Effect of frame size and time-on-pasture on steer performance, longissimus muscle fatty acid composition, and tenderness in a forage-finishing system.

Angus-cross steers (n = 96; BW = 309 ± 34 kg; 13.5 mo of age) were used to determine the effects of frame size (medium or small) and time-on-pasture (TOP) on meat composition and palatability in a 2-yr study. Finishing steers grazed mixed pastures (bluegrass/white clover; April start) and were slaughtered after 89-, 146-, and 201-d TOP. At 24 h postmortem, carcass traits were collected and a rib from each carcass was obtained for proximate and fatty acid composition, Warner-Bratzler shear force (WBSF), and postmortem proteolysis. In yr 1, postmortem aging treatments included 14 and 28 d, whereas in yr 2, postmortem aging treatments included 2, 4, 7, 14, and 28 d. Increasing frame size of the finishing steers produced greater (P < 0.05) ADG by 0.10 kg, BW by 24 kg, HCW by 14 kg, and ribeye size by 2.65 cm(2). All other carcass, meat composition, and tenderness measures did not differ (P > 0.05) due to frame size or 2-way interaction with TOP. Increasing TOP resulted in quadratic increases (P < 0.01) in BW and HCW. Ribeye area, fat thickness, KPH, marbling scores, quality grades, and yield grades increased (P < 0.001) linearly as TOP increased. Time-on-pasture linearly increased (P = 0.001) palmitic (C16:0) acid, oleic (C18:1 cis-9) acid, SFA, and MUFA in the LM. Both n-6 PUFA, linoleic (C18:2) and arachidonic (C20:4) acids, decreased linearly (P = 0.001) with increasing TOP. Increasing TOP linearly reduced (P = 0.01) concentrations of all n-3 fatty acids in the LM. These changes resulted in a linear reduction (P = 0.01) in n-6 to n-3 fatty acid ratio with advancing TOP; however, the magnitude of the difference was small (1.46 vs. 1.37). At 14 d of postmortem aging, WBSF was lowest (P < 0.001) for 89-d TOP and greatest (P < 0.05) for the 201-d TOP. After 28 d of postmortem aging, WBSF values for 89- and 146-d TOP did not differ (P > 0.05) compared to the 14-d postmortem aging WBSF values. However, in steaks from 201-d TOP, additional postmortem aging to 28 d reduced (P < 0.001) WBSF. In pasture-based beef finishing systems, increasing TOP increases animal age, HCW, fat thickness, and marbling score; however, tenderness of ribeye steaks decreased with advanced TOP such that longer postmortem aging times were required to achieve similar tenderness levels.

Effects of forage species or concentrate finishing on animal performance, carcass and meat quality.

Angus-cross steers (n = 128; initial BW = 270 ± 3.8 kg) were used in a 3-yr study to assess effects of forage species grazed before slaughter versus concentrate finishing on carcass and meat quality. At the completion of the stockering phase, steers were randomly allotted to mixed pasture (MP; n = 36/yr) or corn-silage concentrate (CON; n = 12/yr) finishing treatments. At 40 d before harvest, MP steers were randomly divided into 3 forage species treatments: alfalfa (AL), pearl millet (PM), or mixed pasture (MP). Average daily BW gain was greater (P = 0.001) for CON than for forage-finished (FOR) steers during the early and overall finishing phase. During the late finishing phase when FOR steers were grazing difference forage species, ADG was greater (P = 0.03) for PM than MP or AL. Harvest weight and HCW were greater (P < 0.001) for CON than FOR due to the differences in animal performance. Total fat percentage of the 9th to 11th rib section was 46% less(P = 0.028) for FOR than CON due to reductions (P < 0.001) in the percentage of subcutaneous fat. Warner-Bratzler shear force (WBS) values at 14 d and 28 d of aging did not differ (P > 0.78) between CON and FOR and were not altered (P > 0.40) by forage species. Trained sensory panel juiciness, initial tenderness, and overall tenderness scores did not differ (P > 0.17) by finishing treatment or forage species. Beef flavor intensity was greater (P < 0.001) for CON than FOR. Beef flavor intensity was greater (P < 0.02) for AL and PM than MP. Off-flavor intensity was greater (P < 0.001) for all forage-fed steaks, regardless of forage species, than CON. Finishing on forages reduced (P = 0.003) total lipid content by 61% for the LM compared with CON finished cattle. Forage species grazed before harvest did not alter (P > 0.05) total lipid content of the LM. Oleic acid concentration and total MUFA of the LM were 21% and 22% less (P = 0.001) for FOR than CON. Concentrations of all individual [linolenic acid, eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosadexaenoic (DHA) acids] and total n-3 fatty acids were greater (P < 0.001) for FOR than CON. Finishing on AL increased (P = 0.017) the concentration of linolenic acid compared with MP or PM. The ratio of n-6 to n-3 fatty acids was greater (P = 0.001) for CON than FOR and did not differ (P = 0.88) by forage species. Concentrate finishing increases carcass weight with same time endpoints and accelerates deposition of MUFA in comparison with FOR, which reduces carcass weight and fat deposition but maintains high concentrations of n-3 and CLA fatty acids. Finishing system or forage species grazed 40 d before slaughter did not alter beef tenderness but FOR had greater off-flavors according to both trained and descriptive sensory panelists.

