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.     

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.     

Influence of Both Endophyte Infestation in Fescue Pastures and Calf Genotype on Subsequent Feedlot Performance of Steers

Three experiments were conducted to determine the influence of both the concentration of endophytic fungus infestation in tall fescue pastures and calf genotype on the subsequent health and performance of steers in the feedlot. In Exp. 1 and 2, Angus steers grazed fescue pastures in Georgia containing low, moderate, or high endophyte infestations for 182 d (Exp. 1) or 78 d (Exp. 2) with 12 steers per treatment. Steers were transported 1,600 km to Texas in October (Exp. 1) and July (Exp. 2), were fed a 93% concentrate diet during the finishing period, and were harvested at an estimated backfat thickness of 12 mm. In both trials, DMI over the entire feeding period and carcass characteristics were not affected (P>0.05) by endophyte infestation. In both trials, pasture ADG decreased, and feedlot ADG and gain to feed ratio increased as the previous pasture endophyte infestation increased (P<0.05). Serum cholesterol concentrations tended (P<0.10) to decrease with increasing endophyte infestation during the first 14 d in the feedlot. In Exp. 3, Angus and Brahman × British crossbred steers grazed fescue pastures in Georgia containing low, moderate, or high endophyte in each of 2 yr. Six steers of each breed group were on each treatment each year. Steers were transported to Texas in late August of each year, were fed a 93% concentrate finishing diet, and were harvested at an estimated individual backfat thickness of 12 mm. As endophyte infestation increased, serum urea N concentrations and gain to feed ratios increased (P<0.05), whereas pasture ADG, initial BW, transit shrink, serum cholesterol concentrations, final BW, and carcass weights decreased (P<0.05) in Angus steers, but not in Brahman-cross steers. In these studies, the adverse effects of high endophyte infestations in fescue pastures appeared to carry over to the feedlot for ca. 14 d. However, steers from highly infested pastures can compensate for poor pasture performance with improved performance in the feedlot when no adverse health effects occur. Any impact of the endophyte seems to be similar in Brahman-cross and Angus steers.     

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.     

Growth rate and physiology of steers grazing tall fescue inoculated with novel endophytes

Cattle grazing tall fescue (Festuca arundinacea Schreb.) often develop fescue toxicosis. This condition is thought to be caused by ergot alkaloids produced by the endophyte Neotyphodium coenophialum. Endophytes from wild tall fescue plants, which do not produce ergot alkaloids, were transferred into the endophyte-free tall fescue germplasm, HiMag. The novel associations also lacked the ability to produce ergot alkaloids. Our objective was to determine whether cattle grazing these novel endophyte associations showed signs of fescue toxicosis. At the Fayetteville, Arkansas location, tester steers (n = 72) were assigned to one of four pasture treatments: endophyte-free HiMag tall fescue (HiMag-); 'Kentucky-31' tall fescue infected with its native, toxic endophyte (KY+); and two novel endophyte-infected tall fescue associations, HiMag4 and HiMag9. At the Mount Vernon, Missouri location, steers (n = 54) were used to test three of the four cultivars (HiMag9 was not tested). Ergot alkaloid concentrations in the forage of HiMag4 and HiMag9 were low or undetectable. Respiration rate, rectal temperature, ADG, and hair scores were measured during the grazing period. Blood was collected via jugular venipuncture and used for prolactin, aspartate aminotransferase, alkaline phosphatase (ALP), lactate dehydrogenase (LDH), cholesterol, triglyceride, and creatinine analysis. Weight gains by steers grazing HiMag4 and HiMag9 did not differ from those of steers grazing HiMag-, but were greater than gains (P < 0.05) by steers on the KY+ treatment. Steers grazing KY+ had higher (P < 0.05) respiration rates, rectal temperatures, and hair scores than did steers grazing novel endophyte and HiMag- pastures. Prolactin, ALP, cholesterol, LDH, and triglycerides all were suppressed (P < 0.05) in steers grazing KY+ compared with steers grazing novel endophyte and HiMag- pastures. Steers grazing the novel endophyte tall fescues did not suffer from the decreased weight gains and toxicities associated with fescue toxicosis, resulting in enhanced animal production.     

