Typically a nutritionist wants to sample individual ration ingredients for lab analysis. They then will put together a ration with these results, though many times they will not actually sample the TMR or final product.
One reason for this is difficulty in getting a proper mixture of the ingredients. However, if careful sampling protocol is followed a meaningful lab analysis can be obtained. A feedstuff sampling guide can be found under “Tools” at www.vtdairy.dasc.vt.edu.
We have been sampling TMR’s of some cooperator heads for the last three years. Some are feeding only one ration and a few are grouping by production. These TMR’s averaged 47.2% dry matter. Protein averaged 16.9% of the dry matter and TDN 73%. Starch averaged 24.3% with a range of 20.3 to 27.2% and non fiber carbohydrates 38.7% with a range of 32.1 to 43.9%. Acid detergent fiber averaged 21.6% and neutral detergent fiber 34.8%. The macromineral results averaged .87% calcium, .39% phosphorus, .34% magnesium, 1.47% potassium, and .41% sodium. The magnesium, potassium, and sodium amounts are similar to what is recommended for hot weather feeding and are greater than required during cooler times of the year. The level of phosphorus indicates effort by these herds to reduce the amount being fed although still above the requirement. The micro minerals averaged 85 PPM manganese, 103 PPM zinc, and 26 PPM copper. All are well over the required amounts for lactating cows indicating some over supplementation. This is probably an attempt to boost the immune system which is a problem with early lactation cows.
These numbers are being provided to give a benchmark for comparison. Check your calculated ration nutrients against these numbers. If you are interested it is possible to sample your TMR and compare.
Virginia Cooperative Extension materials are available for public use, re-print, or citation without further permission, provided the use includes credit to the author and to Virginia Cooperative Extension, Virginia Tech, and Virginia State University.
Issued in furtherance of Cooperative Extension work, Virginia Polytechnic Institute and State University, Virginia State University, and the U.S. Department of Agriculture cooperating. Alan L. Grant, Dean, College of Agriculture and Life Sciences; Edwin J. Jones, Director, Virginia Cooperative Extension, Virginia Tech, Blacksburg; Jewel E. Hairston, Administrator, 1890 Extension Program, Virginia State, Petersburg.
October 1, 2009