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Biomedical subjects

M F Miller

Publications and source records attributed to M F Miller.

At least 55 records · Page 3Linked to original sources
PubMed1997

Phenotypic characterization of Rambouillet sheep expressing the callipyge gene: II. Carcass characteristics and retail yield.

Paternal half-sibling Rambouillet ram lambs (n = 18) representing two muscle phenotypes were slaughtered at 54.5 kg to evaluate carcass characteristics and composition. Lambs were produced from a sire that was heterozygous for the callipyge gene. Carcasses were broken into wholesale and retail cuts to evaluate percentage bone-in retail yield of carcasses at various fat trim levels and percentage of boneless retail cuts. Retail cuts were trimmed to .6 and then to 0 cm fat trim and bones were removed to determine boneless, closely trimmed retail cut yield. Chemical composition was determined using proximate analysis. Lambs expressing the callipyge gene had higher dressing percentages (57.3 vs 53.9), leg (14.4 vs 11.0) and conformation (14.4 vs 11.0) scores, and larger longissimus muscle (LM) areas (17.6 cm2 vs 10.3 cm2). All other carcass measurements were similar between phenotypes except marbling score, which was higher (417.8 vs 325.6) for controls. Lambs expressing the callipyge gene had a higher (40.2 vs 32.9) percentage boneless retail yield than controls. Retail yield of the boneless shoulder did not differ between phenotypes (8.9 vs 8.0). All other percentages of boneless retail cuts were higher (P < .02) for lambs expressing the callipyge gene. Carcasses from lambs with the callipyge gene had higher protein (16.6 vs 15.2), moisture (63.6 vs 58.6) and ash (.85 vs 77) percentages and lower fat (18.9 vs 25.4) percentages than controls. These data suggest that ram lambs expressing the callipyge gene have an advantage in retail yield and carcass conformation when compared to normal-muscled half-siblings.

Animals↗
PubMed1997

Phenotypic characterization of rambouillet sheep expression the callipyge gene: III. Muscle weights and muscle weight distribution.

Paternal half-sibling Rambouillet ram lambs (n = 18) representing two muscle phenotypes were slaughtered at 54.5 kg to evaluate the effect of the callipyge gene on muscle mass. Lambs were produced from a sire that was heterozygous for the callipyge gene. Nineteen muscles were dissected from the right side of each carcass to evaluate muscle weights relative to carcass weight. Excised muscle mass as significantly higher (42%) for lambs exhibiting a callipyge muscle phenotype than for half-siblings. In the pelvic limb, all excised muscles except the peronius tertius were larger in lambs expressing the callipyge gene (P < .001). In the torso, the longissimus (P < .001), psoas major (P < .001), and psoas minor (P < .01) were larger in lambs with the callipyge phenotype. In the thoracic limb, the biceps brachii (P < .001) triceps brachii (P < .002), and extensor carpi radialis (P < .01) were larger in lambs with the callipyge phenotype. Total pelvic limb (P < .001) torso (P < .001), and thoracic muscle weights were higher (P < .01) in lambs with the callipyge phenotype. Callipyge lambs had a higher (P < .01) percentage of excised muscle weight in the pelvic limb and torso and a lower (P < .01) percentage in the thoracic limb when compared to controls. These data indicate that the magnitude of expression of the callipyge gene is dependent upon the location of the muscle on the body and that the increased muscle mass was concentrated in the leg and loin.

Animals↗
PubMed1997

Phenotypic characterization of rambouillet sheep expressing the callipyge gene: I. Inheritance of the condition and production characteristics.