Performance, body composition and carcass characteristics of finishing steers as influenced by previous forage systems

To evaluate effects of previous forage systems on feedlot performance, yearling Hereford steers (average initial weight of 249 kg) were grazed on tall fescue (TF), smooth bromegrass-red clover (BG-RC) or orchardgrass-red clover (OG-RC) pastures before finishing. Serial slaughter was utilized during the first 2 yr of this study to determine changes in carcass characteristics throughout finishing, while steers were slaughtered at approximately 29% body fat during the third year. Steers grazing TF entered the feedlot at lighter weights and maintained lighter weights throughout finishing (P less than .05) even though dry matter intakes and feed conversions were similar (P greater than .05) among treatments. Steers that previously grazed TF had less (P less than .05) body fat, body protein, fat thickness and marbling, smaller (P less than .05) ribeye areas and lower (P less than .05) USDA yield and quality grades than than those that grazed BG-RC and OG-RC. However, linear contrasts indicated that steers grazing TF were compensating in ribeye area, marbling and quality grade as days in feedlot increased. This was confirmed in the third-year study, since carcass characteristics were similar among all steers. During the third year, linear and quadratic contrasts indicated that steers that grazed TF partially compensated in body protein. As days in feedlot increased, live and hot carcass weights, body fat, fat thickness, kidney, pelvic and heart fat, marbling, and USDA yield and quality grades increased (P less than .05), while ribeye area and body protein plateaued. Although carcass characteristics were similar among treatments, steers backgrounded on TF entered the feedlot at lighter weights, and partially compensated in weight after 134 d of finishing.     

Use of nonergot alkaloid-producing endophytes for alleviating tall fescue toxicosis in stocker cattle

Grazing studies were conducted to determine cattle growth performance, evaluate toxicosis, and compare grazing behavior in stocker cattle grazing nonergot alkaloid-producing endophyte-infected (AR542 or AR502), endophyte-free (E-), or wild-type toxic endophyte-infected (E+) Jesup, Georgia-5, and Kentucky-31 tall fescue. Replicated 0.81-ha tall fescue paddocks were established at the Central Georgia Branch Station at Eatonton and the Northwest Georgia Branch Station at Calhoun during October 1998 and were stocked with beef cattle for autumn and spring periods from fall 1999 through spring 2002. Mean ergot alkaloid concentrations were higher (P < 0.01) on E+ pastures than the other treatments at both locations. At Calhoun and Eatonton, post-treatment serum prolactin concentrations were decreased (P < 0.01) on E+ compared with AR542, AR502, and E- tall fescue. Cattle on AR542, AR502, and E- pastures had lower (P < 0.05) post-treatment rectal temperatures than cattle grazing E+ tall fescue during spring at Eatonton and Calhoun. Calf ADG was higher (P < 0.05) on AR542, AR502, and E- as compared with E+ tall fescue during autumn and spring grazing at Eatonton, and at Calhoun, cattle on E+ pastures had lower (P < 0.05) ADG in both autumn and spring. Gain/hectare was higher (P < 0.05) on AR542, AR502, and E- than on E+ during autumn at Eatonton and during spring at both locations. In autumn at Calhoun, gain/hectare was greater (P < 0.05) on AR502 and E- compared with E+ tall fescue. During April, May, and June, cattle grazing E+ pastures at Eatonton spent more (P < 0.01) time idling, more (P < 0.01) time standing, and used more (P < 0.01) water than cattle on AR542 and E- tall fescue. Daily prehensions and biting rate were each higher (P < 0.01) on AR542 and E- tall fescue than E+ tall fescue in both grazing seasons. There were no differences among pasture treatments for bite size in either spring (P = 0.50) or autumn (P = 0.34). Steers grazing E+ pastures had lower DMI than steers grazing AR542 and E- pastures during spring (P < 0.10) and lower DMI than steers grazing E- pastures during autumn (P < 0.05). Daily steer water usage was decreased (P < 0.10) in E+ pastures compared with AR542 and E- pastures during late fall. These results indicate that nonergot alkaloid-producing endophyte technology is a promising option for alleviating tall fescue toxicosis in stocker cattle.     

