Higher Marbling Research Articles

Correlated responses in productive and adaptive traits and temperament following selection for growth and heat resistance in tropical beef cattle

Selection experiments were established in zebu-derived beef cattle grazed at pasture in the tropics to determine direct and correlated responses to selection. Two lines (AX and UPWT) that differed marginally in their level of adaptation to environmental stressors were selected for high growth, measured by estimated breeding value (EBV) for weight at 600 days. A third line (TEMP) was selected for resistance to heat, measured by low EBV for repeated records of rectal temperature under conditions of heat stress. A control line, CONT (AXBX), was also established, with minimum selection differential for 600-day weight. A derived control line, CONT (AX), based on differences between AX and AXBX lines in the foundation generation was used with CONT (AXBX) and genetic trends to measure responses. Selection for high growth increased weights, period weight gains and direct and maternal genetic components of weights between birth and 18 months of age, but did not always increase mature cow weights. Calf birth and mature cow weights were restricted due to environmental effects. Resistance to heat stress improved in UPWT by selection for high growth. Resistance to ticks improved in the more tick-susceptible AX line, but did not change in the more resistant UPWT line. Resistance to worms consistently decreased (worm counts increased) in UPWT, but did not change in AX. Worm numbers over the experimental period were low and may not have biologically impacted on growth rates. There were no general changes in male or female fertility traits, carcass and meat quality attributes or feed efficiency due to selection for high growth. Selection for low EBV for rectal temperature reduced rectal temperatures in TEMP animals. Small correlated improvements in resistance to ticks and worms occurred in TEMP animals. Changes also occurred in pattern of fat distribution in the carcass. TEMP carcasses had higher marbling than CONT (AXBX) carcasses. There were no significant changes to other attributes through selection for low EBV for rectal temperature. Selection within this line may reflect selection for factors other than resistance to heat stress per se.

Ganho de peso antes e após os sete meses no desenvolvimento e nas características de carcaça e carne de novilhos charolês abatidos aos dois anos

Foram estudados o desenvolvimento e as características de carcaça de 157 novilhos Charolês abatidos aos dois anos de idade, classificados em quatro grupos, conforme o ganho de peso médio diário (GMD) antes e após os sete meses: "alto-alto" = novilhos com GMD ³ 0,5 kg desde o nascimento até o abate; "baixo-baixo" = novilhos com GMD < 0,5 kg desde o nascimento até o abate; "alto-baixo" = novilhos com GMD ³ 0,5 kg até os sete meses e GMD < 0,5 kg dos sete meses ao abate; e "baixo-alto" = animais com GMD < 0,5 kg até os sete meses e GMD ³ 0,5 kg dos sete meses ao abate. Do nascimento aos sete meses, os animais permaneceram em campo nativo ao pé da vaca. Durante o primeiro e segundo invernos, foram manejados em pastagem de Avena strigosa + Lolium multiflorum. Aos sete meses, os animais que tiveram menor ganho de peso (baixo-baixo e baixo-alto) apresentaram, na média, 111,2 kg contra 180,1 kg dos alto-baixo e alto-alto. Os animais alto-alto e alto-baixo apresentaram maior peso até os 18 meses e carcaças mais pesadas, mas no peso ao abate não existiu diferença dos novilhos alto-baixo (445,2 kg) para os baixo-alto (428,4 kg) e baixo-baixo (412,6 kg). Os animais alto-alto apresentaram maior espessura de gordura (2,55 mm) que os animais com menor ganho de peso após os sete meses (baixo-baixo = 1,64 mm e alto-baixo = 1,33 mm). Os grupos alto-baixo e baixo-alto apresentaram maior porcentagem de gordura na carcaça (16,9 e 17,3%, respectivamente) que os animais baixo-baixo (14,6%). Novilhos alto-alto mostraram maior marmoreio que os alto-baixo e os baixo-baixo e carne de melhor coloração (4,27 pontos) que os alto-baixo (3,22 pontos). Para características da carne, o baixo ganho de peso antes dos sete meses pode ser compensado com ganhos maiores no período subseqüente e vice-versa,observando-se maior prejuízo, no primeiro caso, para peso de carcaça dos animais e, no segundo caso, para grau de acabamento das carcaças e marmoreio da carne.

