Chronological age and breed-type effects on carcass characteristics and palatability of bull beef

Bulls (n = 115) of four slaughter ages (9, 12, 15 or 18 months) and of 15 genotypes were studied. In this analysis, each bullock was assigned to one of four breed groups-British and British crosses, Brahman and Brahman crosses. Jersey and Jersey crosses or Holstein and Holstein crosses. Slaughter age had an (P < 0·01) effect on marbling score, longissimus muscle area, fat thickness and yield grade while breed group had an (P < 0·01) effect on marbling score and quality grade. In general, British and British cross bullocks produced carcasses with the thickest subcutaneous fat, the highest marbling score and the highest USDA quality grade while Jersey and Jersey cross bullocks yielded carcasses with the lowest weight, smallest longissimus muscle area and the lowest USDA quality grade of the four breed-type groups. Increases in chronological age (from 9 to 18 months) were generally associated with a decrease in USDA maturity score, and increases in marbling score, USDA quality grade, longissimus muscle area, subcutaneous fat thickness and USDA yield grade. Shear force values decreased as bulls matured from 9 to 18 months of age. The meat from Brahman-type bulls had higher shear force values (P < 0·01) than that from bulls of the other breed groups. Steaks from British-type carcasses received the highest numerical ratings for sustained juiciness and flavor while steaks from the Brahman-type carcasses were assigned the lowest numerical ratings for juiciness. Breed-type had a greater effect on tenderness of bull beef than did chronological age.     

The microbiological effects of breaking operations on hanging beef carcass sides

The microbiological effects of six of 16, sequential breaking operations on hanging beef carcasses were examined by swabbing a site selected for each operation, before and after the operation, on carcasses selected at random from those passing through a commercial carcass breaking process. In addition, samples were collected by rinsing or swabbing gloves worn by workers involved in the breaking of hanging carcasses. The data indicated that total aerobic counts at the selected sites increased as a result of operation 4, injecting nitrogen between the shoulder muscles; operation 5, sawing through the back bone; and operation 12, removing the last portions of the ribs and sternum. Total aerobic counts were little affected by operation 1, cutting between the ribs; operation 7, trimming the rump; and operation 8, cutting between the sternum and the rib cage. At five of the six sites the operation related to each did not increase the numbers of the few coliforms or Escherichia coli at the site, but operation 7, trimming the rump, decreased the numbers of coliforms and E. coli at a site in the anal area. E. coli were recovered in relatively large numbers from rinse samples of cotton gloves, but in only small numbers from swabs of those gloves. E. coli were recovered by rinse sampling from only two of the 25 steel mesh gloves that are worn beneath the cotton gloves. The findings show that carcasses entering the breaking facility are largely free of E. coli, except at the anal site, where about 5% of carcasses carry E. coli at log numbers >2 100 cm⁻². These numbers are reduced during the rump trimming operation, but small numbers of E. coli are deposited on the carcasses at various sites contacted by the gloved hands of workers. The gloves must be contaminated with E. coli from surfaces within the breaking facility, as the numbers on them are too large to be derived from the carcasses.     

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.     

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.     

Dietary energy and protein effects on partitioning of carcass components in beef cattle

This study evaluated carcass and wholesale cut composition of 20 Angus steers fed two levels of protein (LP = 8% versus HP = 14%) at two levels of energy intake (LE = 1·96 versus HE = 2·67 Mcal ME) at 6·35 kg head⁻¹ d⁻¹ dry matter intake for 238 d using a factorial arrangement (n = 5/diet). The left side of each carcass was physically separated into wholesale cuts and each cut was, in turn, physically separated into the lean, subcutaneous fat, intermuscular fat, bone portions and cavity fat when applicable. Intramuscular fat for the entire side was chemically determined using only the separated lean tissue component. Energy was the greatest source of variation (P < 0·05) on carcass and wholesale cut composition: HE was associated with more total carcass fat (32·4 versus 23·9%) and less lean (56·7 versus 60·2%) and bone (17·9 versus 20·1%) than LE. Protein by energy level interactions (P < 0·05) were observed for carcass subcutaneous fat and carcass lean in addition to brisket subcutaneous fat, round subcutaneous fat and bone. The HP:HE group had the least carcass lean and the most subcutaneous fat followed by the LP:HE group, LP:LE and then HP:LE. This was also the trend for the wholesale cut composition. These results suggest that fat deposition in cattle can be significantly and favorably reduced in wholesale cuts by adjusting the relative balance of dietary protein and energy.     

