|Starks, Patrick - Pat|
Submitted to: American Society of Animal Science Southern Section Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 10/15/2002
Publication Date: 1/26/2003
Citation: BROWN, M.A., STARKS, P.J., APPEDDU, L.A. 2003. Use of spectral reflectanc measures from hyperspectral radiometry in prediction of lamb gains on Bermudagrass pastures [abstract]. American Society of Animal Science Southern Section Meeting. v. 81(Suppl.2): Abstract p. 26. Interpretive Summary: Abstract Only.
Technical Abstract: Spring-born lambs (n=47) were used to evaluate the potential for predicting lamb growth directly from hyperspectral radiometer data taken on forage canopies in bermudagrass pastures stocked with lambs. Lamb were randomized to each of four 1.6 ha bermudagrass pastures. Lambs weights and spectral reflectance (R) were measured on June 3, June 11, June 25, July 9, July 22, and July 31. Animal growth data was estimated in five time periods: June 3 to June 11; June 11 to June 25 ; June 25 to July 9; July 9 to July 22; and July 22 to July 31. Spectral reflectance data were collected at 252 different wavelengths, from 368.4 nm to 1113.7 nm and converted to absorbance estimates by calculating log(1/R). Each field was sampled eight times along a transect line subsecting the field. Relationships of lamb gain to 252 spectral absorbance estimates were done by pairing averages of each pasture for gain and spectral absorbance at each beginning of each week or period. Stepwise regression was then performed on the twenty observations (4 pastures x 5 weeks) to identify best multiple linear regression models that would account for the largest proportion of total variance in lamb gain. A linear combination of ten spectral absorbance variables ranging from absorbance at 732.3 nm to absorbance at 1025.6 nm accounted for over 94% of the total variance in lamb gains. While further research is needed to verify these results, it appears that prediction of lamb performance from field-level hyperspectral radiometry of forage canopies may be feasible.