mitigation of larkspur poisoning on rangelands through the selection of cattle

Update: Mitigation of larkspur poisoning on rangelands

through the selection of cattle

Ben GreenResearch Pharmacologist

Poisonous Plant Research LaboratoryLogan, Utah

The Larkspur ProblemCattle 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).

• Death occurs from neuromuscular paralysis and/or bloat.

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

Larkspur Breed StudyDeveloped two quantitative

measures of larkspur intoxication.Heart rate.Time to collapse (muscle

weakness).Evaluating cattle breeds for

susceptibility to larkspur intoxication.

Muscle WeaknessThe most obvious clinical sign

in poisoned cattle.Designed a protocol to

measure it.

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

Green et al., 2014. Rangelands. 36:10-15.

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

Breed, (number of

animals)

Time to muscle fatigue,

(minutes)

Angus, 33 17.2 ± 2.7

Brahman, 13 9.4 ± 3.3

Line 1, Hereford, 48 7.4 ± 1.4

Holstein, 15 26.8 ± 3.4

Jersey, 14 29.3 ± 2.9

Green et al., 2014. Rangelands. 36:10-15.

What’s next?

Genomic AnalysisIllumina Bovine SNPHD

genotyping array.777,962 polymorphisms across

the entire bovine genome.Breed associations currently

using the BovineSNP50 for the calculation of genome enhanced EPDs.

We are genotyping our steers in collaboration with MARC at Clay Center, Nebraska and identifying potential markers for further research.

Dendrogram of Genotypes from the Bovine SNPHD array.

Angus

Jersey

Brahman

Holstein

Line 1 Hereford

Analysis by John Keele

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

Green et al., 2014. Rangelands. 36:10-15.

Manhattan Plot of SNPHD Genotypes from 44 Steers

Analysis by John Keele

Genotype-Phenotype Concordance in Angus

Genotyped susceptible and resistant Angus.

One SNP on BTA 4 is significant in Angus.

In Angus, when 40 minute and zero minute animals are genotyped they are characterized by two alleles of a single marker on BTA 4.

Analysis by John Keele

What’s Next?Prospective genomic

study to validate the marker in Angus Steers.

Next generation sequencing to identify neighboring polymorphism on BTA4.

ConclusionsThere are more susceptible and less

susceptible cattle in every breed.We have identified a genetic marker for

larkspur.Currently validating that marker.May be possible to select for less

susceptible animals.

Acknowledgements Dale Gardner, Steve Lee- Chemistry Isabella McCollum- Cell-Based Assays, Cattle Kevin Welch, Zane Davis, Rex Probst-Cattle

Experiments Jessie Roper- Larkspur Analysis Daniel Cook – Larkspur populations John Keele, Warren Snelling, Larry Kuehn, Tara

McDaneld- Genetics and Genomics Clay Center, NE

Vicki Leesburg- Pedigree analysis Miles City, MT