Boost Your Milk Check; Feed for Butterfat
Butterfat appears to be the bright spot in an otherwise dim outlook for milk prices.
A recent AgWeb article, “Time to Feed for Higher Butterfat?”, says butterfat prices could outpace protein and sagging skim milk prices in the next couple of months. My advice for producers is to watch the markets; then look at strategies to maximize milk fat production without reducing volume. 
First, a balanced ration with adequate neutral detergent fiber (NDF) and physically-effective NDF (peNDF) is the basis for a healthy rumen and normal butterfat production. The peNDF can be evaluated using the Penn State Particle Separator. This and the amount of rumen degradable starch are the primary dietary factors that affect rumen pH.
Maintaining a “normal” rumen pH is important, particularly when ruminal pH is less than 5.8. We can’t determine this on the farm, however. So a little cow knowledge, practical experience with different diets, computer modeling predictions and trial and error is needed to tweak peNDF and rumen degradable starch and maintain proper rumen pH. Yeast supplements have also been shown to help maintain rumen pH.
Adjust dietary cation-anion difference (DCAD) in lactating cows if needed. Recommended levels are 35 to 45 in early lactation and 30 in late lactation. Increase sodium with a sodium buffer (bicarb, sesquicarb). Increase potassium (K) up to 1.7% of dry matter with high-K forages and potassium carbonate (not potassium chloride).
High corn silage diets usually require added K. Potassium carbonate has been a staple in most of my Florida diets year-round and butterfat in these herds maintains 3.6% even through heat stress. Adjust magnesium (Mg) in these diets so the K:Mg ratio is 4:1 to 5:1.
Feeding methionine hydroxy analog (such as MHA, Alimet, HMTBa) has been shown to increase butterfat. I’ve seen consistent increases of .2 to .25 percentage points of butterfat when I’ve fed 20 to 25 grams of
methionine analog, especially in high starch, lower forage rations or diets that tend to
depress milk fat.
At the American Dairy Science Association meetings in July, Penn State University researchers presented data basically repeating the research results I had with MHA and Alimet years ago. The cost of 20 to 25 grams is about 10¢ to 15¢ per cow per day. That’s a pretty good ROI if you get 2 points of fat.
Rumen-protected fats typically increase butterfat. They also provide energy for body condition and milk production. You can expect one to two points of butterfat on many diets with ½ lb. to ¾ lb. of supplemental rumen-protected fat.
Finally, monitor factors that increase the risk of milk fat depression. These include
unsaturated fats in the ration, high starch and low effective fiber. High levels of
unsaturated fats from ingredients such as DDG, wet brewers and bakery byproducts can put the rumen unsaturated fatty acid level (RUFAL) over the top. Tom Jenkins determined RUFAL over 600 grams is borderline and over 750 grams is excessive. In my experience, RUFAL is the overriding factor causing milk fat depression.
Butterfat can suddenly plummet to 3% or less. Once this scenario occurs, it may take two to three weeks to dig out even after the dietary factors are corrected. Not a good situation with high butterfat prices.
