Kyle Taysom, CEO Dairyland Labs recently gave a webinar presentation.  In his talk he showed 100 replicate samples from a corn silage pile (see table).  If diets were formulated using an individual sample, 30 of the 100 samples would use a starch value that is wrong by greater than 3 units and 5 of the 100 samples would be wrong by over 6 units.  This is consistent with research at The Ohio State University.  They concluded that “single samples should not be relied upon to provide an accurate description of the feed” (Weiss, 2012).

Taysom, 2020

Dairyland Labs recommends 2 – 4 samples should be analyzed before any decisions are made in formulating rations.  My strategy is to sample a new feed 3 times in a short period of time.  If the results between the 3 samples are consistent, I am confident I have an accurate representation of the feed and use the average of those 3 samples to balance a diet.  I then spot check periodically after.  If there is a lot of variation between the 3 samples, I do more sampling to determine the outliers.

Sometimes we know there is going to be variation due to multiple fields, harvest times, multiple varieties or hybrids, etc. In this case I would use a weighted average which means more weight is given to the most recent sample taken.

I would caution against letting the cost of lab analysis prevent taking enough samples to get an accurate picture of the feedstuff.  If the input data to formulate rations is inaccurate, then the ration is not balanced!  This reduces profits by either reducing performance or increasing ration costs.

Spence Driver

Spence Driver

Dairy Nutritionist