Supplemental fat source affects feedlot performance and carcass traits of finishing yearling steers and estimated diet net energy value.

Two trials that utilized 356 yearling steers were conducted to evaluate the effects of fat sources (3.5% of diet dry matter) in steam-flaked milo finishing diets. Fats differed in fatty acid composition and level of free fatty acids. In Trial 1, soybean oil, tallow and yellow grease were compared to a nonfat control. Feeding fat increased (P less than .05) daily gain, feed efficiency, estimated diet NE concentration, carcass weight and dressing percentage of steers. In Trial 2, fat treatments were control, acidulated soybean soapstock (SBSS), tallow, a blend of 70% SBSS:30% tallow, and yellow grease. Feeding tallow or the SBSS:tallow blend improved (P less than .05) feed efficiency and estimated dietary NE compared to control. Proportions of palmitic, stearic, oleic, linoleic and linolenic acid in longissimus muscle of steers were altered (P less than .05) by source of supplemental fat. Potential variability in animal response to fat blends was demonstrated by differences in animal response to yellow grease in the two trials. It was concluded that fats vary in feeding value and may alter carcass composition, contrary to putative thought. Further, potential associative effects of fat blends and interactions of fat with other dietary components in high-grain finishing diets require further investigation.

The cDNA and deduced amino acid sequence of the gamma subunit of the L-type calcium channel from rabbit skeletal muscle.

Complementary DNAs for the gamma subunit of the calcium channel of rabbit skeletal muscle were isolated on the basis of peptide sequences derived from the purified protein. The deduced primary structure is without homology to other known protein sequences and is consistent with the gamma subunit being an integral membrane protein.

Metabolism of selenite and selenomethionine in the rhesus monkey.

Female rhesus monkeys were fed a commercial monkey diet and given selenium (Se) as either selenite or selenomethionine (SeMet) in the drinking water for 11 mo. Muscle and liver biopsies were taken initially and at the end of the experiment for determination of Se levels and glutathione peroxidase (GPX) activity. Blood was collected at monthly to bimonthly intervals, and the plasma and erythrocytes were subjected to gel filtration to determine the distribution of Se among proteins of various molecular weights. At the end of the experiment, there was significantly more Se in liver, muscle and hair from the monkeys given SeMet than in tissues from those given selenite, but there were no differences in liver or muscle GPX activity between the two treatment groups. The erythrocyte and plasma Se levels were significantly higher in the monkeys given SeMet than in those receiving selenite, but there were no differences in the GPX levels between these groups. About 68% of erythrocyte Se was associated with GPX in monkeys given selenite whereas only 34% was associated with GPX in those administered SeMet. The correlation coefficient for blood Se level and erythrocyte GPX activity was 0.92 in monkeys given selenite but only 0.37 in those given SeMet. Gel filtration of plasma revealed only one Se peak for plasma from the monkeys given selenite but at least two major Se peaks for plasma from monkeys receiving SeMet. The possible implications of these results for humans are discussed, including the reasons for poor correlations of GPX activity and blood Se levels.

Type II fiber activation with electrical stimulation: a preliminary report.

Electrical stimulation to augment or maintain muscle performance has been well documented. The purpose of this preliminary report is to present the results of a single-case study conducted to determine the order of activation of skeletal muscle fibers as a result of electrical stimulation. The subject's quadriceps femoris muscles were electrically stimulated at 80% of maximal isometric torque. Pre-stimulation and immediate post-stimulation muscle biopsy samples were obtained, and a modification of the glucogen-depletion method was used to determine activation of muscle fibers. The pre-stimulation muscle biopsy sample demonstrated uniform periodic acid-Schiff (PAS)-positive staining in all fiber types, whereas the post-stimulation muscle biopsy sample showed glycogen depletion of type II muscle fibers. The most PAS-negative muscle fibers were type IIa skeletal muscle fibers. The results of this single-case study provide evidence that electrical stimulation, as described, selectively activates type II skeletal muscle fibers. The implication of this finding is that, in many chronic diseases, type II fibers are selectively and preferentially affected. Electrical stimulation may be a clinically viable technique to use in patients with type II fiber involvement.

Autoradiographic localization of [3H]RU 486 and [3H]progesterone in the uterus, pituitary and hypothalamus of the rat.

