Cattle diet vs. market high quality: Is there a relationship?

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If you read this column regularly, you will know that I write a lot about background and finishing program design. In these columns, I focus on formulating diets with specific energy and protein levels that target the desired growth rates for different classes of beef. Finishing programs focus not only on performance, but also on achieving the desired carcass weight and grade specifications. In the case of background programs, the goal is to bring weaned calves to an appropriate weight so that they can walk on grass or switch to ready-made feed without fear of being able to cope with too little weight. With this and my next column, I would like to examine how the nutritional program affects the market quality of different classes of beef.

First, let’s take a look at what the market today defines as “quality”. Annual cattle are usually placed in a fattening facility at around 12 or 18 months of age. In the latter case, they are typically moved out over the winter and marketed as “short yearlings” at feeding stations in late winter / early spring. In the former case they are marketed as “long yearlings” from grass. Depending on the program, these cattle can weigh anywhere from 850 to 1,100 pounds. The decisive quality feature is that the cattle that come from these programs contain little fat, ie are not over-conditioned! The goal is to develop frames and muscles, but to minimize fat deposition.

In the case of beef cattle, the definition of quality is more complicated. In Canada, carcasses of young steers and heifers (ie, less than about 30 months old) are graded for quality and yield by the Canadian Beef Grading Agency. Quality grades refer to the amount of marbling or fat within the exposed Ribeye muscle. Carcasses with trace marbling are rated Canada A, while carcasses with light marbling are rated Canada AA. The two highest quality levels are Canada AAA and Prime, with small or somewhat more extensive marbling.

Yield classes, on the other hand, are designed to predict the proportion of the carcass that can be retailed. While there are several factors that affect retail yield, the most important one is the amount of fat on the outside of the carcass (i.e., the subcutaneous fat). There is an inverse relationship between the amount of subcutaneous fat and retail yield. The more subcutaneous fat, the lower the retail return. Canadian yield tiers range from 1 to 5, with Canada 1 having the highest retail yield (52.2 percent or more) while Canada 5 having the lowest (45 percent or less).

In today’s commercial marketplace, Canada Prime and to a lesser extent AAA grade carcasses are the most sought after, especially when combined with Canada 1 or 2 yield grades. Although there are some exceptions in cattle of certain genotypes, it is a difficult task to achieve a high degree of marbling (i.e. Canada Prime) and high retail yield (i.e. Canada 1 or 2) in the same carcass. This difficulty arises from the fact that cattle do not deposit marbling fat independently of other fat deposits. Cattle that deposit a significant amount of fat in muscle tend to deposit fat elsewhere, such as under the skin (i.e., subcutaneous fat), thereby reducing retail yields. However, there are exceptions to this rule, but in most cases it applies, especially when cattle are fed heavier weights for better quality.

Back to my original question – how does the nutritional program design affect the quality of the cattle coming from background and fattening programs? Let’s start by designing rations for the background livestock. Remember, the goal is to raise cattle in these programs, not to finish them off. Background diets should be formulated to achieve specific growth rates, which in turn are based on your expected marketed date and target weight. For example, if you grow 500 pound ox calves to 850 pounds in six months, your program will need to aim for two pounds a day or a little less to reach your goal weight. If these spring calves were meant for grass in the spring, your target weight would likely be lower (i.e. 700 to 750 pounds) and a target gain of 1.2 to 1.5 pounds would be more appropriate.

Assuming all other nutritional-related factors are optimal (e.g. protein, minerals, vitamins), the two keys to achieving targeted profit in a background program are to ensure that the cattle are consuming the expected levels and getting the nutrition up the correct energy density is matched (ie net energy gain value). In terms of intake, cattle on a background diet typically consume 2.5 percent of their body weight on a dry matter basis. This means that a 650 pound Taurus should be consuming about 16 pounds DM. Choosing the right ration energy density using nutrient tables, “COWBYTES” or the services of a nutritionist is crucial, as too high an energy density can cause you to exceed your target gains, while too low an energy density can have the opposite effect.

We will continue this discussion next month, focusing on the impact of the nutrition program on carcass quality and retail yield classes.