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How well do you mix your cattle feed?

Nutrition with John McKinnon

When it comes to putting quality feed in front of cattle, there are about as many ways to accomplish this task as there are cattle operations.

In most finishing operations, we see total mixed rations (TMR) delivered via mixer wagons, while in cow-calf operations we see everything from pail-feeding grain and ad libitum bale feeding to a variety of extended winter grazing scenarios.

With some larger cow-calf operations, a more recent trend is the use of a TMR for at least part of the winter, again delivered via a mixer wagon. What I would like to do with this column is explore the value of feeding a TMR and look at some of the options for delivering feed in this fashion.

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First, let’s review a few terms so we are clear on what we are discussing. A “ration” can be any feed or combination of feeds that an animal consumes in a 24-hour period. It may or may not be nutritionally balanced and may or may not be least-cost. A “nutritionally balanced ration” is one that meets the animal’s nutrient requirements (i.e. energy, protein, minerals and vitamins) for a given level of production, including maintenance and that for pregnancy, lactation or growth. The ration may or may not be least-cost. A “least-cost ration” is typically a computer-generated ration that matches the nutrient content of available feeds to nutrient requirements of the cattle on a least-cost basis. Finally, a TMR is one that blends two or more feedstuffs together so that, from a nutritional perspective, every mouthful of feed is the same. Ideally, it is a least-cost ration, formulated to meet the nutritional requirements for the class of cattle fed.

Feedstuffs included in the mix can range from dry to wet forages, grains, byproduct feeds as well as protein and mineral supplements. A mixer wagon is simply the vehicle used to mix and deliver the ration. There are three common types on the market, including horizontal-reel or auger mixers and vertical mixers. Each type is available in truck-mounted or PTO versions.

A horizontal-reel mixer uses a rotating reel with paddles to move feed in a circular fashion. In addition, augers on either side of the mixer help to move feed in a horizontal direction.

Auger mixers come in a number of configurations including one-, two-, three- and four-auger systems. Counter-rotating augers move feed horizontally, usually in opposite directions. In some cases, knives on augers allow for limited processing of dry forages.

Vertical mixers have one or more large vertical augers equipped with knives. These mixers are wellsuited for processing dry (ie. hay or straw) and high-moisture (i.e. wrapped bale haylage or silage) forages. During mixing, feed ingredients tend to move from the bottom of the mixer to the top and then tumble back down to the bottom.

Horizontal mixers are widely used in cattle finishing operations, particularly those that feed pre-processed forage sources (i.e. silage or tub-ground hay). Vertical mixers find homes in both cow-calf and finishing operations. Their forage processing capability makes them particularly useful for larger cow-calf operations. Both types are equipped with scales for accurate loading of feed ingredients and in many cases can be integrated with computerized feeding systems.

Other less expensive options for mixing feed include bale processors that can process multiple bales as well as grind and deliver grain. While practical, the resulting ration is not necessarily a true TMR as some important ingredients may be lacking from the mix.

Accuracy is of paramount importance during mixer operation. As an operator, you want to ensure that you and/or your hired labour are accurately loading the right feed ingredients in the right amounts to each mix. Order of ingredient inclusion is also important. Bulky ingredients or those added in the largest amounts are typically loaded first, while those added in smaller amounts such as protein and/or mineral supplements are last.

In order to prevent over- or under-mixing, it is important to follow manufacturer-recommended mixing times. For most horizontal mixers, mixing for three to four minutes following the addition of the last ingredient is typical.

To monitor mixer accuracy, one can conduct a validation test. This includes taking pre-determined, equally spaced samples as the mixer is unloaded. Samples are tested for a common nutrient such as sodium. The sample-to-sample variation is then calculated and expressed as the coefficient of variation for that nutrient.

Low variation is important for two reasons. First, the lower the variation, the more accurate the mix and the closer the nutrient profile of the TMR to the original formulation. Second, if you are feeding medicated feeds (i.e. ionophores, antibiotics), the Canadian Food Inspection Agency requires that mixers be tested for accuracy on a yearly basis. In order to be certified, a mixer must have a coefficient of variation less than 15 per cent.

To summarize, while not for everyone, feeding a TMR is an effective method of ensuring cattle get the quality and quantity of feed they require. If you are looking to move in this direction, there are numerous options. A critical review of your needs and what each manufacturer offers can assist in choosing the right mixer for your operation.

About the author

Contributor

John McKinnon

John McKinnon is a Professor Emeritus at the University of Saskatchewan and a consulting nutritionist who can be reached at [email protected].

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