Rangeland Ecology & Management

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SAMPLING PERIOD LENGTH NEEDED TO CHARACTERIZE CATTLE TERRAIN USE ON RUGGED RANGELAND
Author
Gannon, Margaret R.
Mercado, Tatjana J.
Bailey, Derek W.
Thomas, Milton G.
Speidel, Scott E.
Enns, Richard M.
Publisher
Society for Range Management
Publication Year
2018
Body

Terrain use and grazing distribution traits in cattle are difficult to evaluate because movement patterns are temporally variable due to ever changing climatic and forage conditions. Ongoing research suggests that terrain-use phenotypes can be inherited and potentially used in beef cattle genetic improvement programs. Terrain use can be monitored with GPS collars, but the length of tracking is constrained by battery life and on-site management plans. Cattle tracking studies have varied from days to months. The objective of this study was to determine if shorter, 30- to 60-day, sampling durations were as effective as a 3 month tracking periods for characterizing slope and elevation use, and vertical and horizontal distance traveled from water of individual cows. Fifteen Limousin cows from a herd of 250 cows were tracked at 15-minute intervals for 92 days during late winter and early spring in a 9,065 ha pasture that included both gentle and rugged terrain. Terrain use during 30- and 60-day periods at the beginning and end of the tracking were compared to the full 92-day period. Slope, elevation, and vertical and horizontal distance from water from the full sample period were regressed on values from the shorter data subsets and correlations were calculated between sampling periods for each pair of terrain use metrics. The 60-day periods showed strong agreement with the full 92-day period with correlation coefficients varying from 0.90 to 0.97 (P < 0.05). Correlations between 30-day periods and the 92-day period varied from 0.30 (P > 0.05) for distance to water during the early period to 0.90 to 0.93 (P < 0.05) for all traits during the late 30-day period. These preliminary analyses suggest that 2-month tracking periods are equivalent to 3-month tracking periods for identifying differences in terrain use among beef cows.

Language
English
Resource Type
Text
Document Type
Conference Proceedings
Conference Name
SRM Reno, NV