Twenty-one castrated oestrogen-primed Wistar rats, which were 2-months-old, were injected via the jugular vein with 100 mu Ci/100 g body weight of [3H]RU 486 or [3H]progesterone. Some of these received unlabelled compounds for competition studies. Samples of reproductive tract, pituitary and hypothalamus were excised after 15 min. The 4-microns frozen sections were processed for thaw-mounted autoradiography. The exposure time of the autoradiogram was approximately 6 months. After the injection of [3H]RU 486 and [3H]progesterone, the nuclear concentration of radioactivity was most distinct in muscular and stromal cells of the uterus, and the epithelial nuclei of lumina and glands showed weak labelling. Nuclear localization was also observed in muscle cells of the vagina, cervix and oviduct. After injection of [3H]progesterone, the radioactivity was found in the nuclei and cytoplasm of anterior pituitary cells and some cells showed a preferential nuclear concentration of radioactivity. The distribution of [3H]RU 486 in the anterior pituitary was more extensive than that of [3H]progesterone. In the hypothalamus, specific localization of [3H]RU 486 and [3H]progesterone existed in neurones accumulated in the preoptic nucleus, preoptic suprachiasmatic nucleus and the periventricular nucleus. No localization was found in the diaphragm. Pretreatment with RU 486, but not with dexamethasone, reduced the nuclear concentration of radioactivity of [3H]progesterone in the vagina, uterus, oviduct, pituitary and hypothalamus. The nuclear concentration of radioactivity after injection of [3H]RU 486 was also decreased by preinjection with progesterone. The autoradiographic results suggest that RU 486 and progesterone competed for the specific binding site (possibly a progesterone receptor) in the target cells at the levels of the uterus, pituitary and hypothalamus in vivo.

Determination of the alteration in fatty acid profiles, sensory characteristics and carcass traits of swine fed elevated levels of monounsaturated fats in the diet.

The present study was designed to determine the effects of supplemental fat or oil rich in oleic acid on the fatty acid profiles (FAP) and physical and sensory traits of pork carcasses. Sixty barrows and gilts were equally distributed among five dietary treatments consisting of a control diet of corn and soybean meal and four similar test diets that contained 10% animal fat (45.3 oleic), safflower oil (72.1 oleic), sunflower oil (80.9 oleic) or canola oil (57.7 oleic). The pigs were slaughtered after being fed these diets for 90 d at about 100 kg live weight. Carcass traits, FAP and sensory properties were evaluated for each treatment. First-rib fat thickness, ham muscling score and longissimus muscle areas were not different (P less than .05), but last-rib fat thickness was increased (P less than .05) with the supplemental dietary fat or oils. No differences existed for marbling scores, lean color, firmness or texture scores between the controls and pigs supplemented with either animal fat or safflower oil. However, pigs supplemented with sunflower or canola oil had lower marbling scores, lean color, firmness and texture scores. Fat became softer and more oily (P less than .05) with the supplemental dietary safflower, sunflower and canola oils. Sensory evaluation (loin chops) showed no differences (P less than .05) in sustained juiciness, tenderness or flavor intensity evaluations among treatments. However, the pigs fed canola oil had lower (P less than .05) flavor quality scores or overall palatability evaluations. Chops from the pigs fed canola oil also had 46% more off-flavors than all other treatments.(ABSTRACT TRUNCATED AT 250 WORDS)

Primary structure of the gamma subunit of the DHP-sensitive calcium channel from skeletal muscle.

Affinity-purified, polyclonal antibodies to the gamma subunit of the dihydropyridine (DHP)-sensitive, voltage-dependent calcium channel have been used to isolate complementary DNAs to the rabbit skeletal muscle protein from an expression library. The deduced primary structure indicates that the gamma subunit is a 25,058-dalton protein that contains four transmembrane domains and two N-linked glycosylation sites, consistent with biochemical analyses showing that the gamma subunit is a glycosylated hydrophobic protein. Nucleic acid hybridization studies indicate that there is a 1200-nucleotide transcript in skeletal muscle but not in brain or heart. The gamma subunit may play a role in assembly, modulation, or the structure of the skeletal muscle calcium channel.

Dietary effects on cardiac metabolic properties in rodents.