Growth Performance by Stocker Steers Fed Magnesium-Mica During a Grazing and Feedlot Period1,21Contribution No. 00-35-J from the Kansas Agriculture Experiment Station.2Appreciation is expressed to Micro-Lite, LLC, (Chanute, KS) for providing magnesium-mica and partial financial support for the project and to Ronald McNickle, Terry Green, Rick Black, Larry Ellis, and Robert Middleton for assistance with sample collection and animal care.

Abstract Two experiments were conducted to determine the effects of Mg-mica supplementation on grazing and feedlot performance of stocker steers. In Exp. 1, eight groups of six steers were fed a basal diet of 80% ground grain sorghum, 15% corn silage, and 5% control protein supplement (DM basis) or a supplement containing Mg-mica (9% of supplement; 4.5 mg/kg diet DM) for 141 d. Marbling scores tended (P 0.10) higher marbling scores, and a higher percentage of carcasses grading USDA Choice than steers fed the control supplement during the pasture phase. Therefore, adding Mg-mica to pasture supplements or feedlot diets appears to have no impact on grazing or feedlot performance, but may improve carcass quality.

Genetic parameter estimates for serum insulin-like growth factor-I concentration and carcass traits in Angus beef cattle.

Divergent selection for serum insulin-like growth factor-I (IGF-I) concentration began at the Eastern Ohio Resource Development Center (EORDC) in 1989 using 100 spring-calving (50 high line and 50 low line) and 100 fall-calving (50 high line and 50 low line) purebred Angus cows. Following weaning, bull and heifer calves were fed in drylot for a 140-d postweaning period. At the conclusion of the postweaning test, bulls not selected for breeding were slaughtered and carcass data were collected at a commercial abbatoir. At the time of this analysis, IGF-I measurements were available for 1,283 bull and heifer calves, and carcass data were available for 452 bulls. A set of multiple-trait, derivative-free, restricted maximum likelihood (MTDFREML) computer programs were used for data analysis. Estimates of direct heritability for IGF-I concentration at d 28, 42, and 56 of the postweaning period, and for mean IGF-I concentration were .32, .59, .31, and .42, respectively. Direct heritabilities for carcass traits ranged from .27 to 1.0, .26 to 1.0, and .23 to 1.0 when the age-, fat-, and weight-constant end points, respectively, were used, with marbling score having the smallest heritability and longissimus muscle area having the highest heritability in each case. Maternal heritability and the proportion of phenotypic variance due to permanent environmental effect of dam generally were < or = .21 for IGF-I concentrations and for carcass traits other than longissimus muscle area. Additive genetic correlations of IGF-I concentrations with backfat thickness, longissimus muscle area, hot carcass weight, marbling score, quality grade, and yield grade averaged -.26, .19, -.04, -.53, -.45, and -.27, respectively, when carcass data were adjusted to an age-constant end point. Bulls with lower IGF-I concentrations had higher marbling scores and quality grades, but also had higher backfat thickness and yield grades regardless of the slaughter end point. Serum IGF-I concentration may be a useful selection criterion when efforts are directed toward improvement of marbling scores and quality grades of beef cattle.

Performance and carcass traits of early-weaned steers receiving either a pasture growing period or a finishing diet at weaning.

