Feeding dairy cows too little protein can be a problem if total mixed rations (TMR) are inconsistent batch-over-batch.
That was one of the findings from a 2014 study of eastern Ontario farms, highlighted by University of Guelph Animal Biosciences Professor Trevor DeVries during a recent dairy farmer information session hosted by Wallenstein Feed and Supply.
Why it matters: Well-balanced diets are key to predictable milk yields, both in terms of volume and component make-up — both of which help dairy farmers make decisions related to meeting quota requirements.
This year marked the second year Wallenstein Feed and Supply has hosted the information sessions.
Both DeVries and Wallenstein Feed and Supply nutritionist Milos Haas delivered talks focusing on building efficiency in the milking herd, with Haas targeting assessments of each cow’s long-term production numbers and DeVries taking aim at fine-tuning the feeding program for lactating cows.
Haas and DeVries both addressed a variation on one particular piece of wisdom. Every dairy farm, they each suggested, has more than one lactating cow ration: there’s the ration formulated by the nutritionist; the ration delivered to the cows; and the one consumed by the cows. To that list, Devries — taking into account what can happen to some long particles in a TMR — added a fourth ration, the one digested by the cows.
Cows love consistency, DeVries said. Farmers often recognize this when it comes to milking routines. If they haven’t yet made the same connections with respect to feed timing and quality, they should.
The eastern Ontario study sampled the TMRs on 22 dairy farms over seven consecutive days. Results revealed that, on average, the makeup of the actual feed being formulated wasn’t too far off what was originally recommended by the nutritionists. But according to DeVries, there were some farms on which the TMR content had swung considerably, leading to both underfeeding and overfeeding some elements, protein or energy content.
“The nutritionist puts a lot of work into creating a diet that’s balanced, right down to the amino acids,” DeVries said. But without efforts by the farmer and employees to maintain consistency in TMR formulation, that diet can lose its balance.
Have protocols in place that all people involved in feeding can follow, he advised. “We talk about procedural drift,” he said, referring to a tendency to cut corners to save time or physical output. “We do it ourselves, and our employees do it.”
To counter this, he urged producers to review the protocol regularly and have their employees do the same.
Even with strong protocols, though, variation in the source material can lead to TMR inconsistency.
DeVries asked info session attendees to consider how often they test the dry matter (DM) percentage of their stored feed.
“I know some people who do this daily, some once a week, some once a month.”
And there are some who only do it annually, which is almost certainly inadequate given the variations that can occur in DM based on weather at time of harvest, the field that’s being harvested, or other factors.
Particle size is important
Another factor that varied significantly in the eastern Ontario study was maximum particle size. Long particles are thought to be beneficial for stimulating the rumen, but producers should note that anything over four millimetres long can have this effect. If it gets too long, it tends to get sorted out by the cows.
Research has shown a 1.2 kilogram per day decrease in milk yield for every five per cent rise in the presence of long particles in the feed.
“We saw up to a 30 per cent variability day-to-day on some farms in terms of the long particles in the feed,” DeVries said of the eastern Ontario study.
A separate study assessing sorting of long particles by cows revealed the potential for a difference of more than one per cent in the fat content of the milk depending on how much sorting occurred.
This particular study looked at a group of cows producing a similar volume of milk and eating a similar total amount of feed, but those sorting more long particles tended to have lower milk fat.
Devries then showed two videos: one with a cow eating pasture; the other with a cow eating at a feed bunk. He estimated the cow at the bunk was consuming on a dry matter basis at about twice the rate — partly because it was fermented feed with higher DM content, but also partly because the cow knew there would be a time before long at which no more feed was available at the bunk.
To boost feed efficiency, he said, producers should aim to minimize the times when no feed is available, and if possible aim to increase the number of times per day feed is delivered to the bunk. But even if it’s not practical to increase the frequency of feed delivery, consider the timing of the delivery with an aim to spread consumption more evenly throughout the day.
When assessing the timing, he suggested, consider what times of the day cows are most likely to come to the feed bunk. Often, those are immediately after milking, and when feed is delivered. If you currently deliver feed after milking, then two of those stimuli are rolled into one. Instead, try delivering feed a little while before milking so some is consumed at that time. When cows finish milking, they’ll likely return to clean up what’s left.