Answer provided by Al Kertz, Ph.D., nutritionist with Andhil LLC in St. Louis.
Q: With prospects that milk prices will increase and feed prices will be more moderate than they have been, what approaches should dairy owners and nutritionists now take in feeding programs?
A: Perhaps the best initial step is to take an inventory of what feeding program changes were made over the last year in order to reduce feed costs. For instance, what ingredients might have been purchased or used that otherwise might not have been used? Were forage feeding sources and levels changed, were feeding program changes made primarily for mid- or later-lactation cows, what mineral and vitamin supplementation changes were made, what additives may have been reduced or eliminated, were protein levels reduced below requirements and for which cows, and were energy levels reduced and fat supplementation reduced or eliminated?
One of the lessons learned in the 1980s milk diversion program was that feeding lower-energy-level rations for a year to cows was not correctable by just upping the ration energy or feeding level when the program was over. Once a cow’s lactation pattern is set by how she was fed in early lactation, she cannot very well turn up milk production by being fed better later. So particular attention must now be paid to those cows still in earlier lactation and those due to calve within the next several months.
Energy intake is always the largest dietary component. And milking cows are like a large energy bank. They take in energy and can “invest” it in various ways: Maintenance, replenish body condition, produce milk and milk components, re-breed, and maintain pregnancy. But there are limits to energy intake. In a 2003 review, Grummer and Rastani (PAS, 19:197-203) found that cows varied from 30 to 60 days postpartum in how long they were in negative energy balance. Maybe somewhat surprisingly, they found that time required to reach positive energy balance was quite independent of milk yield. The most important factor was net energy of lactation (NEL) intake because it is difficult to increase DMI itself in early lactation. Since NEL is the product of DMI x energy density, increasing energy density will increase NEL intake if there is not a decrease in DMI. Feeding lower forage levels can be problematic for subsequent health issues.
So carefully consider anticipated and unanticipated consequences from what has been done, and what feeding program changes will be instituted in the near future.