Fatty acid metabolism and deposition in subcutaneous adipose tissue of pasture- and feedlot-finished cattle.

An experiment was conducted to evaluate the effects of pasture finishing versus feedlot finishing, over time, on fatty acid metabolism in Angus crossbred steers (n = 24). Ruminal fluid, serum, and adipose tissue biopsies were obtained on d 0, 28, 84, and 140. Pasture forages and diet ingredient samples were obtained at 14-d intervals to determine nutritive value and fatty acid composition. The feedlot diet consisted of corn silage, cracked corn grain, soybean meal, and a vitamin and mineral supplement. The pasture-finished steers grazed sequentially on triticale (x Triticosecale rimpaui)/annual ryegrass (Lolium multiflorum), alfalfa (Medicago sativa)/orchardgrass (Dactylis glomerata), and a cool-season grass/legume mixture. The feedlot diet contained an average of 57% of total fatty acids as linoleic acid and 2% as linolenic acid. The pasture forages contained 9% of total fatty acids as linoleic acid and 66% as linolenic acid. Concentrations (% of total fatty acids) of linolenic acid were greater (P < 0.05) in ruminal fluid, serum, and adipose tissue of the pasture-finished steers, compared with the feedlot-finished steers. Concentrations (% of total fatty acids) of cis-9, trans-11 CLA were greater (P < 0.05) in adipose tissue of the pasture-finished steers than feedlot-finished steers. Concentrations of cis-9, trans-11 CLA in adipose tissue declined (P < 0.05) in the feedlot-finished steers from d 0 to 28 to 84. In the pasture-finished steers, concentrations of cis-9, trans-11 CLA in adipose tissue (mg/g of tissue) peaked (P < 0.05) on d 28 and remained elevated (ranged from 9.91 to 12.80 mg/g of tissue) throughout the duration of the study. In the pasture-finished steers, linolenic acid concentrations tended to peak (P = 0.07) on d 28 and remained elevated (ranged from 0.64 to 0.80% of total fatty acids) throughout the study. It appears that only a short time is needed to alter the n-3 and CLA composition of adipose tissue in cattle finished on pasture.

Effects of winter stocker growth rate and finishing system on: III. Tissue proximate, fatty acid, vitamin, and cholesterol content.

Angus-cross steers (n = 198; 270 kg of BW; 8 mo) were used in a 3-yr study to assess the effects of winter stocker growth rate and finishing system on LM proximate, fatty acid, cholesterol, vitamin, and mineral composition. During the winter months (December to April), steers were randomly allotted to 3 stocker growth rates: low (0.23 kg/d), medium (0.45 kg/d), or high (0.68 kg/d). At the completion of the stockering phase, steers were allotted randomly within each stocker growth rate to a high concentrate (CONC) or pasture (PAST) finishing system and finished to an equal time endpoint. Winter stocker growth rate did not alter (P > 0.05) proximate, cholesterol, or vitamin content of the LM. All interactions among winter stocker growth rate and finishing system were nonsignificant, indicating that supplementation systems during winter stocker period did not influence beef composition after finishing on PAST or CONC. Finishing steers on CONC decreased (P < 0.001) moisture content of the LM and increased (P < 0.001) lipid content of the LM. Protein, ash, and cholesterol content of the LM did not differ (P > 0.05) between finishing systems. alpha-Tocopherol and beta-carotene content of the LM were 288 and 54% greater, respectively, for PAST-finished cattle than CONC. B-vitamins, thiamine and riboflavin, were also present in greater (P = 0.001) concentrations for PAST than CONC. Calcium, Mg, and K contents of the LM were greater (P < 0.05) for PAST than CONC. Total fatty acid content of the LM was 49% less for PAST than CONC. Myristoleic, palmitoleic, and oleic acid concentrations were all less (P = 0.001) for PAST than CONC. Trans-10 octadecenoic acid percentage in LM was 97% greater (P = 0.001) for CONC than PAST; conversely, trans-11 vaccenic acid percentage in the LM was 90% greater (P = 0.001) for PAST than CONC. Conjugated linoleic acid, cis-9, trans-11 isomer, percentage was greater (P = 0.001) by 117% for PAST than CONC. Linoleic acid (C18:2) concentration did not differ (P > 0.05) among PAST and CONC. Concentrations of all n-3 fatty acids (linolenic acid, eicosapentaenoic, docosapentaenoic, docosahexaenoic) were greater (P = 0.01) for PAST than CONC. Total n-6 PUFA percentages were unchanged (P > 0.05) among finishing systems. The ratio of n-6 to n-3 fatty acids was 4.84 for CONC and 1.65 for PAST. Beef from CONC finished has a greater total, saturated, and monounsaturated fat content; in contrast, beef from PAST finished has less total, saturated, and monounsaturated fat content with greater contents of n-3 fatty acids and a decreased n-6 to n-3 ratio. Beef from PAST finished also has greater contents of B-vitamins and antioxidants (vitamin E and beta-carotene).

