They point out that controlled-energy diets are recommended for use in the far-off dry period in one- or two-group management systems. That approach has been successful in some but not all dairies, and they think some of the failures may be attributed to a transition to an inappropriate fresh-cow diet.
Seventy-two Holstein cows were used to evaluate the effect of starch content in corn silage-based diets on early lactation performance following a shortened (40-day) dry period when a controlled-energy diet was fed. The scientists point out that controlled-energy dry-cow diets typically contain 12-16% starch on a dry matter basis, much less than lactation diets. A phase feeding or step-up approach during the pre- and post-freshening periods is often recommended, but the optimal increase in starch from a controlled-energy dry diet to a lactation diet is unknown.
Treatments included a low-starch diet (21.0%) for the first 91 days in milk, a medium-starch diet (23.2%) for the first 21 days in milk followed by a high-starch diet (25.5%) for the next 70 days, and a high-starch diet (25.5%) for the first 91 days. Corn meal was replaced partially with soy hulls and wheat middlings in the low- and medium-starch diets.
Cows fed the low-starch diet for the 91 days tended to consume more dry matter and produce more milk than did the high-starch group. Those fed a medium-starch diet for 21 days followed by a high-starch diet for 70 days outperformed cows fed the high-starch ration throughout the trial. That shows the benefit of using a step-up starch feeding approach when a controlled-energy dry-cow diet is fed, say the researchers.