• Alkaloids as anti-quality factors in plants on western U.S. rangelands

      Pfister, J. A.; Panter, K. E.; Gardner, D. R.; Stegelmeier, B. L.; Ralphs, M. H.; Molyneux, R. J.; Lee, S. T. (Society for Range Management, 2001-07-01)
      Alkaloids constitute the largest class of plant secondary compounds, occurring in 20 to 30% of perennial herbaceous species in North America. Alkaloid-containing plants are of interest, first because alkaloids often have pronounced physiological reactions when ingested by livestock, and second because alkaloids have distinctive taste characteristics. Thus, alkaloids may kill, injure, or reduce productivity of livestock, and have the potential to directly or indirectly alter diet selection. We review 7 major categories of toxic alkaloids, including pyrrolizidine (e.g., Senecio), quinolizidine (e.g., Lupinus), indolizidine (e.g., Astragalus), diterpenoid (e.g., Delphinium), piperidine (e.g., Conium), pyridine (e.g., Nicotiana), and steroidal (Veratrum-type) alkaloids. Clinically, effects on animal production vary from minimal feed refusal to abortion, birth defects, wasting diseases, agalactia, and death. There are marked species differences in reactions to alkaloids. This has been attributed to rumen metabolism, alkaloid absorption, metabolism, excretion or directly related to their affinity to target tissues such as binding at receptor sites. In spite of alkaloids reputed bitter taste to livestock, some alkaloid-containing plant genera (e.g., Delphinium, Veratrum, Astragalus, Oxytropis, and Lupinus) are often readily ingested by livestock. Management schemes to prevent losses are usually based on recognizing the particular toxic plant, knowing the mechanism of toxicity, and understanding the temporal dynamics of plant alkaloid concentration and consumption by livestock. Once these aforementioned aspects are understood, losses may be reduced by maintaining optimal forage conditions, adjusting grazing pressure and timing of grazing, aversive conditioning, strategic supplementation, changing livestock species, and herbicidal control.
    • Cattle and Sheep Diets Under Short-duration Grazing

      Ralphs, M. H.; Kothmann, M. M.; Merrill, L. B. (Society for Range Management, 1986-05-01)
      Studies have shown a negative relationship between stocking rate and animal performance in conventional grazing systems. However, short-duration grazing (SDG) proponents state that stocking rates can be increased and still maintain acceptable animal performance by reducing the length of stay on a pasture. The objective of this study was to determine if sheep and cattle diet quality could be maintained in SDG as stocking rates increased from the level recommended for moderate continuous grazing to 2.67 times the recommended level. Small pastures ranging from 1.68 ha to .47 ha were fenced to give the desired stocking rates. Pastures were grazed 3 days and rested 51 days. Diets were collected from esophageally cannulated sheep and cattle during the 3-day grazing periods. Botanical composition of diets was determined and crude protein and IVOMD were analyzed to estimate diet quality. As live green forage was depleted diet selection shifted to reserve forage resulting in a decline in diet quality as stocking rate increased in pastures where reserve forage was abundant during the cool season. There were few shifts in diet selection and diet quality where vegetation was more homogenous and lacked reserve forage. Grazing pressure declined during the warm season in all pastures due to above-average forage production. Only cattle diets showed a decline in digestibility as stocking rates increased and diet selection switched from mature warm-season grass to reserve forages. Diet quality declined within the short 3-day grazing periods and the decline was greater at the higher stocking rates.
    • Cattle diets in tall forb communities on mountain rangelands

      Ralphs, M. H.; Pfister, J. A. (Society for Range Management, 1992-11-01)
      Thirteen grazing studies have recently documented diet botanical composition of cattle in tall forb plant communities on mountain rangelands. In forb-dominated plant communities, cattle selected forbs in proportion to their availability, (46 to 83% of their diets). In grass-dominated communities, forbs comprise only 11 to 32% of diets. On a landscape scale cattle preferred and spent proportionally more time grazing in forb-dominated communities. Taken together, these studies indicate that cattle have a wide acceptability for forage classes and can effectively utilize forb-dominated high mountain rangelands.
    • Cattle grazing tall larkspur on Utah mountain rangeland

