Influence of Stock Density and Rate and Temporal Patterns of Forage Allocation on the Diet Mixing Behavior of Sheep Grazing Sagebrush Steppe
Document Type
Article
Journal/Book Title/Conference
Applied Animal Behaviour Science
Volume
100
Issue
3-4
Publisher
Elsevier
Publication Date
2006
Recommended Citation
Shaw, R., Villalba, J., & Provenza, F. (2006). Influence of stock density and rate and temporal patterns of forage allocation on the diet mixing behavior of sheep grazing sagebrush steppe. Applied Animal Behaviour Science, 100(3-4), 207-218. doi:10.1016/j.applanim.2005.12.002
First Page
207
Last Page
218
Abstract
An animal's ability to select a diet depends on forage availability, the density of herbivores, and the allocation of forage resources. We hypothesized that the temporal and spatial availability of forages in sagebrush steppe vegetation both influence food selection and may encourage lambs to learn to use sagebrush, a shrub that contains high levels of terpenes that limit food intake. We conducted a field study with three treatments of 20 lambs each. Forage resources were manipulated by restricting grazing areas. Lambs in treatment H grazed at a high stock density, whereas lambs in treatment L grazed at a low stock density; both groups were moved to fresh pasture daily. Lambs in treatment H3 had three times the area of treatment H, but they were moved every 3 days, making the total area grazed by H and H3 equal, but with a different temporal allocation of forage. Scan sampling was used to record the incidence of consumption among sagebrush and understory herbs. During 24 days of conditioning, stock density and temporal patterns of forage allocation both influenced the behavior of lambs. Lambs in H spent more time foraging on sagebrush (25%) than lambs in H3 (16%), and lambs in both H and H3 spent more time foraging on sagebrush than lambs in L (1%) (P < 0.05). For lambs in H3, foraging on sagebrush was cyclic and depended on the daily availability of herbs. Use of sagebrush, expressed as a percentage of total foraging time, wasH3 > L (P < 0.005). Thus, the availability of alternative foods, manipulated through animal density and the temporal allocation of those resources, both affected how readily lambs learned to use sagebrush.
Comments
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