Ration consistency is often overlooked as a source of variation in milk yield and feed efficiency.
A study conducted in Ontario by scientists from the University of Guelph looked at the daily variation in total mixed ration (TMR) on 22 farms. Average farm size was 162 cows; each farm was visited in both the summer and winter. Only the TMR from the highest producing group was analyzed.
Interestingly, daily variation in TMR was not as large as the variation between the formulated diet and the delivered diet. The delivered diet had excess energy, acid detergent fiber, calcium, phosphorus, magnesium and potassium compared to formulated diet. The same farms underfed crude protein, neutral detergent fiber, and sodium. Four out of the 22 farms underfed protein by at least one percentage unit as compared to formulated diet.
Daily variation in the TMR was lower. Net energy for lactation varied 1.2% of mean energy on a daily basis. The long particles varied 16.1% from the mean value on a daily basis. The scientists linked variation of nutrients to test day milk yield and efficiency of test day milk yield (Intake lb/Milk Ib). Every 5% decrease in long particle variability of a farm’s TMR yielded 2.6 lbs. more milk/cow and 2.65% increased milk yield efficiency. Every 0.5% decrease in daily variation of energy (NEL) of the diet was associated with 7 lbs. greater milk yield.
The impact of inconsistent TMR can be costly in increased feed costs and decreased milk production. The benefits of reducing variability of TMR are immediate and require low investment. One way to limit variability of particle length and energy value would be to look at the mixing and forage processing equipment that you use every day. Inconsistent forage processing can be the result of many mixing errors, but dull blades, and worn scrapers, augers, and mixing bars are the fastest and easiest issues to identify.
A quick look inside the machine each day would identify immediate problems. Monthly checks should be made to insure that scrapers reach the bottom of the tub to scoop up small particles. Auger/ screw type mixers have bolts connecting the auger to the drive shaft that should be torqued to proper specifications. Mixer wagons with high use may need to have bars and scrapers replaced regularly. Stainless steel liners are also used to prolong the life of the wagon; when the liner pits and wears it can be replaced at less cost than patching the wagon.
Mixing time and order of ingredient addition also influence the variability of forage length. Farms using bales of hay should add bales first, and mix until the forage has broken down.
The best way to evaluate if a mixer wagon is mixing well is to observe loads being mixed from above. Dead spots in the mixing process can be caused by uneven wear or missing blades. Forage rings around the bottom of augers and TMR remaining in the wagon after feed out are also signs of worn parts. When working with wagons that have a horizontal reel, a feeder should make sure the TMR has room to drop as it reaches the top of the rotation. The forage particles need to drop in order to properly mix. Some companies have added colorful markers such as marshmallows or colored candy to the TMR to observe how evenly small particles are distributed. Such an exercise is a good visual representation of ideal mixing time and performance of the mixer wagon.
It is clear that on the average farm, consistent TMR is still a goal to strive for. Routine maintenance of blades, augers and scrapers, as well as observation of the mixing process can help farmers to identify dead spots and forage rings created by wear and broken blades. Daily observation can help to identify problem areas early and give feeders a good sense of required mixing time and technique.
* Liz Remick participated in the 2014 Advanced Dairy Management program at Miner Institute. After graduating from the University of Vermont in May, she returned to Miner as the yearlong research intern. Find the Miner Institute January Farm Report online here: http://whminer.org/farmreport.html.