The objectives of this study were to determine the model of inheritance of the callipyge gene and to evaluate the growth, ADFI, feed efficiency, reproductive performance, and wool growth of sheep that are heterozygous for the callipyge gene. Ewes (n = 236) with a normal muscle phenotype and genotype were mated to three heterozygous rams that expressed the callipyge gene. Lambs (n = 311) were subjectively classified at weaning (90 to 120d) according to muscle phenotype by a panel of three evaluators working independently. The callipyge muscle phenotype was expressed in 150 lambs, whereas 161 lambs expressed a normal muscle phenotype. The percentage of lambs expressing the callipyge muscle phenotype (48.2%) did not differ (P > .1) from the expected 50%. Growth rate was similar for lambs of both phenotypes regardless of sex. Feed efficiency was superior (P < .05) for both male and female lambs with the callipyge muscle phenotype. Average daily feed intake was lower for male (P < .02) and female (P < .004) lambs with the callipyge muscle phenotype. Grease fleece weight and staple length at 12 mo were superior (P < .03) for ewes with a normal muscle phenotype. These results indicate that the callipyge gene in sheep is dominant when inherited from the paternal parent and lambs expressing the callipyge gene have increased feed efficiency and reduced ADFL.

Animals↗
PubMed1997

Improving tenderness of normal and callipyge lambs with calcium chloride.

Effects of CaCl2 injection on meat quality traits of 10 normal and 10 callipyge phenotype crossbred lambs were studied. Primal cuts from one side of each carcass served as the control and cuts from the other side were injected. After storage for 14 d at 2 degrees C, chops were evaluated by Warner-Bratzler shear (WBS) force, trained sensory panel, and consumer sensory panel. Treatment of the muscles with 200 mM CaCl2 increased (P < .05) tenderness and lamb flavor intensity scores by the trained sensory panel and decreased (P < .05) WBS force in both normal and callipyge phenotypes. When callipyge muscles were not injected, consumers rated 94% of leg chops, 60% of loin chops, and 89.4% of shoulder chops acceptable in tenderness. However, when callipyge muscles were CaCl2-injected, consumers rated 96.5% of leg chops, 85.4% of loin chips, and 93.5% of shoulder chops acceptable in tenderness. Normal phenotype carcasses had more marbling (P < .05) in a firmer, finer-textured, brighter cherry red longissimus muscle. Injection of CaCl2 did not affect visual lean color or L, a or b values during retail display of the chops. However, CaCl2 injection decreased color uniformity, increased discoloration, and increased browning at d 2. Therefore, a 5% (wt/wt) injection of 200 mM CaCl2 solution can be applied to improve normal and callipyge lamb tenderness and reduce tenderness and juiciness variation without detrimental effects on other palatability traits when evaluated by trained sensory panelists or consumers.

Animals↗
PubMed1997

Slaughter plant location, USDA quality grade, external fat thickness, and aging time effects on sensory characteristics of beef loin strip steak.

A boneless beef strip loin (IMPS #180) was fabricated from each of 320 carcasses to study the effects of slaughter plant location, quality grade, fat thickness, and aging time on beef tenderness and palatability. Carcasses were selected for fat thickness (< .5 cm or > or = .5 cm fat thickness) and USDA quality grade (Select or Low Choice) from two slaughter facilities (IBP, Inc., Garden City, KS or Excel Inc., Plainview, TX), and the strips were aged for either 7 or 14 d. Aging steaks 14 d improved all sensory traits and Warner-Bratzler shear (WBS) values regardless of all other main effects (P < .05). Steaks from Choice carcasses that were processed in Kansas had higher initial and sustained tenderness ratings than steaks from carcasses that were processed in Texas or Select steaks from Kansas after 7 d of aging (P < .05). However, aging for 14 d removed differences from all sensory characteristics of steaks from Kansas and Texas. All sensory scores for steaks from carcasses that graded Choice were higher than those from carcasses that graded Select (P < .05). The USDA quality grade did not affect WBS values, and fat thickness did not affect sensory characteristics or WBS values (P > .05). Therefore, aging beef strip loin steaks for 14 compared with 7 d improved sensory score and decreased WBS values, but fat thickness had no effect on the palatability of loin strip steaks processed under these conditions.

Abattoirs↗
PubMed1997

Calcium chloride injection and degree of doneness effects on the sensory characteristics of beef inside round roasts.

