How size of cattle influences grazing behaviour

摘要

Intake is determined by size and physiological state of animals. In grazing conditions, Allden and Whittaker (1970, Aust J Agric Res 21, 755-766) defined herbage intake (HI) in terms of the components of ingestive behaviour : bite weight (BW), bitingrate (BR) and grazing time (GT) : HI = BW × BR × GT. The aim of this study was to assess how size of cattle, which was fixed by age, influences grazing behaviour. Two animal groups, balanced in weight, were chosen from a Charolais herd. Each group comprised 3 types of females : four mature dry cows, four 18-month-old heifers and four 8-month-old weaned calves. A factorial design with 2 sward heights and 2 periods was used. Animal groups were allocated to different sward heights according to period. Cattle were strip-grazed (a fresh area of herbage each day) on leafy regrowths of cocksfoot differing in age (2 or 8 weeks), corresponding to sward heights (15 to 51 cm) which have been considered as unrestrictinq intake.