Forage systems for cow-calf production in the Appalachian region.

Small cow-calf operations are common in the Appalachian region. Tall fescue [Lolium arundinaceum (Schreb.) S. J. Darbyshire] is the dominant forage in these systems for direct grazing as well as for stockpiling. The present study was conducted from 2001 to 2005. A total of 108 Angus and Angus crossbred cows were allotted randomly to 6 forage systems and then to 3 replicates within each system. In brief, system 1 had a stocking rate of 0.91 ha/cow in a Middleburg 3-paddock (A, B, and C) system. System 2 was similar to system 1 except for a stocking rate of 0.71 ha/cow. A stocking rate of 0.71 ha/cow also was used in systems 3 through 6. All A paddocks had tall fescue, whereas B paddocks had tall fescue/white clover (Trifolium repens L.) except in system 6, which had tall fescue/lespedeza [Lespedeza cuneata (Dum. Cours.) G. Don]. System 3 evaluated a 2-paddock (A and B) rotational grazing system, and system 4 evaluated a 3-paddock (A, B, and C) rotational grazing system, with paddock C containing orchardgrass (Dactylis glomerata L.) and alfalfa (Medicago sativa L.). Systems 5 and 6 differed from system 2 in the areas of paddocks B and C as well as in the forage mixtures used. In paddock C, system 5 had switchgrass (Panicum virgatum L.) and system 6 had tall fescue and birdsfoot trefoil (Lotus corniculatus L.). System 1 had the greatest average herbage availability from weaning until breeding (P < 0.05) with the least amount of hay fed (P = 0.03) when compared with the remainder of the systems. Differences (P > 0.05) in percentage of ground cover were not detected among systems. There was no year x system interaction effect on the cow or calf performance variables evaluated and no treatment effect on cow performance variables. There was a treatment effect on calf performance variables. System 2 produced the greatest adjusted weaning weight, kilograms of calf weaned per hectare, and kilograms of calf per kilograms of cow at weaning (P < 0.05). Numerical ranking for total calf production per hectare from the greatest to least was system 2, 6, 3, 5, 4, and 1. Systems evaluated did not affect cow performance although differences in calf performance and overall productivity of the systems were observed.

Parenteral selenium and vitamin E supplementation of weaned beef calves.

BACKGROUND: The weaning process in beef calves elicits physiological stress responses that can negatively affect performance and health. Supplementation of vitamins and minerals, particularly selenium (Se) and vitamin E, might be warranted. HYPOTHESIS: That parenteral administration of Se or vitamin E would correct or prevent deficiencies of these nutrients in postweaned beef calves during a backgrounding period (42 days after weaning). ANIMALS: One hundred and forty-four weaned steers (200-250 kg) in 3 trials. METHODS: One trial was conducted with cattle on a dry lot fed a total mixed ration and 2 trials were conducted on cattle on pasture. Selenium was administered at 0.05 mg/kg BW (SC) and vitamin E was administered at 1500 IU on days 0 and 28 (SC). RESULTS: A treatment effect attributable to Se or vitamin E supplementation on average daily gain was not detected in any trials. Parenteral supplementation with Se on days 0 and 28 resulted in higher serum Se concentrations as compared with controls on day 42. Parenteral supplementation with Se on days 0 and 28 improved Se status from marginal to adequate in 1 trial. Parenteral supplementation with vitamin E did not improve serum vitamin E concentrations in any experiment. CONCLUSIONS AND CLINICAL IMPORTANCE: Supplementation with vitamin E or Se or a combination of both did not have a significant effect on calf performance during the 42-day backgrounding period.

Influence of finishing systems on hydrophilic and lipophilic oxygen radical absorbance capacity (ORAC) in beef.

The aim of this research was to: (1) develop a reliable extraction procedure and assay to determine antioxidant activity in meat products, and (2) assess the effect of beef finishing system (forage-finished: alfalfa, pearl millet or mixed pastures vs. concentrate-finished) on longissimus muscle antioxidant activity. The effect of extraction method (ethanol concentration and extraction time), protein removal, and sample preparation method (pulverization or freeze drying) were first evaluated to develop an antioxidant assay for meat products. Beef extracts prepared with low ethanol concentrations (20%) demonstrated higher hydrophilic ORAC. Protein removal prior to extraction reduced hydrophilic ORAC values. Sample preparation method influenced both hydrophilic and lipophilic ORAC, with pulverized samples containing higher hydrophilic and lipophilic ORAC values. Beef cattle finishing system (Forage: alfalfa, pearl millet, or natural pasture vs. concentrates) had little impact on muscle hydrophilic ORAC, but muscle from forage finished beef contained greater lipophilic ORAC. In addition, broiling of steaks reduced hydrophilic ORAC.

Effects of winter stocker growth rate and finishing system on: II. Ninth-tenth-eleventh-rib composition, muscle color, and palatability.

