Biomedical subjects

M Koohmaraie

Publications and source records attributed to M Koohmaraie.

At least 19 recordsLinked to original sources

PubMed1996

Prediction of breeding values for tenderness of market animals from measurements on bulls.

Data were tenderness measures on steaks from 237 bulls (Group II) slaughtered after producing freezable semen and on 1,431 related steers and heifers (market animals, Group I) from Angus, Hereford, Pinzgauer, Brahman, and Sahiwal crosses from the Germ Plasm Evaluation project at the U.S. Meat Animal Research Center. Tenderness was assessed through Warner-Bratzler Shear Force (SF), taste panel tenderness (TPT), marbling score (MS), and myofibrillar fragmentation index (MFI). For all traits, as fraction Bos indicus inheritance increased, implied tenderness decreased. Heritability estimates were generally not significantly different from zero. Genetic correlations generally indicated favorable associations among the traits. The range in predicted breeding values of bulls for market animal tenderness was small and from -.34 to .32 kg for market animal shear force. Because of low estimates of heritability for SF or TPT, results from this experiment indicate that selection based on tenderness of steaks sampled from intact or late castrate males slaughtered following collection of freezable quality semen would not be very effective in improving average tenderness of steaks from steers of heifer progeny. If a mean of heritability estimates reported in the literature of .27 for shear value was assumed for market steer and heifer progeny instead of .02 as found in the present study, then selection based on estimates of shear force in young bulls would be relatively more effective in improving shear force of market progeny.

Animals↗

PubMed1996

Development of an enzyme-linked immunosorbent assay (ELISA) for quantification of skeletal muscle calpastatin.

An indirect antibody ELISA was developed for rapid and sensitive quantification of skeletal muscle calpastatin. Polyclonal antibodies were raised in rabbits against recombinant calpastatin, corresponding to domains 2, 3, and 4 of bovine skeletal muscle calpastatin. Western blot analysis revealed that these antibodies specifically recognize an immunoreactive calpastatin protein of approximately 130 kDa in prerigor skeletal muscle extracts. The intensity of the immunoreactive bands corresponds qualitatively with assayable calpastatin activity. For ELISA development, optimum dilutions of sample, primary anti-calpastatin antibody, and peroxidase-conjugated secondary antibody were determined by titration. A dilution optimum for coating of Immulon 4 (Dynatech) plates was observed when heated muscle extracts were diluted to 2 to 4 micrograms of protein/mL and incubated for 2 h at 37 degrees C. Optimum primary (30 micrograms IgG/mL) and secondary (Sigma A-6154; 1:1000 dilution) antibody incubations were for 1 h at 37 degrees C. Tetramethylbenzidine was used as substrate and A450 of the stopped reaction product was recorded in an automated plate reader. Calpastatin ELISA results were linearly related to calpastatin activity (calpain inhibitory activity) of heated longissimus muscle homogenates from prerigor lamb (r2 = .89; n = 40) and beef aged for 24 or 48 h (r2 = .90; n = 47). Intra-assay CV was < 5% (n = 8) and inter-assay CV was < 6% (n = 5). This assay offers advantages of speed, simplicity, and sensitivity over conventional methodology for calpastatin quantification.

Animals↗

PubMed1996

Meat toughening does not occur when rigor shortening is prevented.

The objective of this experiment was to test the hypothesis that meat toughening during the first 24 h postmortem results from sarcomere shortening during rigor mortis development. Eleven market-weight lambs were used to measure changes in shear force of clamped longissimus during rigor development. Within 15 min of exsanguination, while attached at both ends, each longissimus was separated from the vertebrae body and clamped between three sets of metal plates to prevent muscle shortening (six clamped sections per lamb). Five of the clamped sections were placed at -1.1 degrees C for 0, 3, 6, 12, or 24 h. After storage at their respective times at -1.1 degrees C, the samples were placed at -30 degrees C for 90 min and then at -5 degrees C for 8 d. The sixth section (168-h section) was stored at -1.1 degrees C for the first 24 h, at 4 degrees C for 144 h, and then treated the same as other sampling times. Sections were sampled for pH, sarcomere length, shear force, and Western blot analyses before and after storage at -5 degrees C. Shear force values were the same (P > .05) from 0 to 24 h (4.5 kg at 0 h to 4.9 kg at 24 h) then declined (P < .05) to 3.3 kg at 168 h postmortem. As evident by lack of statistical difference in the sarcomere lengths, we were successful in holding the muscle length constant. Western blot analyses of nebulin, vinculin, and troponin-T indicated that minimum degradation occurred through 12 h, was slightly increased by 24 h, and was relatively extensive by 168 h postmortem. Although limited proteolysis occurred during storage at -5 degrees C for 8 d, this by itself had no effect on shear force. Results indicate that shear force values do not increase during rigor development when muscle is prevented from shortening; thus, the toughening that occurs during the first 24 h of slaughter is most likely due to sarcomere shortening.

