Collection, Handling and Analysis of Forages for Concentrate Selectors

Forage collection practices must be consistent among studies for accurate and comparable results. Forage samples should be collected in the context of the feeding habits of the focal species to accurately represent available nutrition, but inconsistent handling and analysis of forages also could bias nutrient reports. Previously described methods of forage collection based on agricultural protocols are adequate for studying diets of intermediate browsers and grazers, but likely are inaccurate for application to concentrate selectors. More specifically, the agricultural protocols generally underestimate nutritional quality for concentrate selectors because leaf collections avoid the physiologically young plant parts that concentrate selectors seek. Furthermore, agricultural drying practices are designed for forage samples lower in water content than the young plant parts selected by concentrate selectors, which may create inaccuracies in subsequent nutrient assays. Also, laboratory methods and accuracy may affect nutrient reports in addition to collection and handling procedures. As a whole, improper collection, handling, or analysis of forages leads to improper conclusions and invalid comparisons across studies. Herein, we review protocols reported in empirical studies from agricultural and wildlife research and provide guidelines for standardizing collection, handling, and analyses of forages with the goal of providing a framework for researchers studying diets of concentrate selectors and related nutritional indices. These protocols will ensure valid conclusions are drawn and allow valid comparisons among related studies in future research.