Do You Provide the Perfect Dining Experience?
You have a palatable, well-formulated ration sitting in the feed mixer – now how do you create the ideal feeding environment for your cows to respond to that diet? It boils down to the basics of ensuring feed availability 24/7, managing competition at the feedbunk so that access to feed is never limited, having plenty of water, and making certain that there are no restrictions on resting or ruminating activity.
To provide the ideal dining experience, you also need to know the customer – the cow. Her natural feeding behavior is crepuscular meaning she naturally prefers to eat at sunrise and sunset. Dairy cows are allelomimetic which means they like to eat together, and they are competitive so we must design feeding facilities and manage cows to minimize negative consequences of excessive competition. As we think about the cow’s dining experience, a fundamental question is: “does the feeding environment on your farm accommodate or frustrate these basic feeding drives?”
And don’t neglect water – the most critical and ignored nutrient. Recent work from Canada found that milk yield increases by 2.1 lb/day for every 1 in/cow of water trough space within the range of 1.5 to 5 in/cow. When creating the ideal eating environment, drinking water is critical.
The Feeding Environment and Rumen pH
In the first study, we fed two diets comprised primarily of corn silage and haycrop silage typical of the Northeast and Midwestern US. One diet had 3.5% chopped wheat straw in place of a portion of the haycrop silage to boost the physically effective NDF (i.e., particle length) and undigested NDF at 240 hours from 8.5 to 9.7% of the ration dry matter. Both diets were typical, highly digestible diets, but the straw diet provided more fiber to stimulate chewing and help fill the rumen – in other words, a “safer” diet.
These diets were then fed to cows in pens with 2 rows of head-to-head stalls and 24-in headlocks at two stocking densities: 100 and 142% of headlocks and freestalls. Higher stocking density resulted in nearly one hour less lying time per day, and less rumination while lying down in the stalls. Although total rumination did not change with diet or stocking density, we noticed that cows that spent more time ruminating in the stalls at higher stocking density had better rumen pH. Overall, adding straw improved rumen pH at either low or high stocking density, but the effect was much more important for overstocked cows. Cows that ate the lower fiber diet with overstocked conditions had by far the most hours below pH 5.8 which is a common benchmark for sub-acute rumen acidosis.
The bottom line is that overstocking had a greater negative effect on rumen pH than dietary fiber, and the combination of lower fiber and overstocking was the worst. In a world where cows are too often overcrowded at the feedbunk, this tells us that we have to boost fiber to help maintain good rumen health. And if we seek to maintain good rumen pH, we cannot substantially overcrowd.
Similarly, we have found that slick bunks combined with overstocking severely depress rumen pH. In fact, when cows are stocked at 142% and their feed access is restricted by 5 h/day to simulate slick bunk feeding, rumen pH is below 5.8 for nearly 9 h/day. That is very unhealthy and the long-term health and productive consequences of this degree of sub-acute acidosis on a herd of cows could be devastating.
Feedbunk Management and Milk Composition
We have been collaborating with Cornell University over the past two years to determine what on-farm management practices boost the de novo fatty acids in milk fat. Why the focus on de novo fatty acids? First, de novo fatty acids are those fatty acids that are made from scratch in the mammary gland as opposed to fatty acids from the diet or from mobilized body fat. The de novo fatty acids are synthesized from the primary products of rumen fiber fermentation: acetate and butyrate. So, the fraction of de novo fatty acids in milk fat should be a good barometer of rumen health and fermentation activity. Importantly, Cornell University research has shown that herds with higher de novo fatty acids produce more total milk fat and protein likely reflecting better rumen fermentation and microbial protein production. Increasingly, milk cooperatives are beginning to use routine milk fatty acid analyses to monitor feeding and management practices on the farm.
We monitored 79 herds in Vermont and Northern New York State and found that the top-4 factors affecting de novo fatty acid and total milk fat and protein output were: stocking density, feeding frequency, physically effective NDF, and dietary fat. Herds with high de novo fatty acids were 10x more likely to have at least 18 in/cow of bunk space and 5x more likely to have stall stocking density less than 110%. In fact, stocking density alone explained 65% of the variation in de novo fatty acid synthesis among farms. We see time and again that overstocking has a large and negative impact on cow health and performance.