Animals↗

PubMed1996

Effects of a beta-adrenergic agonist (L-644,969) and male sex condition on muscle growth and meat quality of callipyge lambs.

The objective of this study was to determine the effects of dietary administration of a beta-adrenergic agonist (BAA; L-644,969) and male sex condition (ram vs wether) on muscle growth and meat quality of Dorset x Romonov lambs believed to be heterozygous for the callipyge gene. At approximately 17 wk of age, lambs were blocked by weight within each sex condition and randomly assigned to BAA treatment group. The interaction of BAA and male sex condition was not significant for any of the traits measured. Rams had greater initial and final live weights, average daily gain, and hot carcass weight (P < .01). Rams did not differ (P > .05) from wethers with respect to any of the carcass traits, possibly because the wethers were so lean and heavily-muscled that there was little room for improvement. Kidney-pelvic fat weight was reduced 26% by BAA (P < .05). Knife separable lean weight and whole carcass proximate composition were not affected (P > .05) by BAA or male sex condition. Administration of BAA increased calpastatin activity at 20 d (1.1 vs 1.5 units/g), but not at 0 h (3.9 vs 4.8 units/g) postmortem, decreased myofibril fragmentation index (60.7 vs 44.9), and increased shear force (8.2 vs 10.9 kg) at 20 d postmortem (P < .05). These data suggest that muscle growth rates are near maximum in lambs expressing the callipyge gene, regardless of male sex condition or BAA treatment. Therefore, it seems that the callipyge gene exerts most, but not all, of its effect through intracellular events similar to those initiated by administering BAA.

Adrenergic beta-Agonists↗

PubMed1996

Sampling, cooking, and coring effects on Warner-Bratzler shear force values in beef.

A series of experiments was conducted to determine the effects of various factors on Warner-Bratzler shear force measurement of cooked beef. As the extent of thawing of frozen steaks before cooking for shear force evaluation increases (-2 vs 12 degrees C), shear force decreases (P < .05; 7.34 vs 5.99 kg). Location within the longissimus thoracis et lumborum from which steaks were obtained (caudal, medial, or cranial) did not affect (P > .05) shear force (5.21, 5.15, or 5.26 kg, respectively) or any sensory trait. Mean shear force of longissimus steaks cooked to either a constant temperature of 70 degrees C (6.97 kg) or for a constant time of 30 min (6.38 kg) was not different (P = .06), but shear force repeatability was higher for steaks cooked to constant temperature (.79 vs .53). Mean shear force (6.20 vs 6.33 kg) and shear force repeatability (.74 vs .68) of longissimus steaks cooked by either electric broiler or convection oven broiler, respectively, were not different (P > .05). Meat cores obtained perpendicular to the steak surface, from one location within the muscle, had lower (P < .05) mean shear force (3.41 vs 4.17 kg) and much less repeatable shear force (.12 vs .66) than cores obtained parallel to muscle fiber orientation. Use of more than five cores per animal did not significantly increase repeatability of mean shear force. Numerous factors must be carefully controlled to ensure measurement of shear force is as accurate and repeatable as possible.

Animals↗

PubMed1996

Effect of vitamin C concentration and co-injection with calcium chloride on beef retail display color.

