Presenting a nutritionally correct diet is important when caring for a dairy cow, but to assume that it is all that is required in terms of the animal’s nutritional well-being is incorrect. “We need to focus on what the cow does with that feed,” says Trevor DeVries, associate professor in the Department of Animal and Poultry Science at the University of Guelph – Kemptville.
“Nutritional models have ignored how diets are consumed,” DeVries continues. “Rations are formulated without considering how feed is consumed, when feed is consumed, what feed is consumed and if cows have easy access to their feed.”
How do cows eat?
Cows were designed to graze, taking small bites and consuming small meals throughout the day. In a freestall, cows are eating 200 to 300 times faster than grazing because her feed is already cut for her.
“The way the cow consumes her feed can have a direct impact on rumen digestion,” DeVries says.
Fewer larger meals have shown a larger decline in rumen pH. Longer feeding times and a slower feeding rate allow for a more steady input to rumen. The cow can then salivate and chew more, yielding an increase in rumen buffering.
When do cows eat?
Research in 2007 observed cows on pasture that were milked twice a day. Those cattle engaged in feeding activity in the morning and in the afternoon. Similar morning and afternoon feeding activity was observed in a freestall barn.
“We timed cows to be milked and fed at the same time, two times a day,” DeVries says.
In an experiment where feeding time was moved away from milking, cows completely shifted their feeding pattern to eat when the feed was delivered.
What do cows actually consume?
Cows that sort for smaller feed particles are at risk of experiencing a depressed rumen.
DeVries reports two separate studies found the same linear relationship when it comes to sorting – milk fat drops by .15 percent for every 10 percent refusal of long particles.
“Think about how this might affect other cows,” he adds. As cows sort out the ration, those in the pen that eat later could be consuming a very different ration than what was intended.
“The way cows eat, when they eat and what they eat has a significant impact on rumen digestion, health and efficiency of a cow. We can use that knowledge, therefore, to improve our feeding management strategies,” he says.
DeVries points out two important management factors to keep in mind:
1. Ensure cows have access to freshly delivered feed. By increasing feed delivery, cows spend more time at the feedbunk across the day, consume smaller and more frequent meals throughout the day and have more equal access to feed.
According to DeVries, less sorting was noticed when feed was delivered more often (2X compared to 1X). With increased delivery, dry matter intake becomes more consistent, both in time and composition. This leads to improved rumen fermentation and less variation in pH.
Some believe cows should have access to fresh feed upon their return from milking in order to keep cows on their feet longer so teat canals have time to close. DeVries says there is some data to support this, but it is not entirely clear.
Research has also been done to look at the effect of empty feedbunks. In one study, cows fed with 14 hours of feed access ate the same amount of food as cows with 24-hour access because the cows learned that consistency. “The problem is when you are inconsistent in time without feed,” he says.
To allow for an empty bunk in order to achieve zero refusals might end up promoting bad feeding behavior, limiting intake for cows and getting a greater variability in cow responses.
2. Minimize competition at the feedbunk. Cows fed in a competitive environment eat more than 50 percent faster than non-competitively fed cows. “That is not the best thing from a rumen standpoint,” DeVries says.
When bunk space is reduced, feed intakes drop during the peak feeding time as cows don’t compensate during low feeding times.
“When given a choice, subordinate cows will choose to eat alone versus next to a dominant cow. They will also choose to have nutritional stress versus social stress,” he says.
Competition also reduces dry matter intakes during transition, particularly before calving. “This is the exact time period we don’t want reduced intakes,” DeVries says.
Simply delivering the perfect ration is not enough when it comes to dairy cow welfare. Producers also need to ensure the feed in front of the cows is fresh, feed is delivered as often as feasible and competition at the feedbunk is reduced. PD
References omitted due to space but are available upon request. Click here to email an editor.
Karen Lee
Editor
Progressive Dairyman