Herds with high de novo fatty acids also were 5x more likely to feed the total mixed ration twice rather than once per day. Tie stall herds with high de novo fatty acids were 11x more likely to feed greater than 5 times daily. Not surprisingly, the high de novo herds were 10x more likely to feed adequate physically effective NDF and they also fed lower dietary fat.
The bottom line is that there is a direct relationship between rumen pH and milk composition. Having a well-formulated diet is critical, but recent research clearly tells us that the feeding environment has the greatest impact on rumen pH and milk composition. We must focus on stocking density, feeding frequency, and feed availability to boost milk component production.
Food For Thought – Assessing Industry Norms
As we design the ideal feeding environment, we focus on the basics: feed push-ups, feeding frequency, feed refusals, and bunk space. There are proven ways to boost dry matter intake such as ensuring a smooth manger eating surface, manger height 4 to 6 inches above the floor, and feed alley width of 14 ft to allow unhindered cow flow. Remember that one pound of dry matter intake translates into about 2 pounds of milk for a Holstein cow.
Let’s focus on current recommendations for these key components of the cow’s feeding experience and what recent research tells us about the adequacy of these recommendations.
Feed push-ups. Cows naturally have an aggressive feeding drive. They willingly exert greater than 500 lb of force against the feed barrier while eating. For comparison, it only takes about 225 lb of force to cause tissue damage. So, cows will injure themselves in an effort to reach feed. As herd mangers we cannot allow this to happen routinely. Over time, when a cow is forced repeatedly to reach for pushed-back feed at the bunk, she will become less aggressive and less likely to approach the feed bunk when fresh feed is delivered or pushed up.
Although feed push-up may not stimulate feeding at the bunk as much as fresh feed delivery, it is critical to keep feed within easy reach and well distributed along the entire length of the feed manger. Researchers at the University of Arizona focused on the two hours after feed delivery since it is the most competitive time with the greatest number of displacements from the bunk. In this study, feed was either pushed up each half-hour for the first two hours or once per hour for the first two hours after feed delivery. Cows were fed three times daily and all other management practices were similar between the two push-up strategies. Cows with greater feed push-up frequency during the two hours after feed delivery produced more milk on the same dry matter intake – they were 10% more efficient.
Since cows produced more milk from the same pounds of dry matter, digestive efficiency was truly increased which translates into a substantial economic boost for the farm. The take-home message from this study is not to push up feed twice an hour after feeding, but rather to focus on those 1-2 hours right after feed delivery and figure out the optimal times to push up feed for each individual farm. Once the cows begin to reach for feed and press against the feed barrier, the ration ought to be pushed up to avoid excessive force and injury, dampening of their natural aggressive feeding drive, and greater milk production efficiency.
Feeding frequency. Delivery of fresh feed, feed push-up, and milking all stimulate feeding by the dairy cow, but the single biggest driver of feeding is delivery of fresh feed. Twice versus once daily feeding results in more feed availability throughout the day, less sorting, and greater feed efficiency. In fact, University of Guelph researchers found that 2x versus 1x/day feed delivery improves dry matter intake by 3.1 lb/d and milk yield by 4.4 lb/d. Previous work has shown that greater feeding frequency improves rumen fermentation, stimulates rumination, and promotes eating activity. Feeding 4 or 5 times daily may actually reduce performance if it inadvertently interferes with resting time, but the data are clear that 2x/day promotes better feed efficiency than 1x/day feeding. This would be especially true during heat stress conditions when the ration can easily reheat and go out of condition in the feed bunk.
Feed refusal level. Overfeeding cows can reduce efficiency of milk production. For each 2 percentage-unit increase in feed refusals there is a 1.3% increase in sorting according to Guelph research. And feed efficiency (milk/DMI) decreases by 3% for each 1% increase in sorting. But, the most common problem on-farm is not overfeeding, but trying to manage to very low refusal levels or even “slick bunks.” A common industry guideline is 2-3% feed refusals which may be adequate for some later lactation groups, but certainly not for fresh and high-production pens where 4% is a better target. The management goal should be to never short-change the fresh and high-producing cows.
