Effects of oral vitamin D(3) supplementation and supplement withdrawal on the accumulation of magnesium, calcium, and vitamin D in the serum, liver, and muscle tissue and subsequent carcass and meat quality of Bos indicus influenced cattle

Bos indicus crossbred cattle (n=79) were fed vitamin D(3) (0 or 3 million IU/hd/d) for 5d. Afterwards, half of each group was slaughtered immediately, while half was fed, without supplementation, for 7d before processing. Serum calcium concentration was increased (P<0.05) in cattle after supplement removal, but not immediately following supplementation. This also was observed in the M. longissimus lumborum and M. triceps brachii, but not in the M. semitendinosus. Liver biopsy vitamin D(3) concentrations were higher (P<0.05) in supplemented cattle immediately following supplementation, but were not different from controls after supplement removal. Vitamin D(3) did not affect tenderness at supplement removal day 0, but increased the tenderness of the M. longissimus lumborum and M. semitendinosus at supplement removal day 7. Vitamin D(3) supplementation improves muscle tenderness and may be more effective when supplementation is ceased 7d before slaughter, with minimum food safety concerns.     

Carcass and beef color characteristics of three biological types of cattle grazing cool-season forages supplemented with soyhulls

Soyhull supplementation to divergent biological types of cattle on forage-based systems was studied to determine the impact on carcass and color characteristics. Weaned calves (n=107) biologically classified as large-, medium-, or small-framed and intermediate rate of maturing were allocated to three cool-season grazing systems consisting of either orchardgrass pasture or fescue pasture, each with soyhull supplementation, or fescue pasture with no supplementation as a control. Supplementing cattle with soyhulls allowed for heavier (P<0.05) live and carcass weights, larger (P<0.05) longissimus muscle area, increased (P<0.05) backfat, kidney, pelvic and heart fat (KPH), and yield grades, and improved (P<0.05) marbling scores and quality grades. Utilizing cattle biologically classified as large- or medium-framed allowed for heavier (P<0.05) carcass weights without reducing (P<0.05) marbling scores or quality grades when compared to small-framed cattle. Instrumental color analysis of lean and adipose tissue revealed improved (P<0.05) lightness (L (?)) in lean color for supplemented carcasses as compared to the control. There were no differences (P<0.05) between dietary treatments for L (?), a (?) or b (?) values of adipose tissue. These results indicate that supplementing forage-grazing cattle with soyhulls can improve carcass merit, and utilizing large- or medium-framed cattle can allow for increased carcass weights without decreasing carcass quality.     

Lipid stability and meat colour of beef from pasture- and grain-fed cattle with or without vitamin E supplement

Meat from pasture-fed cattle can have high contents of α-tocopherol and other anti-oxidants originating from naturally occurring compounds present in grasses. However, meat from pasture-fed cattle may have an increased demand for endogenous anti-oxidants because of its high content of polyunsaturated fatty acids, which in turn, may affect its colour and lipid stability. In the work described, we evaluated the effects of pasture-feeding alone and with vitamin E supplementation and compared the findings with those obtained for grain-fed cattle (predominantly sorghum) with and without supplementation. Within each nutritional background, vitamin E supplementation did not alter meat colour or colour stability of fresh or 47-day aged muscle during 7-day aerobic storage. However, both control and supplemented grain-fed product had better meat colour (more redness) compared with meat from grass-fed cattle. These differences in redness between pasture- and grain-fed fresh beef were not apparent after ageing. The treatments did not affect the lipid stability of fresh meat during aerobic storage; however, supplementation reduced (P<0.01) lipid oxidation in grain-fed aged beef compared with pasture-fed aged beef, despite both having similar α-tocopherol contents. Pasture-fed beef had more linolenic acid, less linoleic acid and, overall, was more polyunsaturated than grain-fed beef (P<0.05). In summary, vitamin E supplementation of pasture-fed cattle did not alter muscle tocopherol contents but pasture-fed beef (both control and supplemented) was more susceptible to lipid oxidation following ageing than vitamin E supplemented grain-fed beef.     

