“Dry matter content changes as you go through the bunker, and when you have rainfalls, that can really affect dry matter content. And that is how most people initially will use this technology, to do more frequent measurement of dry matter content on a daily basis,” he adds. “Rain events can affect dry matter and depress milk production, so knowing moisture content allows one to adjust rations accordingly,” Dr. Shaver says.
Study compares on-farm NIR to oven method
Dr. Shaver’s graduate student, Matt Akins, presented a paper “Evaluation of On-Farm Forage Dry Matter Determined by Near Infrared Spectroscopy” at the 2012 American Dairy Science Association conference in Phoenix. They have conducted their research using the portable AgriNIR™ Portable Analyzer for Forages from dinamica generale US, Inc.
The objective of the study was to evaluate the use of near infrared spectroscopy (NIRS) for on-farm measurement of forage dry matter content, Dr. Shaver says. The NIRS measured protein, NDF, ADF, starch, ash and fat, but only compared dry matter content to results from an oven method. The 11-week study measured 94 corn silage samples from six silo bags and two bunkers, and 20 alfalfa silage samples from one bunker, using the oven method and the NIRS.
“Overall, the on-farm NIRS measured dry matter content comparable to the oven method,” the study concludes.
Goal is TMR consistency
Evaluating forages more consistently and frequently means more consistent TMRs, says Tom Oelberg, Regional Sales Manager, Diamond V. “I would envision sampling the TMR 10 times for each load if needed.”
TMR audits are another use. “When we make changes from a TMR audit to improve consistency, we’re seeing a 1 to 3 lbs increase in milk production and a point or two improvement in milk components. It can have a huge economic impact, especially in the larger operations.”
Kurt Ruppel, Cargill Technology Leader, agrees. “If a change in a major ingredient is varying a half a percent, it can mean 20 cents per cow per day,” he says. “If a major ingredient is varying a lot, we want to know why. Constantly changing the nutrients delivered to the cow creates inconsistent production and reduced feed efficiency.”
According to a 2012 Ohio State University study, substantial day-to-day variability in dry matter, NDF, CP and starch in corn silage and haycrop silage is very large and often as great as month-to-month variation. Over the course of the day-to-day variation, specific nutrients, such as starch, did not follow any discernable pattern. Because diets are formulated on a dry matter basis but delivered on an as-fed basis, a deviation of dry matter could substantially alter the diet composition in just one day.