      Pfister, J. A.; Ralphs, M. H.; Manners, G. D. (Society for Range Management, 1988-03-01)
      Ingestion of tall larkspur (Delphinium barbeyi L. Huth) is a major cause of cattle death on ranges where the plant occurs. The amount and timing of tall larkspur ingestion by grazing cattle was studied from 30 July to 2 September 1986 on high mountain rangeland in central Utah. Forbs dominated the vegetation and were also the major dietary item selected by cattle (>70% of total bites). There was a negative relationship (r=-0.62) between standing crop of other forbs and tall larkspur consumption. Cattle began eating substantial quantities (>10% of bites) of tall larkspur about 10 August, and consumption had increased to 20% when the study ended. Tall larkspur leaves and pods were the major parts selected. At the time of major consumption, leaves were relatively low and declining in total alkaloid concentration (TAC) (1.0-0.6%) while pods were approximately 1.0% TAC and increasing when the study ended. Time spent per feeding station (TFS) was influenced by the vegetation area where animals foraged. TFS in the grass-forb, currant (Ribes spp.), and larkspur areas were 11.2, 25.9, and 22.0 s, respectively. Cattle grazed most efficiently (bite rate:step rate) in the grass-forb areas, and least efficiently in the current areas. Cattle ate large quantities of tall larkspur during the study with no deaths, probably due to the low alkaloid levels in the tall larkspur. Larkspur consumption was not correlated with previous 12- or 24-h precipitation totals. However, cattle did begin major consumption of tall larkspur after 2 rain showers fell following a several week dry period.
    • Cattle grazing white locoweed in New Mexico: Influence of grazing pressure and phenological growth stage

      Ralphs, M. H.; Graham, D.; James, L. F. (Society for Range Management, 1994-07-01)
      Locoweed poisoning generally occurs in early spring when other forage is dormant or in short supply and locoweed is the main green plant available to grazing livestock. The objective of this study was to estimate the amount of white locoweed (Oxytropis Sericea Nut. ex T&G) consumed by cattle, and to determine if cattle graze locoweed because it is relatively palatable, or if they are forced to graze it because of decreasing availability of other forage. Three grazing trials were conducted that corresponded to the vegetative, flower, and pod phenological growth stages of white locoweed. Four cows were used in Trial 1 (vegetative growth stage), and 7 cows were used in Trials 2 (flower stage) and 3 (pod stage). Pastures were fenced for the 10-day grazing trials, so that forage became limited and grazing pressure increased as the trials progressed. Acceptance of white locoweed at the beginning of each trial, when there was adequate forage, would indicate preference. Rejection of white locoweed at the beginning of the trials, followed by increasing consumption as the trials progressed would indicate that grazing pressure was forcing the cows to select white locoweed. White locoweed was readily accepted by 1 cow in the vegetative trial, and by 2 cows in the flower trial (these cows were termed "loco-eaters"). The remainder of the cows (termed "normal") rejected white locoweed in the vegetative and flower trials until the availability of new growth cool n grasses decreased, after which they started to select white locoweed. AD cows rejected white locoweed at the beginning of the pod trial but consumed it as availability of other plants decreased. Regression analysis showed that grazing pressure was positively associated with ingestion of white locoweed (r2 = .46 to .88) by the "normal" cows.
    • Cattle Grazing White Locoweed: Diet Selection Patterns of Native and Introduced Cattle

      Ralphs, M. H.; Mickelsen, L. V.; Turner, D. L. (Society for Range Management, 1987-07-01)
      Cattle preference for immature white locoweed (Oxytropis sericea Nutt.) seed pods reported in a previous intensive grazing study was confirmed using free-ranging cows under natural grazing conditions. Diets were quantified by bite count. The succulent immature seed pod was palatable and preferentially selected until its supply was exhausted. Locoweed flowers or mature seed pods were not grazed and very few locoweed leaves were consumed. Native cows (born and raised on the range) and introduced 2-year-old replacement heifers (raised in another part of the state with no prior grazing experience with locoweed) consumed similar amounts of locoweed pods.
    • Cattle Grazing White Locoweed: Influence of Grazing Pressure and Palatability Associated with Phenological Growth Stage

