Date post: | 20-Jun-2015 |
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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