Cattle Do Not Like Hot Bunks

Jun 14, 2021

Tara Ellerman
Countryside Feed Livestock Production Specialist
What is it?
Bunk heating is an indication of feed spoiling in the feed bunk. Typically, yeasts, molds, and bacteria from fermented forages begin to ferment the readily available nutrients in a TMR when they are exposed to oxygen. This fermentation produces the heat you feel when reaching into the bunk. TMR heating can be a problem year-round, but in the hot humid months, spoilage occurs at a much higher rate. The rate of aerobic microbial growth doubles for every 10?F increase in environmental tem[erature.

What impacts can it have?
Reduced feed intake and performance are two of the major symptoms of bunk heating. Cattle do not like eating hot feed when under heat stress. Aerobic fermentation also depletes nutrients in the TMR, leading to lower quality feed being consumed!
Some toxins produced by yeast, mold, and bacterial aerobic fermentation can also cause other, more severe health problems. Sudden loss of production and onset of diseases can be attributed to toxins hindering the immune system.

How to to prevent it?
  1. Proper harvest and storage of forages
Fullly fermented forages, that have reached a stable pH, make an environment that is not ideal for the growth of aerobic microbes that cause spoilage. Producing a nice, stable, cool source of fermented forages goes a long way in preventing bunk heating! Sound silage harvest and storage practices to abide by include: chopping at a proper moisture and chop length, inoculating, covering, and packing.
  1. Feedout and face management
Again, “hot” feeds are the major culprit in bunk heating. Managing silage faces properly will help start the TMR with cool feeds and reduce risk of spoilage. Always keep silage faces as vertical as possible, and shave feed off of the face from top to bottom before picking it up. Lifting up with the loader bucked creates fracture lines that expose silage to oxygen several feet back in the pile, leading to aerobic fermentation and heating.
  1. Mix feed directly before feeding
Moisture, hot temperatures, and plenty of available nutrients make the ideal environment for microbial growth. Mixing feed right before feeding will reduce the time feed is exposed before cattle have access to it.
  1. Consider increasing number or timing of feeding
The less time feed spends in the bunk the better. That being said, many dairy cattle and beef cattle on full feed typically are fed to have feed in front of them 24-hours a day. In these scenarios, consider feeding a larger portion of feed at night when temperatures are cooler or feeding multiple times a day.
  1. Clean bunks
Excess feed in bunks is a great environment for microbial growth that causes spoilage. It is amazing how well cattle can detect moldy feed and refuse to eat the feed near it. If bunks are not clean, scoop out the old feed before continuing to add new feed on top!
  1. TMR preservers
Feed additives are available to help preserve TMRs in the feed bunk. Proprionic acid products help to reduce the microbial load in mixed feeds, resulting in less bunk spoilage!

Contact your Countryside Feed representative to discuss problems with bunk heating and to design a strategic approach that fits your operation!

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