Effects of metabolic modifiers on carcass traits and meat quality

Much research has been conducted and published about metabolic modifiers that increase growth rate, improve feed efficiency, increase carcass leanness, and decrease carcass fatness. Most of these metabolic modifiers have been developed to improve efficiency and profitability of livestock production and to improve carcass composition, with fewer of them developed and researched specifically to improve meat quality. Some of the metabolic modifiers can have negative effects on visual and sensory meat quality, especially when not used as recommended. This review evaluates the various kinds of metabolic modifiers that have been researched for their effects on production efficiency, carcass composition, and meat quality. Nutritional composition of meat generally is improved from use of most of the metabolic modifiers, visual quality is improved by others, but some can have a negative effect on marbling and tenderness. Anabolic steroid implants are very cost effective and practical for beef cattle production but aggressive implants used within 70 days of slaughter or too frequent use of them will reduce tenderness and marbling. Somatatropin and approved β-agonists are very effective in improving growth performance and carcass leanness in pigs, and β-agonists are effective in cattle, but improper use of them can have negative effects on marbling and tenderness. Feeding supplemental levels of vitamin E is quite beneficial for improving meat color and shelf-life of beef, lamb, and pork, whereas not supplementing diets with vitamin A has potential for improving marbling in cattle. Immunocastration shows promise for capitalizing on the efficiency of muscle growth of young boars up to a few weeks before slaughter, at which time boar taint is prevented and marbling is improved by immunocastration. Potential exists for improving the fatty acid profile of lipids and increasing conjugated linoleic acid content in beef through dietary manipulation. Supplementing swine diets with conjugated linoleic acid can improve carcass composition of swine, but is not yet cost effective to use. Dietary inclusion of magnesium, manganese, or chromium in diets of pigs and sheep has potential to improve meat color and water-holding capacity. Although, not all of these metabolic modifiers are approved in all countries, proper use of the ones that are approved offers opportunities for economically improving production efficiency and carcass leanness while maintaining acceptable marbling and tenderness, while some provide opportunities to enhance meat color and quality.     

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.     

POSTMORTEM ENVIRONMENTAL FACTORS AFFECTING BEEF CARCASS LEAN MATURITY AND MARBLING EVALUATIONS

Postmortem environmental factors such as chill time before ribbing, evaluation time after ribbing, interstate shipment, ribeye condition and ribeye cover condition were related to beef carcass lean maturity and marbling evaluations. Also, effects of lighting type and intensity on the evaluation of beef quality factors were studied. Beef carcasses chilled 48 h or less before ribbing required additional chilling after ribbing (greater than 30 min) in order to optimize lean maturity and marbling scores. I n general, carcasses that are thoroughly chilled and have covered ribeye surfaces are likely to maintain or develop more youthful lean maturity evaluation scores during shipment. Carcasses that were less chilled at initial evaluations and had ribeye surfaces that remained substantially covered during transportation were more likely to increase in marbling scores during transportation. Carcasses chilled for only 24 h at initial evaluation and that had a “Small” or lower amount of marbling were more subject to change in marbling score during shipment than carcasses that were more thoroughly chilled or carcasses that had higher levels of marbling. Lean maturity evaluations were optimized when beef carcasses were evaluated under “high” incandescent (1937 lux) lighting, whereas marbling scores were optimized when beef carcasses were evaluated under “medium” incandescent (1076 lux) lighting.     

Effect of vitamin E supplementation on α-tocopherol and β-carotene concentrations in tissues from pasture- and grain-fed cattle

The effects of dietary vitamin E supplementation of grain-fed cattle on lipid oxidation and meat colour have been extensively investigated, but little attention has been given to pasture-fed cattle where meat is likely to contain naturally high amounts of α-tocopherol and carotenoids. In the work described, we evaluated the effects of pasture-feeding alone and with vitamin E supplementation on tissue levels of anti-oxidants and compared the findings with those obtained for grain-fed cattle with and without supplementation. Sorghum was the major component of the grained-based ration. α-Tocopherol concentrations in plasma, muscle and fat tissues of pasture-fed cattle were not affected by vitamin E supplementation (2500 IU/head/day for 132 days prior to slaughter) while those of grain-fed cattle increased significantly. The α-tocopherol concentrations in the supplemented grain-fed cattle were similar in muscle and liver to pasture-fed animals but were lower in their fat (P<0.05). The major carotenoid present in all tissues studied from pasture-fed was β-carotene and its contents in plasma, liver, fat and muscles were decreased (P<0.05) by supplementation with vitamin E. Carotenoids were essentially absent in grain-fed cattle except for small amounts in liver. The implication of this study for the meat industry is that cattle grazed on good pasture can achieve concentrations of α-tocopherol in muscles and other tissues at least as high as those obtained by supra-nutritional supplementation of grain-fed cattle with vitamin E. However, α-tocopherol supplementation of pasture-fed cattle reduced tissue concentrations of β-carotene, which would reduce carcase fat yellowness and make pasture-fed cattle more acceptable to some Asian markets.     

