Can Seminatural Grassland Vegetation in Abandoned Fields Support the Nutritional Requirements of Grazing Goats? A Study in Central Japan

Abstract

The nutritional value of wild plants varies greatly, and some species have nutritional values and digestibility comparable to those of commonly cultivated grass varieties. Thus, we hypothesized that foraging on seminatural grassland vegetation in abandoned fields could fulfill nutritional requirements for goat maintenance, and selective foraging could ensure greater availability of these nutrients, contributing to the maintenance of livestock and their growth. This study aimed to evaluate the nutritional value of semi-natural grassland vegetation in abandoned fields with selective foraging by goats and to estimate whether the vegetation in abandoned fields can satisfy the nutritional requirements of goats through the seasons. We used 16 goats to conduct grazing trials throughout the seasons in two experimental areas of an abandoned field. The variations in the chemical components of each plant group were also evaluated for each season. The nutritional composition of the goat ingesta was estimated from the number of bites of the ingested plant species, chemical components, and bite mass. The goats grazed on 33–43 plant species across the seasons, and the plants that the goats foraged changed throughout the seasons. Goats shifted their foraging from forbs to multiple other plant categories (bamboo species and the Poaceae and Cyperaceae families), increasing their intake of crude protein (CP) and minerals. Grazing under seminatural grassland vegetation in such fields allowed goats to meet their nutritional requirements of CP, calcium, magnesium, phosphorus, potassium, iron, cobalt, manganese, zinc, and chlorine and support a daily gain (DG) of 100 g throughout the season. In contrast, grazing in seminatural grassland vegetation caused excess Fe intake and deficiencies in selenium and copper. However, this study suggests that goats grazing under seminatural grassland vegetation in abandoned Japanese fields could support the nutritional requirements for a DG of 100 g in terms of CP and several minerals.