Cattle grazing white locoweed in New Mexico: influence of grazing pressure and phenological growth stage.

Author: 
Ralphs, M.H.
Graham, D.
James, L.F.
Publisher: 
Rangeland Ecology & Management / Journal of Range Management Archives
Publication Year: 
1994
Description: 
Locoweed poisoning generally occurs in early spring when other forage is dormant or in short supply and locoweed is the main green plant available to grazing livestock. The objective of this study was to estimate the amount of white locoweed (Oxytropis Sericea Nut. ex T&G) consumed by cattle, and to determine if cattle graze locoweed because it is relatively palatable, or if they are forced to graze it because of decreasing availability of other forage. Three grazing trials were conducted that corresponded to the vegetative, flower, and pod phenological growth stages of white locoweed. Four cows were used in Trial 1 (vegetative growth stage), and 7 cows were used in Trials 2 (flower stage) and 3 (pod stage). Pastures were fenced for the 10-day grazing trials, so that forage became limited and grazing pressure increased as the trials progressed. Acceptance of white locoweed at the beginning of each trial, when there was adequate forage, would indicate preference. Rejection of white locoweed at the beginning of the trials, followed by increasing consumption as the trials progressed would indicate that grazing pressure was forcing the cows to select white locoweed. White locoweed was readily accepted by 1 cow in the vegetative trial, and by 2 cows in the flower trial (these cows were termed "loco-eaters"). The remainder of the cows (termed "normal") rejected white locoweed in the vegetative and flower trials until the availability of new growth cool n grasses decreased, after which they started to select white locoweed. AD cows rejected white locoweed at the beginning of the pod trial but consumed it as availability of other plants decreased. Regression analysis showed that grazing pressure was positively associated with ingestion of white locoweed (r2 = .46 to .88) by the "normal" cows.
Document Type: 
Journal Issue/Article
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Rangeland Ecology & Management (formerly the Journal of Range Management) serves as a forum for the presentation and discussion of facts, ideas, and philosophies pertaining to the study, management, ecology, and use of rangelands and their resources. The journal is peer-reviewed and provides international exchange of scholarly research and information among persons interested in rangelands. The Global Rangelands collection includes REM content up to 5 years from the current year. More recent content is available by subscription from BioOne and the Society for Range Management, and may be available at your local university library.
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