Previous studies have shown that dietary provision of carbohydrate can alter cardiac isomyosin distribution in hormonally deficient rats. The main objective of this study was to determine if varying the heart's potential to utilize carbohydrate for energy provision can influence the cardiac isomyosin expression in normal weanling rats. Animals were assigned to one of five groups according to dietary and/or metabolic treatment: (1) mixed-control--(M); (2) high carbohydrate--(H); (3) low carbohydrate--(L); (4) mixed-diet supplemented with oxfenicine, a cardiospecific fatty acid oxidation inhibitor--(MO); and (5) high carbohydrate diet supplemented with oxfenicine--(HO). The results show that 4 weeks of dietary manipulations aimed to either increase or decrease carbohydrate supply to the heart, failed to induce any alterations in either cardiac myosin ATPase activity or isoenzyme pattern. However, extremes in carbohydrate provision altered the metabolic properties of both heart and skeletal muscle. A low carbohydrate diet increased 3-hydroxyacyl CoA dehydrogenase (P less than 0.05) and citrate synthase activities (P less than 0.05) and decreased glycogen content in both heart and soleus muscle; whereas, a high carbohydrate diet, in conjunction with oxfenicine, tended to increase hexokinase activity in these same tissues. These alterations provide indirect evidence that the contributions of both fat and carbohydrate to the energy balance of the heart and skeletal muscle were altered by the imposed dietary interventions. Collectively, these results suggest that although the substrate utilization patterns of the normal weanling heart can be modified via dietary manipulation, such shifts do not exert any regulatory influence on cardiac isomyosin expression.

Assessment of intracellular magnesium depletion in rat striated muscle by in vivo 31P NMR.

Previous in vivo studies have demonstrated that alpha, beta, and gamma ATP chemical shifts measured by 31P NMR spectroscopy can be used to determine intracellular magnesium in erythrocytes, but up to now such results have not been confirmed in striated muscle in vivo. We report beta ATP chemical-shift in vivo measurements revealing the depletion of free intracellular magnesium in striated muscle of rats fed a magnesium deficient diet.

Cardiac-type excitation-contraction coupling in dysgenic skeletal muscle injected with cardiac dihydropyridine receptor cDNA.

There are dihydropyridine (DHP)-sensitive calcium currents in both skeletal and cardiac muscle cells, although the properties of these currents are very different in the two cell types (for simplicity, we refer to currents in both tissues as L-type). The mechanisms of depolarization-contraction coupling also differ. As the predominant voltage-dependent calcium current of cardiac cells, the L-type current represents a major pathway for entry of extracellular calcium. This entry triggers the subsequent large release of calcium from the sarcoplasmic reticulum (SR). In contrast, depolarization of skeletal muscle releases calcium from the SR without the requirement for entry of extracellular calcium through L-type calcium channels. To investigate the molecular basis for these differences in calcium currents and in excitation-contraction (E-C) coupling, we expressed complementary DNAs for the DHP receptors from skeletal and cardiac muscle in dysgenic skeletal muscle. We compared the properties of the L-type channels produced and showed that expression of a cardiac calcium channel in skeletal muscle cells results in E-C coupling resembling that of cardiac muscle.

Iodine in milk and meat of dairy cows fed different amounts of potassium iodide or ethylenediamine dihydroiodide.

Relationships between I intake by lactating Holstein cows and iodine concentrations in milk and meat were investigated. Six treatment groups with seven cows assigned to each treatment were fed a basal diet containing .8 mg I/kg alone or supplemented with I at 1, 2, or 4 mg/kg in four 5-wk periods. Basal alone was fed in the first and third periods and the I supplement was potassium iodide in the second period and ethylenediamine dihydroiodide in the fourth period. Iodine concentrations in milk increased with each increase in dietary I from 205 ng/ml for basal periods to 404, 477, and 757 ng/ml when 1, 2, or 4 mg/kg I was fed as potassium iodide; and 467, 535, and 869 ng/ml when 1, 2, or 4 mg/kg I was fed as ethylenediamine dihydroiodide. Concentrations of I in skeletal muscle after the fourth period were not affected by 2 mg/kg I and only increased from 166 to 199 ng/g when supplemental I was 4 mg/kg. Moderate changes in dietary I are quickly reflected in milk I, but I in meat is relatively stable.

