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Short-term foraging dynamics of cattle grazing swards with different canopy structures
P Gregorini1, S A Gunter, P A Beck
1Department of Animal Science, University of Arkansas Division of Agriculture, Fayetteville 72701, USA.
Journal of Animal Science
|August 18, 2009
Summary
Wheat pasture structure impacts steer foraging. Taller pastures with accessible leaves improve intake rate and grazing efficiency, suggesting optimized pasture management.
Area of Science:
- Agronomy
- Animal Science
- Forage Ecology
Background:
- Understanding sward canopy structure is crucial for optimizing grazing management.
- Wheat (Triticum aestivum L.) pastures offer a unique environment for livestock foraging dynamics.
- Previous research has not fully elucidated the relationship between specific canopy structures and steer intake.
Purpose of the Study:
- To characterize the sward canopy structure of three wheat pastures.
- To correlate these structures with short-term herbage intake rate and foraging behavior in steers.
- To identify optimal pasture characteristics for efficient cattle grazing.
Main Methods:
- Sward sampling for leaf/stem fractions across canopy strata (bottom, middle, top).
- Measurement of sward surface height, tiller, and bulk densities.
- Steer grazing trials using a Latin square design, with ruminal content analysis for intake.
- Video analysis of grazing sessions to quantify feeding stations, bites, and feeding rates.
Main Results:
- Sward surface height and leaf proportion in upper canopy strata varied significantly between pastures.
- Herbage intake rate, bite mass, and bite area differed significantly among treatments.
- Steers on taller pastures with greater leaf accessibility exhibited faster eating, slower navigation, and higher grazing efficiency.
Conclusions:
- Pasture sward height and upper canopy leaf accessibility are key factors influencing steer foraging efficiency.
- Taller wheat pastures with accessible leaves allow cattle to achieve intake goals faster and more efficiently.
- Management strategies could involve adjusting area and time allocations based on sward characteristics for improved productivity.
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