A 2-yr study was conducted to evaluate 1) steers fed ad libitum high concentrate after weaning (CONC), or 2) steers grown on pasture for 82 d, followed by high-concentrate finishing (PAST), on the performance and carcass traits of 74 early-weaned (117 d of age) steers. Potential breed differences were evaluated using crossbred steers of three types: 1) 3/4 Angus x 1/4 Simmental (BRI), 2) 3/4 Simmental x 1/4 Angus (CON), and 3) 1/2 Wagyu x 1/4 Angus x 1/4 Simmental (WAG). Steers were randomly assigned within breed to the two treatments. There was no interactions (P > .10), so the data were pooled over years. The CONC steers had an ADG that was .17 kg/d higher (P = .0001), intake 1.09 kg/d lower (P = .0001), and gain:feed ratio .013 unit better (.190 vs .177, P = .008) than PAST steers overall. Growing treatment did not affect total concentrate consumed (P = .97). The BRI steers required 31 d less than did CON steers (P = .008), and 23 d less than WAG steers (P = .05) when fed to a constant fat end point (1.1 cm). The BRI steers exhibited an ADG .16 kg/d higher (P = .0003), tended (P = .07) to have an ADG intake .49 kg/d higher, and exhibited gain:feed .01 unit better (.189 vs 180) than WAG steers. When compared with CON steers, BRI steers consumed 310 kg less total concentrate (P = .0003). No differences (P > .38) were observed between growing treatments for carcass characteristics or sensory attributes except that CONC steers tended (P = .11) to improve percentage of steers grading Average Choice or higher by 47% over PAST steers. The WAG steers had a 76-unit higher marbling score (1,000 = Small00, 1,100 = Modest00) (P = .006) than BRI steers, resulting in 19% more (P = .09) steers grading > or = Choice and 82% more (P = .03) grading > or = Average Choice. Liver (P = .15) and rumen (P = .01) weights as a percentage of hot carcass weight were reduced for CONC steers. The CONC steers had higher gain, lower intake, better efficiency, reduced liver and rumen weights, and consumed the same amount of total concentrate when compared with PAST steers. The BRI steers had less finishing days and lower daily intake compared with CON steers. The WAG steers had more days finishing, lower gain, lower intake, more undesirable efficiencies, consumed the same amount of total concentrate, and improved quality grades compared with BRI steers.

Identification of a Brahman sire whose progeny have high marbling scores and high intramuscular fat content

Summary. A Brahman sire (Select Brahman) whose steer progeny had both high marbling scores and high intramuscular fat content has been identified. The effect was independent of dam breed (5 different dam breeds were analysed), was present in both grain-finished and pasture-finished progeny, and was independent of hormone growth promotant treatment. From pasture, over twice as many progeny from the Select sire (62.5%) had high marbling scores as progeny from 10 other Brahman sires (25.9%). The effect was not as marked in grain-finished steers but the Select sire still produced one-third more high marbling progeny (84.6%) than the other sires (63.6%). The Select sire’s progeny were equal to or better than progeny from Tuli sires in producing high marbling scores. The intramuscular fat content (3.5 ± 0.3 g/100 g) of the progeny from the Select sire was greater than double that of progeny from other Brahman sires (1.9 ± 0.2 g/100 g; P&lt;0.0001) and higher than progeny from Tuli sires (2.3 ± 0.1 g/100 g; P&lt;0.0001). The increased marbling and intramuscular fat content were not associated with increased subcutaneous fat deposition, decreased muscle deposition, lower growth rate or smaller mature size since there were no differences in age, hot standard carcass weight, rump fat depth and rib eye muscle area between the Select sire’s progeny and those of other Brahman sires. The identification of a high marbling trait in a Bos indicus sire is of considerable significance to the northern Australian beef industry because it enables markets requiring marbled carcasses to be targeted while maintaining the advantages of tropical adaptation.

Usage of crossbred cattle for the progeny testing of Japanese black cattle (Wagyu)

The Japanese black cattle (Wagyu) is well known for their high marbling and price meat. Usually purebred calves from Japanese black cattle are used for the station or field progeny testing. If genetic variance of particular traits of the dam breed is much smaller than that of the sire breed, breeding values of sires can be estimated accurately from their crossbred progeny because genetic difference among dams is relatively small and can be ignored. The objective of this study was to investigate the possibility of using crossbred for progeny testing of Japanese black sires. Since marbling scores or carcass prices of Holstein cattle are low and do not vary widely, crossbred between Japanese black and Holstein was chosen in this study.

Study of the Physicochemical and Sensorial Characteristics of Dry-Cured Hams in Three Pig Genetic Types

Physicochemical and sensorial characteristics of dry-cured hams from three genetic types-a Landrace x Large White cross (L line), a Duroc strain (D line) and a heavily muscled strain formed from the purebreeds Pietrain and Belgian Landrace (B line)-were determined on the Biceps femoris muscle after 9 months of ageing. The correlation between variables and their discriminant ability were evaluated. Hams from the D line were characterised by higher marbling, a higher dry-cured ham flavour and lower processing weight losses. Hams from the B line showed more holes and the highest intensity of pastiness, crumbliness and brightness and non-protein nitrogen and tyrosine contents. Hams from the L line were the saltiest. A principal component analysis showed that pastiness, brightness, non-protein nitrogen content and tyrosine content were positively correlated to each other. The most discriminant parameters according to the genetic types were sensorial descriptors. Marbling, saltiness and dry-cured ham flavour classified correctly 93% of the hams.

