periods for collagen content or collagen solubility. Tenderness differences were closely correlated with the contractile state of the muscle which, in turn, was associated with weight, subcutaneous fat thickness and temperature decline of the carcass.     

Growth and carcass characteristics of Angus and American Wagyu steers

Ten purebred Angus and ten crossbred (3/4–7/8) American Wagyu steers were fed a corn and barley-based diet for 552 days and slaughtered. All USDA and Japanese yield and quality grade factors were evaluated and the amount of extractable lipid and moisture in totally trimmed muscle was determined. Angus steers gained 0·9 kg/head/day and American Wagyus gained 0·7 kg/head/day. This difference in growth rate resulted in Angus steers having a heavier final weight (P < 0·05). Angus steers required less feed per unit of gain than did American Wagyu steers. Adjusted fat thickness over M. longissimus dorsi opposite the 12th rib was approximately 3·5 cm and was not statistically different between the two breeds (P > 0·05). Average ribeye area and kidney, pelvic and heart fat were similar for the two breeds. The calculated USDA yield grade for both breeds exceeded 6. Average USDA marbling score was nearly a degree of marbling higher for American Wagyu than for Angus, but variation within breed groups was high. Average USDA quality grade was well into USDA Prime for all carcasses and did not differ by breed (P > 0·05). Japanese yield grade factors were similar for both breeds except for cold left side weight and the yield estimation which includes an adjustment factor that favors American Wagyu. American Wagyu steers merited a higher Japanese marbling score than did Angus (P < 0·05). Beef color score, firmness, texture and firmness and texture grade were also different between the breeds (P < 0·05). Fat colour, luster and quality were not different (P > 0·05). These data clearly show that some American Wagyu steers have the genetic ability to deposit as much marbling as Japanese Black cattle raised in Japan.     

Effects of cryogenic chilling on beef carcass grade, shrinkage and palatability characteristics

Alternate right or left sides of 90 carcasses were randomly selected and chilled at -70°C for 5 h, held at +16°C for 4 h and held at 1°C for 15 h (rapid chill-RC). The remaining sides were chilled at -7°C for 24 h (conventional chill-CC). Physical measurements and USDA quality grade data were obtained at 24 h post mortem and palatability samples were collected at 3-5 days post mortem. RC sides had 0·9% less shrinkage (P < 0·05) at 24 h post mortem when compared to paired CC sides. Beef sides that were given the RC treatment had a darker, softer lean (P < 0·01) and received higher marbling scores (P < 0·01) at 24 h post mortem than did CC sides. Loin steaks from RC sides had longer sarcomeres, less shear resistance and higher sensory panel tenderness ratings. It may be possible to rapidly chill carcasses with less carcass shrinkage and with no detrimental effects on USDA quality grade or on beef palatability.     

Carcass merit between and among family groups of Bos indicus crossbred steers and heifers

Differences in live and carcass traits attributable to increasing Bos indicus breed influence were compared to the differences between families with similar proportions of B. indicus influence. Families of offspring from 1/2 Angus×1/2 B. indicus mated to Angus, B. indicus, and 1/2 Angus×1/2 B.indicus were raised under similar conditions. Average daily gain, slaughter weight, and dressing percentage were measured in addition to USDA yield and quality grade factors. Breed type did not affect average daily gain, slaughter weight, dressing percentage, carcass weight, adjusted 12th-rib fat thickness, estimated percentage kidney, pelvic, and heart fat, or carcass maturity. Predominately (3/4) Angus progeny produced greater (P<0.05) longissimus muscle areas than 3/4 B. indicus animals. Predominately Angus cattle also had greater (P<0.05) marbling scores and USDA quality grades than predominately B. indicus cattle. Families within breed types differed (P<0.05) with regard to all traits measured. This is interesting in light of the lack of differences between breeds for most traits. In some instances, the differences in marbling score and longissimus muscle area between families within a given breed type were similar or greater in magnitude than the differences observed between predominately Angus and predominately B. indicus breed types. Whereas growth and carcass traits varied between levels of B. indicus breeding, the opportunity does exists to improve these traits by selecting within specific family lines.     