Recovery study in Mg-deficient rats given an organic source of Mg.

Recovery from Mg deficiency was studied in rats given an organic source of Mg derived from yeast (Saccharomyces cerevisiae) cultured in an Mg gluconate-enriched medium, as the only source of Mg. Magnesium was given either at a rate above the RDA or as a supplement to the regular laboratory diet at the rate of 70 mg Mg/100 g food, of which 40 mg Mg was in the form of MgCO3 and the remaining 30 mg Mg was in the form of the organic product under study. The results showed a good degree of digestive and metabolic utilization of the organic compound, which led to the recovery of normal Mg levels in blood and bone by the end of the 1st week of treatment, and in muscle by the 3rd week of treatment. Muscle Mg content appears to be a good indicator of deficiency. Supplementation above the RDA failed to improve recovery rates in deficient animals.

Effects of potassium or potassium/magnesium supplementation on potassium content of body tissues and fluids in furosemide-treated rats on magnesium-deficient or magnesium-sufficient diet.

Persistent Mg2+ deficiency may interfere with restoration of normal tissue K+ levels. This study examined: a) the effects of chronic furosemide treatment on K+ of sartorius, aorta and ventricle of rats fed Mg2(+)-deficient (100 ppm) or Mg2(+)-sufficient (400 ppm) diet and deionized water; b) whether normal tissue K+ is restored by oral K+ or K+/Mg2+ supplementation with continued furosemide therapy. Levels of Mg2+ were also measured. Furosemide (20 mg/kg i.p.) decreased K+ in sartorius, aorta and ventricle by 5.5, 4.3 and 19.9 microEq/gm (p less than .05), respectively, in rats fed 100 ppm Mg2+ diet. Furosemide did not alter K+ levels in rats fed 400 ppm Mg2+ diet. K+ supplementation (1 mEq/kg for 7 days) restored K+ to normal in sartorius but the addition of Mg2+ supplementation was necessary to restore K+ levels to normal in ventricle and aorta. These data indicate that furosemide can decrease tissue K+ in rats on a Mg2(+)-deficient diet. This decrease can be reversed during diuretic administration by K+ supplementation in sartorius, or K+ plus Mg2+ supplementation in ventricle and aorta.

Enhancement of arm exercise endurance capacity with dihydroxyacetone and pyruvate.

The effects of dietary supplementation of dihydroxyacetone and pyruvate (DHAP) on endurance capacity and metabolic responses during arm exercise were determined in 10 untrained males (20-26 yr). Subjects performed arm ergometer exercise (60% peak O2 consumption) to exhaustion after consumption of standard diets (55% carbohydrate, 15% protein, 30% fat; 35 kcal/kg) containing either 100 g of Polycose (placebo, P) or DHAP (3:1, treatment) substituted for a portion of carbohydrate. The two diets were administered in a random order, and each was consumed for a 7-day period. Biopsy of the triceps muscle was obtained immediately before and after exercise. Blood samples were drawn through radial artery and axillary vein catheters at rest, after 60 min of exercise, and at exercise termination. Arm endurance was 133 +/- 20 min after P and 160 +/- 22 min after DHAP (P less than 0.01). Triceps glycogen at rest was 88 +/- 8 (P) and 130 +/- 19 mmol/kg (DHAP) (P less than 0.05). Whole arm arteriovenous glucose difference (mmol/l) was greater (P less than 0.05) for DHAP than P at rest (0.60 +/- 0.12 vs. 0.05 +/- 0.09) and after 60 min of exercise (1.00 +/- 0.12 vs. 0.36 +/- 0.11), but it did not differ at exhaustion. Neither respiratory exchange ratio nor respiratory quotient differed between trials at rest, after 60 min of exercise, or at exhaustion. Plasma free fatty acid, glycerol, beta-hydroxybutyrate, catecholamines, and insulin were similar during rest and exercise for both diets. Feeding DHAP for 7 days increased arm muscle glucose extraction before and during exercise, thereby enhancing submaximal arm endurance capacity.

Effect of feeding rabbits on naturally moulded and mycotoxin-contaminated diet.

