TMRs are commonly fed to dairy animals because they provide all the nutrients the cow needs in one go. The volatility of feed raw materials in terms of both availability and price, is putting increasing pressure on dairy units. High quality and nutritionally balanced feed must be delivered to the animal to achieve optimal levels of performance.
Any wasted feed represents a big cost to the producer directly and indirectly (extra labour required to remove refused feed, lower outputs). So, ensuring feed is eaten by the cows is vital. But how can the nutritional quality of TMR be maintained, especially during the warmer months of the summer?
Jan-Hendrik Puckhaber is an expert on TMR. Together with his wife, they run a 180-head dairy herd in north-east Germany milked by three robotic milkers. We asked Jan-Hendrik for the latest information about feeding TMR, especially as we move into the warmer summer months in the northern hemisphere.
1. What are the most common nutritional problems you see on dairy farms?
Dry matter intake (DMI) is the key to avoid most nutritional problems. You have to stabilize the DMI especially during high temperature and high humidity weather conditions. Failure to stabilize the TMR leads to heating in the forage, a reduction in feed quality and a sharp fall in DMI.
2. Why are the higher temperatures of the summer months a problem when feeding TMR?
When the temperatures rise, you have less time from exposing silage to oxygen to the growth of Yeasts and Molds - it is much shorter than in colder winter times. The “Bad Bugs” can roughly double their growth rates when the temperature rises 10 degrees. We see this in less stable silage and TMR - a TMR that’s stable in winter or spring will heat up quickly in Summer. The weather and humidity of the barn environment are key components when it comes to heating of TMR.
3. What causes the temperature of the TMR to rise when it is fed out?
After feed is out the silage it is exposed to oxygen and suddenly shifts from an anaerobic to an aerobic state. This allows unwanted and undesirable microorganisms like yeasts, molds and Enterobacteria to grow exponentially. These microorganisms rapidly double their numbers! When there are enough of them, the silage will first lose its taste (Cows realize this very fast), later it will heat up. When you add just little warm or already spoiled (contaminated) feed into your TMR you speed up this process, because the doubling rates start at much higher numbers.
4. How can you spot secondary heating in TMR? What are the key signs to look for?
The Cows tell the truth! At first, they will avoid to eat in the last hours before delivery of fresh TMR. Why eat a bad tasting TMR when you know that in 3-4 hours there will be fresh one arriving? But this leads a greater pH-level changes in the rumen because of more ‘slug feeding’ behaviour. When this gets worse cows reduce their DMI! Also, animals know where are “bad spots” along the feed bunk- and they avoid eating there.