The objectives of these experiments were to determine 1) the most effective vitamin C concentration to stabilize color of beef cuts during retail display and 2) the effect on color of incorporating vitamin C into a calcium chloride (CaCl2) injection solution. Top round cuts (semimembranosus and adductor) were injected with 5% by weight of a 0, .25, .5, 1, 2, or 4% sodium ascorbate solution (Exp. 1) or a 0, .5, 1, or 1.5% sodium ascorbate solution (Exp. 2). In Exp. 1, vitamin C resulted in more (P < .05) stable lean color during 9 degrees C display, and .5, 1, and 2% vitamin C were most (P < .05) effective. In Exp. 2, all concentrations of vitamin C maintained redder (P < .05) steaks after 3, 5, and 7 d of display than control steaks and had a lower (P < .05) percentage of surface discoloration after 5 and 7 d of display at 1 degree C. Experiment 3 used beef bottom round cuts (biceps femoris) to compare control, vitamin C- (1%), CaCl2-(200 mM) and vitamin C + CaCl2-treated steaks displayed at 1 degree C. Calcium chloride-treated steaks were more (P < .05) brown and had a higher (P < .05) percentage of surface discoloration on d 5 and 7 than control steaks, whereas steaks treated with vitamin C or vitamin C + CaCl2 were more (P < .05) red and had lower (P < .05) discoloration on d 5 and 7 than control steaks. Vitamin C can be injected into beef subprimals to enhance lean color stability and extend retail display life. Vitamin C also can be used in combination with CaCl2 to offset potential color deterioration, after 5 d of display, due to salt-induced oxidation.

Animals↗

PubMed1995

The effects of in utero exposure of lambs to a beta-adrenergic agonist on prenatal and postnatal muscle growth, carcass cutability, and meat tenderness.

The objectives of the present experiment were to examine the effects of in utero exposure to a beta-adrenergic agonist (L644,969) on prenatal and postnatal muscle growth and meat tenderness of lambs. Thirty twin-pregnant Composite IV (1/2 Finnsheep, 1/8 Dorset, 1/8 Rambouillet, 1/8 Targhee, 1/8 Suffolk) ewe lambs were used for this experiment. All ewes were fed an alfalfa hay-corn-based diet throughout gestation and lactation. From d 25 to 95 of gestation, the diet of one-half of the ewes contained 2 ppm of L644,969 on an as-fed basis. Treatment did not ( P > .05) affect lamb weights at any point in the growth cycle (birth to 43 kg). Heart weights of neonatal and market lambs were increased ( P < .05) by in utero exposure to L644,969. However, weights of lamb carcass components and weights of individual muscles were not affected by treatment (P > .05). Additionally, treatment did not alter the activities of any of the components of the calpain proteolytic system in neonatal or market lambs. Concomitantly, there was no effect of treatment on myofibril fragmentation index or Warner-Bratzler shear force. Moreover, there was no effect of treatment on muscle fiber type distributions, fiber sizes, or apparent fiber number. It seems that the lack of an effect of treatment on apparent fiber number would explain the lack of an effect on muscle weight. Thus, in utero exposure to L644,969 does not seem to have promise as a method for improving lamb carcass cutability. Other methods of improving the rate and composition of lamb carcass growth while maintaining acceptable meat tenderness must be developed.

Adrenergic beta-Agonists↗

PubMed1995

Effects of slaughter age on meat tenderness and USDA carcass maturity scores of beef females.

Two experiments were conducted to determine the effect of carcass maturity on meat palatability using concentrate-fed cattle of known history and to determine the relationship of chronological age to carcass maturity scores. Yearling heifers (n = 28) and 2-yr-old cows (n = 25) of similar breed groups were fed a high-energy-density diet for 90 d before slaughter. Longissimus muscle Instron peak load (Warner-Bratzler shear force) did not differ between age groups; but, fail elongation was higher for the 2-yr-old cows (P < .05). Overall tenderness ratings were lower for the 2-yr-old cows; however, the magnitude of the tenderness difference between age groups was small (.4 units on an 8-point scale). There was 10-fold more variation in tenderness within each age group than there was between age groups. Carcass maturity scores and chronological age were compared for heifers and cows (n = 249) ranging in age from 1.7 to 13.9 yr. Carcass maturity scores increased with increasing chronological age at a much faster rate than indicated by USDA. The following chronological age groups most accurately reflected the chronological age associated with each USDA carcass maturity class: A, 9 to 24 mo; B, 24 to 36 mo; C, 36 to 48 mo; D, 48 to 60 mo; E, > 60 mo. These results indicate that efforts to control variation in tenderness would be more effective if they targeted factors that have a greater effect on meat tenderness than does maturity class. Moreover, our results indicate that cows may grade lower at a given age than what USDA standards imply.

