The remaining feed can look very different from what was fed if cows sort. Even with the fiber cut to a shorter length, the animals will consume more physically effective fiber than if they sort against the longer material. Using a particle separator on the initial feed and refusal will not tell the entire story because different animals may make different choices as they separate the feed. This offers a fair estimate that the cows consumed enough physically effective fiber. When cows are panting due to heat stress, far fewer animals will be ruminating.
Poor ventilation can reduce feed intake, even if the ration itself is well formulated.
Although this is a very subjective point of evaluation, it is an important one. Calm, comfortable animals devote more of their feed resources to production. Manure Observations of the manure can give a qualitative index of what type of diet the cows consumed and to what extent and where they digested it. Samples should be collected from several different cow pies in a group. Good or bad, manure from cows fed the same diet should look similar, if they are all eating the same diet.