      Ralphs, M. H. (Society for Range Management, 1987-07-01)
      Understanding the conditions in which livestock consume poisonous plants is necessary to develop management strategies to reduce losses. Three 10-day grazing trials were conducted to observe consumption of white locoweed (Oxytropis sericea Nutt.) by cattle. The trials corresponded to the phenological growth stages of white locoweed: (1) flower; (2) immature seed pod; and (3) mature seed pod/seed shatter. Six esophageally fistulated Hereford steers were used to collect diet samples. In trial 1, steers selected the locoweed flower only when supplies of grass and other forbs were depleted. In trial 2, steers voluntarily selected the immature pod, which comprised 50% of their diet by the middle of the trial. There was very little consumption of locoweed in trial 3. Few locoweed leaves were consumed throughout the experiment. Immature locoweed pods were palatable and readily selected by cattle. By restricting access at the immature pod growth stage and insuring adequate forage is available at other times, cattle consumption of white locoweed on this site should be minimized.
    • Cattle prefer endophyte-free robust needlegrass

      Jones, T. A.; Ralphs, M. H.; Gardner, D. R.; Chatterton, N. J. (Society for Range Management, 2000-07-01)
      Robust needlegrass (Achnatherum robustum [Vasey] Barkw. = Stipa robusta [Vasey] Scribn.) is a high-biomass rangeland species that is adapted to warmer temperatures and matures later than most cool-season grasses. However, it has been associated with negative animal effects including avoidance. We compared populations of Neotyphodium and P-endophyte-infected endophyte-infected (E+) and endophyte-free (E-) robust needle-grass for animal preference. Leaf blades were fed to yearling heifers in 3 trials of 8-min cafeteria sessions for 4 to 5 days each. Trial 1 (27-30 May) compared E+, E-, basin wildrye (Leymus cinereus [Scribn. Merr.] A. Löve), and tall wheatgrass (Thinopyrum ponticum [Podp.] Barkw. D.R. Dewey). Basin wildrye consumption (425 g) did not differ from tall wheatgrass (342 g), but basin wildrye consumption exceeded E- (258 g), which in turn exceeded E+ (117 g) (16 animal-sessions). Basin wildrye was dropped from Trial 2 because its consumption exceeded that of both E- and E+. In Trial 2 (1-5 June), consumption of E-, E+, and tall wheatgrass did not differ. Tall wheatgrass was dropped from Trial 3 to allow direct comparison of E- and E+. In Trial 3 (13-17 July), consumption of E- (585 g) exceeded E+ (145 g) (15 animal-sessions). In Trial 3, animals often rejected E+ forage before tasting. Discrimination against E+ was greater at the end of Trial 3 than at the beginning. The reputation of robust needlegrass for animal avoidance may be more related to its endophyte infection status than to the grass itself. Differences in forage-quality parameters were not large enough to account for the observed differences in preference. Ergot and loline alkaloids were not found in either E- or E+, therefore they cannot be responsible for the observed avoidance of E+. Non-trace amounts of ergot alkaloids were found only in seed collected in the Sacramento Mountains of New Mexico and not at other locations in New Mexico, Arizona, or Colorado.
    • Cattle preference for 4 wheatgrass taxa

      Jones, T. A.; Ralphs, M. H.; Nielson, D. C. (Society for Range Management, 1994-03-01)
      We compared the preference of cattle for 12 entries, 2 of crested wheatgrass [Agropyron desertorum (Fischer ex Link) Schultes], 5 of thickspike wheatgrass [Elymus lanceolatus (Scribner & J.G. Smith) Gould ssp. lanceolatus], 3 of Snake River wheatgrass (proposed name E. lanceolatus spp. wawawaiensis), and 2 of bluebunch wheatgrass [Pseudoroegneria spicata (Pursh) A. Love] in May 1989 and 1990 at Logan, Utah. Spaced plants were randomly arranged in 4 paddocks which were grazed once by 2 animals in late spring each year. Number of bites and number of visits were recorded for each entry in each paddock for the 2 animals individually. Cattle preferred Hycrest and Nordan crested wheatgrasses both years. Number of bites per plant for crested, thickspike, Snake River, and bluebunch wheatgrasses averaged 9.1, 4.3, 3.1, and 4.1, respectively, in 1989 and 6.7, 3.3, 3.5, and 3.6, respectively, in 1990. Number of visits was highly correlated with number of bites across entries. Grazing preference among entries was more highly correlated with biomass score and canopy height than basal area or maturity. Cattle preferred crested wheatgrass over the native wheatgrasses tested here during the spring grazing season.
    • Cattle preferences for Lambert locoweed over white locoweed