DISPLAY LIFE OF FRESH BEEF CONTAINING DIFFERENT LEVELS OF VITAMIN E AND INITIAL MICROBIAL CONTAMINATION

Strip loins from beef cattle fed diets supplemented or not supplemented with α-tocopheryl acetate (vitamin E; 500 IU·animal⁻¹·d^-1) were fabricated into steaks inoculated at three initial levels (1.7 to 1.9; 2.3 to 2.5; 6.4 to 7.1 log CFU/cm²) of bacterial contamination (from over aged retail steaks) and evaluated for psychrotrophic plate counts (PPC), overall appearance and color during 6 days of simulated retail display (0 to 4C). Initial contamination affected changes in PPC (P < 0.05) during display, while the highest level of initial contamination eliminated benefits of high vitamin E concentrations on product color within 4 days of retail display. However, increased vitamin E concentrations in steaks were associated with higher (P < 0.05) CIE a* values appearance scores when the level of initial contamination was less than 2.5 CFU/cm². Results indicated that vitamin E supplementation does not mask high levels of bacterial contamination.     

Influence of production system on carcass characteristics of F(1) Wagyu × Angus steers and heifers

American Wagyu × Angus steers (n = 15) and heifers (n = 26) were finished to typical Japanese market weight and degree of finish using two different feeding methods. The first method (deferred) consisted of two growing/ finishing phases: a forage-based diet for approximately 8 months followed by a high concentrate diet fed ad libitum for an additional 8 months while the second finishing method (linear) was designed to produce a linear rate of gain for the entire 16 months that the cattle were on feed. Even though there were substantial differences in daily weight gain (P < 0.05) within the two growing/finishing phases, total weight gain for the entire 16 months was not different between the two feeding methods (P > 0.05). Cattle produced by the linear growth method were superior to deferred growth cattle for carcass weight (as estimated by cold left side weight), rib thickness, dressing percentage, marbling score, fat color, fat luster, fat quality, as well as in scores for meat color, brightness, firmness and texture (P < 0.05). Fat thickness was not affected by treatment (P > 0.05). These data indicate that the linear method of production is more consistent with producing carcasses for the Japanese beef market.     

Effects of dietary vitamin D(3), vitamin E, and magnesium supplementation on pork quality

Meat quality traits and palatability characteristics were evaluated on 240 barrows and gilts subjected to one of eight dietary regimens: (1) control (no supplement), (2) vitamin D(3)(D(3)), (3) vitamin E (E), (4) magnesium (Mg), (5) vitamins D(3) and E (D(3)/E), (6) vitamin D(3) and magnesium (D(3)/Mg), (7) vitamin E and magnesium (E/Mg), and (8) vitamins D(3) and E, and magnesium (D(3)/E/Mg). Barrows supplemented with D(3)/E/Mg had the highest (P>0.05) ultimate pH. Those supplemented with E had a higher ultimate pH than those supplemented with D(3)/Mg or the control. Gilts supplemented with Mg had the highest ultimate pH of all of the gilts while those supplemented with D(3) had the lowest. Barrows supplemented with Mg or E had more marbling than those supplemented with D(3) or D/E. Gilts supplemented with Mg had the most marbling when compared to other gilts. At 48 h postmortem, no differences due to dietary treatment were observed in L (?), a (?) or b (?) value, drip loss or purge loss. At 14 days postmortem, no differences due to diet existed in sensory characteristics. Results suggest that supplementation of swine diets with some dietary supplement combinations of containing Mg may have some potential benefit for increasing ultimate pH.     

Subjective evaluation of the colour of pig muscle. I. Accuracy of subjective measurements of colour

A randomly-selected viewing panel scored the colour of commercially important pig muscles under standard viewing conditions. The variation in scores between different observers for a given muscle was highly significant. Panel members who had previously used this method of subjectively evaluating colour reproduced their scores more accurately than did those members who were using the method for the first time. Training is therefore important before members of a viewing panel are selected. No correlation was found between the degree of red-green colour blindness and the accuracy of observers in duplicating their colour scores. There was no difference in the accuracy of scoring between men and women. The accuracy of individual observers did, however, vary between muscles. A high content of pig intramuscular fat (‘marbling’) appeared to reduce considerably the accuracy of scoring.     

