Prevention of larkspur issues by grazing management.

1. Ben Green
Research Pharmacologist
Poisonous Plant Research Laboratory
Logan, Utah

2. 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.

3. 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.

4. 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.

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

6. 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.

7. Muscle Weakness
 The most obvious clinical sign in
poisoned cattle.
 Designed a protocol to measure it.

8. Cattle responses to 8 mg/kg
MSAL-type alkaloids.
Green et al., 2014. Rangelands. 36:10-15.

9. 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.

10. What’s next?

11. Genomic Analysis
 Illumina 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.

12. Dendrogram of Genotypes from
the Bovine SNPHD array.
Angus
Jersey
Brahman
Holstein
Line 1
Hereford
Analysis by John Keele

13. Cattle responses to 8 mg/kg
MSAL-type alkaloids.
Green et al., 2014. Rangelands. 36:10-15.

14. Manhattan Plot of SNPHD
Genotypes from 44 Steers
Analysis by John Keele

15. 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

16. What’s Next?
 Prospective genomic
study to validate the
marker in Angus Steers.
 Next generation
sequencing to identify
neighboring
polymorphism on BTA4.

17. Conclusions
 There 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.

18. 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