      Ralphs, M. H.; Greathouse, G.; Knight, A. P.; James, L. F. (Society for Range Management, 2001-05-01)
      White (Oxytropis sericea Nutt. in T. G.) and Lambert (O. lambertii var. biglovii Pursh) locoweed grow adjacent to each other on the foothills of the Rocky Mountains from southeastern Wyoming to northeastern New Mexico. Lambert locoweed matures later and flowers about 3-4 weeks after white locoweed, thus potentially increasing the critical period of poisoning when livestock graze areas infested by both species. The objective of this study was to evaluate cattle consumption of these 2 species as they progress phenologically. In 1998, 15 Hereford cows grazed a 32 ha pasture infested with both species from the time white locoweed flowered in mid June until both species were mature and senesced in August. In 1999, 4 cows were placed in a 5 ha pasture infested with both species for 4 days in each of the following periods: (1) flower stage of white locoweed, (2) flower stage of Lambert locoweed, immature pod at white locoweed, (3) immature pod stage of Lambert locoweed, mature pod while (4) mature pod and seed shatter stage respectively. Diets were estimated by bite-count. Lambert locoweed was preferred over white locoweed in the season-long grazing trial in 1998, and in each of the 4 intensive grazing trials in 1999. The cows consumed white locoweed as availability of Lambert locoweed declined in 1998, but little white locoweed was consumed in the 4 intensive grazing trials in 1999. The toxic locoweed alkaloid swainsonine ranged from 0.04 to 0.06% in white locoweed, but was not detected in Lambert locoweed in this study.
    • Clipping and precipitation influences on locoweed vigor, mortality, and toxicity

      Ralphs, M. H.; Gardner, D. R.; Graham, J. D.; Greathouse, G.; Knight, A. P. (Society for Range Management, 2002-07-01)
      White locoweed (Oxytropis sericea Nutt. in TG) is widespread throughout the short-grass prairies and mountain grasslands and causes chronic poisoning of cattle, sheep, and horses. The objective of this study was to determine the effect of clipping (simulated grazing) on vigor, mortality and toxic alkaloid concentration of white locoweed. One hundred locoweed plants were marked at each of 3 locations (New Mexico, Colorado, and Utah). Plants were stratified into 2 age/size classes: young/small < 5 stalks; older/large > 7 stalks (n = 50 in each class). Pairs of plants within each age class that were as similar as possible were selected, and 1 of each pair (n = 25) was clipped at ground level annually for 4 years. Vigor indices included number of stalks, number of flowering heads, leaf length, and flowering head height. Mortality was recorded and the toxic alkaloid swainsonine was measured. Clipping did not consistently reduce vigor. Flowering heads/plant declined in most clipped plants (P < 0.05), but stalks/plant declined only in large clipped plants in Utah and small clipped plants in New Mexico (P < 0.01), and clipping did not greatly affect leaf length or flowering head height. Clipping did not increase mortality, and did not affect swainsonine concentration. However, there was a natural die-off that may have been related to precipitation. There were negative correlations between precipitation and locoweed mortality (r = -0.42 to -0.84), with most of the marked plants dying during the recent drought. Grazing locoweed for short periods would likely not affect its vigor or toxicity, but its population dynamics were affected by drought.
    • Conditioned taste aversion: potential for reducing cattle loss to larkspur

      Lane, M. A.; Ralphs, M. H.; Olsen, J. D.; Provenza, F. D.; Pfister, J. A. (Society for Range Management, 1990-03-01)
      Barbey larkspur (Delphinium barbeyi L. Huth) is a palatable poisonous plant that causes a large number of cattle deaths on mountain rangelands. The objective of the study was to determine whether or not cattle could be conditioned to avoid eating larkspur. Five heifers were conditioned to avoid eating larkspur by intraruminal infusion of lithium chloride whenever they consumed larkspur in a pen feeding trial. Five control heifers were likewise infused with distilled water. Following the conditioning, the heifers were taken to mountain rangeland in central Utah and observed in 1986 and 1987. The non-averted heifers consumed larkspur throughout the 1986 field trial, while the averted heifers generally consumed little larkspur. The aversion from the previous summer persisted as the averted heifers refused to eat larkspur in the first grazing trial in 1987. During the second grazing trial in 1987, the averted heifers were placed in a pasture with non-averted heifers to determine if social influences would affect learned aversions. A rapid breakdown of the aversions was observed and the averted heifers continued consuming larkspur after being separated from non-averted heifers.
    • Continued food aversion: Training livestock to avoid eating poisonous plants

