Target NDF at 0.9% of body weight
Increasing forage levels in milking rations leads to a bunch of good things, especially at today’s high grain prices, says Larry Chase, a Cornell University dairy nutritionist.
His list: better rumen health; less acidosis; reduced culling; reduced vet bills; improved whole farm nutrient balance; improved milk components; reduced purchased feed costs; and improved opportunity for profitability.
So how high can you go in feeding forage while maintaining acceptable milk production? Based on work at the U.S. Dairy Forage Research Center in Wisconsin, cows can perform well when forage neutral detergent fiber (NDF) is a minimum of 0.9% of body weight. For a 1,450-lb. Holstein, that works out to about 26 lb. of forage dry matter, assuming the forage is 50% NDF.
Several years ago, Chase and his colleagues surveyed 16 New York dairy farms that were achieving this level of intake or higher. The herds ranged in size from 56 to 550 cows. Tank averages ranged from 68 lb. to 100-plus lb.
"These herds primarily used mixtures of corn silage, legume or mainly legume forages in their rations," Chase says. "This data should not be used to indicate that corn silage or legume forages are required to feed higher forage rations." Three herds used brown midrib corn silage; another used grass silage as the only forage. In formulating high-forage rations, forage quality is more important than forage type.
Chase also tracked a 100-cow Holstein herd as it ramped up forage.
During a five-month trial, forage went from 50% to 65% of the total ration, and forage NDF intake as a percentage of body weight climbed from 0.85% to 0.95%. Milk production climbed from 71 lb. to 75 lb. per cow per day. Income over feed cost jumped from $4.27 to $5.58 per cow per day, resulting in $130 more per day. And this was calculated when milk prices were about $12 per cwt.
There are eight key components, Chase says, to achieving higher forage intake:
- Mindset. Both the dairy producer and the nutritionist must buy in to the concept.
- Consistence. Remember that vari-ations in forage quality are magnified.
- Inventory. Higher forage levels require 15% to 30% more forage for the same number of cows.
- Allocation. High-quality forage must be segregated so it can be targeted to appropriate groups.
- Analysis. Frequent testing is needed to keep rations balanced. NDF digestibility should be part of the regime.
- Formulation. Rations need to be monitored closely to determine if adjustments are needed. Track dry matter intake and feed refusals.
- Feed management. With silage-based high-forage rations, feed shelf life may be a problem in summer. More frequent feed push-ups also might be required.
- TMR mixer management. High-forage rations are bulkier and less dense, which may mean mixing more batches of feed each day or purchasing a larger mixer.