For studying the effects of naturally moulded diet on mature female-rabbits, Buskat rabbits were fed for 6 weeks on a naturally moulded diet comparing with the other similar group of animals which was fed also on the same ingredients in the first diet, except that, they were sound (not moulded apparently). The results which were obtained from this study due to the feeding on the moulded diet were as follows: 1. Decreasing the feed intake significantly (P less than 5%) and increasing somewhat the water consumption, but the water/feed ratio increased significantly (P less than 5%). 2. Reduction of the digestibility of most nutrients, especially of the crude fibre (P less than 1%) and crude protein (P less than or equal to 5%). 3. Changing in the relative weights of different organs particularly the significant (P less than 5%) decrease in weight of the liver and spleen as well as the significant (P less than 5%) increase in weight of empty stomach and female genital tract. 4. The most important haematological changes were the reduction in cholesterol content and the elevation of phospholipid concentration, thus the cholesterol/phospholipid ratio decreased by the rate of 40.7%. Calcium/phosphorus ratio increased by the rate of 9.5% as a result of increasing calcium content in the control serum. 5. Chemical analyses revealed a significant (P less than 1%) reduction in ash content of the liver and magnesium content of the tibia bone, a slight decrease in liver content of iron and ether extract, and significant (P less than 5%) rise in femoral muscle content of the ether extract.

Utilization of medium-chain triglycerides by neonatal piglets: I. Effects on milk consumption and body fuel utilization.

Two experiments were conducted utilizing neonatal piglets. In the first experiment, 18 piglets were used to determine the effect of an oral supplement of 0, 12 or 24 ml of a medium-chain triglyceride (MCT) product on subsequent milk consumption. Results from the weight-suckle-weight experiment showed that force-feeding 24 ml of the MCT decreased (P less than .05) milk intake but 12 ml did not. In the second experiment, two trials (each with 24 piglets) were used to investigate the effect of 12 ml of MCT or 12 ml of MCT plus .6 mmol of L-carnitine on the concentration of blood glucose, ammonium N and urea N at 0, 12 or 24 h and liver and biceps femoris glycogen at 24 h post-treatment. Blood urea N decreased (P less than .05) in piglets receiving the MCT. Blood ammonium N and glucose concentrations were not different (P greater than .10) among treatments. In Trial 1, the predicted loss of liver glycogen was less (P less than .05) in pigs given the MCT treatment, but this response was not repeated in the second trial. In general, supplemental carnitine provided no added benefit over the MCT treatment alone. The results from this study indicate that MCT is utilized as a fuel by the newborn piglet and that its use may spare critical fuels, glycogen and protein, that were stored in the piglet prior to birth.

Effects of vitamin B-6 deficiency on selenium metabolism in the rat.

Rats were fed for 23 d diets adequate or deficient in vitamin B-6 and containing selenium as either sodium selenite, selenocysteine (SeCys) or selenomethionine (SeMet). They were then injected with 75Se of the same chemical form and killed 2 d later. Tissue deposition of stable and radiotracer selenium and the activity of glutathione peroxidase (GSHPx) were used to assess selenium utilization. Erythrocyte levels of selenium and GSHPx were lower in vitamin B-6--deficient animals for all forms of selenium; however, 75Se deposition in erythrocytes was not affected by vitamin B-6 status. The activities of cystathionine lyase, aspartate aminotransferase and selenocysteine lyase were lower in livers of vitamin B-6--deficient rats than in vitamin B-6--supplemented rats. The proportion of liver and kidney 75Se soluble in 5% trichloroacetic acid and 0.1 M 2-mercaptoethanol was consistently lower in vitamin B-6--deficient animals, but cation-exchange chromatography of tissue extracts did not identify a specific low-molecular-weight species. Tissue retention of 75Se provided as SeMet was increased in vitamin B-6--deficient animals, but the proportion of 75Se retained in muscle and liver as SeCys was significantly reduced. These findings suggest that the conversion of SeMet to a form available for GSHPx synthesis is reduced by vitamin B-6 deficiency.

Glutamine-containing dipeptides as infusion substrates in the septic state.