      Ralphs, M. H. (Society for Range Management, 1992-01-01)
      Animals can be trained to avoid eating specific foods by offering them the food and subsequently administering an emetic to induce nausea. The animal associates the taste of the food with the induced illness and subsequently avoids eating that food. Conditioned food aversion (CFA) is a potential tool to prevent livestock poisoning from palatable and abundant poisonous plants. Cattle have been trained to avoid eating tall larkspur (Delphinium barbeyi L. Huth), a particularly troublesome poisonous plant. However, several factors influence the acquisition and retention of food aversions under field grazing conditions. The age and sex of an animal may influence its ability to form and retain aversions. Novelty of the plant and the intensity of the induced illness determine the strength of the aversion. Social facilitation or peer pressure motivates animals to sample the averted food, and the aversion will extinguish if it is not reinforced. Generalizing the aversion created under controlled conditions in a pen, to a complex vegetation community in the field, may be difftcult for some animals. If these obstacles can be overcome, CFA may be an effective tool to reduce the risk of poisoning on poisonous plant infested rangeland.
    • Creating aversions to locoweed in naive and familiar cattle

      Ralphs, M. H.; Graham, D.; Galyean, M. L.; James, L. F. (Society for Range Management, 1997-07-01)
      The objective of this study was to determine if cattle that were familiar with white locoweed (Oxytropis sericea Nutt, ex T&G) could be aversively conditioned to avoid eating it. In the first preliminary trial, we tried to aversely condition native steers that were already eating locoweed. Six of 12 steers were penned, fed fresh-picked locoweed, then dosed via a stomach tube with lithium chloride (LiCl, 200 mg/kg BW). When released into the locoweed-infested pasture, they gradually increased locoweed consumption over the next 5 days. The conditioning procedure was repeated with a lower dose (100 mg/kg BW), but locoweed consumption increased within 10 days until they were consuming as much as the non-averted controls. In the second trial, we compared the strength and longevity of aversion between steers that were familiar with locoweed (n = 6) and naive steers (n = 6). Both groups were averted to locoweed as described in Trial 1 and returned to locoweed-infested pasture. The Familiar group decreased locoweed consumption for the first 2 days, then gradually increased locoweed consumption and extinguished the aversion. The Naive group subsequently refused to graze locoweed. In the third trial, aversions were reinforced following grazing locoweed in the pasture. Three steers from the Familiar group were allowed to graze locoweed for 30 min. periods, then were returned to the pen and dosed with LiCl (100 mg/kg BW). These steers were kept in the pen and allowed to recover for 36 hours. This reinforcement process following grazing was repeated 4 times. Steers in the Reinforced group abstained from eating locoweed when released into the locoweed-infested pasture for the remainder of the trial. Reinforcement of aversions following field grazing of locoweed prevented cattle that were familiar with locoweed from grazing it.
    • Damage from the larkspur mirid deters cattle grazing of larkspur

      Ralphs, M. H.; Jones, W. A.; Pfister, J. A. (Society for Range Management, 1997-07-01)
      The larkspur mirid (Hopplomachus affiguratus) is host specific to tall larkspur (Delphinium barbeyi Huth). These insects suck cell solubles from leaves and reproductive racemes, causing flowers to abort and leaves to desiccate. Cattle generally prefer lark spur flowering heads, pods, and leaves, and are frequently poisoned. The objective of this experiment was to determine if cattle would avoid eating mirid-damaged larkspur. A 2-choice cafeteria feeding trial was conducted to determine preference for mirid-damaged and undamaged larkspur. Four cows were offered a choice of the 2 types of larkspur in 10 min. feeding trials in the morning and evening for 5 days. Cows preferred the undamaged larkspur plants (0.8 kg +/- 0.08, SE) over mirid-damaged plants (0.1 kg +/- 0.03, SE). The cows were then turned out into a larkspur-infested pasture and consumption of mirid-damaged and undamaged larkspur was quantified by bite count. The cows did not select any mirid-damaged larkspur. Consumption of undamaged larkspur peaked at 17% of bites on the second day of the grazing trial, then declined as mirid damage on the plants increased. If the density of mirids on larkspur is sufficiently high to damage most of the leaves and flowering racemes, grazing by cattle may be deterred, and subsequent poisoning avoided.
    • Early season grazing by cattle of tall larkspur-(Delphinium spp.) infested rangeland

