Nutritionist > Equine
Endophytes
Fescue is a pasture plant, which is normally quite hardy. The plant may become infected by endophytes which can then produce ergot alkaloids (ergopeptine alkaloids). Horses suffering from endophyte fescue toxicity may have a poor appetite, lose weight/condition, reduced performance, have a rough coat and develop an elevated temperature.
Endophytes may also have negative effects on the reproductive system of mares, as mares are sensitive to alkaloid concentrations as low as 300-500ppb. Common symptoms of ergot alkaloid poisoning in pregnant mares are.
- Extended gestation to 12 months
- Dystocia
- Red bag delivery
- Thick oedematous placentas
- Weak/dead foals with aspiration pneumonia
- Difficulty in foals breaking through toughened placenta
- Lack of mammary development or lactation
- Stillbirths
Heavily pregnant mares should be removed from fescue pasture contaminated with endophytes by 300 days of gestation. Two weeks prior to the expected delivery date, mares can be treated with domperidone to reduce the effects of ergot alkaloid toxicity.
Laboratory tests for ergovaline (the ergot alkaloid of fescue toxicity) and lolitrem B (the ergot alkaloid of perennial rye grass) are commonly available for veterinary investigation.
Neotyphodium coenophialum is also an endophyte which causes fescue toxicity by producing ergot alkaloids and it spends its whole life cycle within the plant. N.coenophalium causes dystocia in mares and deaths of perinatal foals.Ryegrass tremorgens causes ryegrass staggers in horses. This endophyte proliferates in hot dry conditions followed by periods of rain. Symptoms of ryegrass staggers include ataxia, head shaking, loss of co-ordination and eventual collapse. Horses that may be standing quietly, when “spooked” can completely over react. Fortunately the neurological effects appear temporary and when horses are removed from the pasture the horse usually returns to normal after a week or so.
These endophytes may be passed from one generation of plants to the next via the seeds. It is important to make sure that purchased seed is endophyte-free prior to seeding pastures for horses.