How long can the feedbunk be empty? There is one study that assessed the effect of 0, 3, 6, or 9 h/day of feed restriction on dairy cows. This research found that cows were highly motivated to eat after only 3 hours without feed. In other words, they were hungry. It may well be that high-producing cows become hungry sooner than 3 hours, but the research has not been done. From a practical perspective, this means that bunks should not be empty for longer than 3 h/day and ideally never.
Researchers at the University of British Columbia restricted feed access for 10 h/day, from 8:00 pm to 6:00 am. This severe feed restriction caused twice as many displacements at the feedbunk and dry matter intake was reduced by 3.5 lb/day per cow. Nebraska scientists conducted a case study where the feedbunk was empty from midnight to 6:00 am, an example of bare bunk disease which may happen too routinely on commercial dairy farms. In this study when the bare bunk was corrected, milk yield increased by nearly 8 lb/day per cow, there was 1.8x greater lying in the stalls, twice as much feeding at the bunk, the cows were generally less restless at night, and stall use was much more uniform.
Feedbunk stocking density and feeding behavior. As feedbunk stocking density increases, we typically see greater aggression and displacements, a shift in time of day that subordinate cows eat, fewer meals, faster eating rate (i.e., slug feeding), and a greater potential for sorting. As always, the most negative impact will be observed for the less competitive subordinate cow. Within limits, cows can adjust their feeding behavior to maintain dry matter intake in the face of overcrowding, but eventually the overcrowding will reach a point where they can no longer practice natural feeding behavior, and health and performance of the cow suffers. In many situations, that point will occur at about 110 to 120% stocking density of the feedbunk and free stalls.
A study conducted by the same British Columbia research group assessed the effect of bunk space on feed choice by subordinate cows. In this study, subordinate cows were given a choice between a high- or low-palatability grain mix. The low-palatability mix could be eaten alone, while the high-palatability mix had to be eaten beside a dominant cow who was either 12, 18, 24, or 30 inches away. With highly restrictive manger space (i.e., 12 and 18 in/cow), the subordinate cows chose overwhelmingly to eat the less desirable feed alone. When manger space was 24 or 30 in/cow, then the subordinate cows chose the two mixes equally. But, even with 24 (industry standard) or 30 inches of bunk space, about 40% of subordinate cows still chose to eat the less desirable feed alone.
This is a natural behavior of dairy cows that likely cannot be changed and it represents a major challenge to the dairy industry going forward.
How do we ensure adequate access to high quality feed when some cows will choose lower value feed in an effort to avoid competition with a more dominant cow? The answer requires that we optimize all of the components of the feeding environment discussed in this article. Additionally it may be a perfect opportunity for precision management where we can individually supplement cows within a group setting.
The big question is: “are 24 inches of bunk space per cow enough?” It is the industry standard, yet all cows cannot eat together at 24 in/cow. Research shows that, as bunk space per cow increases from 24 to 36 inches, bunk displacements decrease and there is more feeding time. So, if you ask the cow – and that is what research trials do – the resounding answer is no!
The Perfect Dining Experience
As we consider all of the accumulated research and practical, on-farm knowledge regarding feedbunk management and optimizing dry matter intake, here is a check list of management factors that should constitute an ideal dining experience for cows in your herd:
- Management that enhances rest and rumination
- Feed available on demand
- Bunk empty no more than 3 h/day and ideally never
- Consistent feed quality and quantity along the entire length of the bunk
- Bunk stocking density ≤100% (greater than 24 in/cow)
- Total mixed ration fed twice per day
- Feed push-up focused on two hours post-feeding
- Approximately 3-4% feed refusal target
To enhance the dining experience and maximize cow comfort economics, we must provide ample bunk space, manage competition, and design feeding systems that optimize feeding, resting, and ruminating behavior.
Editor’s note: This information was prepared for publication by Dr. Grant from his presentation at the California Animal Nutrition Conference, held May 10 & 11 in Fresno.