“We put a lot of effort into making good feed, but the value of feed is based on how the cow interacts with it,” Dr. Trevor DeVries, University of Guelph, said at the 2018 PDPW Herdsperson Conference held in November in Wisconsin.
Feed intake drives milk production, and DeVries noted the relationship between dry matter intake (DMI) and time spent eating. “It’s not a perfect relationship, but the highest-intake cows are typically the ones that spend the most time at the feedbunk per day,” he said. “If you want cows to eat more, you need to stimulate them to get to the feedbunk more often.”
DeVries also explained how a cow eats affects how she digests her meal. He indicated that in modern dairy facilities where cows are fed a TMR inside, compared to grazing outside, they are likely consuming twice as much dry matter in one-third the amount of time. This feed is also more fermentable and digested within a shorter period of time. When large meals are consumed quickly, there can be negative consequences, such as major pH swings in the rumen environment. However, with more, smaller meals, the rumen environment stabilizes, which results in improved milkfat content and efficiency of production.
Thus, getting cows to eat the diet in front of them is more than just diet composition. According to DeVries, there are three key concepts to manage mealtime for maximum performance:
- Encourage consumption of small, frequent meals
- Make sorting difficult
- Stimulate rumination
1. Encourage small, frequent meals
Cows can’t eat when the bunk is empty, which is why feed delivery and push-ups are critical to encouraging more frequent, smaller meals. “We want to minimize the amount of time cows are without feed,” DeVries said.
Going from feeding just once to twice per day can reduce sorting and increase bunk time, which translates to healthier, more stable rumens and production responses. DeVries noted a correlation between more frequent feeding and higher milkfat percentage. A study of Northeast dairy herds showed improved levels of de novo fatty acids (precursors for milkfat production in the udder) among herds fed more frequently (twice versus once daily).
“We have the opportunity to think about timing of feeding to create eating opportunities across the day,” he said. The biggest feeding response happens after the bunk is cleaned out and new feed is delivered. “Ultimately, we get better feed efficiency when cows eat in a more stable pattern throughout the day, by spreading out intake and keeping it consistent across the day,” he said.
Just as important is pushing up feed as often as possible. “If you push up feed and cows come running because of it, that means feed is not being pushed up often enough,” he said. Getting feed in front of cows helps them to use their time more efficiently, so they can spend more time lying down and being productive when not eating.
According to DeVries, cows tend to have six to 10 meals per day, which equates to three to five hours per day eating. Every 10 additional minutes per day spent at the feedbunk, as well as each additional meal per day, each results in a half-pound more of feed intake per day. Therefore, feeding time and meal frequency are driving factors behind increasing dry matter intakes.
Accessibility is another important component to encourage feed consumption. “Cows should be able to access feed when they want to,” DeVries said. Cows that can’t reach feed will stand around and waste time, instead of lying down. More dairies are incorporating automated feed pushers to increase the frequency and consistency of push-ups and, thus, feed accessibility. A study from the University of Minnesota that looked at 33 robotic milking herds in the Midwest saw an average of 11 more pounds of milk per day on those dairies with an automated pusher compared to those with manual feed-pushing methods. Further, a Canadian study by DeVries’ group revealed increased lying time with extra feed push-ups.
Overcrowding the bunk may not only limit dry matter intake, but also alter behavioral patterns leading to consequences on health and production. As an example, in a field study of Canadian herds, DeVries found that for every additional 4 inches of bunk space beyond the average of 22 inches per cow, milkfat increased by 0.06 percentage points and somatic cell count decreased by 13 percent. He also explained that too much competition at the bunk can be particularly detrimental to close-up, fresh, timid and lame cows.
2. Make sorting difficult
In addition to how a cow eats, DeVries said we must also think about what she consumes. More sorting at the bunk level results in variation in what cows consume relative to that which they are formulated to consume. This has been demonstrated to reduce production and efficiency, and reduce yield of components. As cows sort against longer particles, there tends to be lower milkfat content. A similar association has been noted with milk protein content.
DeVries cited a study comparing fresh cow diets with long (2- to 3-inch) versus short (1-inch) straw chop length. Though there was no noticeable difference in intakes over the first 28 days in milk, cows on the short diet produced 167 more pounds of milk in that time period and showed a more stable rumen pH than their counterparts, which were doing more sorting on the long-chopped diet. Cows on the long diet spent 50 percent more time with depressed rumen pH during the second week of lactation, indicating a greater risk of subacute rumen acidosis during that time period.
3. Stimulate rumination
Healthy rumen function requires eight to 10 hours a day of ruminating, and more rumination also encourages greater passage rate and, thus, greater dry matter intake. “Anything we do to limit that behavior can negatively impact intake level and production,” DeVries said.
Some dairies see a benefit in feeding additives to stabilize rumen conditions. Monensin and sodium bicarbonate are commonly added to the diet for this purpose, as well as yeast supplements. DeVries noted several studies showing more, smaller meals associated with feeding yeast products and, thus, better rumen function, including more rumination and stabilized milkfat.
Rumination is also inherently linked to resting time in cows. Thus, poorly designed or maintained stalls, which limit resting time, will also reduce the amount of time cows devote to rumination, leading to reduced production. DeVries noted that other stressors, including heat stress and social stress (example: regrouping), may cause cows to reduce their rumination, leading to reduced intake and production. Dairy producers, thus, need to focus on minimizing those stressors.
Providing ample and consistent opportunities for cows to consume feed more frequently throughout the day in smaller meals not only encourages greater consumption, but also a healthier rumen environment. Further, preventing sorting behavior can result in higher milkfat and milk yield. Finally, maximizing the amount of time cows can devote to rumination will also help maintain good rumen health and high production. 
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Peggy Coffeen
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PHOTO: Overcrowding the bunk may not only limit dry matter intake, but also alter behavioral patterns leading to consequences on health and production. As example, in a field study of Canadian herds, DeVries found that for every additional 4 inches of bunk space beyond the average of 22 inches per cow, milkfat increased by 0.06 percentage points and somatic cell count decreased by 13 percent. Photo by Peggy Coffeen.
