Monitoring diet composition and quality of ranging goats by faecal NIRS
2007
Glasser, T.; Landau, S.; Muklada, H.; Dvash, L.; Perevolotsky, A.; Ungar, E.D., Agricultural Research Organization, Bet Dagan (Israel). Institute of Field and Garden Crops, Department of Natural Resources
The present study tested the ability of faecal NIRS to predict quantitative and qualitative attributes of the diets of goats grazing Mediterranean scrubland in the Carmel mountain ridge of Israel. This landscape is dominated by the shrubs Pistacia lentiscus and Phillyrea latifolia, with interspersed patches of herbaceous vegetation. A group of 12 goats foraged in the study area for four hours daily and were supplemented with 100-300 g per day of concentrate feed. During two observation days, one randomly-selected focal goat was observed continuously, and the species foraged, the number and size category of bites removed were recorded by dictation into a tape-recorder. Periodically, bites of each selected species and size category were sampled by clipping and collected for estimation of bite weight and quality. Following suitable preparation, faecal samples were scanned by NIRS, and clipped samples were dried, weighed and analysed for chemical attributes by standard procedures. Calibrations were based on 23 pairs of faeces and diets of the observed goats. Equation quality was evaluated by R2 and the standard error of cross validation (SECV). The equations for P. lentiscus, P. latifolia and PEG-binding tannins were applied to a set of 83 samples from a previous experiment for external validation. Results suggest that faecal NIRS can be calibrated under free-grazing conditions but larger calibration datasets will need to be gathered in order to secure the robustness of this technology
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