TOXICOLOGY AND SNOW STORMS

TOXICOLOGY AND SNOW STORMS No snow in itself is relatively nontoxic however we often have toxic effects of livestock as the result of snow storms. The reason is cattle eat what is sticking out of the snow and is available. The taller plants that are out there in a snow storm are the ones that have not been grazed. These plants tend plants of low palatability, lower nutritional value or have toxic substances which discourage grazing. In Eddy County the plant that concerns me the most are Shinnery oak, Mesquite bean, Rayless goldenrod, and broom snake weed. These are all plants that stick up through snow and are available. Shinnery oak is found mostly on the east side of the county in sandy range sites. It is most toxic in a 30 day period in the spring when the buds are formed and leaves are immature. Freezing of young Shinnery oak leaves causes an increase the toxin content in the leaf. The plant has some toxins all year around so in the winter there is toxic content in the leaves as well the stems but is lower than when actively growing. It is toxic to all livestock. All oaks contain tannic acid and most likely other toxins. The toxicity is low and losses usually occur only when oak is eaten almost exclusively, such as in drought or heavy snows cover other forage. Feed exclusively on oak cause impaction of the rumen, constipation, which is exasperated when water is not available and snow is the source of water. Cattle pass small amounts of hard brownish black pelleted feces that later changes to diarrhea contain blood and mucous. Prevention is the only alternative there is no cure. Insuring other forage is best. Supplemental feeding of 3 pounds per head per day with alfalfa hay if forage is scarce or covered with snow. A high protein feed that containing hydrated lime can prevent or minimize tannic acid poisoning but cannot cure it. Mesquite like Shinnery is only a problem when it is feed upon almost exclusively. The mesquite bean is a high protein sources but complication occur with impacted rumen. It appears to also contain substances that make it addictive to cattle. Cattle forced upon mesquite bean due to snow will feed exclusively upon even when other forage becomes available. Unfortunately cattle will gain weight immediately after feeding on beans but can months after the bean have been consumed the rumen quits working they become gaunt and emaciation. Carcasses are found with a ball of beans in the rumen. Adding soap to the diet helps prevent this. Rayless Goldenrod, alkali weed, jimmyweed, is similar in that it is a wood half shrub that is 1 to 3 feet tall or so. All parts of the plant are toxic and it is toxic all year around. All classes of livestock are subject to poisoning. When a sub-acute dosage is consumed cow, mare or ewe the toxin is passed to the offspring through the milk. The offspring may die before the mother because of dosage to weight ratio. Animal have to feed on 1.5% of their body weight for a 2 to 3 week period. The toxic substance is an alcohol called tremetol. The disease is called trembles because the muscular trembling or twitching after exercise. This trembling is particular around lips, nose, withers or hips. The animal will stand humped up almost like hardware disease, and have a stiff gate. Eventual the animal will not want to move and be unable to rise. There is no cure but your veterinarian may be able to administer treatment which will help. The animal should not be moved but can be feed and watered in place until the tremetol is metabolized. Once it is metabolized the animal can resume normal activity and productivity. Broom Snake weed is similar to Rayless Goldenrod, in that it is a half shrub that is 1 to 2 feet tall, all parts are toxic and it is toxic all year around. However it is often not fatal, but it can be if prolonged forging occurs. The major issue is it induces abortion in livestock. As little as 20 pounds consumed in a week will cause cows to abort as well as retain placenta.100 to 200 pounds consumed in a two week period will cause death to a 1000 pound cow. So cows that were settled will start cycling again after a few months of eating a subacute dosage. Unfortunately when snow cover up many of the shorter, more desirable species of forage, leaving only the taller plants available to livestock is when toxic plants are consumed. Under these conditions, livestock can only be moved to pastures that have fewer toxic plants or fed hay. I hope that we are fortunate this year in that we had a lot of tall grass from adequate moister this past summer. This information can be found in "Livestock-Poisoning Plants of New Mexico Reangelands, by Dr. Chris Allison NMSU CES circulare 531. 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