Sex and crossbreed effects on the characteristics of dry-cured ham

The right ham of 76 gilts and 82 barrows from five different crossbreeds, which included Duroc (DU), Landrace (LR), Large White (LW) and Belgian Landrace (BL) lines — DUx(LRxLW), LWx(DUxLW), LWx(LRxLW), BLx(DUxLW) and BLx(LRxLW) — were processed to produce dry cured hams. The external appearance of the hams, and the colour and thickness of the subcutaneous fat were determined. Chemical analyses, appearance, texture, flavour and odour were evaluated on biceps femoris (BF) muscle. The hams from the barrows showed a thicker and whiter layer of subcutaneous fat, higher marbling and lower processing loss than those from gilts. Hams from DU-sired pigs presented the highest marbling, but the worst texture characteristics. The texture characteristics of the hams from the LBx(LRxLW) cross were similar to those of the hams from DU-sired pigs. The hams from the LW-sired crosses showed the highest intensity of holes surrounding the coxo-femoral joint. The LBx(DUxLW) could be the most suitable among the five crosses studied for dry-cured ham production under the processing conditions used in this study.

The effects of fat thickness and degree of marbling on pork colour and structure

Fat thickness (3rd–4th last rib) was weakly correlated with subjective pork structure score (R2 = 1.0%) and marbling score (R2 = 1.6%) in 399 boneless pork backs sampled from commercial processing plants. Pork colour and structure scores (R2 = 5.9 and 11.1%) were more highly correlated with marbling score than carcass fat and muscle depths (R2 = &lt; 2.0%). Pork backs that had structure scores of 1 and 2 (extreme to slight soft and exudative pork) tended to have low amounts of marbling (traces or less). A second trial with 311 pork backs also indicated that higher marbling scores were associated with lower frequencies of pale, soft and exudative pork. Key words: Pork quality, marbling, PSE

Effect of prepubertal body weight gain and breed on carcass composition at puberty in beef heifers

Fourteen prepubertal Angus heifers, all of which reached puberty, and 11 Santa Gertrudis (SG) heifers, eight of which reached puberty, were divided into two treatment groups. There was no breed difference in age at puberty for those that reached puberty. Treatment 1 (T1) heifers, fed to gain .5 kg/d, tended (P < .11) to be older than Treatment 2 (T2) heifers, fed to gain 1 kg/d, at puberty. Body weight and height were greater (P < .01) in SG than in Angus heifers at puberty. Angus heifers in T2 deposited more fat over the rump during the 15 wk before puberty, whereas T1 SG heifers deposited the least amount of fat (P < .05). Heifers in T2 were heavier at puberty (P < .05), had faster growing longissimus muscle areas (P < .05), and deposited more fat over the rib (P < .01) as they approached puberty. The T2 (P < .05) and Angus (P < .05) rib sections had more dissectible subcutaneous fat than did T1 and SG rib sections. Angus heifers had higher marbling scores (P < .05), as well as higher total lipid percentages for seam fat (P < .05), longissimus muscle (P < .01), other lean tissue (P < .05), and subcutaneous fat (P < .01). Predicted total lipid content for the edible portion of the dressed carcass was higher for T2 heifers (P < .09).

