The length of change-over periods in change-over designs with grazing cattle

Abstract

The data obtained from a change-over experiment with grazing dairy cows was used to estimate the optimum length of the change-over period. Two models were investigated to describe the change in production following the feeding of 2.72 kg (six lb) of crushed oats per day. The total difference in production obtained from the eight cows when they were receiving the supplement and when they were not was related to the length of time following the implementation of supplementary feeding. Milk, four per cent F.C.M., milk fat, solids not fat, protein, and total solids production data were fitted to two models and coefficients of determination of between 0.582 and 0.880 were obtained when relating change in production following a dietary change with time. The data indicated that with period lengths of two weeks or less changeover periods of four days should account for about 95 per cent of the total change in production that can be expected.