Decreasing ration protein is environmentally and economically sound
Research shows that milking rations as low as 14% in crude protein still yield 90 lb. to 100 lb. of milk per cow per day, even with midlactation cows. But does this work in the real world?
Larry Chase, a Cornell University dairy nutritionist, thinks it does. In fact, he knows it does.
There are, of course, some caveats:
- On-farm feed management must be accurate and consistent.
- Daily variations in forage quality and dry matter need to be minimal, and adjusted for when they change.
- Forages must be accurately tested for fiber, fiber digestibility, protein and soluble protein.
- Producers and their nutritionists must determine how much of a "safety net" of excess crude protein requirement is needed to minimize the risk of not meeting needs and jeopardizing milk flow.
The benefits of lowering crude protein result in more efficient use of the protein fed, less loss of protein in urine, lower ammonia emissions and improved income over feed cost (IOFC). Fewer acres are needed for manure application since nitrogen levels in manure are lower.
Chase worked with two New York herds to lower the milking ration crude protein over an eight-month period in 2008–2009.
Herd A, with 400 cows, took protein from 17.5% to 16.6%. Milk urea nitrogen (MUN) went from 14.8 mg/dl to 12.5 mg/dl. Nitrogen excreted in feces and urine dropped by 59 gm per cow per day.
Pounds of milk produced went up 1 lb. per cow per day, to 80 lb. True milk protein also went up, from 3.03% to 3.11%, likely the result of feeding more starch. Feed cost per cow per day went from $5.88 to $5.43. As a result of feeding less protein and getting more milk, IOFC went up 75¢ per cow per day.
Herd B, with 600 cows, took protein from 17.7% to 16.9%. MUN went from 14.5 mg/dl to 12 mg/dl. Nitrogen excreted in feces and urine dropped 28 gm per cow per day. Milk per cow per day dropped 2 lb. to 80 lb., but there was also a decrease in rBST use. True milk protein went from 2.96% to 3.07%. Feed cost per cow per day went from $6.14 to $5.97. As a result of feeding less protein, IOFC still went up 21¢ per cow per day.
These results should encourage producers to lower crude protein levels in their milking rations, Chase says.
Is your herd a candidate for a lower crude protein ration? It might be if your crude protein exceeds 16.5%; MUN exceeds 12 mg/dl; and you offer cows highly consistent rations and monitor forage dry matter daily.
"On many farms, there is an opportunity to lower ration crude protein by 0.5 to 1.5 units with minimal risk of lowering milk production," Chase says. "Don’t get hung up on going to 16% or less. Even if you can lower crude protein by one percentage unit, you’re making progress."
The point is to make the change, then monitor your herd’s milk production, MUN levels and other factors to gauge whether the change is worthwhile, he says. In many cases, it will be.