Effects of oestradiol-17β implantation on performance, carcass traits, meat sensory traits and endocrine aspects of bulls and steers

Twenty-eight Simmental bull calves were randomly allotted to one of three treatments at birth. Ten bulls (IB) and nine steers (IS), castrated within 3 days of birth, were implanted with oestradiol (E(2)). The remaining calves were non-implanted, control bulls (CB). Calves were implanted within 3 days of birth and at 200-day intervals until slaughter at 14·8 months of age and at a mean carcass weight of 381·6 kg. Blood samples were taken every 14 days from 9·8 through 14·8 months and serum was analyzed for E(2) and testosterone (T) levels. Carcasses were chilled in a 3 to 7°C cooler. Carcass data were obtained and aged longissimus dorsi steaks were evaluated by a trained sensory panel and a Warner-Bratzler shear (WBS) device. Scrotal circumferences were smaller (P < 0·0.5) for IB than for CB. Control bulls had heavier weaning weights (P < 0·05) than IB and higher (P < 0·05) feedlot gains than IS. Implanted steers required more (P < 0·05) feed/unit of gain than CB and IB. Implanting bulls with E(2) increased (P < 0·05) serum E(2) levels and tended (P < 0·10) to reduce T levels. Serum E(2) in IS and IB were drastically increased (P < 0·05) for 4 to 6 weeks following re-implantation during the feedlot phase, then sharply declined. Implanted steer carcasses had more youthful maturity scores than CB carcasses. The incidence of hear ring (dark, coarse, band formation) was greater (P < 0·05) for IB than for IS, probably because of the thinner fat cover (P < 0·05) on IB. Ribeye areas were smaller (P < 0·05) and yield grades were higher for IS than for CB. Testicle weights were not significantly different between IB and CB, although variability was greater for IB. Carcass masculinity was least (P < 0·05) for IS, and IB were less (P < 0·05) masculine than CB. The only difference in longissimus dorsi sensory traits was that steaks from IB were juicier than steaks from CB. Also, WBS values were lower (P < 0·05) for IS than for CB.     

Effects of USDA feeder grade and time-on-feed on carcass characteristics and cooked beef palatability

Yearling feeder steers (n = 128), selected to vary in frame size and muscle thickness, were fed for 100, 130 or 160 days and then slaughtered. USDA grade data were collected and cooked rib steaks were evaluated for palatability attributes. Frame size was positively related to carcass weight and longissimus muscle area and negatively related to all fatness measures and to USDA yield grade. Steaks from large-framed steers received the lowest sensory panel ratings for juiciness and overall palatability. Muscle thickness of feeder steers was positively related to all measures of carcass muscling. Steaks from thinly muscled (No. 3) steers received higher ratings for juiciness and overall palatability than did steaks from thickly muscled (No. 1) steers. Large-framed or thickly muscled (No. 1) steers produced the lowest percentages of carcasses with at least Choice quality. Although some statistically significant differences were observed when the data were sorted by frame size or muscle thickness, few real trends were evident that would be of value to cattle feeders.     

The effects of withholding feed and water on carcass shrinkage and meat quality in beef cattle

Eighty beef crossbred steers with an average weight of 493 kg (4·66 kg SD) were allocated at random to one of five treatments to assess the effects of withholding feed and water on carcass shrinkage and meat quality. The five treatments were: slaughter from the feedlot (T1); and 12, 24, 36 and 48 h periods without feed and water prior to slaughter (T2-5).Weights were taken of the live animal and the carcass to monitor shrinkage along with relevant meat quality measurements. There were no treatment differences (P > 0·05) in initial farm weight, but plant weight shrinkage increased from 31gkg(-1) for T1 to 106 g kg(-1) for T5. Warm carcass weight decreased (P < 0·05) from 278·8 kg for T1, to 270·7 kg for T3 and 261·9 kg for T5. Liver, alimentary tract components, hide and head decreased as a proportion of farm weight as time without feed and water increased. Muscle pH at 6 days post mortem was increased (P < 0·05) in T3-5 compared to T1, with the result that muscle colour became darker, and steaks had less drip loss. Shear values increased (P < 0·05) from 6·3 kg in T1 to 7·7 kg in T4 and T5 indicating an increase in muscle toughness as time without feed and water increased. It was concluded that steers lose live weight rapidly within the first 24 h without feed and water, and that these relatively short periods of time (24 h) can have detrimental effects on carcass shrinkage and muscle quality.     

