Dairy cattle nutrition can be viewed from a variety of different approaches. Remember back in the day when cows scattered pastures and grazed primarily on grass? These cows loved roaming the land and eating lush green forages.
Today, grazing fits into many different management systems, but how do we incorporate these forages into total mixed rations?
What is considered a high-forage ration?
High-forage rations typically consist of a forage dry matter percent of 60 percent or more. Forage dry matter takes into account the amount of forage versus the grain ratio in the ration. What does it take to feed a high-forage ration? The sole factor comes down to forage quality.
A higher-quality feed always feeds better than a low-quality feed. Not only is the feed quality higher, but the palatability to the cow is that much greater. Remember, a cow will always eat soft, lush hay versus one that is coarse and stemmy.
Evaluating your feeds for quality
What makes a feed high-quality? There are a few different tips to look into when analyzing your forage reports, since some of the numbers can be confusing at times. Remember these sole values: dry matter, crude protein, acid detergent fiber (ADF), neutral detergent fiber (NDF), NDF30 (NDF at 30 hours), starch and sugar.
Dry matter measures the amount of forage available minus the moisture in the feedstuff. There are many different target moistures for feeds. Consult your nutritionist if you have questions on what moisture your forages should be.
Crude protein is the total protein present in your feedstuff. Alfalfas will typically carry more crude protein than most, while corn silage typically carries the least. Usually, the higher the quality of your feed, the higher the protein content will be. This will also save money on your feed bill in the long run, allowing your nutritionist to feed less purchased protein.
ADF and NDF are measurements of fiber in the forage. The lower the quality of feed, usually the higher these two values will be. NDF30 shows how much of the feedstuff is digested within 30 hours in the cow. I strongly suggest all producers watch this value.
Furthermore, starch comes in with some grain forages and corn silage. Starch is an energy used in the rumen to help the cow function in her natural state. This energy is calculated into NEL (net energy lactation) and can be used toward maintenance, milk production or reproduction.
Lastly, sugar is present in many of our feeds. What does sugar do for you? Sugar is a quick energy in the rumen; feeding the rumen bugs much before forage or even starch will. It also helps break down both forages and starch, making the rumen much more efficient at what it does – digesting feed.
How do my feedstuffs bring in these values?
Picking the right variety and having a proper cutting interval can help tremendously. Pick a variety that is disease-resistant and is high in digestibility. A higher-digestible forage will allow you to feed more forage with a higher energy content than one that has lower digestibility. Lower-digestible feeds will fill the cow up faster with more bulk, less energy content and raise your purchased feed costs.
This principle is very important when driving dry matter intake and milk production. These two things go hand in hand. The higher the digestibility, the higher the intake goes, thus driving more milk production.
Differences in forages
Grasses and small-grain forages are typically higher in digestibility and can help one achieve a higher forage ration when fed in conjunction with corn silage and haylage.
Take a look at Figure 1 from Dairyland Labs. In the 2016 crop season, over 140,000 samples were analyzed for overall quality and digestibility (NDF30).
Legume haylages, also known as alfalfa haylages, had an average digestibility around 45 percent. All corn silages, with brown midrib (BMR) included, averaged around 55 percent. Furthermore, grass haylages averaged around 54 percent digestibility along with cereal grain silages averaging around 56 percent.
Let’s take these averages and see how they compare to the small-grain cover crops put up year to year. Table 1 shows these averages along with the typical minimums and maximums we can expect. Remember the NDF30 value we touched on?
On the small-grain cover crops, we saw an average of over 59 percent on last year’s crops even though our ADF and NDF values were higher. It all comes down to digestibility and not so much our fiber indicators.
Differences in cover crops
With that said, there are differences in cover crops; I will briefly touch on this. Oatlage is a fairly common one that I typically run into. Not only is oat seed very economical to plant, but it is readily available. Oats on average will carry 12 percent crude protein with an average digestibility of 57 percent.
Rye is also another fairly common crop. When harvested in spring, we typically will see 12 percent crude protein with a digestibility around 64.8 percent. To obtain this high digestibility, you will want to take these two crops in the late vegetative state or early boot stage. Much beyond these stages, we see an increase of fiber, and our digestibility drastically drops off.
Total digestibility with a good length of cut is key to feeding a high-forage ration. Cover crops can easily fit into both total mixed rations and a grazing system, providing the modern dairy cow with high-quality feedstuffs to milk off of, even though they carry less protein.
Making sure the crop is cut at the proper stage will ensure it is fit for the lactating herd. I encourage producers to once again take a look into these crops to not only increase tonnage, but to increase forage quality and digestibility in the overall ration of your cows. 
Stephanie Nagel is a dairy nutrition/consultant with CP Feeds LLC. Email Stepanie Nagel.
