Poisonous Plants That Contaminate Hay and Forages in the Western United States

AND INTRODUCTION In the Western United States poisonous plants are estimated to cost the animal industry more than 200 million dollars annually. The majority of these losses are attributed to livestock grazing on rangelands. Little has been done to determine the costs of livestock poisoned by contaminated feeds which are probably more frequent and costly. Grazing livestock generally avoid eating free standing poisonous plants when there are adequate and acceptable alternative forages. However, feeding pressure, palatability and subsequent poisonings are much different when toxic plants contaminate prepared and stored feeds. Alternatively, under some conditions, safe forages can produce and/or accumulate toxins and poison livestock. Although animal deaths and loss of production is costly, there are additional larger economic losses attributed to decreased product quality and loss domestic and international markets. Identifying toxic plants and recognizing when forages may be toxic is essential in avoiding these problems. To better ensure the quality and safety of prepared and stored forages the objectives of this presentation are to: 1) review some basics of toxic plant identification in forages; 2) introduce common toxins and poisonous plants that are likely to contaminate hay and prepared forages; and 3) identify the conditions when feeds are likely to be contaminated. SAMPLING AND PLANT IDENTIFICATION Many toxic plants are exotic, noxious weeds that invade pastures and fields and many have the potential to be harvested with the desired forage. These plants are often weedy in nature, their growth is not uniform, and the subsequent contamination is patchy. Additionally, the nature of harvesting and storing forages smashes, fractures, ensiles and possibly cooks fragile plant parts resulting in destruction of many of the characteristic plant structures that are essential for identification. To overcome these problems, adequate sampling is often a herculean task as numerous samples may need to be examined to identify the 4 or 5 contaminated bales from a field of hay. Optimally it is best to inspect fields before the forage is harvested and processed as identification of standing toxic plants is relatively easy. Certainly knowing and identifying all potentially toxic plants can be challenging. Local extension agents and veterinarians are good sources as they are often familiar with local plants and problems. Unknown plants may be 1 Portions including tables and photographs have been published in Rangelands 34:2-11, 2012 2 B.L. Stegelmeier, DVM PhD Diplomat ACVP, USDA/ARS Poisonous Plant Research Laboratory, 1150 East 1400 North, Logan UT 84341 Email: [email protected], Internet Page: www.pprl.ars.usda.gov . In: Proceedings, 2013 Western States Alfalfa and Forage Symposium, Reno, NV, 11-13 December, 2013. UC Cooperative Extension, Plant Sciences Department, University of California, Davis, CA 95616.(See http://alfalfa.ucdavis.edu for this and other alfalfa symposium