Final report for OW20-355
Project Information
Larkspurs (Delphinium spp.) are native plants that grow on foothill and mountain rangelands of western North America and have a long history of poisoning grazing cattle. Ranchers who graze cattle in rangelands with large populations of toxic larkspur often have yearly herd mortalities up to 10%. These losses amount to millions of dollars due to animal deaths, increased management, and veterinary treatment costs.
We propose to compare animals from a herd grazed on larkspur-containing pastures (larkspur-native) to cattle from a herd that has never been exposed to larkspur (larkspur- naive). We hypothesize that fewer larkspur-native animals will be lost to larkspur poisoning than larkspur- naive cattle.
The sourcing of replacement cattle from larkspur-native herds could be a simple and sustainable solution for reducing cattle losses and increase the profitability of cattle production on larkspur-infested rangelands. The results from this study will have regional impacts that will affect producers throughout the western U.S. Livestock death losses cause undo stress on livestock owners and reducing that worry and stress by knowing the livestock that are grazing larkspur-infested rangelands are resistant to the plant alkaloids can help enhance the quality of life for livestock producers.
The outcomes from this study will be disseminated through extension fact sheets, a field day, presented at scientific and producer meetings, and a peer-reviewed publication.
The objective of this study is to test the hypothesis that fewer larkspur-native animals will be lost to larkspur poisoning than larkspur-naive cattle. After the grazing season, surviving cattle will subsequently be tested for larkspur resistance at the PPRL as previously described (Green et al., 2014), to determine their larkspur phenotype and genotype. The phenotypes and genotypes will be incorporated into a genetics of larkspur resistance in cattle study currently underway at the PPRL (genotyping costs will be paid by the PPRL).
To complete this objective, grazing studies will be conducted when larkspur is growing and toxic to cattle (May 1 to October 1). Twenty Angus steers, that have not been preselected due to culling practices, and are naive to larkspur poisoning and twenty Angus steers from ranches that have historically preselected animals, due to culling practices, that are more resistant to larkspur (native) will graze together. Preliminary research (Figure 1) with six larkspur-naive Angus steers from the US Meat Animal Research Center, Clay Center, NE (USMARC) had a shorter exercise times after receiving an oral dose of dried ground larkspur compared to the exercise times of twenty-six larkspur-native Angus steers from Montana that received an oral dose of larkspur. The cattle were exercised 24 hours after the oral dose of dried ground D. barbeyi. Larkspur resistant cattle walk longer than larkspur susceptible cattle because the toxins in larkspur cause muscle weakness and resistance to exercise (Green et al., 2019a).
Year 1 grazing study will occur from May 1, 2020 to October 1, 2020. GPS collars will be place on cattle prior to turning out to graze and removed at the end of grazing. Bite counts will be collected between July 15, 2020 and August 15, 2020. Cattle will be taken to PPRL following the grazing study (October 1, 2020) to test for larkspur susceptibility and genetic testing. The year 2 grazing study will occur from May 1, 2021 to October 1, 2021. GPS collars will be place on cattle prior to turning out to graze and removed at the end of grazing. Bite counts will be collected between July 15, 2021 and August 15, 2021. Cattle will be taken to PPRL following the grazing study (October 1, 2021) to test for larkspur susceptibility and genotyping.
Cooperators
Research
The timeline has been adjusted due to restrictions in travel caused by Covid-19.
Experiment 1: Six larkspur-naïve Angus steers from USMARC (Nebraska), that have not been, or their parents have not been exposed to larkspur, along with six larkspur-native Angus steers from a ranch that due to culling practices, are thought to be more resistant to larkspur, were grazed during the summers of 2022 and 2023. Animals grazed a mountain rangeland infested with duncecap larkspur (Delphinium occidentale) in southeast Idaho. Six pastures (0.97 ha each) were established using electric fence encompassing an area with an abundant larkspur population in 2022 with pastures set up in the same area and the same way for 2023. Six native cattle (356±2 4 kg BW in 2022; 341 ± 11 kg BW in 2023) were randomly assigned to 1 of 3 pastures with two native animals per pasture and six naïve cattle (385±3 6 kg BW in 2022; 374 ± 5 kg BW in 2023) were assigned to 1 of 3 pasture with two naïve animals per pasture. Cattle grazed for a 13-day period in each year. Forage was clipped in each pasture prior to grazing and at weekly intervals to determine forage availability and quality. Bite counts were recorded by forage class (grass, forbs, and larkspur) on each animal to determine diet. Each animal was observed for five minutes before moving to the next animal. Animals were observed during active grazing bouts throughout the day. Larkspur plants were collected on a weekly basis to quantitate the larkspur alkaloid concentration during the grazing study. Blood was collected from animals on a weekly basis to determine alkaloid concentrations in the serum. Bite count data and larkspur alkaloid concentration were analyzed using the GLIMMIX procedure in SAS. Means ± SE were calculated for forage availability and forage quality.
