Precision management is a hot topic in the dairy industry, and rightfully so. We read about precision feeding, reproduction, and nutrient management to name a few. The focus is on efficient use of resources to reduce the environmental footprint of dairy production. New technologies such as activity monitoring enhance our ability to precisely manage cows.
Precision feeding seeks to optimize the rumen environment. I feel there are two pillars of precision feeding: getting the right quality forage to the right cows and creating a management environment that bolsters the cow’s eating experience and optimizes feed intake. If we accomplish both, then rumen function is optimized. Because the rumen is inside the cow, we strive to ensure cow well-being and its ability to practice natural behaviors.
As I have thought about precision management, it seems to me that in one way or another, many of our present and future dairy systems seek to meet the cow’s needs for natural eating and recumbent rumination behavior as precisely as possible. Recumbent rumination simply means rumination that occurs while lying down.
I cannot think of much that is more fundamentally important to the cow’s health and performance than achieving the correct balance between chewing while eating, and chewing while sternally recumbent. I like to think of forage fiber and particle size, and an optimal feeding environment, as “precision chewing management.” I would argue it is the basis of all successful dairy management systems.
Finding a balance
Successfully balancing eating, resting, and rumination time is critical for precise and efficient feeding of dairy cattle. Ideally, cows should eat between three and five hours daily. Under these conditions, they will have natural and healthy meal patterns and rates of feed consumption. If a feed or management factor pushes a cow to spend more than about five hours per day eating, the cow will either run out of time to eat, thereby reducing dry matter intake, give up resting time, or both.
It is well known that forage fiber characteristics affect eating time. We’ve come to realize that the particle size of the ration differs from the particle size in the swallowed bolus. In many rations, the swallowed bolus particle size is much more uniform. In our studies at Miner Institute, we have measured up to a six-fold reduction in particle length before a bolus of feed is swallowed while eating. This reduction in size takes up time — eating time.
Italian research first showed that the particle size of the swallowed bolus is close to the size of ration particles retained on the 8-mm sieve (also known as the second sieve) of the Penn State Particle Separator. Precision management of forage and ration particle size should aim to make eating relatively easy for the cow. That means chopping forages and mixing rations that are enriched with the fraction of particles retained on the second tier of the Penn State Particle Separator. These particles, along with those on the 4-mm sieve (the third tier), stimulate rumination effectively but can also be easily eaten and swallowed by the cow.
Eating takes time
A 1:1 trade-off between greater eating time and less resting time seems to exist for dairy cattle. When cattle are fed rations with too much coarse forage, eating time increases as intake drops. Rumination is less affected because of what we just discussed about particle size being reduced to a more uniform endpoint before swallowing during eating. Research shows that as total chewing time rises, resting time goes down, and lost resting time is never good.
What is the ideal balance between eating and recumbent rumination? Optimal eating behavior occurs when cows consume their daily dry matter intake within three to five hours. We know that cows typically lie down between 11 and 12 hours per day when housed indoors. Pasture cattle will lie down less.
In a cow’s ideal world, at least 80% of the eight to nine hours of daily rumination time occurs while lying down. Optimizing the relationship between eating and recumbent rumination is critical to cow health and performance. Developing monitoring technology systems to precisely manage this chewing relationship is needed. Imagine being able to monitor and manage the cow’s distribution of chewing time between the feedbunk and in the stalls!
All rumination isn’t equal
Recent research tells us cows that ruminate more while lying down have higher rumen pH, consume more dry matter, and yield milk with higher percentages of fat and protein. In fact, at Miner Institute we recently discovered the strongest positive relationship between behavior and milk components was between rumination while lying down and milk fat. Think about this: cows may have similar daily rumination time, but those that ruminate more while lying down eat more and produce milk with extra fat and protein.
We must ensure that forage and feeding management allow the cow ample time to practice recumbent rumination. Ensure that every cow can consume its daily dry matter intake requirement within three to five hours and has access to a comfortable stall or resting place to practice the all-important recumbent rumination. For me, recognizing the fundamental importance of recumbent rumination was surely a “eureka moment.”