Productivity of cow-calf pairs grazing tall fescue pastures infected with either the wild-type endophyte or a nonergot alkaloid-producing endophyte strain, AR542

The nonergot alkaloid-producing endo-phyte, AR542, has been shown to improve the persistence and yield of tall fescue pastures without causing the animal disorders commonly associated with tall fescue toxicosis. A 3-yr grazing study was conducted to compare effects of AR542-infected tall fescue pastures with wild type endophyte-infected (E+) tall fescue pastures on cow-calf performance. Replicated 7.3-ha pastures of each treatment were grazed by cow-calf pairs (16 pairs per pasture replication) each year from March to weaning in September. The cows were exposed to breeding on their respective pasture treatments from April 1 through June 15. The treatment groups were compared for reproductive performance, ADG, BCS, calf growth rate, and weaning weight. Blood samples were also collected for serum prolactin (PRL) analysis. There were no significant differences in calving rate (P = 0.98) or calving interval (P = 0.62) between pasture treatments. Cows that grazed the AR542 pastures subsequently gave birth to calves that were heavier (P < 0.05) than calves from cows that had grazed the E+ pastures. Cows grazing the AR542 pastures had higher (P < 0.05) BCS at the end of the grazing period, and had higher ADG during the grazing period. Calves raised on the AR542 pasture had higher (P < 0.05) ADG and weaning weights than calves of the same sex raised on the E+ pastures. Serum PRL concentrations were decreased (P < 0.05) in both cows and calves on the E+ pastures compared with serum PRL concentrations in cows and calves grazing the AR542 pastures. The results indicate that grazing tall fescue pastures infected with the AR542 endophyte may give significant advantages in cow-calf growth rates and BCS over grazing E+ pastures. However, there did not seem to be any benefit in reproductive performance in this trial. There was a small, but significant increase in birth weight in cows grazing AR542 pasture.     

Steer and pasture responses for a novel endophyte tall fescue developed for the upper transition zone

A 2-yr grazing experiment was conducted with crossbred steers (8 to 10 mo and with initial BW of 304 kg ± 34 kg in 2008 and 277 kg ± 24 in 2009) to evaluate animal performance and pasture responses of a late maturing tall fescue [Lolium arundinaceum (Schreb.) Darbysh; KYFA9301] population infected with the AR584 novel, non-toxic endophyte (Neotyphodium coenophialum; NE9301) as compared with Kentucky 31 fescue infected with the common toxic endophyte strain (KY31), 'Jesup' MaxQ fescue infected with the AR542 endophyte (MaxQ), and endophyte-free KYFA9301 (EF9301). Treatments were assigned for seeding in 1.0-ha pastures in a randomized complete block design with 3 replications. Pastures were grazed from 6 May to 23 July in 2008 (76 d) and 2 April to 25 June in 2009 (84 d). Each pasture was grazed with 4 tester steers and put-and-take steers were used to maintain forage mass at 2,500 ± 250 kg DM/ha. Shrunk BW was taken at initiation and termination of grazing each year. Rectal and skin temperatures were recorded, and jugular blood was collected each year at approximately d 28, 56, and study completion. Forage samples were collected at 2-wk intervals for analyzing CP, IVDMD, ADF, and NDF. Responses were analyzed with mixed models, and preplanned orthogonal contrasts were used to compare KY31 with non-toxic fescues, EF9301 vs. novel endophyte fescues, and NE9301 vs. MaxQ. All steer responses were similar (P > 0.10) among the non-toxic fescues. Average daily gains and total BW gain/ha for the 3 non-toxic fescues were greater (P < 0.001) than for KY31. Rectal/skin temperatures for the 3 non-toxic fescues were less (P < 0.001) and serum prolactin concentrations were greater (P < 0.01) than for KY-31. Pasture carrying capacity was greater (P = 0.003) for KY31 than the 3 non-toxic fescues and was greater for EF9301 (P = 0.017) than the 2 novel endophyte fescues. However, stocking rates (kg BW/ha) at the initial and midpoint days of grazing were similar (P > 0.40) among endophyte-fescue combinations, but by the end of the grazing season, stocking rate was greater (P < 0.001) for KY31 than for the non-toxic fescues and was greater (P = 0.053) for NE9301 than for MaxQ. Results indicated that NE9301 is as effective as EF9301 and MaxQ in improving BW gain and alleviating fescue toxicosis and that NE9301 can provide greater carrying capacities than MaxQ in late June and July.     

Effect of level of endophyte infection, nitrogen fertilization rate, grazing period, and paddock exchange on some chemical properties of four bovine tissues.

