Effect of breed of cattle and season on diet selection and defoliation of competitive plant species in semi‐natural grasslands

Abstract

AbstractTo maintain biodiversity in semi‐natural grasslands, the choice of breed of livestock and season of grazing can be important. The objective was to determine the effects of breed and season on the composition of plant fragments in the faeces of cattle grazing a heterogeneous semi‐natural grassland. Twelve heifers of the traditional Swedish Väneko breed (live weight 309 kg) and twelve heifers of the Charolais breed (live weight 431 kg) were allocated to three pastures per breed. Faeces samples were collected in spring, summer and autumn for micro‐histological examination of plant fragments. On the same occasion, defoliation of four competitive plant species was recorded. Faecal plant fragments mainly consisted of grasses but also herbs, whereas Cyperaceae, despite their abundance on the pastures, only composed a small proportion of fragments. Season affected the composition of plant fragments in the faeces, with a higher proportion of Cyperaceae and herbs in spring than later in the grazing period (P < 0·001), and the heifers ingesting more grasses and woody plants in autumn. In spite of a clear difference in live weight between the two breeds, no effects of breed on the composition of plant fragments in faeces were observed, although Väneko heifers defoliated more Filipendula ulmaria in spring than the Charolais heifers (P < 0·01). In addition, defoliation of Alnus glutinosa increased later in the grazing period (P < 0·05), especially for the Väneko heifers, indicating control of pernicious brushwood by grazing may be more effective in autumn.