The metabolic profile involves blood sampling 3 groups of cows (freshly calved cows, cows around 100 days calved and dry cows). The tests are really designed to highlight any energy or protein problems in the ration, although some mineral levels are also checked using the same blood samples.
A metabolic profile will often highlight any ration issues before it is too late. One of the most common findings is cows in the late dry period and early lactation are in negative energy balance. Cows which are already struggling pre-calving will inevitably have problems post calving especially with retained cleansings and reduced dry matter intakes. We often see fertility issues with cows which have lost too much body condition in early lactation. These cows take long periods of time to recover, failing to reach their potential yields and are very difficult to get back in calf. Both of these issues are very costly in terms of lost revenue.
Remember it is best to act to prevent a problem happening. It is always more difficult and costly to chase the solution.