Experiment 2: Data from GPS collars was collected from 13 stocker cattle in 2021, in 2022, and again in 2023. Data from 2021 shows the distribution of cattle on the ranch in northwest Wyoming (Figure 1). GPS collars were placed on stocker cattle during the grazing season of 2023 but have not been retrieved from the livestock producer at this time.
Larkspur locations will be mapped, summer 2024, to determine livestock utilization of larkspur patches. Larkspur plants will be collected at each mapped larkspur patch to determine alkaloid concentration of each larkspur patch and if there is a difference in livestock utilization based on alkaloid concentration.
Experiment 3: Larkspur plants were collected over the growing season, in 2020, 2021, and 2022 to determine alkaloid content of larkspur plants over the growing season at different geographical locations and between two different larkspur species (D. occidentale and D. glaucescens). Larkspur collection started in June 18, 2020, May 3, 2021, and May 17, 2022 and subsequent collections occurred at 3-week intervals, through September 24, 2020, September 1, 2021, and September 20, 2022. Larkspur plants were collected from nine locations (Figure 2).
Four locations were selected near the Peterson ranch, that is utilized by two cooperators, that currently graze stocker cattle and have lost cattle in the past from larkspur poisoning. The first location (P.ranch 1; 44.85426951°;-109.50920815°, 2166 m) was located approximately 51 km northwest of Cody, WY. The second location (P.ranch2; 44.85540863°;-109.53971708°, 2121 m) was located approximately 52 km northwest of Cody, WY. The next two locations were on the same ranch but at higher elevation. The third location (P.ranch 3; 44.92723610°;-109.67780830°, 2334 m) was located 67 km northwest of Cody, WY. The fourth location (P.ranch 4; 44.93322795°;-109.63305998°, 2698 m) was located 64 km northwest of Cody, WY. One location was collected in Idaho (Targhee Pass; 44.68116702°;-111.26860801°, 2117 m) 29 km north of Island Park, ID. Four locations were collected in Montana. The first location (Dillon 1; 45.3589483°; -112.9014000°, 2314 m) located approximately 25 km northwest of Dillon, MT. The second location (Dillon 2; 45.3745650°; -112.89917670°, 2458 m) located approximately 26 km northwest of Dillon, MT. The third location (DooLittle 1; 45.7195617°;-113.3276217°, 1927 m) 77 km northwest of Dillon, MT. The fourth location (DooLittle 2; 45.7175567°; -113.3437150°, 1871 m) located approximately 78 km northwest of Dillon, MT. Ten plants were collected from each location and separated into leaves, stems, and reproductive parts. Plants were placed in a 40° C oven to dry. Larkspur plants were ground, in a Wiley mill to pass through a 1-mm screen. Larkspur plants were then analyzed for alkaloids using a rapid flow injection-electrospray ionization-mass spectrometry (Gardner et al., 2021).
Experiment 1:
2022:
In the grazing study during 2022, forage availability increased from July 11 to July 18 as forage was still growing. It then decreased from July 18 to July 25 as it stopped growing and cattle were consuming forage (Table 1).
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Table 1. Forage availability during the 2022 grazing study (kg/ha ± SE). |
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|
Date |
Grass |
Other forbs1 |
Larkspur |
|
July 112 |
992 ± 81 |
812 ± 57 |
247 ± 39 |
|
July 18 |
1263 ± 104 |
1402 ± 88 |
679 ± 126 |
|
July 25 |
1146 ± 121 |
1007 ± 70 |
565 ± 62 |
|
1All other forbs except for larkspur. Shrubs were not included in forage availability measurements. 2Average of six pastures on each date. |
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Forage quality was greatest at the start of the study and slowly declined as the season progressed (Table 2).