      Pfister, J. A.; Ralphs, M. H.; Manners, G. D.; Gardner, D. R.; Price, K. W.; James, L. F. (Society for Range Management, 1997-07-01)
      A series of summer grazing studies were conducted to evaluate cattle consumption of preflowering tall larkspur (Delphinium barbeyi [Huth] or D. occidentale [Wats.] Wats.) on mountain rangeland in Utah, Colorado, and Idaho during 1987 to 1995. Cattle ate little or no larkspur before flowering racemes were elongated. Consumption of tall larkspur by cattle was also generally low during the early flower stage, with some notable exceptions at the Salina and Manti, Utah sites. These grazing studies indicate that risk of losing cattle to tall larkspur is low if plants have not flowered. Even though concentration of toxic alkaloids is typically much higher in immature compared to mature tall larkspur, toxicosis is unlikely to occur because consumption by cattle is low. Many livestock operations can gain 4 to 5 weeks of low-risk grazing on tall larkspur-infested rangeland early in the grazing season, and this should be considered in developing grazing management plans.
    • Ecological relationships between poisonous plants and rangeland condition: A Review

      Ralphs, M. H. (Society for Range Management, 2002-05-01)
      In the past, excessive numbers of livestock on western U.S. rangelands, reoccurring droughts, and lack of management resulted in retrogression of plant communities. Poisonous plants and other less palatable species increased with declining range condition and livestock were forced to eat these poisonous species because of a shortage of desirable forage, resulting in large, catastrophic losses. The level of management on most western rangelands has improved during the last 60 years, resulting in marked improvement in range condition; yet losses to poisonous plants still occur, though not as large and catastrophic as in the past. Some poisonous species are major components of the pristine, pre-European plant communities [tall larkspur (Delphinium barbeyi Huth), Veratrum californicum Durand, water hemlock (Cicuta douglasii (DC.)Coult. Rose), bracken fern (Pteridium aquilinum (L.) Kuhn), chokecherry (Prunus virginiana L.), Ponderosa pine (Pinus ponderosa Lawson), and various oak species (Quercus spp.)]. Although populations of many poisonous seral increaser species have declined with better management, they are still components of plant communities and fluctuate with changing precipitation patterns [locoweed (Astragalus and Oxytropis spp.), lupine (Lupinus spp.), death camas (Zigadenus spp.), snakeweed (Gutierrezia spp.), threadleaf groundsel (Senecio longolobis Benth.), low larkspur (Delphinium nuttallianum Pritz.), timber milkvetch (Astragalus miser Dougl. ex Hook.), redstem peavine (A. emoryanus (Rydb.) Cory), western bitterweed (Hymenoxys odorata D.C.), orange sneezeweed (Helenium hoopesii Gray), twin leaf senna (Cassia roemeriana Schelle), and white snakeroot (Eupatorium rugosum Houtt)]. Many of the alien invader species are poisonous: [Halogeton glomeratus (Bieb.) C.A. Mey, St. Johnswort (Hypericum perforatum L.), poison hemlock (Conium maculatum L.), tansy ragwort (Senecio jacobaea L.), hounds tongue (Cynoglossum officinale L.), leafy spurge (Euphorbia esula L.), yellow star thistle (Centaurea solstitialis L.) and other knapweeds (Centaurea spp.)]. Poisoning occurs when livestock consume these plants because they are either relatively more palatable than the associated forage, or from management mistakes of running short of desirable forage.
    • Economic feasibility of controlling tall larkspur on rangelands

