Finishing steers with diets based on corn, high-tannin sorghum, or a mix of both: feedlot performance, carcass characteristics, and beef sensory attributes.

The objective of this work was to compare feedlot performance, carcass characteristics, and beef sensory attributes from steers finished with diets based on corn, high-tannin sorghum (HTS), and a mix of both grains. Angus crossbred steers (n = 11 steers per treatment, initial BW = 404 +/- 18 kg) were finished on diets containing 765 g/kg of DM of corn, HTS, or a 1:1 mix of corn and HTS. Final BW (P < 0.01), ADG (P < 0.001), and G:F (P < 0.01) were reduced in steers fed HTS when compared with steers fed corn. Steers fed the mixed diet had greater G:F than the average between corn and HTS diets (P = 0.04), which indicated that mixing corn and HTS had positive associative effects. Estimated NE(m) of HTS was 1.91, and estimated NE(g) was 1.35 Mcal/kg of DM. Hot carcass weight (P < 0.01), trimmed carcass weight (P < 0.01), yield grade (P = 0.04), and 12th-rib fat thickness (P = 0.01) were less in steers fed HTS than in those fed corn. Estimated percentage of HCW as boneless, closely trimmed retail cuts was greater in steers fed HTS compared with those fed corn (P = 0.02) but, due to the decreased HCW, estimated amount of boneless, closely trimmed retail cuts was less in steers fed HTS than in those fed corn (P = 0.03). Steers fed HTS had greater pH on LM (P = 0.02) than steers fed corn, but the difference was small (5.42 +/- 0.02 vs. 5.36 +/- 0.02, respectively) and within the range of normal beef pH. Diet had no effect on Warner-Bratzler shear values (P > or = 0.72). Multivariate ANOVA indicated a difference in sensory attributes of beef from corn and HTS steers (Wilks' Lambda, P = 0.04). When evaluating each sensory attribute independently, panelists found beef from steers fed HTS to be less juicy (P < 0.01), less tender (P = 0.03), and more cooked (P < 0.01) than beef from animals fed corn. Data from this study indicated that by using a 1:1 mix of HTS and corn it is possible to finish steers to similar BW and carcass quality as by using a corn-based diet. Also, total replacement of corn by HTS in the diets produced lighter and leaner animals. Total replacement of corn by HTS in the finishing diet changed beef sensory attributes, reducing the perception of beef tenderness and juiciness by panelists but without changing instrumental tenderness.

[Standardized bicycle ergometry test in mitochondrial myopathies. Indications, interferences and clinical parameters]. / Standardisierter Fahrradergometertest bei mitochondrialen Myopathien. Indikation, Störfaktoren und klinisch aussagekräftige Parameter.

Exercise tests are widely used as simple, non-invasive screening methods in the differential diagnosis of metabolic myopathies. Exercise protocols have not been standardized with regard to duration of the test, workload, or monitored metabolic parameters. Potentially interfering parameters such as gender or maximal isometric force of the individuals have not been investigated. Here we describe a standardized bicycle ergometry protocol with a stepwise increasing workload between 30 and 100 watts. The venous lactate/pyruvate (L/P) ratio proved to be the one clinically most useful parameter in the functional diagnosis of mitochondrial myopathies with pathological exercise values in all nine examined patients. Additionally, the effects of coenzyme Q therapy in these patients were most clearly mirrored by changes in the L/P ratio. Nonspecifically elevated venous lactate concentrations above 5 mmol/l are rarely found in healthy female volunteers with low maximal isometric force of the M. quadriceps femoris. Other parameters such as serum free fatty acids, ketone bodies, intermediate products of the Krebs cycle or spirometric investigations add only little additional information. The exercise test described may be useful as an additional investigation in the differential diagnosis of metabolic myopathies.

Color coordinates for assessment of dietary vitamin E effects on beef color stability.

