Some thoughts on cattle feeding program design

Nutrition with John McKinnon

In my last column, I discussed some of the issues cattle feeders — particularly those new to feeding — face when starting calves on feed. The basic message was that with feed intake, these animals need to get off to a fast start to minimize issues associated with weaning stress and the various disease challenges they face.

The goal is to get calves eating at 2.5 to 2.7 per cent of body weight on a dry matter (DM) basis, ideally within the first two to three weeks of arrival at the feedlot. With this column I want to continue this discussion with a focus on the feeding program design.

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While there is a wide range of feeding programs in use across the country, most feedlots use a step-up feeding program that consists of a series of rations formulated to increase in energy density as you move from one ration to another. In the case of finishing operations, such a program might consist of six to eight rations that range from the starter through to the final finishing ration. In the case of backgrounding operations, there might be three or four rations, depending on the nature of the operation.

As mentioned last month, the starter ration typically comprises 30 to 40 per cent concentrate (i.e. cereal grains), 55 to 65 per cent forage and three to five per cent supplement (DM basis). Typical net energy of gain values will range from 0.95 to 1.00 Mcal per kg DM (67 to 69 per cent TDN), with crude protein levels ranging from 12.0 to 13.0 per cent. A liquid or dry supplement balances the ration for protein, minerals and vitamins.

As we move from the starter ration, the ratio of concentrate to forage changes at each step such that the amount of concentrate increases by approximately 10 per cent and the level of forage deceases by 10 per cent (DM basis). If we look at the finishing ration for example, in most cases it will range from 80 to 90 per cent concentrate, seven to 15 per cent forage and three to five per cent supplement. Net energy of gain values will range from 1.25 to 1.37 Mcal kg DM (78 to 83 per cent TDN), depending on the makeup of the ration with crude protein levels typically between 11.5 and 12.5 per cent. Between the starter and finisher, there can be anywhere from five to six steps that sequentially increase in energy concentration with each step of the program.

In the case of a backgrounding operation, the feeding program typically consists of the starter ration and anywhere from two to four rations that again increase in energy content by varying the concentrate to forage ratio. Depending on the desired performance level, energy levels of the final growing ration could range from 0.88 to 1.11 Mcal per kg of DM (65 to 73 per cent TDN), with crude protein levels from 11 to 13 per cent. Once the calves are eating well on the starter, they are moved up the program until the desired growing ration is reached.

A step-up feeding program as outlined above is a fundamental management tool that is used to start cattle on feed and to target specific performance goals. Step-up programs are also a means of introducing cattle to high-grain rations and for managing digestive disorders. For example, if we look at a pen of 900-pound yearling steers that have just come off grass, most cattle feeders I know would want to get these animals on the finishing ration as quickly as possible. However, these cattle have not previously seen grain and if placed directly on the finishing ration can be subjected to a variety of digestive disorders ranging from issues with cattle going off feed to downer animals suffering from acute acidosis.

In contrast, through appropriate use of a step-up program, you can start the cattle on a relatively low level of grain and once they are eating appropriately, you can step them up the program, spending three to four days on each ration until you reach the final finishing ration. By so doing, you expose the cattle to higher grain levels at each step and allow them to adapt to the higher energy levels without going off feed. Similarly, newly weaned calves can be gradually introduced to grain feeding without serious digestive upsets occurring.

Ingredient composition will vary at each step of the program. Silage (corn, barley, or alfalfa) typically comprises the majority of the forage component. However, many feedlots will feed a grass or an alfalfa/grass hay along with silage if economically priced, particularly in the initial steps of the program. Concentrate sources in backgrounding diets can include cereal grains, grain screening products, mill-run pellets, as well as a variety of locally available byproduct feeds.

As you move to higher-energy rations, it becomes necessary to feed more concentrated sources of energy such as corn, wheat or barley grain. In terms of protein supplementation, there is a wide range of options. These include byproducts such as dried distillers grains, canola meal, soybean meal as well as commercial supplements, including those based on urea.

Next article we’ll focus on management of the feeding program, particularly concerns with keeping cattle on high-grain diets for extended periods.

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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