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Table 2. Nutrient content1 (% ± SE) of forage classes on each collection date. |
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|
Date and plant class |
CP |
NDF |
IVDMD |
|
July 11 |
|
|
|
|
Larkspur |
12.8 ± 0.34 |
33.7 ± 0.85 |
84.5 ±0.65 |
|
Grasses |
8.7 ± 0.25 |
63.5 ± 0.46 |
74.4 ± 0.63 |
|
Other forbs |
13.3 ± 0.33 |
35.6 ± 0.91 |
82.0 ± 0.84 |
|
July 18 |
|
|
|
|
Larkspur |
12.8 ± 0.40 |
34.9 ± 0.89 |
81.7 ± 0.82 |
|
Grasses |
8.4 ± 0.24 |
67.9 ± 0.42 |
73.7 ± 0.52 |
|
Other forbs |
12.5 ± 0.28 |
37.5 ± 1.51 |
77.9 ± 0.70 |
|
July 25 |
|
|
|
|
Larkspur |
9.9 ± 0.36 |
37.1 ± 0.98 |
77.7 ± 0.98 |
|
Grasses |
8.3 ± 0.28 |
67.1 ± 0.46 |
61.5 ± 0.76 |
|
Other forbs |
11.9 ± 0.27 |
38.8 ± 0.87 |
76.4 ± 0.78 |
|
1All concentrations are on a DM basis. All analysis were done on clipped forage samples collected to determine forage availability. CP = crude protein, NDF = neutral detergent fiber, IVDMD = in vitro dry matter digestibility. |
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Methyllycaconitine (MLA) is the toxic alkaloid in larkspur. There was a difference in MLA concentration in larkspur plants during the 2022 season (P = 0.0039). MLA increased from July 11 to July 18 and then decreased July 25 (Figure 3).
Cattle preferred grass at the start of the 2022 grazing season and consumption of grass decreased as the season progressed (Figure 4; P < 0.001). Consumption of other forbs increased as the season progressed (Figure 4; P < 0.001). There was no difference in utilization of grasses or forbs between native or naïve cattle (P > 0.60).
Naïve cattle consumed more larkspur (3 ± 0.4% of diet; Figure 4; P = 0.001) than native cattle (1 ± 0.2%) during the 2022 grazing study.
2023:
In the grazing study during 2023, forage availability increased from July 17 to July 24 as forage was still growing. It then decreased from July 24 to July 31 as it stopped growing and cattle were consuming forage (Table 3).
|
Table 3. Forage availability in 2023 (kg/ha ± SE). |
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|
Date |
Grass |
Other forbs1 |
Larkspur |
|
July 172 |
973 ± 113 |
1228 ± 88 |
258 ± 39 |
|
July 24 |
1305 ± 115 |
1918 ± 128 |
483 ± 128 |
|
July 31 |
1024 ± 126 |
1340 ± 91 |
284 ± 42 |
|
1All other forbs except for larkspur. Shrubs were not included in forage availability measurements. 2Average of six pastures on each date. |
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Forage quality along with MLA analysis of larkspur plants are being processed in the lab and results are currently not available.
Cattle preferred grass at the start of the 2023 grazing season and consumption of grass decreased as the season progressed with a substantial decrease between July 23 and 24 (Figure 5; P < 0.001). Consumption of other forbs increased as the season progressed with a large increase from July 23 to July 24 (Figure 5; P < 0.001). There was no difference in utilization of grasses or forbs between native or naïve cattle (P > 0.77).
There was a tendency for native cattle to consume more larkspur (3.2 ± 0.7% of diet; Figure 5; P = 0.009) than naïve cattle (0.8 ± 0.2%) during the 2023 grazing season (Figure 5; P = 0.09).
In conclusion, naïve cattle consumed more larkspur than native cattle during the 2022 grazing season however, the opposite was observed during the 2023 grazing season with native cattle consuming more larkspur than naïve cattle. More of the native cattle showed signs of intoxication during the 2022 grazing season with no difference between treatment groups observed during the 2023 grazing season. Both plant and animal factors make larkspur toxicity a complex issue. The results from this study indicate that larkspur toxicity is more complex than simply identifying animals that are not going to graze larkspur or are not susceptible to larkspur toxicity.
Experiment 2: GPS collars were placed on stocker cattle during the grazing season of 2021, 2022 and 2023. Collar data, from 2021 and 2022, has been downloaded and processed and overlayed onto a map of the study site (Figure 1 and 6). Collar data, from 2023, has not been downloaded at this time. Vegetation maps will be created using ArcGIS software so that the collar data can be overlaid onto the vegetation map to determine grazing patterns in larkspur infested areas. GPS collars will be placed on stocker cattle for a fourth year (2024) because some of the collars have been lost and fewer animals with data are available at this time.