Color stability was investigated in longissimus lumborum (LL), semimembranosus (SM), and gluteus medius (GM) muscles from Holstein steers fed diets including doses of alpha-tocopheryl acetate that were 0 (EO), 250 (E250), 500 (E500), and 2,000 (E2000) mg.steer-1.d-1 for 42 or 126 d. Longissimus lumborum was aged for 14, 28, and 56 d and GM and SM were aged for 14 d. Effects of vitamin E dose on retention of redness (a*), yellowness (b*), color saturation (chroma), and proportions of redness and yellowness (hue angle) following an aging period of 14 d were E2000 > E500 = E250 > EO (P < .01). Effectiveness of dose duration on the color parameters was 126 d > 42 d (P < .01). Dietary vitamin E supplementation stabilized redness and color saturation, decreased yellowness, and extended color display life of fresh beef. A technique for estimation of color display life based on hue angle measurements of fresh beef is described. Color display life estimates based on hue angle measurements were more consistent with vitamin E supplementation effects on metmyoglobin percentage and hue angle than were estimates obtained from the metmyoglobin threshold method. Color display life across LL, SM, and GM stored until d 14 and then displayed under simulated retail conditions was extended (P < .01) 2.0 (E250) to 5.0 d (E2000). Coefficients of determination for regressions of color display life on muscle alpha-tocopherol concentration were .81, .64, and .63 in LL, SM, and GM muscles aged 14 d, respectively. Supplementation of 500 mg of alpha-tocopheryl acetate per steer daily improved (P < .01) the mean color display life of these three muscles by 2.3 d, or 100%.

Titration of fresh meat color stability and malondialdehyde development with Holstein steers fed vitamin E-supplemented diets.

Pigment and lipid oxidations were investigated in longissimus lumborum (LL), semimembranosus (SM), and gluteus medius (GM) from Holstein steers fed four doses of vitamin E (64 [control], 295, 550, or 2,173 IU/d) for two durations (42 or 126d). Vitamin E dose did not affect (P = .30) carcass quality or yield characteristics. The LL was stored in vacuum packages at 4 degrees C for 14, 28, and 56 d, and GM and SM were stored for 14 d. Increments of dose and duration of vitamin E supplementation increased (P < .001) alpha-tocopherol concentration in blood plasma and in these muscles. During simulated retail display, accumulations of metmyoglobin (METMB) and thiobarbituric acid reactive substances (TBARS) were greater (P < .01) in beef from control than in beef from supplemented steers. In cubic models, muscle alpha-tocopherol accounted for 79% of the variation in TBARS and 66% of the variation in METMB. Color display life, calculated by the METMB threshold method, revealed fewer dose and duration effects of vitamin E than were evident following analysis of variance of the METMB responses. Across durations and muscles, color display-life of fresh beef calculated by the METMB threshold method was extended (P < .05) .9 to 1.8 d by vitamin E supplementation (P < .05). Storage for 28 or 56 d caused only a slight decline (P < .001) in LL alpha-tocopherol concentration but diminished (P < .05) vitamin E effects on color display-life. Although the ranking of alpha-tocopherol accumulation was GM > SM > LL, the color display-life ranking of these muscles across vitamin E treatments was LL > SM > GM.

Tissue equilibration and subcellular distribution of vitamin E relative to myoglobin and lipid oxidation in displayed beef.