Effects of dietary vitamin e supplementation and packaging on the quality of minced beef

Friesian cattle, aged 26-27 months, were fed a diet supplemented with 2000IU α-tocopheryl acetate/kg feed/day and another group was fed a basal diet (20IU/kg feed/day) for approximately 50 days prior to slaughter. Following frozen storage (-20°C for 8 weeks) semimembranosus muscles from basal and α-tocopheryl acetate supplemented cattle were minced and vacuum packaged, aerobically packaged or packaged under modified atmospheres (MAP) (30% O(2): 70% CO(2); 70% O(2): 30% CO(2); 80% O(2): 20% CO(2)). Samples were held under refrigerated (4°C) display (fluorescent lighting, 616 lux) for eight days. Vacuum-packaged samples were held under similar conditions but in complete darkness and allowed to bloom for a minimum of 4hr prior to taking colour readings. TBARS values and Hunter a values in minced beef were measured every two days. α-Tocopherol concentrations were significantly (p<0·05) higher in minced meat samples from the supplemented group than in the basal group. Significant (p<0·05) reductions in α-tocopherol concentrations in supplemented meat samples were observed with increased concentrations of oxygen in different packaging systems after eight days of refrigerated storage. TBARS values were reduced over the whole retail display period for all packaging systems when α-tocopheryl acetate supplemented beef was used. TBARS values increased as oxygen levels increased in MAP. Hunter a values showed that vitamin E supplementation in combination with vacuum packaging and MAP improved the colour stability of meat during the first 4 days of storage, however, the failure of MAP to extend meat colour for longer periods of time was probably the result of prior storage at -20°C for 8 weeks.     

Effects of muscle α-tocopherol level and surface microbiological contamination on retail caselife of fresh beef from the US, Japan and Australia

This study evaluated effects of dietary supplementation of vitamin E (1000 IU vitamin E/daily for 100 days prior to harvest) to fed cattle on retail caselife performance of fresh US beef in an export market (Japan). Economic performance (monetary losses associated with color deterioration) for US beef from vitamin E supplemented cattle vs beef from non-vitamin E supplemented cattle was contrasted. An additional, controlled study was performed to compare muscle α-tocopherol concentrations, color changes and microbiological growth for fresh beef derived from vitamin E supplemented US cattle and fresh beef from cattle with an unknown history, but from other countries. Australian strip loin steaks had the highest muscle α-tocopherol concentrations (4.6 μg/g tissue), followed by US strip loin steaks derived from vitamin E supplemented cattle (3.4 μg/g tissue) and Japanese strip loin steaks (2.8 or 2.5 μg/g tissue). US strip loin steaks from non-vitamin E supplemented cattle had the lowest (p<0.05) α-tocopherol levels (1.7 μg/g tissue). Aerobic plate counts and total coliform counts were generally low at 0 days of retail display, and they changed similarly among treatments over 6 days of display, regardless of the country of origin of the beef. Vitamin E supplementation of US cattle reduced total Japanese retail store losses due to discoloration of US beef, in yen, by 5.2 percentage points (p<0.05), saving Japanese retailers US $0.24/kg. Data suggest that US beef-normally perceived, in Japan, to discolor more quickly in the retail display case than beef from Australia-would compete more favorably, in shelf-life, with beef from other countries if it was derived from cattle that had been fed supplemental vitamin E.     

Reduced serum vitamin D concentrations in healthy early-lactation dairy cattle

Cattle obtain vitamin D by ingestion or cutaneous exposure to UV light. Dairy cattle diets are frequently supplemented with vitamin D to compensate for limited sun exposure or during times of increased metabolic demands, such as the periparturient period, to maintain calcium homeostasis. Whether housing and supplemental vitamin D practices supply adequate amounts of vitamin D to optimally support the transition from gestation to lactation in dairy cattle is unknown. Our objective was to determine how serum vitamin D concentrations of dairy cows change with season, age, parity, and stage of lactation. Clinically healthy cows (n = 183) from 5 commercial dairies were enrolled in the study. Serum samples were collected at dry off, within 7 d of entering the close-up group, and within 7 d after calving (calving+7). Vitamin D status was determined by measuring serum 25-hydroxyvitamin D [25(OH)D] by radioimmunoassay. We performed repeated-measures mixed-effects linear regression to determine the effects of season, age, parity, and lactation stage (dry off, close-up, and calving+7) on 25(OH)D concentrations in serum. Bivariable analysis indicated that parity, age, and season were not associated with serum 25(OH)D concentrations. Sample period affected 25(OH)D concentrations, with the highest 25(OH)D levels at dry off (99.7 ± 1.9 ng/mL) followed by close up (93.8 ± 2.1 ng/mL), with the lowest levels at calving+7 (82.6 ± 1.7 ng/mL). These data showed a large depletion of 25(OH)D in dairy cattle postpartum compared with late prepartum, although the biological significance of this change in these healthy cattle is unclear. Consumption of serum 25(OH)D by immune system functions and calcium homeostasis in early lactation likely caused the reduction in serum 25(OH)D concentrations after calving. These results suggest that determining whether serum 25(OH)D concentrations are associated with the incidence of transition period disease is an appropriate next step. Assessing the effects of enhanced vitamin D supplementation of cows in early lactation on postpartum diseases may be warranted.     

