True metabolizable energy of moist-soil seeds

Habitat objectives for migrating and wintering waterfowl are often established by converting population energy demands into an equivalent measure of foraging habitat. In some areas, seeds produced from moist-soil plants provide a significant proportion of the energy available to waterfowl. To accurately establish habitat objectives for migrating and wintering waterfowl, managers must estimate seed production from moist-soil plants and have information on metabolizable energy (ME) of moist-soil seeds. Although methods for estimating seed production have been developed, ME has been determined for few natural seeds. We determined true metabolizable energy (TME) of 10 moist-soil seeds commonly consumed by wintering and migrating ducks. TME estimates were similar (P>0.05) for hairy crabgrass (Digitaria sanguinalis; 3.09 kcal/g), little hairy crabgrass (D. ischaemum; 3.10 kcal/g), pigweed (Amaranthus spp.; 2.97 kcal/g), yellow foxtail (Setaria lutescens; 2.88 kcal/g), fall panicum (Panicum dichotomiflorum; 2.75 kcal/g), curly dock (Rumex crispus; 2.68 kcal/g), and wild millet (Echinochloa crusgalli; 2.61 kcal/g), but less (P<0.05) for beakrush (Rynchospora corniculata; 1.86 kcal/g), paspalum (Paspalum laeve; 1.57 kcal/g), and nodding or curltop ladysthumb smartweed (Polygonum lapathifolium; 1.52 kcal/g). TME values determined for moist-soil seeds in this study will allow managers to accurately estimate carrying capacity of waterfowl habitats.