Supplementary alpha-tocopheryl acetate (vitamin E) was fed to provide none (E0), 2,000 IU/d (E2000), 5.8 IU/kg live weight (E5.8), or 8.6 IU/kg live weight (E8.6) to steers that were individually fed mainly a corn diet. Three steers were placed on each of 10 treatments: E0, E2000, E5.8, E5.8 to d 126 then E0 to d 266, E0 to d 126 then E5.8 to d 266, E8.6, grazing followed by either E0 or E8.6 all with Holstein steers; and E0 and E2000 with crossbred beef steers. During the last 100 d, vitamin E consumption (International Units/day) averaged 96 for E0, 1,840 for E2000, 2,520 for E5.8, and 3,610 for E8.6. Concentrations of alpha-tocopherol in plasma and in liver and longissimus lumborum biopsy samples obtained every 42 d were elevated (P < .01) by vitamin E supplementation. Tissue saturation was approached at these vitamin E intakes causing similar incorporation of alpha-tocopherol with both per day and per BW supplementation strategies. Maximum accretion or depletion of alpha-tocopherol in plasma and liver occurred before 42 d, but accretion required 120 d and depletion required 180 d in longissimus lumborum. Vitamin E supplementation elevated (P < .01) concentrations of alpha-tocopherol in liver, lung, subcutaneous fat, omental fat, perirenal fat, kidney, diaphragm, spinal cord, longissimus lumborum, and plasma at slaughter with maximum accretion achieved (P < .01) in lung, subcutaneous fat, kidney, diaphragm, and spinal cord. Depletion was not achieved in longissimus lumborum and spinal cord (P < .01), subcutaneous fat (P < .06), and perirenal fat (P < .08) within 140 d. Vitamin E inhibited (P < .01) oxidation at the surface and center of longissimus lumborum steaks displayed for 19 d. Lipid oxidation occurred throughout E0 steaks, but metmyoglobin accumulation occurred more rapidly (P < .01) on the surface than in the center. Myoglobin and lipid oxidation were not concurrent events. Supplementation with vitamin E increased (P < .01) alpha-tocopherol concentrations in longissimus lumborum fractions (mitochondria, microsome, cytoplasm, connective, and remainder) but, except for connective tissue, the proportional distribution of total longissimus lumborum alpha-tocopherol was not affected (P > .1) by vitamin E supplementation. Vitamin E supplementation for at least 44 d at 1,300 IU/d is expected to incorporate adequate amounts of alpha-tocopherol into muscle (3.3 micrograms/g for longissimus lumborum) to produce beef with extended color and lipid stability.

Effect of long- or short-term feeding of alpha-tocopheryl acetate to Holstein and crossbred beef steers on performance, carcass characteristics, and beef color stability.

Three experiments were conducted to examine the effects of vitamin E supplementation on feedlot cattle. Vitamin E supplementation did not affect feedlot performance or carcass characteristics of cattle fed a high-concentrate diet (P greater than .1). The major finding was the effectiveness of vitamin E in extending the color stability of displayed beef (P less than .01). Color stability during display of longissimus lumborum steaks from cattle supplemented with 300 IU/d for 266 d, 1,140 IU/d for 67 d, or 1,200 IU/d for 38 d was extended by 2.5 to 4.8 d. Gluteus medius steaks had an extended color display life of 1.6 to 3.8 d. The accumulation of lipid oxidation products, but not aerobic microbes, associated with displayed longissimus lumborum was suppressed for muscle from vitamin E-supplemented steers. Taste panelists detected no difference among longissimus lumborum steaks from control and vitamin E-supplemented steers but found (P less than .01) steaks aged for 21 d to be more tender than steaks aged for 7 d. Supplementing cattle with vitamin E should reduce economic losses associated with discolored beef during retail display.

Chronic heat stress and respiratory alkalosis: occurrence and treatment in broiler chicks.

The occurrence of respiratory alkalosis and potential benefit derived from treatment were examined in thermostressed 4-week-old broiler chicks. Blood pH was greater (P less than .05) in heat-stressed (32 C) panting birds (7.395) than either nonpanting (7.28) or birds raised at 24 C (7.28). Acute thermostress, obtained by elevating ambient temperature from 32 to 41 C over a 20-min period further elevated (P less than .05) blood pH to 7.521. Chronic heat-stressed broiler chicks suffer from intermittent respiratory alkalosis during panting; with acute heat stress, chicks pant continuously and suffer from alkalosis. Including .5% sodium bicarbonate (NaHCO3) in the diet of birds subjected to chronic heat stress enhanced body weight gain by 9% even though it tended (P less than .10) to increase blood pH in nonpanting birds. Adding .3 or 1% ammonium chloride (NH4Cl) to diets decreased blood pH (P less than .01) to 7.194 and increased (P less than .05) body weight gains by 9.5 and 25%, respectively. Effects appeared linear with NH4Cl dose to 1% NH4Cl, but 3% NH4Cl elevated weight gains by only 8% and precipitated blood acidosis (pH 7.09) in nonpanting birds. Supplementing the 1% NH4Cl diet with .5% NaHCO3 increased weight gains an additional 9%. Manipulating sodium: chloride ratios by addition of calcium chloride increased body weight gain 8% and slightly reduced severity of alkalosis. Data indicate that blood alkalosis limits growth rate of broiler chicks reared under chronic thermostress and that the respiratory alkalosis and weight gain depressions attributed to thermostress can be partially alleviated dietarily.