Three grazing experiments were conducted to determine the effect of level of endophyte infection, rate of N fertilization of tall fescue grass, grazing period, and paddock exchange on selected chemical properties of four bovine carcass tissues. Samples of semitendinosus and longissimus muscle and of subcutaneous and perinephric adipose tissue were excised from the left side of each carcass. In Exp. 1, percentage of stearic acid was higher (P less than .05) and percentages of palmitoleic and oleic acid were lower (P less than .05) in all tissues from steers grazed on LELN Au-Triumph fescue than in tissues from steers grazed on LELN KY-31 fescue. Grazing periods of 175 or 245 d or paddock exchange (Exp. 2) had no significant effect on proximate composition of semitendinosus and longissimus muscles; however, moisture content was higher (P less than .05) in the semitendinosus muscle from steers grazed on 100% (100E) endophyte-infected KY-31 fescue. Forage treatment, grazing period, and paddock exchange (Exp. 2 and 3) had no significant effect on percentage of saturated fatty acids in the subcutaneous, semitendinosus, and longissimus tissue samples. In Exp. 2 and 3, percentages of saturated fatty acids were higher (P less than .05) in subcutaneous and perinephric adipose tissue samples from steers grazed on 100E than in samples from steers grazed on zero endophyte (OE) fescue.(ABSTRACT TRUNCATED AT 250 WORDS)     

Behavior of steers grazing monocultures and binary mixtures of alfalfa and tall fescue.

Spectral analysis was used to relate dietary quality and herbage species to the behavior of grazing steers. Four .3-ha paddocks were established with either 'AU-Triumph' tall fescue (F; Festuca arundinacea Schreb.), 'Apollo' alfalfa (A; Medicago sativa L.), 1/3 fescue and 2/3 alfalfa (2/3A), or 2/3 fescue and 1/3 alfalfa (1/3A). Each paddock was stocked with 10 to 16 steers and defoliated in 5 d. Three steers on each paddock carried vibracorders to monitor grazing time. Daily forage samples were taken in 10-cm layers and weighed. Esophageal extrusa were collected from fistulated steers to measure diet quality. Daily grazing time did not differ (P = .37) among treatments; however, steers grazing mixtures grazed numerically longer (1.4 h/d) than steers on monocultures. Spectral analysis revealed that steers grazing A and 2/3A had many daily meals of short duration, but steers grazing 1/3A and F consumed three meals daily at 8-h intervals. Throughout the 4.67-d grazing period, quality of the diet linearly declined in crude protein and herbage digestibility, linearly increased in neutral detergent fiber and cellulose, and exhibited quadratic changes in lignin and ash. For most quality values, the tall fescue monoculture differed from the others (P < .05). Steers selected diets with similar quality for the A, 2/3A, and 1/3A treatments. This study illustrates how differences in forage diets alter grazing behavior of steers.     

Effects of implants on daily gains of steers wintered on dormant native tallgrass prairie, subsequent performance, and carcass characteristics

Fall-weaned crossbred steer calves (n = 300; 184 +/- 2.9 kg) received either no implant (Control) or were implanted with Synovex-C (SC = 10 mg estradiol benzoate + 100 mg progesterone), Synovex-S (SS = 20 mg estradiol benzoate + 200 mg progesterone), or Revalor-G (RG = 8 mg estradiol-17beta + 40 mg trenbolone acetate) to determine the effects of implants on weight gain during winter grazing on dormant tallgrass prairie, subsequent grazing and finishing performance, and carcass characteristics. Steers grazed two dormant tallgrass prairie pastures from October 16, 1996, until March 29, 1997 (164 d), and received 1.36 kg/d of a 25% CP supplement that supplied 100 mg of monensin/steer. Following winter grazing, all steers were implanted with Ralgro (36 mg zeranol) and grazed a common tallgrass prairie pasture until July 17 (110 d). After summer grazing, all steers were implanted with Revalor-S (24 mg estradiol-17beta + 120 mg trenbolone acetate), and winter implant treatment groups were equally allotted to four feedlot pens. Steers were harvested November 17, 1997, after a 123-d finishing period. Daily gains during the winter grazing phase averaged .28, .32, .32, or .35 kg/d, respectively, for Control, SC, SS, or RG steers and were greater (P < .01) for implanted steers than for Controls. Summer daily gains were similar (1.05 +/- .016 kg/d; P > or = .61) for all treatment groups. Feedlot daily gains were also similar (1.67 +/- .034 kg/d; P > or = .21), with implanted steers weighing 14 kg more than Control steers (P = .05) at harvest, despite similar management during summer grazing and feedlot phases. Control steers tended (P = .06) to have lower yield grades. There were no differences (P = .99) in marbling between implanted and nonimplanted steers. Steers implanted during the wintering phase had increased skeletal and overall (P < .01) carcass maturities compared with nonimplanted steers, which resulted in more "B" and "C" maturity carcasses. Because carcass maturity score affects quality grade, the increased maturities of implanted steers resulted in a $9.04 decrease in carcass value/100 kg (P < .01) compared with Controls. The results of this study indicate that growth-promoting implants are efficacious for cattle wintered on dormant native range despite low daily gains. This increased weight is maintained through the summer grazing and feedlot phases; however, the benefit of the increased weight may be offset by decreased carcass quality grade and value due to increased carcass maturity.     

