The nature and design of backgrounding rations

Nutrition with John McKinnon

Over the past number of years, I have had the opportunity to work with several operations whose business plans focus on backgrounding weaned calves. These programs generally fall into one of two categories. The first involves feeding calves weighing 550 to 650 pounds over the winter and marketing them in the spring at weights ranging from 800 to 900 pounds. Target daily gains typically range from 1.75 to 2.75 pounds depending on the weight and frame of the cattle.

The second program involves backgrounding for grass. This involves taking lighter calves weighing 350 to 500 pounds in the fall or early spring and feeding them at rates of gain ranging from 1.25 to 1.75 pounds per day, with target weights in April or May ranging from 650 to 750 pounds.

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From a nutritional perspective, providing a low-cost, balanced ration that supplies required nutrients for the desired rate of gain is key to the success of both programs. With this column I want to discuss the nature of these feeding programs as well as some of the issues producers face when developing these rations.

Central to success of these operations is their forage program. Many of these operations are silage-based with corn silage common in Eastern Canada and barley, and increasingly, corn silage used in Western Canada. Both crops, when harvested at the correct stage of maturity, have a high water soluble carbohydrate content and make excellent silage. Whole plant barley is typically cut for silage at the mid-dough stage. When stored in bunker silos, moisture content should be between 60 and 70 per cent, with an ideal target of 65 per cent.

Corn is typically ensiled at 65 to 70 per cent moisture. Corn moisture content can be monitored by following milk line development. Values of one-half to two-thirds milk line are commonly used as targets for optimal maturity. However, depending on growing conditions and corn hybrid (flint vs. dent), these values may or may not correspond to optimal moisture content for harvest. I recommend monitoring moisture content to ensure the correct stage of maturity for cutting.

Both crops are excellent energy sources with barley silage typically ranging from 60 to 65 per cent total digestible nutrients (TDN) and corn silage ranging from 65 to 70 per cent TDN. Crude protein (CP) levels for barley silage range from 10 to 13 per cent and eight to 10 per cent for corn silage. Although less common, alfalfa silage is also used as both an energy and protein source in many backgrounding operations.

In addition to silage, it is not uncommon to see some form of dry forage in these rations, typically a grass or grass/legume hay. Nutrient values for grass hays will typically range from 53 to 58 per cent TDN and 10 to 13 per cent CP, while a grass/legume hay can range up to 65 per cent TDN and 13 per cent or greater CP. Inclusion levels are dictated by relative forage cost, supply, need for processing and contribution to dietary energy and protein levels. Cereal and pulse straws are also used to either dry silage-based rations and/or to lower dietary energy levels to control growth rates.

Cereal grains such as barley, oat and corn are used sparingly to provide supplemental energy and protein. As with silage, corn grain has a higher energy (i.e. 88 vs. 82 per cent TDN) and a lower CP (i.e. nine vs. 12 per cent) content than barley grain. Feeding whole oat grain, particularly to lightweight calves, is an effective method of lowering ration processing costs yet still supplying supplemental energy and protein. Depending on cost and availability, there are also numerous byproduct feed options that can be used to supplement energy. Examples include pelleted grain screenings, lentil screenings and malt sprouts.

Perhaps the greatest challenge for these operations is meeting the mineral, vitamin and protein requirements of their cattle. Protein supplementation is often required, particularly with corn silage-based diets. In such cases it is not uncommon to see byproducts such as wheat or corn distillers grain, canola meal and soybean meal used as protein supplements. Each of these byproducts are in excess of 30 per cent protein and are extremely palatable to cattle.

As well, there are numerous commercial protein supplements available. These can range from a low of eight to a high of 40 per cent CP. Your feed company/nutritionist can help you match the appropriate supplement to your forage supply. In addition to crude protein content, give attention to the urea level in the supplement. Urea is a source of nitrogen and can be used to meet protein needs of rumen bacteria when there is a relatively high level of grain in the diet. With backgrounding diets, the ability of rumen bacteria to effectively utilize urea is limited.

Commercial supplements are usually formulated to meet the mineral and vitamin needs of the cattle, in addition to protein. They can also supply feed additives such as an ionophore. In most cases these supplements are pelleted. However, operations not purchasing a commercial protein supplement can feed a mineral/vitamin mash.

Hopefully this discussion gives food for thought on the nature of backgrounding rations and assists you with planning next fall’s feeding program.

About the author

Contributor

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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