Experiment 3: Larkspur plants have been collected over the growing season, in 2020, 2021, and 2022 to determine alkaloid content of larkspur plants over the growing season at different geographical locations and between two different larkspur species (D. occidentale and D. glaucescens). Total and MLA alkaloid concentrations were measured in D. occidentale and D. glaucescens plants from 5 locations across Montana, Idaho, and Wyoming (Figure 2). Plants were collected during vegetative, bud, flower, pod, and shattered pod growth stages each year. MLA and total alkaloid concentrations are greatest early in plant growth stages in both D. occidentale and D. glaucescens (Figure 7, 8). Concentrations of MLA were greater in D. glaucescens than D. occidentale early in the season. Alkaloid concentrations decrease throughout the season as the plant matures. Alkaloid concentrations are high in the reproductive plant parts during the pod stage.
Alkaloid concentrations of larkspur vary across geographic locations (Figure 9).
Both D. occidentale and D. glaucescens are toxic throughout the growing season. At the shattered growth stage, plants are senesced but plants that contain pods are still toxic. Caution should be taken when larkspur plants are present within these geographic locations.
Research Outcomes
Both plant and animal factors make larkspur toxicity a complex issue. Results from this study, along with previous research, indicate that larkspur toxicity is complex and it may not be possible to identifying animals that are not going to graze larkspur.
Results from this study, along with previous research, indicate that larkspur is toxic throughout the growing season. Larkspur alkaloids are at the highest concentration early in vegetative growth and decrease as the season progresses. However, palatability is lowest during the early vegetative growth stages and increases as the plants mature. Cattle should avoid grazing larkspur when it is in the flower and pod stages of growth as this is often when cattle are typically poisoned from larkspur.
Education and Outreach
Participation Summary:
In 2020, two agricultural professionals consulted with a livestock producer and his ranch hand in regard to livestock losses to larkspur. In 2021, a meeting was held at Peterson ranch near Cody, WY in which two agricultural professionals met and consulted with 3 Forest Service personnel, 1 University of Wyoming extension personnel, and 13 ranch personnel to discuss losses that can occur due to larkspur poisoning and how to potentially avoid livestock losses.
Oral presentation of larkspur information at the Central Utah Grazing Expo in Richfield, Utah on October 18, 2022, to 50 livestock producers and government agency personnel. Oral presentation of larkspur information at the Central Utah Grazing Expo in Price, Utah on October 19, 2022, to 45 livestock producers and government agency personnel.
Poster presentation “Does cattle selection matter? Testing larkspur-native vs larkspur-naïve cattle to reduce death losses on larkspur infested rangelands” at the Society of Range Management 76th annual meeting in Boise, Idaho on February 14, 2023, with 1500 meeting attendees including college students, livestock producers, extension personnel, government agency personnel and college professors.
Oral presentation “Geographical and seasonal variation in larkspur alkaloids” at the Society of Range Management 76th annual meeting in Boise, Idaho on February 14, 2023, with 100 college students, livestock producers, extension and government agency personnel in the room.
Oral presentation of larkspur research at the Wyoming state section of Society of Range Management 2023 annual meeting in Laramie, Wyoming on November 30, 2023, with 150 college students, livestock producers, extension and government agency personnel present.
Producers reported gaining knowledge, attitude, skills and/or awareness as a result of the project.
Central Utah Grazing Expo in Richfield, Utah on October 18, 2022, 60% of attendees reported an increase in knowledge gained and 40% reported no change in knowledge.
Central Utah Grazing Expo in Price, Utah on October 19, 2022, 77% of attendees reported an increase in knowledge gained and 23% reported no change in knowledge.
Poisonous plant booth at the Society of Range Management 76th annual meeting trade show in Boise, Idaho. Trade show was held from February 12th to 14th. Presented information on larkspur and other poisonous plants with 1500 meeting attendees including college students, livestock producers, extension personnel, government agency personnel, and college professors.
Engaged and informed 20+ producers, that contacted the Poisonous Plant Research Lab, on livestock poisoning from larkspur.
Education and Outreach Outcomes
We were asked, by livestock producers, if larkspur toxicosis causes a change in basal diet consumption by cattle. We conducted a research trial to answer the question and the results have been published in a peer review journal.
Stonecipher, C.A., Green, B.T., Welch, K.D., Gardner, D.R., Cook, D. 2023. Larkspur toxicosis alters basal diet intake by cattle. Applied Animal Science 39:257-263.
The article was chosen by the editor-in-chief of Applied Animal Science as Editor's Choice for that issue.