Uniformity of Total Mixed Rations and Its Potential Economic Benefits

Dr. Allen Young
USU Extension Dairy Specialist

A common problem on many dairies that feed a total mixed ration (TMR) is lack of uniformity of the ration. Cows do much better if the ration is consistent. It has been hard for me to document the effects of consistency because of lack of complete information, but two unrelated studies from New York state reported at the American Dairy Science Association meetings last summer documented this problem and possible economic benefits.

An abstract by Predgen and Chase from Cornell University evaluated the ration uniformity at five commercial dairies on three different days. Samples were collected from five sequential locations in the feedbunk immediately after delivery of the TMR. A major finding was that 14 out of 15 samples had a coefficient of variation (measure of uniformity) of over 10% (higher value = greater variability) for coarse particles. This means that it was difficult to maintain uniformity of coarse particles in the ration. An example of the percent of coarse particles for one day on one dairy for samples 1 to 5 was 24.0, 26.4, 26.5, 21.6 and 28.5%. Day-to-day variability was much greater than variability within day. The major day-to-day variations, in order from greatest to least, were particle size, dry matter, pH and crude protein. No differences were found in ADF. They suggested that feed variations, operator differences, loading procedures, mixing time and scale errors could contribute to variability. I have also seen major variability due to the mixer itself.

The question that might be asked is whether or not this can have an effect on income? An abstract by Tylutki and Fox, also from Cornell University, reported the results of simulation models based on feed composition and production data collected from a 600-cow dairy over a two-year period. They looked at the effect of feed composition variability on income over feed costs (IOFC). Three simulations (scenarios) were run to determine the IOFC for a ration. The first was based on the actual variability of the dairy (baseline), in the second the hay crop silage DM was kept constant (no variability), and in the third the chemical analysis of the hay crop silage was kept constant. The results, based on $14/cwt milk, suggest that failure to analyze feeds resulted in $4,380 in foregone annual income per 100 cows. Dry matter analysis was related to $1,095 of the total, $2,190 was related to chemical analysis and $1,095 related to variability of concentrate in the ration.

The results of these two studies reinforce the concepts that day-to-day variability of rations can be a big problem on dairies, and that failure to account for the variation through feed analysis or loading consistency can cost you money in lost IOFC. Daily consistency should be the goal on your dairy. There are several computer programs, such as EZ-Feed, available to help maintain uniformity on your dairy. For additional help, please contact your extension agent. ©