There were large variations in concentrate feeding among farmers, perhaps reflecting the mixture of control and volunteer farmers in the group.

It would also appear that not all control farmers followed the guidelines given to volunteer farmers and continued to feed low levels of concentrates to their cows at any stage of lactation.

As suggested earlier in this case study, it might be interesting to categorise farmers into groups according to the average levels of concentrates fed (say, high-high, high-low, low-low for early-late lactation) and fit a lactation curve to each group. One might expect the shape of the curve to be flatter for cows fed low concentrates throughout than for those fed higher concentrations at the start.

This is addressed by one of the study questions.