Effect of grain feeding on fat colour and other carcass characteristics in previously grass-fed Bos indicus steers

One hundred Brahman cross steers were removed from pasture and fed a high grain diet for a finishing period of 0, 35, 70, 105, or 175 days. The steers were then slaughtered and assessed for subcutaneous fat depth, fat colour, meat colour, marbling, and p-carotene and lutein concentrations in the fat and serum.The average liveweight gain was 0.7 kg/day. After35 days of grain feeding, fat colour was significantly(P&lt;0.05) decreased from 3.9 to 2.4 when assessed using grading chips ranging from 0 (polar white) to 9 (creamy yellow). There was a trend to a further decline in fat colour over longer finishing periods (1.7 at 105 days and 2.0 at 175 days), although 1 steer had a fat colour core of 6 at 70 days and 1 at 105 days slaughter, and another had a score of 4 at 175 days. Steers fed for175 days had higher marbling but darker meat than those fed for the other finishing periods (P&lt;0.05).Subcutaneous fat depth at 105 and 175 days (17.3 mm) was greater than at 35 and 70 days (14.5 mm) and significantly (P&lt;0.05) greater than at the initial slaughter (12.5 mm).Fat colour was correlated (in the subcutaneous and intermuscular fat, respectively) with p-carotene (r = 0.61 and 0.55) and lutein (r = 0.53 and 0.52) concentrations, and in the serum, with p-carotene (r = 0.49) concentration. Objective assessment of fat colour, the Minolta b* value, was also correlated (in the subcutaneous and intermuscular fat, respectively) with p-carotene (r = 0.85 and 0.80) and lutein (r = 0.74 and 0.73) concentrations and was correlated with p-carotene (r = 0.61) concentrations in the serum. It was s demonstrated that grain feeding had an effect on changing bovine fat colour, and although p-carotene was predominant in serum, both p-carotene and lutein contributed to the yellowness in bovine carcass fat.

Effect of agricultural by-product diets on carcass characteristics of four types of cattle in the feedlot

Five type of formulated diet from agricultural by-products (ABP) were fed to four breedtype of cattle in feedlot. The ABP used are palm kernel cake (PKC), palm press fibre (PPF), palm oil mill effluent (POME), cocoa pod (COP), coffee pulp (COF) and pineapple waste (PAP). The formulated diets are PS (52% PKC, 15% PPF and 30% POME), PF (57% PKC, 20% PPF and 20% POME), PA (2% PKC and 55% PAP), CO (42% PKC and 55% COP) and CF (67% PKC and 30% COF) with 1% urea, 1% NaCl and 1% vitamins premix. The cattle breedtypes are Kedah-Kelantan (KK), Brahman-KK (BK), Hereford-KK (HK) and Sahiwal-Friesian (SF). The result showed that breedtype significantly affect all the carcass characteristic except dressing percentage. Each breedtype has it`s specific carcass characteristics. HK cattle gave high marbling, BK has high % of carcass bone, KK has high % of carcass meat and low % of carcass fat (lean meat type) and SF has high % of carcass fat. Diet-type significantly affect the deposition of fat in the carcass. High moisture diets (PA and CO) produced significantly higher % carcass bone, the lowest % carcass fat and the highest % carcass meat (65.3%). PF, CF, PA and CO diets produced 63.4%, 59.9%, 55.3% and 54.1% carcass meat respectively.

Relationships between pork loin palatability traits and physical characteristics of cooked chops

Pork loins (n = 72) were selected so that marbling scores would range from "practically devoid" to "abundant" in the longissimus muscle. Loin chops were cooked and rated by a trained six-member sensory panel. Physical and chemical characteristics were stratified according to marbling level (divided into 10 subclasses), muscle structure, shear force, overall palatability, and juiciness (each divided into three subclasses). The highest ratings for overall palatability were assigned to chops with high reflectance (685 nm), low moisture (70.1%), high i.m. fat (9.1%; or, high marbling score), low protein (19.4%), and low cooking loss (25.9%). Chops with the highest percentage of cooking loss were high in moisture content (75.59%), low in i.m. fat (1.78%), and high in protein content (21.54%). Differences in muscle structure, shear force, overall palatability, and juiciness were associated with differences in percentages of protein, moisture (whole tissue basis [WTB]) and fat (WTB). Pork loins with marbling between "practically devoid-plus" and "small" had (P less than .05) more protein and less fat (WTB) than loins with marbling scores between "modest" and "abundant." Loins with overall palatability ratings between 4.0 and 6.0 had more moisture and protein (P less than .05) than did loins with palatability ratings of 6.1 to 8.0. Selecting pork loins with "small" or less marbling, extremely open structure, a juicy rating of "slightly juicy," and an overall palatability rating of "like slightly" would identify fresh loins that had lower fat and(or) higher protein content.