Twenty USDA Standard beef inside rounds were purchased from the Excel Corp. in Plainview, TX to determine the effects of CaCl2 injection and degree of doneness on inside round roasts. Inside rounds were halved and each half served either as a control or was injected with CaCl2. Each half was cut into four sections with one used for retail case display and the other three subjected to cooking at 60, 70, or 80 degrees C doneness. Roasts injected with CaCl2 were more tender as evidenced by higher initial and sustained tenderness scores and lower Warner-Bratzler shear force values (P < .004). Overall beef mouthfeel also was improved over the control by CaCl2 addition (P < .004). Thaw and purge losses were higher (P < .001) for CaCl2-injected roasts and cooking losses were lower (P < .01) than for controls. Injection with CaCl2 did not affect color, color uniformity, discoloration, or surface browning through 1 d of retail case display (P < .05). However, after 2 d of display, control roasts were superior in these traits (P < .05). Roasts cooked to 60 degrees C of doneness were found to be more palatable than those cooked to higher degrees of doneness (P < .05). The improvement in tenderness through CaCl2 injection for tougher cuts from the round is an important finding for the beef industry. The results from this research support the need to use CaCl2 to improve beef tenderness and consistency.

Animals↗
PubMed1997

Consumer evaluation of beef of known categories of tenderness.

A study was conducted to determine consumer perceptions of beef top loin steaks of known shear force and to evaluate how buying trends were modified by the tenderness and price variations of these steaks. Strip loins were cut into a 2.54-cm-thick steaks, and the center steak from each strip loin was used to determine Warner-Bratzler shear force. The remaining steaks were placed into one of the following shear force categories based on that shear force and color-coded accordingly: 1) 2.27 to 3.58 kg (Red); 2) 4.08 to 5.40 kg (White); and 3) 5.90 to 7.21 kg (Blue). Randomly recruited consumers were allowed to evaluate steaks and then purchase steaks based on their findings. A $1.10/kg price difference was placed between each category. Results of the analysis indicated that consumers were able to differentiate between the three categories of tenderness (P < .05). In addition, consumers gave higher (P < .05) juiciness and flavor ratings to Red steaks than to Blue steaks. Overall satisfaction was higher (P < .05) for Red steaks than for the other two categories of steaks. The following percentages of steaks were purchased: 1) Red, 94.6%; 2) White, 3.6%; and 3) Blue, 1.8%. These results suggest that consumers could discern between categories of tenderness and were willing to pay a premium for improved tenderness.

Animals↗
PubMed1997

A comparison of Warner-Bratzler shear force assessment within and among institutions.

Our objective was to compare measurement of Warner-Bratzler shear force of beef longissimus within and among institutions when each institution used its own protocol and when all institutions used a standardized protocol. In Exp. 1, each of five institutions (A, B, C, D, and E) received two adjacent steaks from each of 27 beef strip loins (longissimus lumborum). Warner-Bratzler shear force was measured for both steaks using the procedures normally used at each institution. In Exp. 2, each institution received two adjacent steaks from each of 45 strip loins. Shear force was measured for both steaks using a standardized protocol. In Exp. 1, Warner-Bratzler shear force was highest (P < .05) for A (4.7 kg) and lowest (P < .05) for B (2.9 kg). Repeatability of shear force was highest for A and C (.73 and .72), intermediate for D (.63), and lowest for B and E (.39 and .44). In Exp. 2, Warner-Bratzler shear force was highest (P < .05) for A (5.1 kg) and lowest (P < .05) for E (3.7 kg). Repeatability of shear force was highest for A (.87), intermediate for B, D, and E (.81, .75, and .80), and lowest for C (.67). Shear force values differed within and among institutions due to protocol, execution of the protocol, and instrument variation. Thus, comparisons of Warner-Bratzler shear force data among institutions are currently not valid. However, it is possible for institutions to obtain the same mean shear force value and have high repeatability if a standard protocol is properly executed with calibrated equipment.

Analysis of Variance↗
PubMed1996

The nanometer-scale structure of amyloid-beta visualized by atomic force microscopy.