Angus-cross steers (n = 198; 270 kg; 8 mo) were used in a 3-yr study to assess the effects of winter stocker growth rate and finishing system on 9-10-11th-rib composition, color, and palatability. During the winter months (December to April), steers were randomly allotted to 3 stocker growth rates: low (0.23 kg/d), medium (0.45 kg/d), or high (0.68 kg/d). At the completion of the stocking phase, steers were allotted randomly within each stocker growth rate to a high concentrate (CONC) or to a pasture (PAST) finishing system. All steers were finished to an equal time endpoint to minimize confounding due to animal age. At the end of the finishing phase, steers were transported to a commercial packing plant for slaughter and a primal rib (NAMP 107) was removed from 1 side of each carcass. The 9-10-11th-rib section was dissected into lean, fat, and bone, and LM samples were analyzed for palatability and collagen content. Hot carcass weight and 9-10-11th-rib section weight were greater (P = 0.01) for high than low or medium. Winter stocker growth rate did not alter 9-10-11th rib composition. The percentage of fat-free lean, including the LM and other lean trim, was greater (P = 0.001) for PAST than CONC. Total fat percentage of the 9-10-11th-rib section was 42% lower (P = 0.001) for PAST than CONC due to lower percentages of s.c., intermuscular, and i.m. fat. The percentage of total bone in the 9-10-11th-rib section was greater (P = 0.001) for PAST than CONC. Finishing beef cattle on PAST increased (P = 0.001) the percentage of lean and bone and reduced (P = 0.001) the percentage of fat in the carcass based on published prediction equations from 9-10-11th rib dissection. Stocker growth rate did not influence the objective color scores of LM or s.c. fat. Longissimus muscle color of PAST was darker (lower L*; P = 0.0001) and less red (lower a*; P = 0.002) than CONC. Juiciness scores were greater (P = 0.02) for CONC than PAST. Initial and overall tenderness scores as well as Warner-Bratzler shear force values did not differ (P > or = 0.28) among finishing systems. Beef flavor intensity was lower (P = 0.0001) and off-flavor intensity greater (P = 0.0001) for PAST than CONC. Total collagen content was greater (P = 0.0005) for PAST than CONC; however, there were no differences in percentage soluble or insoluble collagen. Growth rate during the winter stocker period did not influence rib composition, color, or beef palatability. Finishing steers on forage reduced fat percentages in the rib and LM without altering tenderness of beef steaks.

Effects of winter stocker growth rate and finishing system on: I. Animal performance and carcass characteristics.

Angus-crossbred steers (n = 216) were used in a 3-yr study to assess the effects of winter stocker growth rate and finishing system on finishing performance and carcass characteristics. During winter months (December to April) steers were randomly allotted to 3 stocker growth rates: low (0.23 kg x d(-1)), medium (0.45 kg x d(-1)), or high (0.68 kg x d(-1)). Upon completion of the winter phase, steers were randomly allotted within each stocker treatment to a corn silage-concentrate or pasture finishing system. All steers regardless of finishing treatment were finished to an equal-time endpoint to eliminate confounding of treatments with animal age or seasonal factors. Upon completion of the finishing period, steers were slaughtered in 2 groups (one-half of pasture and one-half of feedlot cattle each time) and carcass data were collected. Winter data were analyzed as a completely randomized design, with winter treatment, pen replicate, year, and the winter x year interaction in the model. Finishing performance and carcass data were analyzed in a split-plot design with finishing system in the whole plot, and winter growth rate and winter x finish in the split-plot. Winter treatment mean within finishing replication was the experimental unit, and year was considered a random effect. Winter stocker phase treatments resulted in differences (P < 0.001) in final BW, ADG, and ultrasound LM area between all treatments for that phase. Pasture-finished cattle had lower (P < 0.001) final BW, ADG, HCW, LM area, fat thickness, KPH, dressing percent, USDA yield grade, and USDA quality grade. Winter stocker treatment influenced (P < 0.05) final BW and HCW, with low and medium being less than high. Steers with low stocker gain had greater (P < 0.05) finishing ADG. Dressing percent was greater (P < 0.001) for high than low, and USDA quality grade was greater (P < 0.05) for high than low and medium. Carcass LM area, fat thickness, KPH, and USDA yield grade were not influenced (P > 0.05) by winter rate of gain. Cattle on low during winter exhibited compensatory gain during finishing but were unable to catch the high group regarding BW or HCW. The USDA quality grade was greater for high than low or medium. Animal performance during the winter stocker period clearly impacts finishing performance, carcass quality and beef production in both pasture- and feedlot-finishing systems, when cattle were finished to an equal-time endpoint.

Fat digestibility in Equus caballus follows increasing first-order kinetics.

