Published online by Cambridge University Press: 27 March 2009
1. Three trials are reported in which the grazing behaviour of separate groups of cows, one receiving supplementary food, either as conserved roughage, concentrate or fodder crop, was observed over 24 hr. periods. A fourth trial, assessing the effect of summer temperatures on unshaded milking cows, is briefly described.
2. In trials 1 and 2 the stall feeding of either conserved roughage or concentrate reduced grazing as compared with unsupplemented cows by approximately 10%.
3. Allowing access to a fresh ‘strip’ of a fodder crop at a set time each day, whilst not altering total grazing time, very markedly altered periodicity of grazing. Cows delayed grazing up to 3 hr. whilst awaiting a fresh ‘strip’.
4. Environmental temperatures up to 87° F. did not alter total grazing time as compared with grazing time when temperature reached a maximum of only 70° F.
5. The value of supplementary feeding of dairy cattle at pasture, at least where the intake of pasture is sufficient for maintenance and a low level of production, appears to be open to question.