Feeder cattle frame size, muscle thickness and subsequent beef carcass characteristics

Sixty feeder steers were assigned scores for frame size (small, medium or large) and muscle thickness (No. 1, No. 2 or No. 3), fed for 112 days and slaughtered. Grade data were collected for all 60 carcasses; 12 sides (four from each muscle thickness group) were fabricated into boneless, closely trimmed retail cuts and the 12 rounds from each of these sides were also physically separated into muscle, fat and bone. Marbling score and USDA quality grade varied inversely (P < 0·05) with frame size. Carcass quality grades were: 33·3% Choice; 67·7% Good and 0·0% Standard for small-framed cattle; 30·3% Choice, 42·4% Good and 27·3% Standard for medium-framed cattle and 5·5% Choice, 66·7% Good and 27·8% Standard for large-framed cattle. Analysis of variance showed significant (P < 0·05) differences among all muscle thickness groups in the longissimus muscle area and carcass weight but no difference in yield grade between the No. 1 and No. 3 muscle thickness groups; the larger mean longissimus muscle area of carcasses from steers in the No. 1 muscle thickness group was offset by their heavier carcass weight and their greater thickness of fat over the longissimus muscle. However, when analysis of covariance was used to hold fatness or fatness and frame size constant, the difference in yield grade between muscle thickness groups No. 1 and No. 3 was significant (P < 0·05). Also, carcasses from cattle assigned muscle thickness scores of No. 1, as feeders, had the highest (P < 0·05) muscle to bone ratio of the round (4·1 to 1) while carcasses from cattle assigned thickness scores of No. 3, as feeders, had the lowest (P < 0·05) muscle to bone ratio of the round (3·4 to 1).     

Microbiological effects of carcass decontaminating treatments at four beef packing plants

The effects on the microbiological conditions of carcasses of decontaminating treatments at four beef packing plants were examined. Spraying with 2% lactic acid, vacuum-hot water cleaning and trimming were generally ineffective. Washing reduced numbers of bacteria on carcasses when numbers were relatively high but not when they were relatively low. Pasteurizing with steam or hot water was consistently effective. The results suggest that the maximum reduction of bacteria on carcasses may be obtained by washing and pasteurizing without the other decontaminating treatments that are currently applied to carcasses.     

Relationship of temperament, growth, carcass characteristics and tenderness in beef steers

Relationships of temperament evaluated at different production stages with growth, carcass characteristics and beef tenderness were determined in Bonsmara crossbred steers managed under commercial managent. Temperament was evaluated at weaning and at initiation of the finishing phase. Steers from a Roswell, NM ranch (n=156) and a Cline, TX ranch (n=21) were stratified at fall weaning by weight and source and randomly allotted to winter ryegrass at Uvalde or Overton, TX followed by feeding in a commercial feedlot near Batesville, TX. Cattle were observed for temperament (escape velocity, EV, m/s; pen and chute temperament score, PTS and CTS) at weaning and upon entry to the feedlot. Cattle were harvested at approximately 7 mm 12th rib fat. Carcass data was taken approximately 36 hrs post-mortem and 2.5cm thick steaks were removed from the 13th rib for Warner-Bratzler shear force (WBS) determination. The only measures of temperament significantly related to performance were EV and PTS. Weaning EV appeared to be more related to feedlot ADG (r=-0.26, P<0.003), ribeye area (r=-0.37, P<0.0008), yield grade (r=0.29, P<0.01) and WBS, r=0.27, P<0.005) than did the later measures of temperament. However, in-feedlot EV was associated with feedlot weights (r=-0.28, P<0.0004). Results of this research suggest temperament, particularly at weaning, is related to feedlot performance, carcass merit, and beef tenderness at a low to moderate level and evaluation of this trait may be a helpful management tool.     

Cow biological type affects ground beef colour stability

To determine the effects of cow biological type on colour stability of ground beef, M. semimembranosus from beef-type (BSM) and dairy-type (DSM) cows was obtained 5 d postmortem. Three blends (100% BSM, 50% BSM + 50% DSM, 100% DSM) were adjusted to 90% and 80% lean points using either young beef trim (YBT) or beef cow trim (BCT), then packaged in high oxygen (High-O₂; 80% O₂) modified atmosphere (MAP). The BSM + YBT patties had the brightest colour initially, but discoloured rapidly. Although DSM + BCT patties had the darkest colour initially, they discoloured least during display. Metmyoglobin reducing ability of ground DSM was up to fivefold greater than ground BSM, and TBARS values of BSM was twofold greater than DSM by the end of display (4 d). Though initially darker than beef cow lean, dairy cow lean has a longer display colour life and may be advantageous to retailers using High-O₂ MAP.     