      Nielsen, D. B.; Ralphs, M. H.; Evans, J. O.; Call, C. A. (Society for Range Management, 1994-09-01)
      Larkspur (Delphinium spp.) poisoning of cattle poses a serious economic problem on many western rangelands. Losses varied from 1.5% to 12.3% of the grazing cattle over a 15-year period on the Manti Canyon grazing allotment. Three herbicides and different application methods were compared for control of tall larkspur. The 3 herbicides were: glyphosate [N-(phosphonmethyl) glycine]; picloram (4-amino-3,5,6- trichloro-2-pyridine carboxylic acid); and metsulfuron 2[[[[(4-methyoxy-6-methly-1,3,5-triaxin-2-yl) amino] carbonyl] amino] sulfonyl] benzoic acid. A boom type sprayer and a carpeted roller applicator were tested for the selective herbicides. Spot treatment and backpack sprayers were tested for the nonselective herbicide (metsulfuron). The internal rate of return was used to evaluate the economic feasibility of each alternative control method. A treatment was considered economically feasible if the internal rate of return was equal to or higher than the cost of borrowing money. Each treatment was evaluated for an assumed cattle death loss of 4.5% and 2.25%. A 10-year life was considered for each treatment. All of the herbicides and application methods tested were economically feasible. The internal rates of return varied from 14.23% to 133.38%. An internal rate of return above 100% occurs when the benefits in a single year exceeds the total cost of control. The cost of herbicides have increased considerably over the past few years, but they can still be used economically if treatment results in death loss reductions described in this study.
    • Effects of phenology, site, and rumen fill on tall larkspur consumption by cattle

      Pfister, J. A.; Manners, G. D.; Ralphs, M. H.; Hong, Z. X.; Lane, M. A. (Society for Range Management, 1988-11-01)
      Tall larkspur (Delphinium barbeyi) is a major cause of livestock death on mountain ranges. The influence of plant phenology, grazing site, and rumen fill on tall larkspur consumption was evaluated during July and August, 1987. Livestock consumption of larkspur was determined using bite counts during 4 phenological stages: bud, early flower, flower, and pod. Further, we examined larkspur ingestion in a shaded tree site and in an open sun site at 0, 50, and 100% rumen fill levels using ruminally cannulated steers. Steers on the 0, 50, and 100% fill levels consumed 9, 15, and 17% larkspur, respectively (P=0.15). There was a site effect (P=0.06) with steers eating 17 and 11% larkspur in the shade and sun sites, respectively. Over the summer, larkspur comprised 6% of cattle diets. No larkspur was consumed during the bud stage. Larkspur consumption peaked at 10% of cattle diets during the pod stage. Leaves of tall larkspur contained >3% total alkaloids (dry weight) in early July, but declined greatly with maturation. Larkspur was very nutritious, with crude protein levels 12 to 20%, and fiber levels <20% during most of the summer. Cattle diets, as determined with esophageally fistulated animals, were also high in crude protein and low in fiber during the summer. We propose a toxic window hypothesis relating larkspur palatability and toxicity. This hypothesis predicts that most cattle losses will occur during the flowering stage. We found that tall larkspur was unpalatable to cattle from the bud stage until the flowering racemes had elongated, and then consumption generally increased with plant maturation. Even though palatability and consumption increase during the grazing season, cattle can graze tall larkspur with a much lower risk of toxicosis when toxicity is low later in the grazing season.
    • Grazing behavior and forage preference of sheep with chronic locoweed toxicosis suggest no addiction

      Ralphs, M. H.; Panter, K. E.; James, L. F. (Society for Range Management, 1991-05-01)
      Addiction is commonly cited as a clinical sign of locoweed (Astragalus spp. and Oxytropis spp.) poisoning. In a previous study, ewes progressively poisoned on locoweed ("locoed") in cafeteria trials did not become addicted to locoweed. Following a year of recovery, these ewes were allowed to graze locoweed-infested rangeland to determine if there was any residual preference for, or addiction to, locoweed. Neither the locoed nor control ewes consumed appreciable amounts of locoweed on rangeland where associated forage was succulent and actively growing, and where grazing pressure was sufficiently low to allow selective grazing. There was no residual preference for locoweed in previously locoed ewes. However, locoed ewes often exhibited sudden involuntary seizures when attempting to take a bite of forage. The head would tremble and tuck up under the brisket in a bobbing motion, and eye lids fluttered for a few seconds before the animal was able to proceed in feeding. Biting rate of locoed ewes was about a third less than that of the control ewes (P<.05) , and locoed ewes took fewer bites of grass than the control ewes (P<.01). Physical inhibitiion of feeding caused by the sudden seizures and reduced consumption of coarse forage, which may be more difficult to prehend, may contribute to the persistent emaciated condition and reduced productivity of some locoed animals.