9 critical control points for TMR consistency
The feeding process requires skill and attention to detail to deliver a high-quality, uniform ration to all cows within a pen. The following nine critical control points can help you achieve TMR consistency.
1. Forage dry matter (DM): Changes in forage DM can have considerable impact on how the consumed ration compares to the one on paper. Ideally, forage DM should be measured multiple times per week, especially if the forage is stored in bags.
2. Mixing faced silage: Nutrient composition across the face of a bunker or drive-over pile can vary considerably due to the nature of silo filling (i.e., multiple fields, DM changes, varieties, etc.). Faced silages for that day’s feeding should be piled and mixed with a loader bucket to decrease nutrient variation from load to load.
3. Ingredient loading location: For vertical TMR mixers, the feeder should always load in the center of the mixer box to promote distribution of the ingredient throughout the mix. Loading location is less important for horizontal mixers, but loading in the center is still preferred. Use of liquid ingredients – such as water, molasses or whey permeate – makes loading location especially important, as dense liquid feeds can be difficult to distribute if loaded on either end of the vertical mixer.
4. Mixer levelness: Mixers perform best when they are level so they don’t have to fight gravity to distribute ingredients.
5. Overfilling: A general guideline for maximum load size in vertical mixers is to keep the feed level no more than 2 feet above the augers. Horizontal mixers should have 4 to 6 inches between the feed and the rails on the reel to allow for the feed to fall at the 12 o’clock position on the reel.
6. Underfilling: Underfilling typically happens with rations for dry cows or fresh cows as their pen sizes are much smaller than those of lactating cows. For these loads in vertical mixers, pay special attention to loading location and mixing speed to avoid concentrates and other feeds remaining on the augers. Minimum load size is enough feed to move feed off the augers while achieving an adequate mix.
7. Final mix time and mixer rpm: It is critical that the TMR receives a final mixing for enough time and with adequate revolutions per minute (rpm). This final mix should occur after the last ingredient is added with the mixer level and preferably stationary. This final mix should last three to five minutes with the mixer in the highest gear. Speed recommendations will vary among manufacturers, but a typical goal is greater than 30 rpm during the final mix.
8. Equipment wear: For vertical mixers, key wear points are the kicker plate, leading edge, knives and mixer walls. For horizontal mixers, the condition of the auger flighting and reel crossbars can impact ration uniformity.
9. People: Protocol drift, ineffective training and poor communication among different work groups can also lead to inconsistent feeding.
Dr. David Carlson is a Vita Plus dairy nutritionist and technical services specialist.