育成期营养水平对育肥皖南牛背最长肌不同部位肉品质的影响

研究育成期营养对育肥皖南牛背最长肌的上脑、眼肉和西冷的肉品质的影响。30头去势的体质量相近的7月龄皖南牛,随机分成5组,各组根据体质量的1.9%、1.6%、1.3%、1.0%和0.7%补充育成期精料饲养到24月龄进行育肥,在各组饲养程序相同条件下育肥期3个月屠宰。结果显示:育成期按1%体质量饲喂精料的G1.0组的p H值、大理石纹、系水力、蒸煮损失和嫩度等肉品质都优于其他各组,且G1.0组组内不同部位不同肉品质变化范围小、一致性强,皖南牛具有生产大理石纹甚至雪花牛肉的潜质。     

Impact of a multiple-micronutrient food supplement on the nutritional status of schoolchildren

BACKGROUND:. Multiple-micronutrient deficiencies exist in many developing nations. A system to deliver multiple micronutrients effectively would be of value in these countries. OBJECTIVE:. To evaluate the delivery of multiple micronutrients through the food route. The goal was to test the stability of the supplement during cooking and storage and then to test its bioefficacy and bioavailability in residential schoolchildren 5 to 15 years of age. METHODS: A pre- and post-test design was used to study children 5 to 15 years of age, with an experimental and a control group. The experimental group (n=211) consisted of children from two residential schools, and the control group (n=202) consisted of children from three residential schools. The experimental group received a micronutrient supplement containing vitamin A, vitamin B2, vitamin B6 vitamin B12, folic acid, niacin, calcium pantothenate, vitamin C, vitamin E, iron, lysine, and calcium daily for 9 months. There was no nutritional intervention in the control group. Children in the experimental and control groups were matched by socioeconomic status, age, and eating habits at baseline. All of the children in the experimental and control schools were dewormed at baseline, after 4 months, and at the endpoint. Biochemical measurements (hemoglobin, serum vitamin A, serum vitamin E, serum vitamin B12, and serum folic acid) were measured at baseline, after 4 months, and at the endpoint (after 9 months). The heights and weights of the children were also measured at baseline and endpoint. Serum vitamins A and E were measured in a subsample of 50% and vitamin B12 and serum folic acid measured in a subsample of 25% of the children. RESULTS: In the experimental group, the mean gains in hemoglobin, serum vitamin A, serum vitamin E, serum vitamin B12, and serum folic acid over 9 months were 0.393 g/dL, 6.0375 microg/dL, 1037.45 microg/dL, 687.604 pg/mL, and 1.864 ng/mL, respectively. In the control group, the mean losses in hemoglobin and serum vitamin A over 9 months were 0.9556 g/dL and 10.0641 microg/dL, respectively, and the mean gains in serum vitamin E, vitamin B12, and folic acid were 903.52 microg/dL, 233.283 pg/mL, and 0.0279 ng/mL. The mean gain in all biochemical measurements was significantly higher (p < .05) in the experimental group than in the control group. CONCLUSIONS: Vitamin A, vitamin E, vitamin B12, folic acid, and iron are bioavailable from the multiple-micronutrient food supplement used in this study. This method of micronutrient delivery has been beneficial. We believe the study intervention was beneficial because of small doses of the micronutrients added but delivered many times through meals throughout the day, over a period of 9 months.     

