The composition and nutritive value of bracken

Abstract

Samples of bracken were taken at regular intervals between June and October from a hill grazing where losses of cattle from ‘bracken poisoning’ had occurred in previous years. These were separated into leaf and stem for analysis. Dry, mature bracken cut in October was examined for digestibility and nutritive value, and in the following season the digestibility of fresh, green bracken was determined for both cattle and sheep.Chemical composition. Analyses of the fresh bracken fed in the digestibility trials were in line with those of the samples collected in the previous year. Crudeprotein content was high in June and July, but fell markedly in August and September, whilst the crude fibre varied in the opposite direction, increasing markedly in August. An increase in the tannin content was observed in September but this was not comparable with the increases reported by Shearer. An attempt to elucidate the significance of tannin in the in vitro digestion of bracken-leaf protein was unsuccessful. The potassium content was found to be rather lower than in good pasture grass, confirming the findings of Ferguson & Armitage. The potassium was highly soluble in water but the soluble part was not entirely in the form of chloride.