Aging↗

PubMed1995

Relationship between shear force and trained sensory panel tenderness ratings of 10 major muscles from Bos indicus and Bos taurus cattle.

The present experiments were conducted to determine 1) the relationship between shear force and overall tenderness of 10 major beef muscles, 2) the effect of Bos indicus inheritance on the tenderness of various beef muscles, 3) whether differences in tenderness between genotype are affected by method of cookery, and 4) the relationship between tenderness of the longissimus and tenderness of other muscles. To meet the first objective, shear force and trained sensory panel overall tenderness were determined for psoas major (PM), infraspinatus (IS), triceps brachii (TB), longissimus (LD), semitendinosus (ST), gluteus medius (GM), supraspinatus (SS), biceps femoris (BF), semimembranosus (SM), and quadriceps femoris (QF) steaks from grain-fed steer carcasses (n = 16). Shear force did not accurately reflect differences among muscles in overall tenderness. To accomplish the remaining objectives, muscles were removed from grain-fed Bos taurus x Bos taurus (n = 31) and Bos indicus x Bos taurus (n = 18) steer carcasses and aged until 14 d postmortem. Shear force of LD, TB, SS, BF, and QF steaks and QF, BF, TB, and LD roasts was higher (P < .05) for progeny of Bos indicus sires than for progeny of Bos taurus sires. Shear force differences among genotypes were reduced slightly by roasting. Shear force of LD was not highly related to shear force of other muscles. Thus, systems that accurately predict the tenderness of LD of a carcass will likely do little to predict the tenderness of other muscles.

Animals↗

PubMed1995

A muscle hypertrophy condition in lamb (callipyge): characterization of effects on muscle growth and meat quality traits.

The present experiment was conducted to determine the effect of the callipyge phenotype on traits affecting muscle growth and meat tenderness. Dorset wethers (N = 40) that were either carriers or non-carriers were fed grain and slaughtered at 169 d of age. Callipyge phenotype did not affect (P > .05) slaughter weight, hot carcass weight, or weights of the heart, spleen, viscera, kidney-pelvic fat, head, and pelt; however, callipyge lambs had a higher dressing percentage and lighter lungs, liver, and kidneys (P < .01). Callipyge lambs had reduced fat thickness and marbling score and higher leg scores and longissimus area (34%). Adductor (30%), biceps femoris (42%), gluteus group (31%), longissimus (32%), psoas group (20%), quadriceps femoris (18%), semimembranosus (38%), and semitendinosus (26%) weights were higher in the callipyge phenotype (P < .01); however, phenotype did not affect (P > .05) weights of infraspinatus or supraspinatus. Longissimus pH and temperature declines were not affected (P > .05) by phenotype. Longissimus myofibril fragmentation index was lower at 1 (27%), 7 (35%), and 21 (37%) d postmortem and Warner-Bratzler shear force was higher at 1, 7, and 21 d postmortem in the callipyge phenotype (P < .01). Shear force values of callipyge lambs at 21 d postmortem tended to be greater (P = .12) than shear force values of non-carriers at 1 d postmortem . Activities of calpastatin (83%) and m-calpain (45%) were higher in the callipyge (P < .01); however mu-calpain activity was not affected (P > .05). Longissimus and semitendinosus RNA concentration, DNA content, RNA content, protein content, and the RNA:DNA ratio were higher (P < .05), but DNA concentration, protein concentration, and protein:DNA were not affected in the callipyge phenotype. The higher calpastatin activity associated with callipyge suggests that protein degradation may be reduced in the live animal. Additionally, the increased muscle DNA content associated with the callipyge phenotype suggests an increase in satellite cell proliferation, and results in an increased capacity of skeletal muscle to accumulate and maintain myofibrillar protein. These results suggests that both reduced rate of protein degradation and higher capacity for protein synthesis are consequences of the callipyge condition.

Actinin↗

PubMed1995

Relationship of restriction fragment length polymorphisms (RFLP) at the bovine calpastatin locus to calpastatin activity and meat tenderness.

