A Double Change-Over Design for Dairy Cattle Feeding Experiments

Summary The design and statistical analysis of a short-time switch-over trial comparing three rations are discussed in this paper. The principal objects of the design are to secure accurate comparisons of the effects of the rations and unbiased estimates of the experimental errors. The design also makes it possible to estimate and adjust for carry-over effects, which have usually been ignored in switch-over trials. The appropriate statistical analyses are illustrated by numerical examples of the case in which carry-over effects are negligible (nutrient consumption) and the case in which they are not negligible (milk production). A corresponding design for four rations is briefly described. A detailed report of the results of this feeding trial will be given in a future paper.