The variation in bale size, forage type and moisture content makes it hard to recommend a single procedure for processing and mixing round bales in all cases. The following are general guidelines for processing single and multiple round bales; ultimately some trial and error will be involved. On-farm trials are recommended to fine tune the process in each case.
1. Have the mixer running relatively slowly (15–20 auger RPM, 200–250 tractor PTO RPM (for 540 PTO RPM direct drive) when adding a bale, just fast enough to reliably prevent stalling during initial cutting. Begin with the restrictor blades withdrawn.
2. Slowly and gently add the bale between the auger and sidewall of the TMR mixer. For single auger mixers, add the bale from the rear of the mixer; for twin auger mixers, add the bale from the side between the two augers.
3. As soon as the bale has been cut into large pieces and is mostly disassembled (0.5 to 1.5 minutes), begin adding the remaining ingredients, especially the wetter ingredients such as haylage, high moisture grain and/or by products, as quickly as possible.
These moisten and add weight to the round bale forage to carry it down the mixer wall to the blades at the bottom of the auger where the most effective cutting action takes place.
In some cases it might be practical and more effective to stop the mixer when initially adding the ingredients so a more uniform downward pressure can be achieved, especially if loading takes a number of trips.
4. Once the round bale forage has been partially processed and is moving with the other ingredients, increase the auger speed to its rated speed of 41 RPM. Monitor the mix until the desired particle size and uniformity of mix is achieved. For more aggressive particle size reduction, engage the restrictor blades at this stage.
Multiple bale procedure for TMR Mixers:
1. Add the first bale as described in steps one and two for the single bale procedure.
2. As soon as the bale has been chopped into large pieces and is mostly disassembled (0.5 to 1.5 minutes), add the next bale.
3. When all the bales have been added and are chopped into large pieces and mostly disassembled, rapidly add the remaining ingredients as described in Step 3 for single bales.
4. Complete processing and mixing as described in Step 4 for single bales.
Note: Be careful not to over-process. A point exists where further processing will no longer reduce the size of the longer, more resistant particles, while the medium and smaller particles continue to reduce in size. This can create a ration with a “bi-modal” particle size distribution that is susceptible to sorting during eating.