Gary D. Manners

Tall Larkspur Ingestion: Can Cattle Regulate Intake Below Toxic Levels

Tall larkspur (Delphinium barbeyi) is a toxic forb often consumed by cattle on mountain rangelands, with annual fatalities averaging about 5%. This study examined the relationship between food ingestion and toxicity in cattle. Two grazing studies suggested that larkspur consumption above 25–30% of cattle diets for one or two days led to reduced larkspur consumption on subsequent days. We subsequently hypothesized that cattle can generally limit intake of larkspur to sublethal levels. This hypothesis was tested by feeding a 27% larkspur pellet in experiment 1. Cattle given a 27% larkspur pellet ad libitum showed distinct cyclic patterns of intake, where increased larkspur consumption on one or two days was followed by reduced (P < 0.025) consumption on the following day. The amount of larkspur (mean 2007 g/day; 17.8 mg toxic alkaloid/kg body wt) consumed was just below a level that would produce overt signs of toxicity. Experiment 2 was conducted to examine cattle response to a toxin dose that varied with food intake. Lithium chloride (LiCl) paired with corn ingestion was used as a model toxin, and we hypothesized that if increased (decreased) consumption was followed by a stronger (weaker) dose of LiCl, cattle would show a transient reduction (increase) in corn intake. There was no difference (P > 0.05) between controls and treatment animals at the 20 or 40 mg LiCl/kg dose in the percentage of corn consumed, but the 80 mg LiCl/kg dose induced a cyclic response (mean 46%) compared to intake by controls (mean 96%) (P < 0.001). At the 80 mg/kg dose, LiCl induced an aversion to corn; when corn intake decreased on subsequent days and LiCl dose also decreased, cattle responded by increasing corn intake and apparently extinguishing the transient food aversion. Experiment 3 was similar to the LiCl trial, except that tall larkspur was the toxin. Cattle responded to oral gavage of ground larkspur with distinct cycles; days of higher corn consumption were followed by one to three days of reduced consumption. Corn intake for controls was higher (P < 0.01) than for larkspur-treated animals (means 84 and 52%, respectively; day × treatment interaction P < 0.01). The threshold for toxic effects on corn intake was 14 mg toxic alkaloid/kg body weight. In conclusion, cattle apparently limit ingestion of some toxins so that periods of high consumption are followed by periods of reduced consumption to allow for detoxification. Cyclic consumption generally enables cattle to regulate tall larkspur consumption below a toxic threshold and allows cattle the opportunity to safely use an otherwise nutritious, but toxic, plant.

Toxic alkaloid concentration in tall larkspur species in the western U.S.

Larkspur (Delphinium spp.) kills more cattle on mountain rangelands in the western U.S. than any other plant, disease or predator. The concentration of toxic alkaloids was measured in 4 larkspur species, at 10 locations, at 2-week intervals during the growing season. In addition, multi-year samples from previous studies were analyzed to determine year-to-year variation in toxic alkaloids. Mountain larkspur (D. glaucum Wats.) had the highest concentration of toxic alkaloids averaged over growth stages (1.01% of dry weight), tall, (D. barbeyi (L.) Huth) and waxy larkspur (D. glaucesens Rydb) were intermediate (0.65 and 0.49% respectively), and duncecap (D. occidentale S. Watts) was lowest (0.29%). Toxic alkaloid concentration generally declined as the plants matured. However, toxic alkaloids in tall larkspur at Yampa, Colo. increased slightly in the pod stage, and toxic alkaloids in waxy larkspur increased from the vegetative to the bud stage. Concentration of toxic alkaloids in tall and duncecap larkspur leaves were higher in plants growing in open sunlight than those shaded under aspen or conifer canopy. Toxic alkaloid concentration varied among individual plants (C.V. 20-60%). Knowledge of the toxic alkaloid concentration of larkspur populations can be used to predict the risk of larkspur poisoning.

Effects of phenology, site, and rumen fill on tall larkspur consumption by cattle.

AbStlBCt Tall I8rkspur (De~hinh burbeyj) is a m8jor cause of livestock death on mount8in ranges. The influence of plant phenoiogy, grazing site, 8nd rumen fill on tall lukapur consumption ~8s evaluated during July 8nd August, 19%7. Livestock consumption of l8rkspur ~8s determined using bite counts during 4 phenologierrl st8ges: bud, e8riy flower, flower, and pod. Further, we ex8mined i8rkspur ingestion in a shaded tree site 8nd in UI open sun site 8t 0, 50, urd 100% rumen fill levels using rumiarlly c8nnuUed steers. Steers on the 0, 50,8nd 100% fill levels consumed 9,15, and 17% Irrkspur, respectively (fiO.15). ,There ~8s 8 site effect (-0.06) with steers eating 17 8nd 11% lukspur in the shade and sun sites, respectively. Over the summer, iukspur comprised 6% of cattle diets. No llukspur ~8s consumed during the bud st8ge. Larkspur consumption pe8ked at 10% of c8ttie diets during the pod strge. Lepves of t8ii larkspur contrined >3% total 8lk8loids (dry weight) in erriy July, but declined greatly with matwtion. Lukspur ~8s very nutritious, with crude protein levels 12 to 20%, and fiber levels <20% during most of the summer. C8ttie diets, as determined with esopbnge8lly flstul8ted animals, were also high in crude prottin 8nd low ia fiber during the summer. We propose a toxic window hypdbesisn~g~~~~~mdtoxidty.Thishypo~~ predicts th8t most c8ttie losses will occur during the flowering st8ge. We found tbrt t8ll iukspur ~8s unp8l8t8bie to c8ttie from the bud st8ge until the flowering r8cemes hrd eiong8ted, md then consumption generally incre8sed with pl8nt nmtmntion. Even though p8l8tPbility md consumption lncrersc during the gr8zing season, c8ttle c8n graze tall I8rkspur with a much lower risk of toxicosis when toxicity is low lrter in the gruing se8eon.