Performance, carcass and palatability characteristics of Longhorn and other types of cattle

Performance, carcass and palatability characteristics of Longhorn steers were compared with those of cattle currently popular in the United States-Hereford, Angus, Brahman, Holstein, two-breed crossbred (British beef breed crosses) and three-breed crossbred (1 4 dairy , 1 4 British beef and 1 2 European beef ) steers. Steers were fed roughage, then a growing diet (42 days), then a high energy (89% concentrate) diet (153 to 179 days by breed group) and slaughtered, individually, at USDA Choice finish or, failing that, after 186 days on the finishing diet. Data suggest that Longhorns, compared with types of cattle currently used: (1) are less desirable in physical appearance; (2) gain weight less rapidly, reaching the desired finish and slaughter weight as older animals; (3) convert feed to liveweight less efficiently; (4) deposit less subcutaneous fat, more internal fat, but essentially the same amount of intramuscular fat; (5) are as muscular (longissimus muscle area, estimated percentage of carcass muscle, muscle to bone ratio, muscle to fat ratio); (6) are as desirable in USDA quality grade and yield grade and (7) produce beef that is a palatable.     

USDA yield grades and various carcass traits as predictors of carcass composition

Twenty-five carcasses from each of three breedtypes (Brahman, Angus and Brahman × Angus) were physically separated into fat, lean and bone. Several muscles from the round and the femur were used to derive equations to predict carcass composition and muscle-to-bone ratio. The femur (as a percentage of the carcass) was shown to predict percentage carcass bone with 90% accuracy. All of the muscles studied were highly related to total carcass lean but the percentage of carcass as M. biceps femoris was the best single muscle indicator of carcass lean of the muscles studied. More variation in carcass lean could be accounted for by a multiple regression equation, involving all four muscles studied, than by any single muscle. M. biceps femoris-to-femur ratio was found to predict carcass muscle-to-bone ratio with a high degree of accuracy. The USDA yield grades were found to be reliable indicators of carcass composition. A two-variable equation involving adjusted fat thickness and biceps femoris accounted for 88·6% of the variation (RSD = 1/·64) in percentage of carcass as separable lean.     

USDA MATURITY INDICES AND PALATABILITY OF BEEF RIB STEAKS1

In a population of 195 beef carcasses, as maturity increased (by whole USDA groups) from A to B, flavor, tenderness and overall palatability ratings for rib steaks decreased (P < .05); further increases in maturity (B vs. E) resulted in subsequent decreases (P < .05) in tenderness and overall palatability. Subdivision of whole maturity groups into thirds and subsequent data analyses supported precepts in USDA grade standards of declining palatability with advancing maturity, but the declines, when they occurred, were nearly linear through the extremes (from A^? to E⁺) and did not support the concept, in USDA grade standards, of a precipitous decline in eating satisfaction at or near the B⁺/C^? maturity line. Among seven carcass maturity indices, all were similarly and singularly related (P < .05) to palatability of rib steaks, with some measure of skeletal maturity (the best of these was color/shape of the rib bones) plus some measure of muscle maturity (the best of these was color of the longissimus muscle) combining (by means of multiple regression analyses) to predict tenderness (panel ratings and shear values) with maximum precision. Neither total pigment concentration (a chemical measure of muscle color), amount of ether-extractable lipid (a chemical measure of intramuscular fatness) nor marbling score (a visual measure of intramuscular fatness) was able to explain more than about 7% of the observed variability in palatability ratings for cooked beef steaks. Data suggest that more attention should be paid to appearance of rib bones in a carcass (to better assess effects of maturity) and that less attention could be paid to differences between SLIGHT, SMALL and MODEST in marbling in the ribeyes, in attempting to predict, via USDA grading, the palatability of beef rib steaks.     