Effect of endophyte type on carcass traits, meat quality, and fatty acid composition of beef cattle grazing tall fescue

Fourteen Hereford steers were used to compare carcass traits, meat quality, and fatty acid composition of beef from cattle grazing tall fescue infected with either wild-type (E+; n = 6) or novel, nil ergot alkaloid (AR542; n = 8) endophyte for 209 d. Average daily gain, live weight, and HCW were greater (P < 0.05) for AR542 cattle than for E+. No differences in LM color or pH were observed between AR542 and E+. Steaks from E+ cattle tended (P = 0.10) to have higher L* and b* than those from AR542 cattle at 0 d of display. Ground beef from E+ cattle also had higher (P < 0.05) L* than AR542 cattle, with no differences in a* or b* at 0 d of display. Color changes during display did not differ for both steaks and ground beef from E+ and AR542. Lipid oxidation levels increased (P < 0.05) during simulated retail display, but they did not differ between endophyte treatments. Adipose tissues from E+ cattle had a higher (P < 0.05) percentage of SFA, and a lower (P < 0.05) percentage of MUFA than adipose from AR542 cattle. Ground beef and i.m. fat had higher (P < 0.05) concentrations of SFA, MUFA, and cis-9, trans-11 isomer of conjugated linoleic acid, and lower (P < 0.05) concentrations of PUFA and PUFA:SFA ratio than s.c. fat. The n-6:n-3 fatty acid ratio did not differ among fat depots. Ergot-alkaloids were detected in s.c. adipose tissues, and alkaloid concentration was greater (P < 0.05) for E+ than AR542. Warner-Bratzler shear force values did not differ between endophyte types, but it decreased (P < 0.01) across the postmortem aging period. Conversely, sensory panel evaluation detected greater (P < 0.01) chewiness and lower (P < 0.05) juiciness for AR542 than for E+ steaks aged for 14 d. Although grazing cattle on tall fescue pastures infected with nil ergot alkaloid endophyte improved cattle performance, these results suggest that endophyte type has minor effects on carcass traits and meat quality of pasture-fed beef. Moreover, finishing cattle on tall fescue pastures showed the potential to enhance the fatty acid profile of beef from a human health perspective. Alkaloid concentration was greater (P < 0.05) in s.c. fat from E+ than AR542 (2.81 vs. 0.92 ppb; fresh-tissue basis). This is the first published report demonstrating the presence of alkaloids in beef tissues.     

Animal performance and economic comparison of novel and toxic endophyte tall fescues to cool-season annuals