The digestibility of ether extract varies greatly from forages to grains and further to added fats consisting mainly of triglycerides. This variation has been attributed to two main factors, the presence of nonhydrolyzable substances in the ether extract, especially in leafy foods, and the dilution of endogenous fecal fat. A compilation of results from 188 equine digestion balance observations on five basal feeds and 18 test feeds with added fats demonstrated a true digestibility of fat approaching 100% and an endogenous fecal fat of 0.22 g x d(-1) x kg BW(-1). The results revealed that nonhydrolyzable ether extract and endogenous fecal fat were insufficient to account for the difference between true digestibility and apparent digestibilities of ether extract in basal feeds and partial digestibilities of added fats in test feeds. A third possible contributing factor was demonstrated: an increasing first-order relationship between observed digestibilities (D, %) and the fat content of the feed (F, g/kg): D = 92.0 - 92.0e(-F/342). r2 = 0.81, P < 0.001. This equation indicates that 46% digestibility (half maximum) occurs at an ether extract or fat content of 24 g/kg, which is common in forages. It is consistent with fat digestibility or efficiency of absorption being a function of the rate of lipolysis, especially when residence time in the small intestine is limited. Consequently, we suggest that the kinetics of lipases, which are difficult to measure, may contribute to low digestibility when substrate concentration in the small intestine is low due to a low fat content in food. The status of vitamins A and E might be affected by low dietary fat contents and might be improved by fat supplementation.

Tasco-Forage: I. Influence of a seaweed extract on antioxidant activity in tall fescue and in ruminants.

Seaweed (Ascophyllum nodosum) is a known source of plant growth regulators, and application to turfgrasses has increased activity of the antioxidant superoxide dismutase (SOD) and specific vitamin precursors. Increased antioxidant activity in both plants and animals diminishes oxidative stress. Two pasture experiments investigated effects of Tasco-Forage (a proprietary seaweed-based product) applied to tall fescue (Festuca arundinacea) on antioxidant activity in plants and in ruminants that grazed the forage. In Exp. 1, fescue was 70 to 100% infected with the endophyte fungus Neotyphodium coenophialum ([Morgan-Jones and Gams] Glenn, Bacon, and Hanlin). Twenty-four wether lambs (initial BW 41 kg; SD = 5) grazed fescue treated with 0, 1.7, or 3.4 kg Tasco/ha applied in April and July, 1994, with four replications per treatment. Grazing occurred for 26 d beginning April 21 and for 22 d beginning July 19. In July, there was a linear increase in daily gains (P < 0.05), and serum vitamin A (P < 0.13) and whole-blood Se (P < 0.10) tended to increase in lambs grazing Tasco-treated fescue. In Exp. 2,48 Angus and Angus x Hereford steers (initial BW 245 kg; SD = 20) grazed infected or uninfected tall fescue in Virginia that was treated (3.4 kg/ ha) or untreated with Tasco in April and July, 1995. Steers that grazed infected tall fescue had lower (P < 0.02) serum vitamin A and E and tended (P < 0.07) to have lower whole-blood Se in September compared with steers that grazed uninfected tall fescue. Tasco decreased (P < 0.06) serum vitamin E but tended to increase whole-blood Se (P < 0.10) in September and serum vitamin A in July (P < 0.12). During 1996 and 1997, the experiment was repeated in Virginia with Angus steers and was replicated at Prairie, MS, where 1/4 Brahman x 3/4 Angus steers were used. Forty-eight steers were included at each location in each year (n = 192 total steers for 1996 and 1997). Steers that grazed infected tall fescue in Mississippi had lower (P < 0.05) serum vitamin E by the end of the grazing season. At both locations Tasco increased (P < 0.05) activity of superoxide dismutase in both infected and uninfected fescue. The endophyte in tall fescue seemed to decrease antioxidant activity in grazing steers, whereas Tasco seemed to increase antioxidant activity in both the forage and the grazing ruminant. Tasco may provide opportunities to reduce oxidative stress in plants and animals.

Tasco-Forage: II. Monocyte immune cell response and performance of beef steers grazing tall fescue treated with a seaweed extract.

Effects of applying Tasco-Forage, an Ascophyllum nodosum seaweed-based product prepared by a proprietary process, to endophyte (Neotyphodium coenophialum [Morgan-Jones and Gams] Glenn, Bacon, and Hanlin)-infected and endophyte-free tall fescue (Festuca arundinacea Schreb.) were studied in each of 3 yr (1995, 1996, and 1997) in Virginia and in 1996 and 1997 in Mississippi. There were 48 steers at each location in each year (n = 240) in a 2 x 2 x 2 factorial arrangement with two replications at each location. Steers in Virginia were Angus and Angus x Hereford with initial weights of 245 kg (SD = 20), 234 kg (SD = 9), and 265 kg (SD = 5) in yr 1, 2, and 3, respectively. Steers in Mississippi were 3/4 Angus and 1/4 Brahman and weighed 230 kg (SD = 8) and 250 kg (SD = 2) in yr 2 and 3, respectively. Tasco (3.4 kg/ha) was dissolved in water and applied to pastures in April before grazing was begun and again in July at the same rate. The grazing period was from mid-April to late September or mid-October. Total gains were higher (P < 0.05) for steers grazing uninfected than for those grazing endophyte-infected tall fescue. Rectal temperatures were increased (P < 0.05) due to endophyte infection at both locations; Tasco application decreased temperature of steers grazing infected fescue in Virginia (interaction, P < 0.07) but increased temperatures of steers grazing infected fescue in Mississippi (interaction, P < 0.05). Presence of the endophyte resulted in rough hair coats and loss of hair color, but the effect was partially offset (P < 0.05) by Tasco application in Virginia in 1995. Both monocyte phagocytic activity (all years and locations) and major histocompatibility complex class II expression (1995 only) were decreased (P < 0.05) in steers due to endophyte infection, but this effect was reversed (P < 0.05) by application of Tasco to pastures. Application of the extract from A. nodosum seems to have use in alleviating adverse effects of endophyte on immune function and may improve hair coat condition in cattle grazing infected fescue, but effects on rectal temperature varied due to location.