Restriction fragment length polymorphisms (RFLP) have been identified at the bovine calpastatin locus. The objective of the present study was to determine whether these polymorphisms are related to variations in calpastatin activity or beef tenderness in unrelated animals of mixed breeding. A sample of 83 crossbred steers from sires representing eight different breeds was examined to determine this relationship. A 2.2-kb cDNA coding for domains 2 through 4 plus a 3' untranslated region of bovine skeletal muscle calpastatin was used as a probe for calpastatin RFLP. Polymorphisms were found using the restriction enzymes BamHI and EcoRI. Polymorphic restriction fragments for BamHI were 9.0 and 5.0 kb and for EcoRI were 6.0 and 4.0 kb. Allelic frequencies for BamHI restriction fragments were .53 for the 9.0-kb allele and .47 for the 5.0-kb allele. Allelic frequencies for EcoRI restriction fragments were .43 for the 6.0-kb allele and >57 for the 4.0-kb allele. No polymorphisms were identified using the restriction enzymes BglII, DraI, or PstI. No associations between EcoRI and BamHI RFLP and 24-h calpastatin activity of Warner-Bratzler shear force at 14 d postmortem were detected. Therefore, the polymorphic EcoRI and BamHI restriction sites within the bovine calpastatin locus do not detect DNA sequence differences responsible for variation in calpastatin activity or tenderness of aged beef. Therefore, these polymorphisms cannot be used to predict tenderness of aged beef from unrelated animals of mixed breeding. These results do not exclude the possibility that other DNA sequences in or near the bovine calpastatin gene are responsible for variation in calpastatin activity or meat tenderness. The lack of a relationship between these calpastatin RFLP and meat tenderness must be distinguished from the well-documented relationship between calpastatin activity and meat tenderness. Therefore, further development of calpastatin-based methods for predicting beef tenderness in unrelated animals of mixed breeding should focus on basic factors influencing calpastatin activity at the molecular and cellular level.

Alleles↗

PubMed1995

Predicting beef carcass cutability.

Analyses were conducted to develop and test the efficacy of beef carcass cutability prediction equations. Data from 1,602 calf-fed steer carcasses (Germplasm Utilization Project; GPU) were used to develop the equations and an additional 1,160 calf-fed steer carcasses (Germplasm Evaluation Project; GPE) were used to validate the equations. In both experimental groups, USDA yield grade ranged from < 1 to > 5 and the SD of yield grade was > .8 indicating a relatively large amount of variation in carcass cutability. Models were developed to predict boneless, totally trimmed retail product yield (RPYD), fat trim yield (FATYD), and bone yield (BONEYD) using 1) carcass traits, 2) carcass traits and wholesale rib dissection traits, 3) carcass traits and 9-10-11 rib dissection traits, and 4) carcass traits and 9-10-11 rib dissection and chemical traits. For each dependent variable, the best single predictor was a wholesale rib dissection trait, and the best higher order model contained at least one wholesale rib dissection trait. Equations developed explained 87, 88, and 77% of the variation in RPYD, FATYD, and BONEYD, respectively. When validated against GPE carcasses, models developed from GPU carcasses explained 74, 78, and 69% of the phenotypic variation and 96, 94, and 84% of the genetic variation in RPYD, FATYD, and BONEYD, respectively. Prediction of carcass cutability using carcass and wholesale rib dissection traits should allow for rapid, precise, and cost-effective assessment of variation in cutability.

Animals↗

PubMed1995

Is Z-disk degradation responsible for postmortem tenderization?

A number of studies have suggested that Z-disk degradation is a major factor contributing to postmortem tenderization. These conclusions seem to have been based largely on experimental findings showing that the calpain system has a major role in postmortem tenderization, and that when incubated with myofibrils or muscle strips, purified calpain removes Z-disks. Approximately 65 to 80% of all postmortem tenderization occurs during the first 3 or 4 d postmortem, however, and there is little or no ultrastructurally detectable Z-disk degradation during this period. Electron microscope studies described in this paper show that, during the first 3 or 4 d of postmortem storage at 4 degrees C, both costameres and N2 lines are degraded. Costameres link myofibrils to the sarcolemma, and N2 lines have been reported to be areas where titin and nebulin filaments, which form a cytoskeletal network linking thick and thin filaments, respectively, to the Z-disk, coalesce. Filamentous structures linking adjacent myofibrils laterally at the level of each Z-disk are also degraded during the first 3 or 4 d of postmortem storage at 4 degrees C, resulting in gaps between myofibrils in postmortem muscle. Degradation of these structures would have important effects on tenderness. The proteins constituting these structures, nebulin and titin (N2 lines); vinculin, desmin, and dystrophin (three of the six to eight proteins constituting costameres); and desmin (filaments linking adjacent myofibrils) are all excellent substrates for the calpains, and nebulin, titin, vinculin, and desmin are largely degraded within 3 d postmortem in semimembranosus muscle. Electron micrographs of myofibrils used in the myofibril fragmentation index assay show that these myofibrils, which have been assumed to be broken at their Z-disks, in fact have intact Z-disks and are broken in their I-bands.