Increased costs of annual establishment of small grain pasture associated with fuel, machinery, and labor are eroding the profitability of stocker cattle enterprises. Interest has therefore increased in development of cool-season perennial grasses that are persistent and high quality. This study occurred on 24 ha (divided into thirty 0.81-ha paddocks) located at the University of Arkansas Division of Agriculture Livestock and Forestry Branch Station, near Batesville. Two tall fescue (Festuca arundinacea Schreb.) cultivars infected with novel endophytes (NE), Jesup infected with AR542 endophyte (Jesup AR542), and HiMag infected with Number 11 endophyte (HM11) were established in September 2002. Jesup AR542 and HM11 were compared with endemic endophyte Kentucky 31 (KY-31) tall fescue; wheat (Triticum aestivum L.) and cereal rye (WR, Secale cereale L.) planted in September 2003, 2004, and 2005; and annual ryegrass [RG, Lolium perenne L. ssp. multiflorum (Lam.) Husnot] planted in September 2004 and 2005. Each year, 3 steers (3.7 steers/ha) were placed on each pasture for fall and winter grazing, and 5 steers (6.2 steers/ha) were placed on each pasture for spring grazing. Animal performance is presented by year in the presence of a year x treatment interaction (P < 0.01). Body weight gain per hectare of steers grazing NE tall fescue was greater (P < 0.01) than those of KY-31 and WR during 2003 to 2004, whereas in 2004 to 2005, BW gain per hectare of steers grazing NE and RG did not differ (P < or = 0.29) and was greater (P < 0.01) than that of WR, which was greater (P < 0.01) than that of KY-31. During 2005 to 2006, BW gain per hectare was greater (P < 0.01) for steers grazing RG than those of NE and WR, which did not differ (P > or = 0.14). Body weight gain per hectare was least (P < 0.01) for steers grazing KY-31. Average net return of NE tall fescue was greater (P < 0.01) than KY-31, but profitability of NE did not consistently differ from cool-season annuals. Across the 3-yr study, NE tall fescue produced net returns per hectare of $219; this level of profitability would require 4 yr for a new planting of NE tall fescue to break even. Novel endophyte tall fescues offer potential benefits related to decreased risk of stand establishment of annual forage crops, longer growing season, and acceptable animal performance.     

Influence of protein supplementation and implant status on alleviating fescue toxicosis

Heat stress is a major problem in transporting stocker calves with symptoms of fescue toxicosis. Removing calves from tall fescue pastures and offering diets devoid of endophyte-infected tall fescue could reduce the severity of toxicosis and precondition calves for transport to the feedlot. In the present experiment, a pasture phase was used to condition yearling steers to grazing tall fescue and induce symptoms of fescue toxicosis, and a pen phase followed to determine effects of implanting at the start of grazing and protein supplementation (hay only vs hay plus supplement) on short-term changes in rectal temperature and serum prolactin concentration. Neither implant status nor protein supplementation affected (P > 0.10) white blood cell count or rectal temperature. White blood cell counts at the conclusion of the pasture phase averaged 8,778 cells/microL and were within a range indicating no immunological response. Changes in rectal temperature and serum prolactin concentration during the pen phase were not influenced (P > 0.10) by implanting or supplementation. Initial rectal temperatures for the pen phase were high (39.9 degrees C) but declined linearly (P < 0.001) over the first 106 h and were below a normal temperature (39.2 degrees C) by 82 h following removal from tall fescue pastures. Serum prolactin gradually increased (P < 0.001) to a peak by 82 h and stabilized thereafter. Results indicate that neither supplemental protein nor an estrogenic implant influenced recovery indices of fescue toxicosis, whereas removing calves from tall fescue pastures and excluding dietary tall fescue for 3 to 4 d may alleviate symptoms of fescue toxicosis.     

Growing steers grazing high versus low endophyte (Neotyphodium coenophialum)-infected tall fescue have reduced serum enzymes, increased hepatic glucogenic enzymes, and reduced liver and carcass mass

It is well established that grazing Neotyphodium coenophialum-infected forages results in reduced BW gain and serum prolactin concentrations of cattle. The objective of this study was to determine the potential effects of toxic endophyte-infected tall fescue consumption on blood metabolites, carcass characteristics, and content of proteins critical for AA metabolism in the liver, kidney, and LM tissue of growing steers. Steers grazed a low toxic endophyte (LE; 0.023 microg/g ergot alkaloids) tall fescue-mixed grass pasture (n = 9; BW = 266 +/- 10.9 kg; 5.7 ha) or a high toxic endophyte (HE; 0.746 microg/g of ergot alkaloids) tall fescue pasture (n = 10; BW = 267 +/- 14.5 kg; 5.7 ha) from June 14 through at least September 11 (> or =89 d). No difference was observed for BW (P < 0.10) for the overall 85-d growth period. Also, no differences were observed for ribeye area/100 kg of HCW (P > 0.91), backfat (P > 0.95), or backfat/100 kg of HCW (P > 0.67). However, ADG (P < 0.01), final BW (P < 0.05), HCW (P < 0.01), dressing percentage (P < 0.01), ribeye area (P < 0.01), whole liver wet weight (P < 0.01), and whole liver wet weight/100 kg of end BW (P < 0.01) were greater for LE steers than HE steers. After 85 d of grazing, serum concentrations of alkaline phosphatase (P < 0.05), alanine aminotransferase (P < 0.01), aspartate aminotransferase (P < 0.03), cholesterol (P < 0.01), lactate dehydrogenase (P < 0.01), and prolactin (P < 0.01) were less for HE than LE steers. At slaughter, hepatic content of cytosolic phosphoenolpyruvate carboxykinase (P < 0.01) was greater in HE steers than LE steers. Hepatic content of aspartate aminotransferase (P < 0.01) also was greater, whereas renal and LM content were not (P > or = 0.42). No differences (P > or = 0.15) were observed for hepatic, renal, and LM content of alanine aminotransferase, glutamate dehydrogenase, glutamine synthetase, and 3 glutamate transport proteins. These data indicate that the HE steers displayed classic endophyte toxicity symptoms for growth and blood variables, classic symptoms that were concomitant with novelly identified altered glucogenic capacity of the liver and decreases in carcass characteristics.     