Tasco-Forage: III. Influence of a seaweed extract on performance, monocyte immune cell response, and carcass characteristics in feedlot-finished steers.

Tall fescue (Festuca arundinacea Schreb.) infected with the endophyte Neotyphodium coenophialum ([Morgan-Jones and Gams] Glenn, Bacon, and Hanlin) causes fescue toxicosis in cattle grazing the forage, but effects of the endophyte were considered to be abated soon after removal of the animals from pastures. Tasco-Forage, a proprietary extract from the brown seaweed Ascophyllum nodosum, is a known source of cytokinins and has increased antioxidant activity in both plants and the animals that graze the forage. Tasco was applied at 0 and 3.4 kg/ha to infected and uninfected tall fescue pastures in Virginia and Mississippi. Forty-eight steers grazed the pastures at each location during each of 2 yr (n = 192) before being transported to Texas for feedlot finishing. On arrival at the feedlot, steers from Tasco-treated pastures had higher (P < 0.01) monocyte phagocytic activity and tended (P < 0.07) to have higher major histocompatibility complex class II expression than steers that grazed the untreated pastures. A depression (P < 0.05) in monocyte immune cell function due to grazing infected fescue was detected throughout the feedlot finishing period but was reversed by Tasco. Rectal temperatures were elevated (P < 0.07) in steers that had grazed the infected tall fescue when they arrived in Texas, but by d 14 no difference was detected. However, by d 28 the temperature effects of infected tall fescue were reversed. Steers that had grazed infected fescue had lower (P < 0.01) rectal temperatures on d 112 of the feedlot period, demonstrating a much longer-lasting effect of the endophyte on thermoregulatory mechanisms than previously thought. Steers that had grazed Tasco-treated pastures had higher (P < 0.01) rectal temperatures on d 56 than steers that had grazed untreated fescue. Steers that had grazed the Tasco-treated pastures had higher marbling scores (P < 0.05) regardless of the endophyte, but no effect of Tasco or endophyte on gain was measured. Our data suggest that Tasco application to tall fescue pastures alleviated some of the negative effects of tall fescue toxicity.

Tasco-Forage: IV. Influence of a seaweed extract applied to tall fescue pastures on sensory characteristics, shelf-life, and vitamin E status in feedlot-finished steers.

Tasco-Forage is an Ascophyllum nodosum seaweed-based product that has increased antioxidant activity in both plants and animals. Endophyte (Neotyphodium coenophialum ([Morgan-Jones and Gams] Glenn, Bacon, and Hanlin)-infected and uninfected tall fescue (Festuca arundinacea Schreb.) pastures in Virginia and Mississippi during 1997 were treated or not with 3.4 kg Tasco/ha in April and July. There were two replications of each treatment at each location. Forty-eight steers (6/replication) grazed pastures at each location (n = 96) from April to October prior to transportation to Texas Tech, Lubbock, for finishing during a 160-d period in the feedlot. Blood (antemortem) and liver (postmortem) samples were collected. After slaughter and chilling, the left strip loins (IMPS #180) were collected from three randomly selected steers from within each pasture replication (n = 48). Strip loins were vacuum-packaged and stored at 2 degrees C. At postmortem d 7, 14, 21, and 28, strip loins were removed from packaging and fabricated into 2.54-cm steaks. Following each fabrication day postmortem, the strip loins were repackaged and stored at 2 degrees C until the following postmortem time. After the prescribed fabrication, steaks were overwrapped with polyvinyl chloride film, subjected to simulated retail display at 2 degrees C for up to 3 d, and subjective and objective color were evaluated daily by a trained panel. Steaks from Mississippi steers that had grazed Tasco-treated fescue retained higher (P < 0.05) CIE a* color scores throughout retail display. Steaks were more uniform and had less discoloration and less browning (P < 0.05) if they were from steers that had grazed Tasco-treated fescue, and the effect was greatest for steers from Mississippi (location x Tasco interaction; P < 0.05). The endophyte in tall fescue may decrease uniformity and increase lean discoloration and two-toning of beef steaks when removed from vacuum packaging on or beyond d 21 postmortem (endophyte x Tasco x postmortem day interaction: P < 0.05). Vitamin E in liver was increased (P < 0.06) and serum vitamin E was decreased (P < 0.09) in steers that had grazed the treated pastures. These experiments indicated that Tasco applied to tall fescue during the grazing season can improve color stability and extend beef shelf-life, particularly in cattle grazing infected tall fescue. The mode of action of Tasco is not clear, but antioxidants and specific vitamins may be involved.