Animals↗

PubMed1995

Postmortem injection of calcium chloride effects on beef quality traits.

Twenty-two Bos indicus type steers were commercially slaughtered, and their carcasses were chilled and processed to determine the effects of injecting calcium chloride (CaCl2) on beef steak palatability and quality traits. Top loin and inside round subprimals were removed from each carcass using industry fabrication procedures. No injection (control) or injection of 200 mM CaCl2 at 5% (wt/wt) was applied at 30 h postmortem to subprimals from alternating right and left sides. After vacuum storage for 7 d postmortem at 2 degrees C, 2.54-cm thick steaks were cut from each subprimal. Eighty-six percent of the control longissimus lumborum (LL) steaks and 78% of the semimembranosus (SM) control steaks had Warner-Bratzler (WBS) values > 4.5 kg, and the injection of CaCl2 reduced this percentage to 43 and 24%, respectively. The injection of CaCl2 improved (P < .05) trained sensory tenderness ratings for both LL and SM, while not affecting (P > .05) flavor intensity or causing any off-flavor problems (P > .05), compared with the controls. Lean color scores for the LL were not affected (P > .05) by the injection of CaCl2, but SM lean color was lighter red (P < .05) than controls. Therefore, a 5% (wt/wt) injection of 200 mM CaCl2 solution can be applied under commercial conditions to improve beef steak tenderness and reduce tenderness variation without detrimental effects on other palatability or quality traits.

Animals↗

PubMed1995

Comparison between 3-methylhistidine production and proteinase activity as measures of skeletal muscle breakdown in protein-deficient growing barrows.

This experiment was conducted to determine the relationship between 3-methylhistidine (3MH) production and proteinase activity in skeletal muscles of growing barrows. Barrows at 13 wk of age were randomly assigned to either control diet available on an ad libitum basis (21% of ME consisted of protein; control group), control diet fed restricted (pair-fed with barrows in protein-free group; intake-restricted group), or protein-free diet available on an ad libitum basis (protein-free group) for 14 d. During the last 3 d, blood samples were collected for determination of 3MH production rate, which is a measure of myofibrillar protein breakdown. At slaughter, two muscles were taken: masseter (M) and longissimus (L) muscles. The muscle samples were analyzed for calpastatin, mu-calpain, m-calpain, multicatalytic proteinase (MCP), cathepsin B, cathepsins B+L, and cystatins activities. Both muscles were also analyzed for amounts of DNA, RNA, total protein, and myofibrillar and sarcoplasmic proteins. Growth rate (kilograms/day) was influenced by dietary treatments (P < .05). Fractional breakdown rate (FBR, percentage/day) of skeletal muscle, as calculated from 3MH production rate (micromoles.kilogram-1.day-1), was 27% higher for the protein-free group than for the control group. However, no differences in proteinase activities were observed, except for lower MCP activity in the M muscle of the protein-free group than in that of the other groups (P < .05). In the present study, no direct relation was observed between myofibrillar protein degradation rate and proteinase activities in skeletal muscle during a protein-free feeding strategy.

Animals↗

PubMed1994

Temporal response of rabbits to beta-adrenergic agonist feeding: tissue weight, calpains and calpastatin activities, and nucleic acid and protein concentrations.