Tasco supplementation: effects on carcass characteristics, sensory attributes, and retail display shelf-life

Two hundred crossbred cattle (Bos indicus x Bos taurus) were supplemented with 2% Tasco (Ascophyllum nodosum) in a commercial finishing facility to evaluate marbling score, USDA quality grade, sensory traits, and retail display shelf life. Treatment animals (n = 100) received a steam-rolled corn (Zea mays)-based diet containing 2% Tasco meal (DM basis), for 14 d beginning at d 45 of the finishing period and again 14 d before slaughter. Control animals (n = 100) received a steam-rolled corn (Zea mays)-based diet without Tasco at identical feeding periods. Carcasses from Tasco-fed cattle exhibited greater marbling scores (P = 0.003) than controls. There were no treatment effects (P > 0.05) on sensory, shear, or purge attributes of striploin or inside round steaks with the exception of inside round steaks from Tasco animals having a greater initial tenderness (P = 0.03) and lower off-flavor score (P = 0.002) than control steaks. The LM samples from Tasco-fed cattle had a greater percentage of ether extractable fat (P = 0.001) and lower percentage of protein (P = 0.001) than controls. Inside round samples from treated animals exhibited a greater percentage of moisture (P = 0.03) than control steaks. Visual lean color of striploin steaks was not affected by Tasco supplementation (P = 0.26); however, steaks from Tasco-treated animals were more uniform and had less discoloration and browning than those from controls (P = 0.005, 0.04, and 0.05, respectively). Inside round visual scores and instrument values reflected similar treatment responses (P < 0.05), with a majority of the effects on muscle redness (CIE a*, hue angle) and measures of discoloration. Tasco steaks were generally more red and less discolored during extended postmortem aging and retail exposure (P < 0.05). The results from this study indicate that short-term supplementation of 2% Tasco meal in feedlot cattle increases carcass quality and prolonged retail shelf life.     

Alterations in serotonin receptor-induced contractility of bovine lateral saphenous vein in cattle grazing endophyte-infected tall fescue

As part of a 2-yr study documenting the physiologic impact of grazing endophyte-infected tall fescue on growing cattle, 2 experiments were conducted to characterize and evaluate effects of grazing 2 levels of toxic endophyte-infected tall fescue pastures on vascular contractility and serotonin receptors. Experiment 1 examined vasoconstrictive activities of 5-hydroxytryptamine (5HT), α-methylserotonin (ME5HT; a 5HT(2) receptor agonist), d-lysergic acid (LSA), and ergovaline (ERV) on lateral saphenous veins collected from steers immediately removed from a high-endophyte-infected tall fescue pasture (HE) or a low-endophyte-infected mixed-grass (LE) pasture. Using the same pastures, Exp. 2 evaluated effects of grazing 2 levels of toxic endophyte-infected tall fescue on vasoconstrictive activities of (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI), BW 723C86 (BW7), CGS-12066A (CGS), and 5-carboxamidotryptamine hemiethanolate maleate (5CT), agonists for 5HT(2A),( 2B), 5HT(1B), and 5HT(7) receptors, respectively. One-half of the steers in Exp. 2 were slaughtered immediately after removal from pasture, and the other one-half were fed finishing diets for >91 d before slaughter. For Exp. 1, maximal contractile intensities were greater (P < 0.05) for steers grazing LE pastures than HE pastures for 5HT (73.3 vs. 48.9 ± 2.1%), ME5HT (52.7 vs. 24.9 ± 1.5%), and ERV (65.7 vs. 49.1 ± 2.6%). Onset of contractile response did not differ for 5HT (P = 0.26) and ERV (P = 0.93), but onset of ME5HT contraction was not initiated (P < 0.05) in HE steers until 10(-4) compared with 10(-5) M in LE-grazing steers. For Exp. 2, maximal contractile intensities achieved with DOI were 35% less (P < 0.05), whereas those achieved with 5CT were 37% greater (P < 0.05), in steers grazing HE pastures. Contractile response to CGS did not differ between pasture groups, and there was an absence of contractile response to BW7 in both groups. There were no differences between endophyte content in contractile responses after animals were finished for >91 d. Experiment 1 demonstrated that grazing of HE pastures for 89 to 105 d induces functional alterations in blood vessels, as evidenced by reduced contractile capacity and altered serotonergic receptor activity. Experiment 2 demonstrated that grazing HE pastures alters vascular responses, which may be mediated through altered serotonin receptor activities, and these alterations may be ameliorated by the removal of ergot alkaloid exposure as demonstrated by the absence of differences in finished steers.     