Transformations of geraniol in aqueous acid solutions

Abstract Geraniol decomposition in aqueous oxalic acid yields twenty-three identified products, most of which retain the oxidation level of geraniol and result from simple hydration and proton-transfer reactions. However, a large quantity of the reduced alcohol, citronellol, is formed along with cymenol, the oxidation product of α-terpineol, indicating that hydride ion transfer reactions play a major role in these terpene alcohol interconversions.

Cattle grazing tall larkspur on Utah mountain rangeland.

Ingestion of t8ll lukspur (De@hinizun barb@ L. Huth) is a mr]or eruse of crttle datb on nagea where the plant occurs. The amount 8nd timing of WI larkspur ingestion by gazing cattle ~8s studied from 30 July to 2 September 1986 on high mount8in mngelrnd in centrrrl Ut8h. Fork dombuted the vegctrtion urd were 8lso the major dietary item selected by c8ttb 070% of total bites). There w8a 8 negative rel8tionship (r=-O.62) between st8nding crop of other forba urd t8ll hrkapur consumption. C8ttle beg811 eating subst8ntirl qu8ntitiee (X0% of bites) of WI lukspur 8bout 10 August, 8nd consumption b8d iacreued to 20% when the study ended. Tall lukspur Ie8ves 8nd pods were the m8jor prrtr selected. At the time of major consumption, leaves were rel8tively low 8nd declining in tot81 8lk8loid concentr8tion (TAC) (1.046%) while pods were 8pproximrtely 1.0% TAC 8nd iacrcdng when the study ended. Time spent per feeding st8tion (TFS) WY influenced by the veget8tion ue8 where urinals tonged. TFS in the gmss-forb, cumnt (Ribes spp.), md lukspur 8re8a were 11.2,25.9, ind 22.0 I, respectively. C8ttle gmzed most efficiently (bite ntetiep rite) in the gr8ss-forh ue8s, urd lcllst effkiently in the curr8nt ueas. C8ttle 8te large quint&a of till lukspur during the study with no de8thr, probrbly due to the low alkaloid levels in the trll lukspur. L8rkspur coneumption ~8s not correlrted with previous 12or 24-h precipit8tion toWs. However, crrffle did hegba major consumption of WI Lrkspur 8fter 2 r8in showers fell following a seveml week dry period.

Isoflavones of the heartwood of dalbergia retusa

Abstract Ether extracts of the heartwood Dalbergia retusa yield two crystalline isoflavones, identified by degradation, spectra, and synthesis as 7,8-dihydroxy-4′-methoxyisoflavone (retusin) and 7-hydroxy-8,4′-dimethoxyisoflavone (8-O-methylretusin).

Quinonoid constituents of Dalbergia retusa heartwood

Abstract Light petrol. extracts of Dalbergia retusa heartwood yield major quantities of obtusaquinone and minor amounts of the blue-black quinhydrone of racemic 4-methoxy-dalbergione.

Biogenetic-type syntheses of isoprenoid and diisoprenoid derivatives of orcinol

Abstract The products formed by condensation of orcinol with 2-methyl-3-buten-2-ol, with geraniol, and with linalool in aqueous solutions of organic acids have been separated and identified. C-isoprenyl- and C-geranyl-orcinols are obtained as major products. Minor amounts of the corresponding hydrates, chromans, chroman hydrates, and hexahydroxanthene derivatives are also formed.

Additional flavanoids in Gliricidia sepium

Abstract A chromatographic examination of the acetone extractives of the moderately marine bore resistant Panamanian wood Gliricidia sepium has resulted in the isolation and characterization of three new flavanoid constituents: an isoflavone, a dihydroflavonol and a β-hydroxydihydrochalcone. These new flavanoids are not related to the marine bore resistance of the wood.

The hydroquinone terpenoids of Cordia alliodora

Six new geranyl-hydroquinone-derived compounds have been isolated from the acetone extract of Cordia alliodora heartwood and characterized. The structural character of these compounds allows the proposal of a detailed bio-genetic pathway to the geranyl-hydroquinone and geranyl-benzoquinone constituents of Cordia sp.