Over the last 10 weeks or so that we have lived through the COVID-19 pandemic, we have come to understand the term “flattening the curve” and its importance to our public health system.
With respect to the beef industry, the largest impact of the virus to date has been on the health and safety of workers at Canada’s beef packing plants. Significant employee infection rates have forced plant closures, single shifts and slowing of line speeds. The impact downstream has been a significant buildup of cattle ready to go to market.
This situation has led to discussions between industry and government about introducing a set-aside program similar to what was in place during the BSE crisis. The goal is to identify cattle that are close to market readiness and to slow their growth so that we can stretch out the supply of finished cattle. In other words, we want to “flatten the cattle supply curve” in hopes that slaughter capacity matches supply.
As I write this article, there has been an announcement by the Alberta government to introduce a set-aside program that will pay producers to hold back cattle for up to nine weeks. Other provinces across the country may introduce similar measures. Producers enrolling in these programs will need to understand some of the basic nutrition principles related to cattle growth, if they are to manage set-aside cattle.
In order to highlight some of these principles, let us first look at an example of a potential hold-back situation. A producer enrols cattle weighing 1,400 pounds (shrunk) into a 63-day set-aside program. The goal is to market the cattle at 1,550 to 1,575 pounds. The cattle need to gain 150 to 175 pounds in 63 days, or on average, 2.6 pounds per day. Up to this point, the cattle have been on a finishing ration and likely have been gaining 3.5 to 3.75 pounds per day or better.
There are two options to achieve the goal of the set-aside program in the above example. One is to continue to feed the high-energy ration, but limit intake of the cattle. This option is only viable if all cattle have access to the bunk at one time. As well, it is necessary to determine and allot daily the specific amount of feed required to achieve the desired rate of gain. Not an easy task!
The preferred option is to develop a ration that targets the desired rate of gain. Typical finishing rations are formulated to energy densities of 1.25 to 1.40 Mcal of net energy for gain (NEg) per kg ration dry matter (DM) and typically consist of 80 to 85 per cent grain (DM basis). Rations formulated to restrict growth need to be formulated to lower energy densities, the exact nature of which will depend on factors such as body weight, environment (i.e. cold stress, pen conditions), sex (steers vs. heifers), breed and expected level of performance.
If we look at the above example using the Alberta Agriculture Cowbytes program, which is based on the National Research Council’s publication Nutrient Requirements of Beef Cattle, 7th revised edition, a 1,400-pound steer eating 28 pounds of DM and gaining 2.6 pounds per day has a NEg requirement of 0.97 Mcal per kg of DM. A set-aside ration consisting of 60 per cent corn silage, nine per cent barley straw, six per cent grass hay, 23 per cent barley grain and two per cent supplement (as fed; using typical feed nutrient specifications) would supply 0.97 Mcal of NEg and target the desired performance. Other combinations of feed ingredients would also work as long as you formulate to the required energy density.
As evidenced above, the key to developing set-aside rations is incorporating a higher level of forage to reduce dietary energy density. Cereal silage works well; however, it is relatively expensive and at this time of the year, silage supplies can be tight for many feedlots. Alternative forage sources such as grass hay, cereal straw, oat hulls, grain and pulse screening byproducts can be used to formulate lower-energy rations that target specific rates of gain for cattle of various weights and sexes.
The above discussion focuses on ration energy density, which is the most important nutrient controlling growth rate. It is important, however, to ensure that requirements for metabolizable protein (see May 2020 column), minerals and vitamins are also met.
There are also a couple of other points to consider when feeding set-aside cattle. The first concerns transitioning cattle from a high-energy to a moderate set-aside ration. While moving cattle down is not as challenging as moving cattle up a step-up program in terms of energy content, it is still a good idea to move from the finishing ration to the set-aside ration in a couple of steps so that you do not throw cattle off feed.
It is also important to evaluate your implant program covering the 63 days of the program. During the BSE crisis, feeding set-aside rations did not seem to have a detrimental impact on carcass quality; however, this might not be the case if you re-implanted during this period, particularly with an aggressive implant.
Finally, if you have concerns about how to manage cattle on a set-aside program, it would be advisable to seek professional advice.