Forage systems for production of stocker steers in the upper south.

The southern states produce large numbers of beef calves that are generally weaned and sold in autumn. Keeping calves in this region beyond weaning to graze high-quality forages through a stocker cattle phase could improve profitability. Autumn-weaned Angus crossbred steers were allocated by breeding and weight to four forage systems that began in mid-November and continued through mid-October as follows: System 1, tall fescue (Festuca arundinacea Schreb.) and Kentucky bluegrass (Poa pratensis L.)-white clover (Trifolium repens L.); System 2, tall fescue, caucasian bluestem (Bothriochloa caucasica [Trin.] C. E. Hubbard) and tall fescue-red clover (Trifolium pratense L.); System 3, orchardgrass-alfalfa and bluegrass-white clover; and System 4, rye (Secale cereale L.), soybeans (Glycine max)-foxtail millet (Setaria italica), and bluegrass-white clover. All steers were supplemented with hay or silage previously cut from their respective systems when forage for grazing was limited. System 2 which used stockpiled tall fescue for winter grazing and caucasian bluestem for summer forage plus fescuered clover for hay and grazing in a three-paddock system, resulted in greater (P < .01) gain per hectare and per steer, more grazing days, and reduced stored forage requirements and produced more surplus feed than the other systems tested. Gains per hectare for Systems 1 through 4 were 454, 554, 472, and 487 kg (SE = 18), respectively. Harvested forage from Systems 1, 2, and 3 met needs for stored forages but System 4 required additional "purchased" hay. Stored forage was fed for 61, 38, 112, or 104 d for Systems 1 through 4, respectively. Within the physio-climatic region of this experiment, a simple three-paddock system based on cool- and warm-season perennial forages could improve beef production per unit of land area while reducing inputs of labor and equipment.

Influence of Neotyphodium coenophialum on copper concentration in tall fescue.

Poor performance of livestock that graze tall fescue (Festuca arundinacea Schreb.) has been associated with the endophyte fungus Neotyphodium coenophialum [Morgan-Jones and Gams] Glenn, Bacon, and Hanlin). Recent evidence suggests lowered Cu status and a depression of Cu-related immune function in steers that graze endophyte-infected (E+) tall fescue. Greenhouse and field studies investigated relationships between the endophyte and Cu concentrations in tall fescue. Seventeen infected 'Kenhy' clones were divided, and one plant of each pair was treated three times with Benomyl to remove the endophyte (E-). Plants were watered with nutrient solution in a greenhouse for 6 mo before sampling. Copper concentrations were greater (P < .001) in E- than in E+ clones (3.4 vs 2.8 microg/g; SE, .06). In the second greenhouse experiment, genetically similar E+ and E- 'Kentucky'-31 (KY-31) and 'Georgia Jessup' were grown from seed and fertilized with nutrient solution to produce mature plants. Copper concentrations were higher (P < .05) in E- than in E+ tall fescue (8.6 vs 7.6 microg/g; SE, .3). In a field plot experiment in Texas, E+ and E- KY-31 were grown with 0, 50, and 100% replacement of potential evapotranspiration. By September, Cu concentrations were higher (P < .05) in E- than in E+ tall fescue (7.3 vs 6.6 microg/g; SE, .2). In pasture experiments, KY-31 E+ (> 70% infection level) and E- (< 5% infection level) tall fescue were grown in Virginia at two locations with three rates of N fertilizer. Copper concentrations were higher (P < .05) in E- than in E+ tall fescue (4.8 vs 4.5 microg/g; SE, .1) and increased (P < .01) linearly in response to N. Our data demonstrate that the presence of the endophyte is associated with lower Cu concentrations in tall fescue, which may contribute to lowered Cu status in animals and thus contribute to the etiology of fescue toxicity.

Monocyte immune cell response and copper status in beef steers that grazed endophyte-infected tall fescue.

A 3-yr study was conducted to evaluate immune response and Cu status of yearling beef steers as a consequence of grazing tall fescue (Festuca arundinacea Schreb.) infected (E+) with the endophyte fungus Neotyphodium coenophialum ([Morgan-Jones and Gams] Glenn, Bacon, and Hanlin). During a preliminary study in 1994, 24 weanling Angus and Angus x Hereford steers were blocked by breed and weight (initial BW 271 kg; SD 25) and were randomized to E+ and low endophyte (E-) fescue in pastures at Glade Spring, VA. Grazing began in April and was discontinued in July. In 1995 and 1996, 24 weanling Angus and Angus x Hereford steers (initial BW 249 kg, SD 20 and 240 kg, SD 15, respectively) were randomized to the E+ and E- pastures at Glade Spring during each year. Grazing began in April and continued until September in 1995 and October in 1996. In 1994, steers that grazed E+ fescue exhibited lower (P < .05) phagocytic activity, major histocompatibility complex (MHC) class II expression, ceruloplasmin, and serum Cu than steers that grazed E- tall fescue. During 1995, steers grazing E+ fescue had lower (P < .05) phagocytic activity and MHC class II expression than steers that grazed E- fescue. In 1996, one-half of the steers within each paddock received a Cu oxide bolus at the beginning of the grazing season. During 1996, phagocytic activity was lower (P < .01) and MHC class II expression tended (P < .07) to be lower in steers that grazed E+ tall fescue than in steers that grazed E- tall fescue. Copper supplementation increased (P < .05) MHC class II expression in July regardless of endophyte status over nonsupplemented steers. Steers that grazed E- tall fescue had higher (P < .05) plasma or serum Cu concentrations than steers that grazed E+ tall fescue in each year of the study. These data indicate that the endophyte compromised the immune function of grazing steers, and the data suggest a relationship with depressed Cu status.

