Fiber is the base of a dairy ration, and while it is the main source of energy for dairy cows, it may also potentially create some challenges in a lactating ration. Understanding the various strategies that make the most of this important main nutrient of a cow’s diet offers opportunities to maximize the production and health of dairy cows.
As much as we discuss ration balancing and feed additives, the digestibility of fiber is most impacted by the maturity of the plant when harvested. Therefore, the timing of harvest and proper harvesting and storage practices are controllable factors for dairies looking to improve fiber digestibility for their herd. Once those high-quality forages are on the farm, utilizing proper feed management strategies and ration-balancing technologies ensures cows will get maximal usage out of the high-quality forages.
Focus on forage quality
Although the weather has a major impact on the time of harvest, understanding how different types of crops mature and the impacts of maturity on the quality and fiber digestibility is valuable. Advantages in fiber quality come at the cost of reductions in the tonnage harvested. Lower tonnage means that more acres will need to be harvested to meet the intake needs of cows, adding to overall feed costs. However, the increased milk and milk components that typically result from higher-quality forages with greater fiber digestibility are often a solid return and well worth the extra investment that goes into either raising or purchasing high-quality forages.
Experience has shown that milk production and components are directly related to the quality of forages in a cow’s diet. If fiber digestibility in the majority of the forages in the diet is less than ideal, there is little that can be done in the way of ration balancing or additives that can make up the difference. Thus, a high-producing cow's diet needs to be top quality, but not all of the forage needs to be highly digestible. Fiber components within the diet require balance. A certain level of slowly digestible fiber has shown to be beneficial in slowing the passage rate and providing a “scratch factor.” As dairies focus on harvesting and feeding very high-quality forages, there are some situations where a small amount of poor-quality forage, such as straw, may actually be helpful for rumen health and milk production.
Feeding strategies to improve fiber digestibility
There are numerous feed management strategies shown to be beneficial for fiber digestibility. The basics of feed management continue to be a focus, as they are beneficial for improving fiber digestibility. To maximize fiber digestibility, remember the following:
- Make sure cows have access to feed at all times. Slug feeding results in swings in rumen pH, which is especially detrimental to fiber-digesting bacteria. Ensuring cows have access to feed throughout the day and night will help cows maintain even eating patterns that promote a healthier rumen.
- Pay attention to mixing. Ideally, cows should be consuming the same diet every meal each day. The same percentage of dry matter of individual feeds should be added to the mixer every day. In addition, the total mixed ration (TMR) needs to be thoroughly mixed to encourage cows to consume as even of a ration as possible. If the feed being placed in the bunk is variable from day to day or is not being mixed correctly, cows will not be consuming a consistent diet and will not be in a situation where fiber digestibility will be maximized.
- Watch for sorting. It doesn't matter if the correct amount of each ingredient is added and the feeds are thoroughly mixed if the cows can sort the feed and only eat certain portions of the ration. The ration should be consistent and in a form that “sticks” together enough that the cows, from the first cows eating to the cows cleaning up the last of the feed, all consume the same diet.
Excellent feeding management is an essential piece of maximizing fiber digestibility. Cows that eat and consume the same well-balanced and mixed ration every day will have the healthiest rumens, resulting in greater fiber digestion.
Feed supplements and additives to maximize fiber digestion
There are a wide variety of nutritional supplements and additives available that show the impact of fiber digestibility. Going back to the basics, remember that even high amounts of corn and other high-starch grains are detrimental to overall fiber digestion. Feeding grain continues to be a fine line between supplying starch as an important energy source for the cow and maintaining a rumen pH and environment that still facilitates optimal fiber digestion.
One of the more well-known supplements linked to fiber digestibility is fat. The negative impacts of fat on fiber digestion have been known for many years, but more recent research has shown the impacts on fat digestion go even deeper than whether or not the fat is saturated or unsaturated and is dependent on the fatty acid composition of the fat source. As knowledge in this area continues to increase, there may be additional changes in how and what fat sources are typically fed to lactating cows to help get the most from fat supplementation. This includes how fat sources interact in the diet and impact fiber digestibility.
When it comes to feed additives and technologies, research on various additives has demonstrated some improvements in fiber digestion. Examples of feed additives that have been shown to improve fiber digestibility are yeasts, yeast cultures, live yeasts, botanical extracts, fiber enzymes, branched-chain volatile fatty acids (BCVFA) and feeding hydroxychloride trace mineral sources. Using silage inoculants at the time of harvest has also been shown to increase forage fiber digestibility.
Check with the makers of any feed additives to verify that the products have undergone research testing in a variety of situations and with feeding programs like those that would be fed on any given dairy. Although it may be difficult to calculate the advantages of an additive in a commercial setting, the products must have a positive return on investment to be included in the ration.
A multifaceted approach maximizes fiber digestion
Maximizing fiber digestion is a multifaceted approach that begins with feeding high-quality forages, having excellent feeding management and taking advantage of various feeding technologies available. Utilizing these various approaches will help cows make the most of the fiber they consume.