Amyloid-beta (A beta) is the major protein component of neuritic plaques found in Alzheimer's disease. Evidence suggests that the physical aggregation state of A beta directly influences neurotoxicity and specific cellular biochemical events. Atomic force microscopy (AFM) is used to investigate the three-dimensional structure of aggregated A beta and characterize aggregate/fibril size, structure, and distribution. Aggregates are characterized by fibril length and packing densities. The packing densities correspond to the differential thickness of fiber aggregates along a zeta axis (fiber height above the x-y imaging surface). Densely packed aggregates ( > or = 100 nm thick) were observed. At the edges of these densely packed regions and in dispersed regions, three types of A beta fibrils were observed. These were classified by fibril thickness into three size ranges: 2-3 nm thick, 4-6 nm thick, and 8-12 nm thick. Some of the two thicker classes of fibrils exhibited pronounced axial periodicity. Substructural features observed included fibril branching or annealing and a height periodicity which varied with fibril thickness. When identical samples were visualized with AFM and electron microscopy (EM) the thicker fibrils (4-6 nm and 8-12 nm thick) had similar morphology. In comparison, the densely packed regions of approximately > or = 100 nm thickness observed by AFM were difficult to resolve by EM. The small, 2- to 3-nm-thick, fibrils were not observed by EM even though they were routinely imaged by AFM. These studies demonstrate that AFM imaging of A beta fibrils can, for the first time, resolve nanometer-scale, zeta-axis, surface-height (thickness) fibril features. Concurrent x-y surface scans of fibrils reveal the surface submicrometer structure and organization of aggregated A beta. Thus, when AFM imaging of A beta is combined with, and correlated to, careful studies of cellular A beta toxicity it may be possible to relate certain A beta structural features to cellular neurotoxicity.

Alzheimer Disease↗
PubMed1996

Effect of beef tenderness on consumer satisfaction with steaks consumed in the home and restaurant.

Loin steaks were eaten by 67 consumers over a 15-wk period (n = 739 consumer observations) to determine the consumer acceptability of beef tenderness in the home and a "white table cloth" restaurant. Steaks were rated for tenderness, juiciness, flavor, and overall palatability on an 8-point scale. The acceptability levels for tenderness were established based on Warner-Bratzler shear (WBS) force values, tenderness ratings, and a chisquare analysis of the judgment of tenderness and overall acceptability by the same consumers in both the home and restaurant. Results based only on observations from consumers in Lubbock, TX indicated that the beef industry should target production of beef steaks that have a Warner-Bratzler shear force value of 4.1 kg or less to ensure high levels (98%) of consumer acceptability. Results suggest that an acceptable level of beef tenderness for consumers can be determined and WBS values can be used as criteria for determining which steaks will be considered acceptably tender to consumers before distribution to retail outlets. The beef industry needs to conduct a nationwide research study to determine whether the results from this study will apply to all U.S. beef consumers.

Adolescent↗
PubMed1995

Non-promoting effects of lean beef in the rat colon carcinogenesis model.

Recent epidemiologic studies have implicated red meat consumption as a risk factor for colon cancer in both men and women. However, it has been very difficult to separate the effects of meat as a protein source from the accompanying fat content of the diets analyzed in these studies. Experimental data from rodent feeding trials show mixed results, with no firm conclusions being possible in terms of the colon-cancer promoting effects of meat fat. The goal of the present study was to compare, in an experimental animal model, the effects of beef with casein as a protein source, within the context of a low- and high-fat diet containing either corn oil or beef tallow, on promotion of colon carcinogenesis. Tumors were induced in Sprague-Dawley rats with 1,2-dimethylhydrazine (20 mg/kg body wt for 10 weeks). Two hundred and eighty male weanling rats were randomized to eight dietary treatment groups of a 2x2x2 factorial design with fat source (corn oil vs. beef tallow), fat level (5% vs. 20%), and protein source (very lean beef vs. casein) as the factors. Diets were fed ad libitum before, during and after carcinogen treatment for a total of 27 weeks. At termination of the study, animals were examined for location, size and type of colon or extracolonic lesions. The total incidence and number of colon tumors were significantly lower in the groups fed beef rather than casein. High fat levels, regardless of source, significantly increased the number of colon adenomas. These results demonstrate that when lean beef is used as the protein source in the context of a low-fat diet, fewer intestinal tumors develop. These data do not support the belief that red meat consumption increases the risk for colon carcinogenesis, but underscores the importance of fat level in dietary context.

1,2-Dimethylhydrazine↗
PubMed1995

Restaurant consumer acceptance of beef loin strip steaks tenderized with calcium chloride.