Cow biological type affects ground beef colour stability

To determine the effects of cow biological type on colour stability of ground beef, M. semimembranosus from beef-type (BSM) and dairy-type (DSM) cows was obtained 5 d postmortem. Three blends (100% BSM, 50% BSM + 50% DSM, 100% DSM) were adjusted to 90% and 80% lean points using either young beef trim (YBT) or beef cow trim (BCT), then packaged in high oxygen (High-O₂; 80% O₂) modified atmosphere (MAP). The BSM + YBT patties had the brightest colour initially, but discoloured rapidly. Although DSM + BCT patties had the darkest colour initially, they discoloured least during display. Metmyoglobin reducing ability of ground DSM was up to fivefold greater than ground BSM, and TBARS values of BSM was twofold greater than DSM by the end of display (4 d). Though initially darker than beef cow lean, dairy cow lean has a longer display colour life and may be advantageous to retailers using High-O₂ MAP.     

Evaluation of live and carcass techniques for predicting beef carcass composition

Fifty beef animals varying in size, age and composition were used to determine the most accurate methods for determining beef composition. Separable and chemical composition of the 9-10-11th rib section and measurements of subcutaneous fat thickness were the most useful for explaining observed variability in carcass composition. For predicting percentage fat in fed steers, composition of the 9-10-11th rib section was the most accurate [coefficient of determination (R(2) 0·85)]. The 9-10-11th rib section was the most accurate and precise technique identified in this study to estimate beef carcass composition across and within all age classes. Specific gravity accounted for 68% of the variation in percentage of carcass fat across all age classes combined; however, specific gravity did not account for a significant portion of the variation within each age class. Deuterium oxide dilution was able to account for 77% of the variation in chemical fat percentage across all age classes combined; however, deuterium oxide dilution was not as effective in accounting for the observed variation in fat percentage within each age class. Ultrasound was found to be an accurate live measure of chemical fat percentage within all age classes combined.     

Weight loss from beef sides during storage post mortem and its effects on carcass composition

The effects of storage on carcass weight, carcass composition and the water content of tissues have been investigated. Ten Friesian-cross steer carcasses were used, one side being dissected 1 day after slaughter and the other after storage at + 1°C and 84 % relative humidity for 20 days. The rate of weight loss from the sides (range in hot weight, 103·0 to 201·5 kg) was linear between days 1 and 20, with a mean loss of 4·2 kg (0·17 %/day). During the period of storage, there was a reduction in weight of all tissues except intermuscular fat (IMF) and fatter sides (range 14·72-32·23 % dissectible fat) had a proportionately smaller loss. In percentage composition terms, there was a significant reduction in subcutaneous fat (SCF)of 0·36 percentage units, P < 0·01, and in lean, of 0·59 percentage units, P < 0·05; there was a significant gain in IMF of 0·63 percentage units, P < 0·01, but it was considered that changes were not large enough to seriously affect the interpretations of dissection data in most experiments. During storage, all tissues except IMF lost water, particularly SCF, which lost 28 % of the original amount. In the day 1 sides, 35 % of the total loss from hot weight to recovered tissue weight (after dissection) occurred during jointing and dissection and 65 % during storage. In the day 20 sides, the values were 12 %, and 88 %, respectively.     

Growth,carcass characteristics,and profitability of organic versus conventional dairy beef steers

Bull calves (n = 49), born at the University of Minnesota West Central Research and Outreach Center (Morris) between March and May 2011, were used to compare growth measurements and profitability of conventional and organic dairy steers. Calves were assigned to 1 of 3 replicated groups at birth: conventional (CONV; n = 16), organic (pasture and concentrate; ORG; n = 16), or organic grass only (GRS; n = 17), and analysis of variables was on a pen basis. Breed groups of calves were Holstein (HO; n = 9); Holsteins (n = 11) maintained at 1964 breed average level; crossbreds (n = 19) including combinations of HO, Montbéliarde, and Swedish Red; and crossbreds (n = 10) including combinations of HO, Jersey, Swedish Red, and Normande. The CONV steers were fed a diet of 80% concentrate and 20% forage. The ORG steers were fed a diet of organic corn, organic corn silage, and at least 30% of their diet consisted of organic pasture during the grazing season. The GRS steers grazed pasture during the grazing season and were fed high-quality hay or hay silage during the nongrazing season. Intakes of a total mixed ration were recorded daily with herd management software. A profit function was defined to include revenues and expenses for beef value, feed intake, pasture intake, health cost, and yardage. The GRS (358.6 kg) steers had lesser total gains from birth to slaughter than ORG (429.6 kg) and CONV (534.5 kg) steers. Furthermore, the GRS (0.61 kg/d) steers had lesser average daily gain from birth compared with ORG (0.81 kg/d) and CONV (1.1 kg/d) steers. The GRS and ORG steers had smaller rib eye area (49.5 and 65.8 cm², respectively) compared with CONV (75.4 cm²) steers. For profitability, GRS steers had 43% greater profit than CONV steers due to organic beef price premiums and lower feed costs. On the other hand, ORG steers had substantially less profit than CONV steers. The higher cost of production for the ORG steers is due to the extreme high value of organic corn. The results of the current study illustrate the economic potential of alternative strategies for growing and marketing male offspring of organic dairy cattle in the Midwest.     

