When feeding salt, minerals, vitamins or supplements to livestock, the goal is to provide the required amount of nutrients each day.
Free choice mineral or salt supplementation on pasture has been shown to be inconsistent at best. In 1996, Rob Hand with Alberta Agriculture determined that cows on average only came for salt once every 4 to 5 days with consumption varying from 1 gram to 774 grams per visit (1.7 pounds). Yearlings and calves came every 2 to 3 days and consumed from 1 to 1140 grams (2.5 pounds). The research didn’t indicate how many cows didn’t come to the salt station.
Cockwill, published results from a study done in 2000. He found the same variability in intake but only 18 to 29% of the cows in the herd visited the salt station over a 6 day period.
These results show that using free choice supplementation is not a reliable method.
One option is to mix the mineral or supplement in a grain mix. This works if the weight of the mixer load of grain is known, and the amount of each ingredient is added according to what is needed to make a balanced ration.
When is it best to add these ingredients to the mixer?
If the mixer has a flat bottom, adding the ingredients to an empty tank results in some of the ingredients staying on the mixer floor below the rotating screw auger. This can cause an uneven distribution of the added nutrients in the load. This can also result in high concentrations or “hot spots” in the load. If an ionophore such as Rumensin is in the mix, cows over consuming Rumensin from one of these “hot spots” which can cause a temporary reduction in feed intake.
Adding the mineral or supplement when the mixer is half full prevents product from accumulating on the mixer floor and helps to the distribution of the product during the grinding or rolling of the second half of the load. Adding product when the mixer is almost full creates the same problem as adding the ingredients when the tank is empty and the load doesn’t mix adequately.
When a total mixed ration (TMR) is used, convenience often dictates the order in which ingredients are added to the batch. According to the University of Minnesota Extension Service publication, it depends on the type of equipment that is being used.
For horizontal auger mixers, dry concentrates should be added first. This includes grains, supplements, minerals, vitamins and salt. Followed by the ensiled “wet” forages such as silage. The last ingredient to go into the mixer is dry hay or straw. They also recommend that the hay or straw be coarsely ground before adding to the mixer.
For vertical mixers, dry hay or forages should be added in first. Followed by the grains, minerals, supplements, minerals, vitamins and salt. The “wet” forages should be added last.
The publication also warns that mixing the load for longer than necessary does two things. First, reduces stem length of the dry forage and reduces effective fibre in the ration. Second, over mixing results in separation of feed types.
A couple links to articles:
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