Evaluating Dietary Treatments in Dairy Cows

The experiment was carried out as a randomized block design with three dietary treatments and 10 blocks (replicates) per treatment. The experiment comprised an 18-d preperiod for the collection of data to facilitate the allocation of cows to the treatments, followed by a 19-d experimental period comprising a 14-d diet adaptation phase, as is recommended for digestibility trials (GfE, 1991 (link)), and 5 d of feces collection. During the preperiod, all cows were fed ad libitum with a mixture of grass silage and corn silage in the same proportions as mentioned above and were supplemented with concentrates (as described above but without supplemental phytase) based on FPCM production. Cows were allocated during the last 3 d of the preperiod to blocks based on parity, DMI, and FPCM production during the preceding week. Within blocks, animals were randomly allocated to treatments.