Date of Award:


Document Type:


Degree Name:

Master of Science (MS)


Agricultural Systems Technology and Education

Committee Chair(s)

Darwin B. Nielsen


Darwin B. Nielsen


Locoweed poisoning, caused by ingestion of certain species of Astragalous and Oxytropis, has had serious economic impacts through a loss of productivity in livestock. This study has attempted to evaluate losses suffered by livestockmen grazing their cattle on areas infested with locoweed species. The results indicate a serious economic impact on these individuals.

Personal interviews were carried out with five cattle ranchers faced with typical locoweed problems. These beef cattle operations were located in Utah, Wyoming, and New Mexico. All of these producers described similar problems and losses due to locoweed poisoning. Information obtained from these interviews was used to estimate a 1978 dollar loss for three ranches, running in common, and located near Park Valley, Utah.

This study found the problem areas to be: (1) reduced weaning weights of calves; (2) increased requirements in the number of replacement heifers; (3) an increase in death loss; (4) reproductive problems (abortions and infertility); and (5) increased costs associated with labor and management problems. The summation of economic losses in each of these problem areas reflected a total estimated loss of $30,689.02 in 1978.

To determine if locoweed poisoning had long-range effects on weight gains, a sample of 20 calves were put on a 138-day feeding experiment. Of these 20 calves, 12 had grazed a locoweed-infested area, while the remaining 8 had no access to the plant. Overall average gain of both groups was found to be nearly identical. This indicates that animals will recover with proper but, sometimes, costly management.

Profitability of spraying locoweed-infested ranges with 2,4-dichlorophenoxy acetic acid (2,4-D) was determined through information supplied by the Wyoming rancher. An internal rate of return of 39.4 percent was found by using this method of locoweed control in this particular instance.

Ranchers interviewed in this study estimated their losses due to locoweed poisoning to be from 30 to 40 percent reduction in profit. Although profit margins were not determined, the estimated loss of $30,689.02 found in this study would be close to their determination. With the rampant increase in operating costs which have occurred in the past decade, producers could not long endure losses of this magnitude. However, it was determined that with proper plant control and management these losses could be substantially reduced.