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).

INFLUENCE OF STEAK TEMPERATURE AT THE BEGINNING OF BROILING ON PALATABILITY, SHEAR AND COOKING PROPERTIES OF BEEF LOIN STEAKS DIFFERING IN MARBLING

Beef loins representing six USDA marbling degrees provided steaks that were subjected to two thawing procedures prior to broiling at 70°C and subsequent evaluation of sensory, shear, and cooking properties. Loins from 120 carcasses were selected from the following six marbling degrees (20 loins/group): Moderately Abundant, Slightly Abundant, Moderate, Modest, Small, Slight. The two thawing procedures provided steaks of two internal temperatures before broiling (high = 10.5°C, low = 4.1°C). Reductions in marbling produced lower tenderness and juiciness ratings regardless of internal temperature prior to broiling. High initial-temperature produced higher tenderness and juiciness scores, less cooking loss, shorter cooking times and a more rare degree of doneness than the low initial-temperature. High initial-temperature resulted in instrumental measures more indicative of tenderness than low temperature, but only for steaks of Small and Slight marbling. However, high temperature produced lower beef flavor intensity in steaks from the higher marbling scores than low temperature. Use of higher internal meat temperatures just before broiling can reduce cooking time while enhancing tenderness and juiciness. With more highly marbled steaks, some additional broiling time may be necessary to develop beef flavor if higher internal meat temperatures were employed prior to broiling. Thawing procedures should be carefully controlled to prevent temperature abuse if it is decided to elevate meat temperatures prior to broiling.

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.

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.

BEEF QUALITY AND PALATABILITY AS AFFECTED BY ELECTRICAL STIMULATION AND COOLER AGING

ABSTRACTFifty light‐weight heifers were slaughtered and selected sides were electrically stimulated with 50 impulses of 1.0 set duration (machine setting = 100 volts, 5 amps, 50–60 cycles per set: producing a 440 volt potential difference between electrodes). Treatment groups consisted of certain combinations of electrical stimulation (ES) and/or paired control (C) sides stored for 7 or 21 days postmortem. In the treatments involving ES vs C, ES had a significant effect on lean maturity and overall maturity (more youthful) and in one group resulted in higher marbling and final USDA quality grade than the C sides. Lean color was significantly improved and incidence of “heat‐ring” was reduced by the ES treatment. Significant decreases in shear force were observed for 21 day ES vs 21 day C; 21 day C vs 7 day C and 7 day ES vs 21 day C. These data suggest that electrical stimulation could be utilized to improve certain quality‐indicating characteristics and allow carcasses to be graded sooner than normally processed carcasses. In addition, the ES treatment could substantially reduce the time of cooler aging needed to assure optimum tenderness.

Production and Carcass Characteristics of Holstein-Friesian Bulls and Steers Slaughtered at 800 or 1,000 Pounds

Holstein-Friesian bulls and steers were evaluated for meat production from birth until slaughtered at 800 or 1,000lb. Bulls reached slaughter weights faster (P<.01) than steers, consumed less total feed per group, and were more efficient in converting it into meat. The 800-lb cattle consumed 32% less total feed per group and required 87 fewer days to reach slaughter weights than 1,000-lb cattle. Bulls had a slightly lower (P<.05) dressing percentage, due to their heavier hides (P<.05) and to the fatter (P<.01) steer carcasses.Bulls had a larger percentage (P<.01) rib eye than steers, the difference being more pronounced at 800lb. Wholesale cuts expressed as per cent of chilled carcass weight showed an advantage in hindquarters for 800-lb cattle (P<.01) and for steers (P<.01). This advantage for steers, however, was due to a higher per cent flank (P<.01) and kidney knob (P<.01) and was less pronounced at 1,000lb. Bulls and 800-lb cattle had an advantage (P<.01 and P<.05, respectively) in per cent desired cuts due to a greater percentage of round (P<.01) and chuck (P<.01).No differences among groups were obtained in carcass conformation scores. Steers had higher marbling (P<.01) and texture (P<.05) scores, more (P<.01) outside fat covering, and lower (P<.01) specific gravity than bull carcasses.