Voluntary intake and ingestive behavior of steers grazing Johnstone or endophyte-infected Kentucky-31 tall fescue.

Effects of grazing low-endophyte (Acremonium coenophialum Morgan-Jones and Gams, less than 1% infection) Johnstone (J) or high-endophyte (60% infection) Kentucky-31 (K) tall fescue (Festuca arundinacea Schreb.) on grazing behavior and voluntary intake were studied. Six Angus steers (average initial BW = 326 kg) grazed 1.21-ha plots of each forage cultivar (three steers per cultivar) in four 28-d periods beginning May 27. Daytime observations (0630 until 2130) revealed that J steers spent more (P less than .10) time grazing and lying down and took more (P less than .05) prehensile bites than K steers did; conversely, steers grazing K spent more (P less than .10) time standing and idling than J steers did. Idling time showed a forage x period interaction (P less than .10). Mean OM bite size (grams per bite) was not affected (P greater than .10) by forage but differed (P less than .10) among periods. Limited nighttime observations (2130 until 0630) revealed no effects (P greater than .10) of forage on grazing time or number of prehensile bites taken. Voluntary intakes of OM and NDF did not differ (P greater than .10) between steers grazing J and K; however, a forage x period interaction (P less than .10) existed such that, during Period 1, steers grazing J had greater (P less than .01) OM and NDF intakes than did steers grazing K. These data suggest that cattle grazing endophyte-infected tall fescue display altered daytime grazing behavior and that reduction of voluntary intake attributable to endophyte infection may be less severe under free-grazing than has been reported for controlled environmental conditions.     

Growth Performance and Serum Prolactin Concentrations of Stocker Steers Implanted with Trenbolone Acetate While Grazing Endophyte-Infected Fescue in the Spring

A 64-d grazing study was conducted with a 2 × 2 factorial arrangement of treatments to evaluate the impact of implant treatment on growth performance, hair score, and serum prolactin levels of steers grazing tall fescue with high (HE) or low (LE) levels of infection with the endophytic fungus Neotyphodium coenophialum. Mixed-breed steers (n = 130; 246 ± 3.5 kg initial BW) were allocated randomly to one of three HE or one of four LE pastures beginning April 13. Within each replication, one-half of the steers were implanted (IMP) with trenbolone acetate (40 mg) and estradiol (8 mg), and one-half were not implanted (NI). No implant treatment × endophyte level interactions were detected (P>0.10). Steers grazing HE had lower (P<0.01) BW gain, inferior (P<0.05) hair scores, and lower (P<0.01) serum prolactin concentrations on d 64 than those steers grazing LE. Total BW gains were greater (P=0.01) from IMP steers than from NI steers, but serum prolactin concentrations and hair scores did not differ (P>0.10) between IMP and NI steers on either d 36 or 64. When tabulated across forage and implant treatments, correlations were negative between overall BW gains and hair scores measured on d 64 (r = 0.28; P<0.01), and positive between overall BW gains and serum prolactin levels measured on d 36 and 64 (r = 0.33 and 0.43, respectively; P<0.001). Therefore, fescue toxicity symptoms were manifested in HE steers, and implanting trenbolene acetate and estradiol improved grazing BW gain, but no endophyte level × implant interactions were detected.