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.     

Optimum conditions for beef carcass chilling

Optimum chilling schemes for a two- or three-stage chilling system were developed using a validated heat and mass transfer model and a pattern search algorithm. The optimization was performed for the ambient temperature during each stage for an air velocity of 0·5 m/s and 90% relative humidity. The experiments were conducted to evaluate the effect of the optimum conditions on beef quality after ageing.     

Meat and storage effects on processing characteristics of beef roasts

Two experiments were done to determine the effect of storage conditions and meat cut on the processing characteristics of beef roasts. The first experiment examined the effect of storage condition (fresh/frozen), cap on/off, thawing regime and holding time post thawing on purge, brine uptake, cook yield and colour of raw and cooked roasts. The second experiment examined the effect of meat cut (insides/flats) and chilled storage for up to 8 weeks on processing characteristics of roast beef. Purge was greater for insides stored frozen without cap and air thawed. Frozen thawed cuts had increased brine retention after injection, after tumbling and after cooking. Flats had less purge and higher cook yields when manufactured into roast beef. Raw and cooked colour was not significantly affected by most factors investigated. Raw meat was more red than meat that had been frozen.     

The effects of hot water pasteurizing treatments on the appearances and microbiological conditions of beef carcass sides

Beef carcasses from a commercial carcass dressing process were selected at random. One side of each selected carcass was deluged with water at 85°C, with 10, 25 and 25 sides being treated for 20, 15 and 10 s, respectively. After cooling, the treated and untreated sides of each carcass were assessed for the appearances of the fat, membrane-covered, cut bone and cut muscle surfaces and for the overall appearance of each side. For all treatments, the differences between the mean scores, on a seven-point scale, for treated and untreated sides were greatest for the appearances of cut muscle surfaces, the differences for that tissue being 1·04, 0·85 and 0·56 assessment units less for treated than for untreated sides from the 20, 15 and 10 s treatments, respectively. Microbiological samples were collected by swabbing both sides of each of the carcasses used in the 15 and 10 s treatments, both after the treatments and after cooling of the sides. Both treatments reduced the log total numbers of the total aerobic counts recovered from 25 sides by about 1·5 and the log total numbers of coliforms and Escherichia coli recovered from 25 sides by about 2. Cooling of the sides resulted in small reductions in the numbers of all three of those groups of bacteria on untreated sides, but similar reductions in only the numbers of coliforms and E. coli on treated sides. One side from each of 25 carcasses which had been heavily contaminated with visible filth during dressing was treated for 10 s. Microbiological samples were collected from both sides of each carcass before and after treatment. The numbers of bacteria recovered from untreated sides were similar to the numbers recovered from the untreated sides from carcasses selected at random, but the treatment reduced the log total numbers of total aerobic counts, coliforms and E. coli recovered from 25 carcasses by only 1, 1·5 and 1·5, respectively. The data indicate that treatment of beef carcass sides with water of 85°C for 10 s will substantially reduce the numbers of bacteria on the meat without unacceptable damage to the appearance of the product.     

Effects of pre-harvest supplemental chlorate on beef carcass and meat quality

Effects of feeding sodium chlorate on carcass quality, tenderness and color stability were evaluated. Heifers (n=64) were fed chlorate at either 0.01% or 0.05% of body weight (BW) in the last feeding or 0.01% for the last 5d before harvest, while control cattle received no chlorate. During the 12h period between feed withdrawal and transport to the harvest facility, the cattle were provided water containing either no sodium chlorate or sodium chlorate (approximately 30mM). Feed treatments at 0.01% of BW produced higher marbling scores than feeding 0.01% of BW for 5d. However, neither of these treatments produced marbling scores that were different from non-treated controls. Water supplementation increased tenderness in cattle fed 0.01% of BW for 5d, but decreased tenderness in cattle fed 0.05% of BW at the last feeding. Although tenderness differences existed, it is not clear whether or not they were caused by the feed or water treatments or by pre-existing variation in the cattle. Neither feed nor water supplementation affected color stability. These data suggest that chlorate preparations could be used to reduce pathogens without adversely impacting meat quality or display life. However, further research is needed to further substantiate these findings.