Although all ANC rations are balanced for fiber, the effective fiber of a ration on the farm may not be acceptable due to particle size. There are several factors that can cause small particle size. The forage may be chopped too short, the silo unloader could be reducing the length, or the TMR mixer may be "grinding" the forage. A combination of any of these factors is also common.

Put forages in mixer last
It is important to pay close attention to particle length, especially in the winter months when unloaders tend to grind forage more. In TMR rations, particle size may be shorter than expected due to the order that ingredients are put in the mixer as well as the amount of time the mixer is run.

We recommend putting haylage and hay in the mixer last and limiting the mixing time. For instance, if a you have a silo that takes 30 minutes to unload, the TMR mixer may not have to mix the whole time the silo is unloading.

ANC purchased a Penn State Forage Separator to analyze particle lengths of TMR and forage samples. We analyzed many samples with it and found that in some cases, the particle length is acceptable when put in the mixer, but too fine when removed! The simple changes of putting forages in last and reducing mixing time made a big difference in particle length.

Analyze particle size now
The best time to think about particle size is now, before a problem arises. Examine what the particle length is going into the silo, coming out of the silo, and coming out of the mixer. If it is too short, it may cause problems such as acidosis, cows going off feed, sore feet, and low butterfat test, among others. All of these lead to a decrease in production and in turn a decrease in profit.

There are several ways to correct short particle length at harvest time. You should chop forage at the longest possible length you can with your facilities. Speeding up the feed rolls will also help and can be done by changing sprockets. In some cases, knives can be removed, but you should check with your dealer before doing this. It is not recommended to over-sharpen knives (razor sharp) because this generally leads to shorter particle length forages.

The April 1996 issue of Dairy Herd Management had a good article on checking equipment to insure proper particle length at harvest time.