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The Forgotten Cost of TMR Sorting

In prior articles we have discussed TMR sorting and how it can lead to sub-acute rumen acidosis (SARA).  This condition has a huge impact on bottom line profits. However, the impact of TMR sorting goes far beyond SARA. When cows sort their TMR they change the nutrient profile of the feed that is left in the bunk.

The behavior of individual cows in the herd has a huge impact on how this sorted feed will affect them.   According to Dr. Trevor DeVries of the University of Guelph, cows are social animals that,  “… tend to synchronize their behavior, including a strong desire to access the feed bunk as a group.  When space is reduced, this behavior increases competition for access [to feed]…”   The most aggressive cows in the herd are more likely to access fresh feed soon after delivery and pick out the grain putting them at a greater risk of SARA.   On the other hand the more submissive cows can be left with feed that is much higher in fiber and lower in carbohydrate.  These cows are more likely to consume a ‘ration’ that has a lower energy density and they may fail to reach their potential peak milk yield and/or lose body condition.   If feed bunk space is limited then the problem is exacerbated.

So the cost associated with TMR sorting goes far beyond the costs associated with SARA.   There are several strategies that can be employed to reduce the sorting of a TMR including:

  • increasing feed bunk space
  • providing headlocks or barriers
  • increasing the frequency of TMR delivery

Providing adequate feed bunk space decreases competition for feed and reduces the incidence of sorting.  When feed bunk space is limited, the competition between cows for feed increases resulting in decreased access to feed for submissive cows, an increased risk of SARA, and an increase in variation of the nutrient profile consumed by individual cows.   In this scenario the aggressive cows discourage subordinate cows from approaching the feed bunk, these more timid cows end up consuming feed that has been picked over by more aggressive cows. The solutions to this issue includes providing more than 24 inches of feed bunk space per cow,  using headlocks, or other barriers that protect submissive cows.  Canadian researchers have even evaluated putting partitions along the feed bunk that resemble a “mini-free stall divider”  to protect cows from competition for feed.

How does your herd measure up?  

Have you stopped to think how TMR sorting could be impacting your bottom line?   Here are steps you can take to evaluate your situation.

  • Compare the fat and protein tests of individual cows in your herd.
    • Do you have cows that have both a very high and very low test? This indicates that sorting could be an issue not only due to SARA (low fat tests) but also submissive cows consuming a low energy density diet.
  • How much bunk space do you have per cow?   If you are under 24 inches then the risk of sorting is significant.
  • Do you have headlocks and/or partitions?  Headlocks make it more difficult for aggressive cows to push submissive cows away from feed.
  • How many times a day do you deliver TMR?   Delivering feed 2 or 3 times a day reduces sorting of feed.

Perhaps the best way to determine how cow behavior is impacting sorting is to watch your cows eat.   Have you taken time to watch and see the patterns of behavior in your herd when fresh feed is delivered?   Do the most aggressive cows come to the bunk to eat and prevent the timid cows from eating or does everyone come up and find a place to eat?  Are only the younger and smaller cows eating while everyone else is resting?    Have you taken time to make these cow behavior observations in the last week? If not then take time today to watch your cows eat and see what patterns of behavior you can detect.

Source: Agri-Nutrition Consulting  – Scott Bascom

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