Poisonings in Alpacas Part 1 - Pasture and Weeds
Ragwort
By Elizabeth Paul - Erewhon Alpacas
Historically in Australia, large scale poisonings of domes�c farm animals such as ca�le and sheep usually occurred during droughts, when large herds were being walked to new areas looking for feed. Since they were not yarded, it would have been difficult to quickly move a large flock of hungry or thirsty animals on from undesirable grazing areas or contaminated water sources before losing a number from poisonings. Alpacas are usually kept on rela�vely small acreages and are not usually walked off farm in large groups. Their feedstuffs and water supplies are more or less carefully monitored, so large scale poisonings of the type above are less likely. Nevertheless, they are bought, sold and agisted around the country, and there is poten�al for poisonings on farm from noxious weeds, pasture, and garden plants. The two most well known and most important types of poisoning in alpacas are ryegrass staggers and facial eczema. In both of these types it is not the plant itself which is toxic, but rather the toxins coming from fungus growing on the plants. RYEGRASS STAGGERS Ryegrass staggers is caused by an endophyte fungus, Acemonium lolii which is o�en applied to the grass seed to help reduce insect a�ack and therefore increase plant growth rates. The fungus produces toxic spores which accumulate around the base and seed heads of the grass. In
humid weather, or when the pasture is new ie short, or eaten down low, or seeding, the toxins from the mass of spores may overwhelm the animal’s nervous system. The symptoms are head nodding, staggering, injuries due to loss of coordina�on, inability to rise, and loss of condi�on. The animal must be taken off the affected pasture into dry yarding and fed only dry hard feed and “old” hay, as freshly cut hay/greenstuff from the same paddock is s�ll toxic. The animal may be supported with various nutri�onal supplements, but even if it recovers, it may always show slight nodding/incoordina�on, especially when under stress. Animals vary in their response and some may be more resistant than others to the effects of the toxin. There are low/no endophyte varie�es, and mixed species pastures would have fewer problems than pure ryegrass. Note endophytes on other grasses may also induce staggers reac�ons. FACIAL ECZEMA Facial eczema is the second important fungal toxin disease. It is more common in New Zealand, but has occurred in parts of Australia as well, par�cularly in irriga�on areas. It affects all grazing species but camelids and deer are most strongly affected. The fungus which causes FE is called Pithomyces chartarum. The spores contain a toxin called sporidesmin, a potent liver toxin which also damages the bladder, and reduces milk yield. It causes photosensi�za�on by blocking the bile ducts, which has the effect of pu�ng bile salts into the system; the animal becomes jaundiced and then 45