Beef strip loins from either the right or left side of 22 carcasses of Bos indicus-type steers were injected with 200 mM calcium chloride (CaCl2) solution at 5% (wt/wt) to determine its effect on tenderness and other selected quality traits of steaks. Loins from opposite sides of the carcasses were untreated and served as the control. The steaks were evaluated for tenderness, juiciness, flavor intensity, tenderness acceptability, and overall acceptability by 62 restaurant consumers over a 6-wk period. The CaCl2 injection improved (P < .05) tenderness and flavor intensity ratings by the restaurant consumers. Tenderness acceptability and overall acceptability were improved 23 and 17%, respectively, by the CaCl2 injection. Flavor was not compromised by the CaCl2 injection. The CaCl2-treated steaks were rated superior(P < .05) for flavor compared to the control steaks. Restaurant consumers preferred the beef loin strip steaks injected with 200 mM CaCl2 at 5% (wt/wt). The results of this study are interpreted to indicate that, from a restaurant consumer perspective, CaCl2 injection is an acceptable means of making beef a more consistently tender product.

Adolescent↗
PubMed1995

Improvement of beef tenderness and quality traits with calcium chloride injection in beef loins 48 hours postmortem.

Boneless strip loin subprimals (n = 24) were fabricated from 12 USDA Standard yield grade 2 carcasses at a commercial beef processing facility and processed 48 h postmortem to determine the effect of injection of 200 or 250 mM calcium chloride (CaCl2) solution at 5% (wt/wt) on beef quality traits. One-third of the subprimal served as the control; the remaining portion was injected with either 200 or 250 mM CaCl2 at 5% (wt/wt). The CaCl2 concentration treatment was randomly assigned to strip loins fabricated from either the right or left side of the carcass. After 7 or 14 d of postmortem storage at 2 degrees C, 2.5-cm-thick steaks were cut from each control and treated portion of the subprimals and evaluated for Warner-Bratzler shear (WBS) force, retail display characteristics, Minolta colorimeter L*, a*, and b* values, and trained sensory panel ratings. Treatment of the muscle with 250 mM CaCl2 increased (P < .05) trained sensory panel tenderness and beef flavor scores, and both CaCl2 concentrations decreased WBS force values, when compared with the control. Scores for color, uniformity, and browning in the retail display case did not differ (P > .05) for the 200-mM treatment compared with the control. Scores for discoloration in the retail display decreased (P < .05) for all three-way interactions of CaCl2 concentration, aging time, and display time after d 2 (except 7-d control, which remained the same [P > .05] d 1 through 5). The L* values did not differ (P < .05) for interactions of CaCl2 concentration, x aging time, and retail display.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1995

Effects of breed type and accelerated fat removal on subprimal yields and carcass values.

Nine Brown Swiss and nine English crossbred steers representing the industry standard were slaughtered to determine the effects of cattle type and hot fat removal on subprimal yields and carcass value. After dressing, cod fat, kidney, pelvic, and heart fat (KPHF), and subcutaneous fat thicker than .6 cm was removed from the right side of each carcass (HFT). The left side was not hot-fat trimmed (NFT). Both sides were fabricated into subprimal cuts with no more than .6 cm of subcutaneous fat. Carcass side values were adjusted to a 300-kg chilled carcass weight basis. All comparisons were made for the carcasses using a USDA Select quality grade end point. English crossbred steer carcasses had more (P < .05) subcutaneous fat on the loin and chuck and more (P < .05) total hot fat trim, when KPHF was not included, than Brown Swiss steers (P < .05). Brown Swiss steers had more (P < .05) KPHF. Hot-fat trimmed sides had higher (P < .05) percentage yields from the chuck, brisket, foreshank, rib, plate, round primal cuts, and most of the subprimal cuts than NFT sides, but the primal loin percentage was higher (P < .05) in the NFT sides. The total subprimal cuts yield was approximately 5% higher for the HFT sides than for the NFT sides, and the total fat trim during fabrication was more than 6% less. When the value of the sides was calculated from unadjusted weights, the NFT sides were approximately $26.50 more valuable than the HFT sides.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