Recently a relationship has been postulated between lowered intracellular glutamine concentrations in the skeletal muscle and the rate of protein synthesis. We investigated the effect of 48 hours of parenteral nutrition supplemented with a solution containing glutamine in free or dipeptide form (alanylglutamine or glycylglutamine) on the intracellular glutamine pool in skeletal muscle and on the hind limb exchange of glutamine in dogs with sepsis after surgery. Before surgery, dogs were fasted for 48 hours. We used glutamine dipeptides as sources because they remain stable in an aqueous solution. Nutrition solutions were isocaloric (17.8 kcal/kg body weight/day on day 1 and 35.6 kcal/kg on day 2) and isonitrogenous (0.33 gm nitrogen/kg body weight/day), providing 2.6 mmol/kg body weight/day as glutamine source. During starvation, muscular free glutamine levels decreased by 41% to 10.4 mmol/L (p less than 0.001). On the second postoperative day the dogs had lowered plasma protein levels, a sharp drop in platelet count, an increase in the leukocyte count, and positive blood cultures. None of the solutions investigated in this study was effective in repleting the glutamine pool during 2 days of postoperative nutrition (11 +/- 2.0 mmol/L without glutamine, 10.3 +/- 2.2 mmol/L with glutamine plus alanine, 9.9 +/- 1.6 mmol/L with alanylglutamine, 7.5 +/- 1.1 mmol/L with glutamine plus glycine, and 7.2 +/- 1.2 mmol/L with glycylglutamine, respectively). The release of glutamine from the hindquarter was 631 +/- 38 nmol/kg body weight/min in the control group and decreased significantly in dogs receiving alanylglutamine (13.5 +/- 45 nmol/kg body weight/min; p less than 0.001) or the constituent amino acids (265 +/- 66 nmol/kg body weight/min; p less than 0.01) but was unchanged in dogs receiving glycylglutamine or glutamine plus glycine. We conclude that the duration and dosage of glutamine administration (equivalent to 26 gm glutamine per day in a patient weighing 70 kg) used in this study are not sufficient to restore glutamine deficiency of the skeletal muscle in the depleted state.

Barley and full-fat canola seed in broiler diets.

Barley and full-fat canola seed (FFCS), with or without an added enzyme mixture, were evaluated in experiments with broiler chicks. In Experiment 1, test diets contained barley, wheat, and soybean meal and were supplemented or unsupplemented with raw FFCS (10%) or canola meal (6%). The control was a wheat-soybean meal diet. Diets were fed to male and female broiler chicks for 7 wk. The diet supplemented with raw FFCS produced significantly (P less than .05) lower weight gains than the other diets. There were elevated levels (P less than .05) of linoleic and linolenic acids (18:2 omega 6; 18:3 omega 3) in tissue lipids of chicks fed raw FFCS. In Experiment 2, broiler chicks were fed diets containing a steam-pelleted barley-FFCS mixture (80:20), included at a 50% level, along with supplemental barley. Total barley level in the experimental diets was 50%. 45%, and 40%. A barley-soybean meal diet was used as a control. All diets were fed with and without an enzyme supplement. Chicks fed the barley-FFCS diets were similar to those fed the control diet in respect to production parameters and carcass characteristics. Supplementation of diets with the enzyme mixture resulted in significantly larger body weight gains and lower feed:gain ratios. In Experiment 3, enzyme supplementation increased (P less than .01) the ME of the steam-pelleted barley-FFCS mixtures and the mixed feed containing barley-FFCS. Data from Experiment 4 indicated that there were no significant differences in availability among amino acids from barley, FFCS, or pelleted barley-FFCS mixture diets.

Monoclonal antibody ALD 180: a reagent specific for a human prenatal skeletal muscle myosin isoform.

We report the characterization of monoclonal antibody (MAb) ALD 180, prepared against the myosin of slow avian muscle, for studies of human muscle development and disease. With the use of radioimmunoassays, Western immunoblots of native and denatured myosins, and epifluorescent indirect immunocytochemistry, we show that ALD 180 is specific for an epitope in human prenatal skeletal muscle myosin heavy chain (MHC), which is expressed in diminishing abundance in fetal fibers from at least 19-22 weeks' gestation to term and also in regenerating muscle fibers seen in diseased muscles from both children and adults. ALD 180 recognizes an epitope apparently different from those reacting with anti-prenatal human myosin MAb previously described, and therefore affords a complementary reagent for use in future studies of human myosin isoform expression and regulation.