You can’t spend much time in the dairy social media world lately without knowing that butterfat prices are really high. This seems to be good timing since butterfat tends to climb in the fall anyway. But how can we enhance this seasonal rise even further and put a few more bucks in your pocket? We don’t always have the opportunity to enhance a natural trend to make it even more impactful. It seems we are usually working against the tide. This time, nature isn’t against us. Nice!

A sophomore dairy science student or any producer who spends time reading dairy magazines could probably make a quick list of the low-hanging fruit for maximizing milk fat. Among these tactics would be feeding buffers, raising the forage percent in the diet, watching starch levels, and more. What, though, are the more nuanced approaches that can help us reach even higher levels and make the initial steps above even more effective? Let’s discuss a few.

Take a look at fiber and starch

First, we should look not just at forage percent and starch content. Though these two tend to have an inverse relationship, that is not always the case. If the forage we are talking about is corn silage, it is really only around 50% forage. So, a 60% forage ration may still be a problem for making good butterfat if you have the blessing of 40% starch corn silage to feed. Instead of thinking about the forage percentage in the diet or the forage to concentrate ratio, we can focus on a few other nutrients. I like to look at uNDF240 as a minimum requirement to be sure there is enough structure in the diet to keep the rumen in good shape. Having too little of this undigestible fiber can result in high intakes, poor feed conversions, and disappointing milk fat results. Think of this fiber as “rebar for the rumen”.

The next type of fiber is what actually makes the butterfat we need. This fiber is fermented in the rumen to create the building blocks that actually become butterfat. Thus, we need as many of these building blocks as possible. The nutrients on your forage analysis that are attempting to describe this fiber are the different time points of neutral detergent fiber (NDF) digestibility. These may be NDFd12, NDFd24, or NDFd30. Other time points may be estimated as well.

This nutrient is not only important on a forage analysis but in diet formulation as well. These digestible fibers don’t have to come from forage sources. They can come from by-products like soybean hulls, almond hulls, or corn gluten. There is no excuse for a ration to not have an adequate supply of this type of fiber. If you didn’t grow it or buy it in hay or silage, you can always get it from various by-products. Each nutrition model has a term for these, and meeting the needs is critical for butterfat. High starch diets may have a risk of being inadequate in this important nutrient, so take care to keep a lid on starch.

Starch is tricky in this conversation because it has such a key role in driving overall energy intake for milk, maintenance, and reproduction. If we are pushing the upper levels of starch as we feed for high milk production but are also doing a good job being sure the cows are well supplied with true roughage, the highly digestible fiber may get squeezed out. Moderating starch a bit to make room for some highly digestible fiber can still support high levels of milk production but not offend milk fat synthesis. Watching manure consistency can be a helpful guide on this topic. Don’t forget that sugars in the rumen act in a similar fashion to starch.

An example of a diet manipulation might better explain this. Let’s say you have an aggressive high-starch ration that is making good milk, but milkfat results are somewhat disappointing. If you have a diet that shakes out nicely with the Penn State particle separator and manure is perfect, what would be a good ration response to low butterfat? If you decide that the problem is high starch, in this situation, based on the manure and the shaker box, adding hay or straw might not be the best response. This ration seems to not need more roughage but instead, it needs less starch and more digestible fiber. Simply moving some corn grain to soybean hulls might be just the trick. The highly digestible fiber in the hulls will generate the right building blocks to make more butterfat.

Thoughts on fat

The second topic is related to starch as well. The focus here, though, is not fiber, forage, starch, or sugar, but fatty acid balance. It is commonly known that feeding high levels of vegetable fat can depress milk fat synthesis. The details here are pretty complicated and might require you digging out your biochemistry textbook from college. Suffice it to say that this type of vegetable oil is a problem for the rumen and has a significant negative impact on the fermentative process that creates the building blocks for butterfat. The lingo here is a bit confusing, and it seems that these terms are used interchangeably to keep everyone a little confused. So, if you hear things like 18:2 fatty acids, linoleic acid, unsaturated fat, or simply vegetable fats, you know they are pretty much describing the same thing. These fats are a problem in the rumen. The data suggests there is a linear relationship between increases in these fats to reductions in milkfat percent and yield. This science is unambiguous. In other words, you can take it to the bank, especially with the current butterfat values.

The immediate thought on this particular risk is distillers grain. However, there are several other common feed ingredients that have nearly the same levels of problematic fat as is found in distillers. It seems that dry distillers are trending lower in fat, which is good. I see levels between 7% and 8% instead of the previously common 10% expectation. Wet distillers may still be higher, and due to this variability, lab tests should be done of these products. While we focus on distillers, ingredients like brewers grain, hominy, and even some bypass soybean meal products are nearly as high as distillers in fat. This fact may not be cut and dry, as not every unsaturated fat behaves the same in the rumen, but care should be taken in any case.

The third topic is also related to fat in the diet. While 18:2 fatty acids can hurt butterfat, other fats that are high in palmitic acid (16:0) can actually enhance butterfat. Raising the 16:0 fatty acid content in the diet will boost milkfat percent and yield. Remember, though, that the carbons in the various fats can only be used once. If you are currently feeding a traditional calcium salt that contains nice levels of 16:0 and shift to a high-palm source (16:0), you may gain butterfat and lose body condition support. A calcium salt has a combination of fatty acids that can support milk, body condition, and butterfat. Taking care to maintain fatty acids for milk and body weight while adding 16:0 for milkfat support will be the best of both worlds. There are several strategies with branded products and even straight tallow to better target the fatty acid balance that fits the particular set of cows and the season of the year.

As we combine these three topics into building a well-balanced ration, we can use milk fatty acid analysis to see how we are doing. This process is often called de novo analysis. This is a good name since the primary goal here is to elevate de novo fatty acids that have as their source the digestible fiber discussed above. Remember, digestible forages or by-products like soybean hulls make your butterfat. Completing milk fatty acids analysis on a pen-by-pen basis is the gold standard for using this emerging tool to the fullest. Bulk tank numbers can be helpful, but since cows at different stages of lactation have some differences based mostly on weight loss or gain, interpretations can be tricky. Still, suffice it to say, if you have a high producing herd, the higher the de novo fatty acids, the better your cows are doing converting forage and by-product fiber into butter. Stay tuned for emerging ideas on how to better use these milk fatty acid results. Some milk co-ops are now reporting these values on every load of milk just like fat, protein, and somatic cells. We can feed cows better by paying closer attention to these values.

One last note relates to things on the dairy as opposed to inside the forage lab and my computer. Factors like cow comfort, bunk space, feed push-ups, number of meals per day, tracking shaker box results, cow cooling, hoof health, overcrowding, and more all have an impact on de novo fatty acid synthesis. Nearly every best management practice for taking care of cows well will enhance de novo fatty acids, your butterfat percent, and your milk income.

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(c) Hoard's Dairyman Intel 2023
November 9, 2023
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