Editor's note: The following information was provided by Dairyland Laboratories in Arcadia, Wis.

Whether the expression "into the ether" refers to vanishing into outer space or the mysterious area just beyond the computer screen, it's an ambiguous phrase that leaves many people confused as to just what the heck the "ether" really is. In dairy nutrition, we have a similarly ambiguous analysis called Ether Extract (EE) which has been used to approximate the fat content of feedstuffs since about 1860.

The problem with EE is that it contains not only fatty acids, but other ether soluble components like glycerol, urea, water, chlorophyll, fat soluble vitamins and pigments. In fact, it's been shown that up to 50 percent of forage and 20 percent of grain EE may be non-fatty acid in nature (Palmquist, 1980).

While this analysis has provided us with an inexpensive estimation of fat content for many years, the nutritional requirements of high producing cows call for more precise feed formulations than EE can provide.

A more direct approach for measuring the fat content of feeds is to measure the total fatty acids by gas chromatography (GC). This wet chemistry technique allows nutritionists to obtain both the quantity (total fatty acids) and quality (fatty acid profile) of a feedstuff in one analysis. In addition, NIR calibrations based on this technique have about 40 percent less error than calibrations for Ether Extract fat.

Currently, NIR calibrations are only available for the "total fatty acids," but a complete profile by gas chromatography is available for around $35. This includes the total, as well as the proportions of 24 individual fatty acids, and a breakdown of monounsaturated and polyunsaturated and rumen unsaturated fatty acids: www.dairylandlabs.com.

The ability to test any type of feedstuff by GC means that this is also a great way to troubleshoot milkfat depression by testing the complete TMR.

In his 2001 article in the Journal of the Science of Food and Agriculture, E.W. Hammond stated that "the invention of gas chromatography is probably the single most important event of 20th century analytical science." With increased use of this technology the dairy industry will be able to take advantage of 150 years of analytical advancement and gain some insight into the effects of fatty acids in dairy rations.