By:  Donna M. Amaral-Phillips                          Printable Version

Weather patterns often determine when forages are harvested and can influence the moisture content of the harvested crop.  This year is a great example of how weather and/or plant health may have influenced harvested moisture content.  Corn harvested for silage may be wetter or drier than normal or planned. 

The moisture (or dry matter) content of forages and other wet ingredients determines the amount which should be fed or added to the TMR mixer.  When silages are wetter, more pounds must be added to the mixer to get an equal amount of dry matter from a particular silage or wet ingredient.  As a nutritionist, we develop recipes to feed your cows based on pounds of dry matter to be fed and then convert these amounts to the amount you add of the forage stored on your farm. 

The dry matter or moisture content of silages and other wet ingredients should be measured on-farm, in addition to when samples are sent to a forage testing lab for nutrient analysis. (Larger herds may run samples daily, whereas small herds weekly, or when notable changes in moisture content have occurred.) To determine the moisture or dry matter of forages being fed, dry matter should be determined routinely using a Koster™ tester, microwave oven, or other properly calibrated method which slowly dries the sample.  A gram scale should be used to weigh the amount of forage before and after drying.

Also, the moisture content at harvest influences the resulting fermentation of the crop and the health and production of the cows fed these silages.  Forages harvested too wet (less than 28% dry matter or greater than 72% moisture) can undergo a Clostridial type of fermentation resulting in higher concentrations of butyric acid.  When fed, these silages may increase the incidence of ketosis in fresh and early lactation cows.  Corn silage harvested too dry (greater than 40% dry matter) has been shown to result in lower milk production when compared to corn harvested between 30 and 40% dry matter.  These drier corn silages have lower starch digestibility; thus proper kernel processing at harvest was critical.