Depending upon how you’re paid for your milk – butterfat can add a significant amount to your milk check. Looking back to 2011, butterfat averaged $2.15 per hundredweight, and that’s no small change. When milk fat levels are depressed, there is no time to waste in finding the cause and resolving the issue quickly.
Hot weather is often blamed for suppressing fat levels, but milk fat depression is actually a multifactorial problem with many moving parts, says Martha Baker, dairy nutrition specialist with Purina Animal Nutrition LLC.
Whether you’re struggling with milk fat depression or want to head it off at the pass, here is a look at six key areas that can influence milk fat production.
Take a look at your total mixed ration (TMR). Evaluate delivery times - including nighttime feedings, feed refusals, availability of bunk space and overcrowding. Avoid slug feeding, as it can create subclinical acidosis which impacts milk fat. “Any of these issues should be addressed right away,” says Baker.
Forages and fiber in the diet
Concurrently, while you are taking a closer look at management factors that influence milk fat, examine the forage and fiber levels in the diet. Use the Penn State Shaker Box to evaluate particle length. “The goal should be to have 47 percent of the TMR in the bottom and 7 percent on top,” says Baker.
Cud chewing can also be a good indicator of forage and fiber in the diet. “Look for 50 percent or better of the pen to be chewing their cud,” she says. The percent of neutral detergent fiber digestibility (NDFD) should also be evaluated to make sure it isn’t too high.
Assess how many pounds and what percent starch is being fed. Technology like rumen degradable starch testing can help assess starch levels in the ration ingredients and how they will perform in the cow. “Different ingredients ferment faster in the rumen than others. This affects the dynamics of the rumen and can have a major impact on milk fat levels,” explains Baker.
“An awareness of the rate of starch digestion, especially in the rumen, is critical when trouble shooting milk fat depression,” she says. “Rumen degradable starch testing allows you to very quickly rule out starch as a culprit of suppressed milk fat levels.”
Fats – saturated vs. rumen inert
Consider the fat level and source in the diet. There shouldn’t be more than 5 percent fat in the diet, notes Baker. Be mindful of polyunsaturated fatty acid or PUFA levels.