Case Study: A Nutritionist’s Strategy for Solving a Starch Discrepancy in the Delivered TMR

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Written by: Kevin Buttles, MAT. PAS

Sometimes it is easy to get lulled to sleep when there is not much going on at a client’s farm – forages are the same, no fresh cow problems, no real health problems, and components are right on target.  A closer look at the farm’s historical data and a frank discussion regarding goals and expectations with the herd owner revealed a recent slump, or at least a stall, in pounds of milk produced.  My first step was to take a TMR sample for analysis and to compare the results to the formulated diet.  We have all done that.  Many of the nutrients were right on, but when the results showed four whole percentage points less in starch (22.5% instead of 26.5%), I knew I had to attack this problem from multiple angles right away.  I implemented the following investigative strategies during the next six weeks to assess big picture items and to scrutinize the smallest of details.

  1. First I retested on-farm forages and HMSC and tested the purchased corn and starch containing commodities. Dry matters needed to be corrected. When I updated the diets, I juggled around different corn sources to take advantage of different starch fermentation rates. I closely evaluated RD starch, kd rates, CHO B3 pdNDF, and uNDF in the CNCPS model.  All seemed to be good.
  2. Then I utilized the oven-dried, 7hr lab procedure on the starch containing feeds to take advantage of one of the newer starch digestibility lab procedures to improve accuracy of reporting starch kd rates.  I felt confident that I was supplying sound nutrient data for the CNCPS model.
  3. Next I sent in another TMR sample along with a manure sample, requesting a TMR digestibility and total tract starch digestibility. The TMR digestibility was average, at best, but starch digestibility was very good.  The amount of starch in the TMR, however, continued to be four points lower than the formulated diet even after raising the percent starch in the diet to 27.5%.
  4. We noticed one of the bars on the reel of the horizontal mixer was bent. This was replaced and a couple of the modifications I recommended were made to the mixing/feeding process.  I knew more changes needed to be made, but the farm crew needed to hear the message from another angle.
  5. I took another TMR and manure sample and sent it to a different lab to help verify that I was getting reliable results. This time I did an even more extensive test: evaluating starch, protein, and NDF digestibilities.  Protein digestibility was low, but starch and NDF digestibilities were both above average. Again, actual starch content was about four percentage points low.
  6. Then there was a corn silage change so the rations were updated and I increased the starch in the diet to 28.5%. The following week I took yet another TMR sample only to find that four- point shortfall again.
  7. Through the leadership of Diamond V, the pioneers of TMR Audits, a TMR Audit was conducted on the farm. This audit was scheduled two weeks earlier, but was postponed until the mixer was repaired.  The TMR Audit revealed additional feeding management modifications that the farm agreed to implement to improve mixer performance and to maximize cow eating behaviors and time budgets.  The changes having the biggest impact in improved cow performance were timing of feed delivery to specific pens and TMR wagon fill amounts, the story the farm had heard before.

As you can imagine, everyone at the farm that deals with the cows and the feeding operations became well aware of the “starch” issue with the TMR and the multiple actions taken to discover the cause and to find a solution.  Everyone started doing his job with a higher sense of accountability.  Cows started to go up in milk and the starch content of my next TMR sample was right on with the most recent starch level that had been formulated.  After that, I backed down on the percent starch in the TMR to a more normal level and it has stayed steady ever since while milk continues to climb.

Have you experienced a similar slump in milk production, and you’re stumped as to why?  Locate an Agri-Nutrition Consulting Consultant near you to help you find the answers!

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