Forty-eight crossbred rabbits were used in three replications of a 2 x 4 factorial arrangement to investigate the short-term responses of tissue accretion, calpains and calpastatin activity, and nucleic acid and protein concentrations to beta-adrenergic agonist (BAA) feeding. Rabbits were fed a 17% CP diet with or without 7 ppm of L644,969 and slaughtered after 1, 4, 8, or 16 d of treatment. Empty body dressing percentage and biceps femoris weight (as a percentage of empty body weight [EBW]) were significantly higher in the treated rabbits than in the controls after 16 d of treatment. Heart and liver weights (as a percentage of EBW) were higher (P < .05) after 1 d and liver weight (as a percentage of EBW) was lower (P < .05) after 16 d in treated vs controls. Except for an elevation of skeletal muscle m-calpain after 16 d, BAA-supplementation did not affect the calpain-calpastatin system. Muscle RNA concentrations and RNA:DNA ratios were higher (P < .05) in treated rabbits after 1 d and remained higher thereafter. Protein:RNA ratios were lower (P < .01) in treated than in control rabbits after 4 d and remained lower throughout the trial. Muscle DNA content was lower after 4 d and higher after 16 d; RNA content was higher after 4, 8, and 16 d; and protein content was higher after 16 d in treated vs control rabbits. Liver nucleic acid and protein concentrations were not affected by BAA treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Agonists↗

PubMed1994

Effect of biological type of cattle on the incidence of the dark, firm, and dry condition in the longissimus muscle.

The objectives of this experiment were to characterize longissimus muscle color, texture, and firmness for beef carcasses of diverse biological types and to determine the genetic parameters of lean color, texture, and firmness. The carcasses (n = 3,641) used in this experiment were from steers produced by mating Angus, Brahman, Braunvieh, Charolais, Chianina, Galloway, Gelbvieh, Hereford, Jersey, Limousin, Longhorn, Maine Anjou, Nellore, Piedmontese, Pinzgauer, Red Poll, Sahiwal, Salers, Shorthorn, Simmental, South Devon, and Tarentaise sires to Hereford and Angus dams. Steers were fed a corn-corn silage diet from weaning until slaughter at 356 to 575 d of age. Steers were slaughtered at commercial packing plants and longissimus muscle color, texture, and firmness were scored by trained carcass evaluators. Sire line least squares means for lean color, texture, and firmness ranged approximately one unit on a 7-point scale. Chianina crosses had darker-colored lean than all breed groups except Tarentaise and Simmental crosses (P < .05). Moreover, a higher percentage (P < .05) of Chianina crosses than of all other breed groups had unacceptably dark-colored ("dark red" or darker) lean. Bos indicus sire lines were not different from Bos taurus sire lines in frequency of carcasses with unacceptably dark-colored lean. However, Bos indicus crosses were more likely to be scored "very light cherry-red." Lean color and texture were lowly heritable, whereas lean firmness was moderately heritable. Thus, this experiment demonstrated that there is genetic variation in the incidence of the DFD condition; however, genetic variation was small relative to environmental variation.

Analysis of Variance↗

PubMed1994

Bovine skeletal muscle calpastatin: cloning, sequence analysis, and steady-state mRNA expression.

Calpastatin is a specific inhibitor of the calpains. Calpains play a key role in postmortem tenderization of meat and have been hypothesized to be involved in muscle protein degradation in living tissue. Isolation, cloning of complementary DNA, and nucleotide sequencing of bovine calpastatin from the longissimus muscle have been completed. Two clones were identified that encompass the entire coding sequence. Clone pCR41, derived by reverse transcription-PCR, covers domains L and 1; clone pBSA1, obtained from cDNA library screening, covers domains 2 through 4 in addition to the 3'-nontranslated region. Nucleotide sequence analysis of the cDNA for bovine calpastatin revealed an average nucleotide sequence identity of approximately 70 to 80% compared with published calpastatin nucleotide sequences of human, rabbit, and pig. Exon 3, corresponding to a highly conserved 22-amino acid region, was deleted from bovine calpastatin domain L. The calculated molecular weight of bovine skeletal muscle calpastatin of 706 amino acid residues (M(r) 75,842) corresponds to the value of purified bovine skeletal muscle calpastatin as determined by SDS-PAGE (M(r) 68,000). Northern blot analysis revealed the presence of multiple calpastatin mRNA transcripts having estimated sizes of 3.8, 3.0, and 1.5 kb in beef and 3.8, 3.0, 2.5, and 1.5 kb in sheep. Calpastatin mRNA expression was increased with beta-adrenergic agonist-induced muscle hypertrophy.

Amino Acid Sequence↗