Nutrient utilization by sheep and performance and carcass characteristics of steers fed crab waste-straw silage.

Crab waste preserved with .2% NaOCl was mixed with wheat straw, liquid molasses, and water (32:32:16:20, wet basis) and ensiled for a minimum of 8 wk with microbial inoculant. A reduction in pH and water-soluble carbohydrates (WSC) and a higher concentration of lactic acid (4.9%, DM basis) were achieved. The trimethylamine (TMA) concentration in the silage was 11.2 mg N/100 g. In a digestion trial, 18 crossbred wethers (43 kg) were fed three diets: 1) basal, 2) a 50:50 mixture, DM basis, of basal and crab waste-straw silage, and 3) 100% crab waste-straw silage. Apparent digestibility of DM, OM, CP, energy, NDF, ADF, cellulose, and hemicellulose decreased linearly (P < .01) with increased levels of crab waste-straw silage. Nitrogen retention increased linearly (P < .05) with level of crab waste-straw silage. Apparent absorption was higher (P < .01) and retention was positive (P < .05) for Ca, Mg, Na, K, Cu, and Fe for sheep fed the highest level of crab waste-straw silage. In a 108-d trial, 30 yearling steers were fed diets in which crab waste-straw silage was included in the diet at 0, 15, and 26%, DM basis. Average daily gain tended to be highest (linear effect, P < .15) and carcass weights were highest (linear effect, P < .05) for steers fed 26% crab waste-straw silage. Average carcass quality grade was low Choice, and yield grade averaged 2.3, with no significant differences among treatments. Consumption of crab waste-straw silage did not adversely affect the taste of the meat. Results indicate that feeding crab waste-straw silage did not adversely affect nutrient utilization or performance of ruminants.

The clinical neuromuscular pharmacology of cisatracurium versus vecuronium during outpatient anesthesia.

UNLABELLED: Neither comparisons of the clinical neuromuscular effects of cisatracurium and vecuronium nor comparative studies of their antagonism by neostigmine have been reported. In addition, the efficacy of administering cisatracurium in divided doses has not been investigated. Accordingly, we applied supramaximal electrical stimuli to the ulnar nerve of 165 ASA physical status I and II patients receiving nitrous oxide/alfentanil/propofol anesthesia. Forty-five patients received cisatracurium 5, 10, or 15 microg/kg, and the evoked response at the adductor pollicis was recorded for 15 min. One hundred-twenty patients received cisatracurium 5, 10, or 15 microg/kg or normal saline placebo followed 5 min later by either cisatracurium 100 microg/kg or vecuronium 100 microg/kg (always after placebo). Time to clinical onset (maximal ablation of single twitch response) was measured. When the evoked response spontaneously recovered to 10% of control height, neostigmine 5, 10, 30, or 50 microg/kg or placebo was administered, and recovery of neuromuscular function was recorded for the next 15 min. The clinical onset of vecuronium without priming (2.8 +/- 0.8 min) (mean +/- SD) was significantly (P < 0.05) faster than the onset of cisatracurium without priming (4.6 +/- 1.4 min). Cisatracurium 5, 10, or 15 microg/kg administered before cisatracurium 100 microg/kg significantly (P < 0.05) accelerated the time to complete ablation of the evoked response (3.9 +/- 0.9, 2.9 +/- 0.8, or 3.0 +/- 0.9 min, respectively) compared with cisatracurium 100 microg/kg without priming. The dose of neostigmine required to achieve 50% assisted recovery of the train-of-four ratio at 5 min was significantly (P < 0.05) smaller in patients who received vecuronium (29.1 [17.9-55.3] microg/kg) (mean [95% confidence interval]) compared with those who received cisatracurium (53.7 [31.6-131.5] microg/kg). Given its faster clinical onset and greater sensitivity to antagonism by neostigmine, we conclude that vecuronium may be more suitable than cisatracurium for use in outpatient anesthesia. IMPLICATIONS: We investigated the onset of muscle relaxation using intravenous vecuronium and cisatracurium and assessed the ability of neostigmine to antagonize (reverse) this effect. Our results suggest that vecuronium works faster than cisatracurium and is more sensitive to neostigmine. Vecuronium therefore may be more useful than cisatracurium in outpatient anesthesia.