Fiber characteristics of the forage and ration affect chewing time as we’ve discussed. Together with the feed, the feeding environment is critical in allowing the cow to consume its daily feed requirement in a healthy manner. Ensuring feed and water availability and avoiding excessive competition are key.
Keep in mind the need for the cow to eat, lie down, and ruminate in a comfortable resting area: stall comfort and deep beds (with at least 4-inch deep bedding) are a critical part of successful feeding management!
Keep it short
Total mixed ration (TMR) particles retained on the 19-mm sieve of the Penn State Particle Separator (the top sieve) are most likely to be sorted by the cow. These longer particles are associated with more variation in chewing time, rumen pH, dry matter intake, and milk yield — especially for cows in early lactation. This reflects the fact that these longer particles can be sorted to varying extents by individual cows, resulting in more variation from cow-to-cow.
Dairy herds with the highest milk fat percentage have greater than 50% of the TMR retained on the 8-mm sieve. This is another good reason to focus on the second sieve of the Penn State Particle Separator when assessing rations for their ability to support healthy and desirable chewing activity.
The ideal particle distribution for TMR is about 2% to 5% of particles on the top sieve to minimize sorting activity (on an as-fed basis). In addition, these particles do not need to be longer than 1 to 2 inches for optimum chewing activity. Greater than 50% of ration particles should be on the second sieve. Typically, an optimally sized ration will contain 50% to 60% of particles on this sieve.
It is important to note that these recommendations are based mainly on rations formulated with corn silage, haylage, and variable amounts of dry chopped forage. Rations composed mostly of dry forages — especially if they are of high quality and fragile — might require more particles in the top two tiers of the separator to ensure healthy rumen function.
Watch the chop length
Details on recommended chop lengths for total mixed rations and forages can be found in an article published last year by Kurt Cotanch and me in the peer-reviewed journal Applied Animal Science (volume 39, pages 146 to 155). Interested readers can go to the website appliedanimalscience.org and search for the title of our paper, “Chewing behavior of dairy cows: practical perspectives on forage fiber and the management environment.”
As explained in the paper, you can imagine a sliding scale for theoretical length of chop between approximately 12 and 22 mm (approximately 3/8 to 3/4 of an inch). Below this range you can expect faster passage rates from the rumen and reduced efficiency. Above this range, the potential for sorting grows. Within the average range, the optimal length of chop can be adjusted based on factors such as maturity at harvest, fragility of the crop, and moisture content.
For example, as a hay crop matures, cut it finer. Drier, more fragile alfalfa should be chopped coarser. Likewise, highly digestible and fragile brown midrib corn silage should be chopped coarser. As corn silage matures and drops in moisture, chop it finer.
This precision approach can be used proactively as crops are harvested to best match crop fiber characteristics with ideal chop size. For instance, if maturity gets away from you, or the corn crop becomes drier in the fall, proactively set the chop length shorter. Take advantage of what you know about how the growing environment affects fiber lignification and its digestibility. I’d suggest that hot and wet weather calls for a shorter chop length since we know these conditions speed up lignification and reduce fiber digestibility.
An important part of precision management of ration particle size is to think about the factors that can further reduce particle size as the forage is mixed and fed to the cows. Some key factors to consider include silage removal and use of defacers, sharpness of mixer knives, and mixing time.
Manage eating time
Precision chewing management allows every cow to achieve the proper balance between eating time and recumbent rumination. Eating time is optimized by feed management that ensures availability 24 hours a day, seven days a week.
The ration itself should have the appropriate particle size, fiber digestibility, and forage content to allow consumption within three to five hours. The particle size of the feed should be enriched with those on the 8-mm sieve of the Penn State Particle Separator to avoid excessive eating time while stimulating ample rumination.
Finally, allow for comfortable conditions where cows can rest for 11 to 12 hours daily, with 80% or more of rumination time occurring while cows are lying down. Precision chewing management ensures optimal dry matter intake, a healthy rumen, and efficient production of fat and protein.
