Within and between cattle breed susceptibility to larkspur by Ben Green, ARS Poisonous Plant...

Ben Green Poisonous Plant Research Laboratory

Logan, Utah

The Larkspur Problem Cattle losses typically

around 5% and can reach 15%.

Producers move cattle off of the larkspur containing pastures resulting in wasted high quality forage.

Loss of a cow leaves an early-weaned, poor performing calf.

Clinical signs of larkspur poisoning

•Staggering gait. •Muscle trembles. •Collapse to sternal and then lateral recumbency (this can lead to death for various reasons). •Difficulty breathing (rapid and shallow). •Death occurs from neuromuscular paralysis and/or bloat.

Methods of Avoiding Death Losses

Drug treatment.

Neostigmine (0.02 mg/kg body weight) (Green et al., 2009. Am J Vet Res. 70:539-46).

Current management -(T0xic Window) (Pfister et al., 1999. J Nat Toxins. 8:81-94).

Future Management - select animals with decreased susceptibility to poisonous plants (Green et al., 2014. Rangelands. Accepted 10-20-2013).

Grazing Management! 1) Graze early before the larkspur flowers. 2) Remove cattle during the “toxic window”. 3) Graze late in the season when the seed pods begin to shatter.

Toxic Window

Pfister et al., 1999. J Nat Toxins. 8:81-94

Quantitative Measures of Larkspur Toxicity in Cattle

Clinical signs of larkspur toxicity are difficult to measure in cattle.

Staggering gait.

Respiratory depression.

Collapse.

Muscle Weakness The most obvious clinical sign in

poisoned cattle.

Designed a protocol to measure it.

Responses of cattle dosed with two different populations of tall larkspur

D. occidentale Dose (mg/kg BW)

(City, State) Animals (#) Total Alkaloid Y/N (#) Time (min)

Victor, ID (toxic) 8 37.6 (8.8 MSAL) Y (12) 17 ±9.9

Logan, UT (less-toxic) 8 37.6 (0 MSAL) N (12) N.A.

Exercise to Collapse

Cook et al., 2011. Am J Vet Res. 72:706-14.

Larkspur Breed Study

Developed two quantitative measures of larkspur intoxication.

Heart rate.

Time to collapse (muscle weakness).

Evaluating cattle breeds for susceptibility to larkspur intoxication.

Cattle responses to 8 mg/kg MSAL-type alkaloids.

Green et al., 2014. Rangelands. Accepted 10-20-2013

Average time (minutes) to exercise-induced clinical signs of poisoning.

Breed, (number of

animals)

Time to muscle fatigue,

(minutes)

Angus, 21 15.3 ± 3.4

Brahman, 13 9.4 ± 3.3

Line 1, Hereford, 36 8.8 ± 1.8

Holstein, 15 26.8 ± 3.4

Jersey, 14 29.3 ± 2.9

Green et al., 2014. Rangelands. Accepted 10-20-2013

Genomic Analysis Illumina BovineHD

genotyping array.

777,962 polymorphisms across the entire bovine genome.

We are genotyping selected Angus and Hereford individuals.

http://www.cancer.gov/cancertopics/understandingcanc

er/geneticvariation/page13

Conclusions

Neostigmine reverses larkspur poisoning in cattle.

There are more susceptible and less susceptible cattle in every breed.

May be possible to select for less susceptible animals.

Goal of this research is to identify a genetic marker(s) to be used for herd management.

Acknowledgements Dale Gardner, Steve Lee- Chemistry

Isabella McCollum- Cell-Based Assays, Cattle.

Kevin Welch, Zane Davis, Rex Probst, Danny Hansen- Cattle Experiments

Jessie Roper- Larkspur Analysis

Daniel Cook – Larkspur populations