Vitamin E requirements of dairy calves

Thirty-two Holstein heifer calves receiving conventional rations were supplemented with 0 (control), 125, 250, or 500 IU of vitamin E/calf per d. The objective was to determine the optimum requirement based on their overall performance from birth to 24 wk of age. Overall weight gains at 24 wk were higher with 125 and 250 IU and intermediate with 500 IU supplementation compared with no supplementation. Total dry feed consumption and fecal scores were similar among treatments. Serum alpha-tocopherol increased with increased supplementation in a quadratic fashion, being almost doubled with 125 IU compared with that of control calves. Serum creatine kinase, glutamic oxalacetic transaminase, and lactic dehydrogenase values in the unsupplemented calves indicated cell membrane damage. Serum glucose was higher at 8 wk in supplemented calves, but no differences among other serum metabolites were observed. Hematological responses at 4 and 8 wk of age indicated lower mean corpuscular hemoglobin in calves given 500 IU than others and lower mean corpuscular hemoglobin concentration in calves given 500 IU than in calves given 125 or 250 IU. We conclude that supplementation of conventional rations with 125 to 250 IU vitamin E/animal per d can increase the performance of calves.     

Children aged 6 to 60 months in Nepal may require a vitamin A supplement regardless of dietary intake from plant an animal food sources

The purpose of this survey was to explore the relationship between the prevalence of the health indicators of malnutrition, diarrhea, and acute respiratory infection and the consumption of vitamin A-rich food and the supplementation status of three groups of children in Nepal (supplemented, supplemented only once, and never supplemented). A trained female community health worker interviewed mothers about vitamin A-rich food feeding practices to children aged 6 to 60 months using a standardized questionnaire and then estimated the nutritional status of the children using mid-upper-arm circumference measurements and recording the incidence of diarrhea and acute respiratory infection from mothers' interviews. Regardless of the amount of vitamin A-rich foods consumed, children who were regularly supplemented with high doses of vitamin A were protected against malnutrition, diarrhea, and acute respiratory infection at a higher rate than children who were supplemented only once or were never supplemented. Regularly providing a high-dose (200,000 IU) capsule of vitamin A to children aged 6 to 60 months, including those who eat vitamin A-rich foods, may be effective in decreasing the prevalence of morbidity from malnutrition, diarrhea, and acute respiratory infection.     

Effects of quality grade on the chemical, physical and sensory characteristics of Hanwoo (Korean native cattle) beef

The effects of quality grade (which reflects relative marbling) on the chemical, physical and sensory properties was investigated using Korean native cattle (Hanwoo) beef. Thirty-six Hanwoo cows were slaughtered and the carcasses were graded at 24h postmortem according to the Korean carcass grading system. The quality grade 1 (high quality), grade 2 and grade 3 (low quality) were based on the marbling score of longissimus dorsi (LD) muscles. The effects of quality grade on the meat quality parameters of beef LD muscle were assessed during aging. Loin-eye area, fat thickness and yield grade were all similar for the three quality groups. Mean lean color, fat color and maturity scores did not differ among quality grade groups (P>0.05). pH, Sarcomere length, WHC, collagen content, cooking loss, shear force and MFI were not affected by quality grade groups. Drip loss for grade 1 group was significantly lower than that for grade 3 groups (P<0.05). At initial tenderness evaluation of steaks, no differences among the three grades were observed; however, with additional days of storage, grade 1 steaks had higher tenderness score than grade 3 steaks (P<0.05). Increased postmortem aging time improved tenderness attributes regardless of quality groups. No significant differences were found among the quality grade groups for flavor (P>0.05). The grade 1 group had the highest juiciness score, and grade 3 groups had the lowest score (P<0.05), but postmortem aging did not influence flavor and juiciness. The quality grades were more strongly related to juiciness than tenderness or flavor.     

A Quantitative and Morphological Study of Bovine Longissimus Fat Cells

SUMMARY— A quantitative and morphological study was made of bovine fat cells from three marbling groups of longissimus muscle. Tracings on acetate paper were made of the visual marbling depots and the area measured at three positions with an ocular grid for both size and distribution of fat cells. Comparisons were also made of subcutaneous, intermuscular and intramuscular fat cell size. Intrafiber lipid accumulation was observed and the average number of red fibers per bundle determined. These results indicate that traceable intramuscular fat is not a good measure of total intramuscular fat. There did not appear to be a consistent medial, central and lateral marbling pattern among the three marbling groups; however, significant differences were apparent within groups. Fat cell size increased with increases in cell mass, marbling and total chemical fat of the muscle.
Fat cells accumulated and grew in close proximity to portions of the circulatory system. Lipid deposits adjacent to the muscle contained larger fat cells than was evident in the extrafascicular spaces within the muscle. Intrafiber lipid was readily apparent in approximately 35% of the muscle fibers and probably represented either mitochondria or triglyceride. The interrelationship of subjective marbling scores, chemically determined fat, fat cell size, fat cell distribution and intrafiber lipid characteristics are complex and require complete investigation before the association of muscle fat and meat quality can be resolved.