Palatability of beef from bulls administered exogenous hormones

One-hundred and forty four weanling bulls of Angus (A, n = 48), Simmental x Hereford (SH, n = 48) and Simmental (S, n = 48) breeding were either castrated, left intact, left intact and implanted with Ralgro or left intact and implanted with Synovex S. Cattle were slaughtered after either 190, 246 or 315 days of high-energy feeding, and the right side of each carcass was electrically stimulated. Sensory analysis was conducted on longissimus dorsi steaks after 5 days aging and Warner-Bratzler shear force (WBS) was measured after 5, 10 and 15 days aging. Steers had lower (P < 0·05) WBS and more desirable sensory panel scores for juiciness, ease of fragmentation, amount of connective tissue and overall tenderness than all intact treatments. The implanting of weanling bulls with synthetic steroid hormone compounds did not make a practical improvement in beef tenderness.     

Microbiological and sensory characteristics of beef loin steaks: Role of intramuscular fat

Beef loin steaks of different grades (Prime, Choice and Good) were packaged and stored in polyvinyl chloride (PVC) film for 0-6 days and in high-oxygen barrier (HOB) film for 0-28 days. Grade had no significant effect (P > 0·05) on the aerobic plate count and did not result in major differences in the distribution of types in the microflora of steaks. Of the sensory characteristics examined, mean surface discoloration and mean overall appearance scores of Prime and Choice steaks packaged and stored in HOB film often were higher (P < 0·05) than those of Good steaks. Differences in metmyoglobin formation among steaks from the three grades were attributed to differences in the inherent characteristics of the muscles; muscle fibers from Prime and Choice samples were probably more red (as evidenced by greater marbling ability), while muscle fibers of Good samples were probably more white (as evidenced by lesser marbling ability). Red muscles have greater cytochrome activity, which will help reduce metmyoglobin to myoglobin in the absence of oxygen.     

Carcass characteristics of Angus steers fed to Japanese market standards

Japanese Black (Wagyu) cattle are characterized by an ability to consistently produce highly palatable, well-marbled beef. The Japanese utilize a unique management program which includes feeding the cattle a high roughage diet for extended periods of time, typically at least twice that of American feedlot practices. In this study, Angus steers were fed a typical US feedlot diet to the Japanese market endpoint of 680 kg. Carcasses were analyzed for marbling score, meat color and fat color by days on feed and adjusted to a common carcass weight. Results indicate that the quality traits studied did change (P < 0·05) with an increasing number of days on feed. The marbling score had a high standard error.     

Comparison of sensory characteristics and fatty acid composition between Wagyu crossbred and Angus steers

Angus (n = 10) and crossbred (3/4 and 7/8) Wagyu (n = 10) steers were fed a diet according to typical Japanese standards for 552 days. The steers were fed to gain approximately 0·90 kg/head/day. Fatty acid composition was determined for subcutaneous and intramuscular adipose tissue, and M. longissimus dorsi muscle. Trained sensory evaluation and a consumer triangle test were performed on M. longissimus dorsi muscle steaks. For subcutaneous and intramuscular tissue. Wagyu adipose tissue possessed higher (P < 0·05) percentages of 14:1, 16:1 and 18:1 and a lower (P < 0·05) percentage of 16:0 and 18:0 than corresponding tissues from Angus steers. Trained sensory panel analysis revealed no differences (P < 0·05) in any of the sensory traits between steaks from Wagyu crossbred and Angus steers. However, a consumer triangle test indicated that consumers can detect a difference between breeds.