A guide on pasture-based beef finishing published by the University of Kentucky covers the challenges producers might face, from growing suitable pasture to bringing animals to a finished weight, to working with a processor, and finally, most importantly, finding customers. In this excerpt, Greg Halich, Jeff Lehmkuhler, Ray Smith and Fred Martz show how to use frame size and body condition scores to determine when you grass-fed beef animal is finished.
Few traditional cattle producers have taken a calf to an optimal finishing weight and consequently may have a difficult time assessing when an animal is ready for harvest. The optimal finishing point will vary depending on breed, frame size, sex, and other animal characteristics as well as the requirements of the end market. You will not know with certainty if you achieved your targeted goal until after the animal is slaughtered and the carcass has been graded. (Beef carcasses are not routinely graded by many processors so you may have to arrange to have this done.) However, using basic information and a few tools detailed in this publication, you can come up with a reasonably accurate estimate of when your animals are ready.
Frame size refers to the overall body size of an animal and varies among breeds and within breeds. Frame size is commonly referenced when marketing feeder calves in graded sales as small, medium, and large. In general, smaller framed animals work better for pasture-based finishing. They finish in a shorter period of time and will generally marble easier compared to large-framed animals.
You can estimate frame size by measuring the height at the hip down to the ground for a given age and gender of animal to derive a frame score. Once you have taken these measurements, you can use Table 6 in conjunction with the sex and age to get an estimate for the frame score, which provides a numerical proxy of cattle frame size.
This frame score can then be used to estimate the expected slaughter weight of the finishing animals. Previous feedlot research investigating the relationship between frame score and finishing weight provides this basis. Because of slower rates of gain, pasture-based finishing will have more skeletal growth compared to feedlot-finished animals, which increases the harvest weight. However, pasture-finished animals are also typically harvested with less backfat compared to conventionally finished beef, which decreases the harvest weight. Using these two modifications in combination with the previous research on conventionally finished animals provides some general guidelines with respect to frame score and expected slaughter weights. Table 7 summarizes these relationships and estimates finishing weights given a variety of frame sizes for both steers and heifers.
While the frame score gives us an estimate of the weight at which animals will finish, you still need to determine when they have reached this last stage. Many producers will not be able to weigh their cattle on a regular basis and thus will need a proxy to determine when their animals are finished (although comparing the actual weight when processed to their best estimate will help calibrate this estimation in the long run). Body conditioning scoring provides this tool.
Most cow-calf producers are familiar with body condition scores. Body condition scoring of beef cows ranges from 1 (an emaciated animal) to 9 (an animal that is excessively conditioned). This system can be applied to finishing animals, and Figure 1 shows the rough relationship between body conditioning score and carcass grade. For most cattle types, a body condition score of 6 to 8 is a good target to reach a USDA grade of upper Select to Choice. Animals should begin to show a blocky appearance with fat around the tailhead and smoothness over the ribs and hip bones, and the brisket should begin to fill out. Unfortunately, animals are often slaughtered at body condition scores less than 6, and owners are disappointed that the cattle did not grade Choice. To obtain marbling, you need an appreciable amount of total body fat, meaning that the animal must begin to appear as if it is “fattened.”
Keep in mind that the recommended finishing weights and body conditioning scores are intended to be a rough guide. Many factors will affect finishing weights, and you should make appropriate adjustments as necessary. However, these general guidelines can be a valuable tool for the beginning finisher. For example, if you are trying to finish a large-framed steer to low Choice, you will quickly understand that a 1,000 pound slaughter weight will not come close to achieving the desired finish level. By knowing the expected slaughter weight in combination with anticipated animal performance, you can more precisely estimate harvest windows for your target market. This information can then be used to help plan your grazing and winter feeding programs.
Ultimately, you will need to create a production system that allows you to have finished animals ready for the time period that your market requires them. A specially designed pasture-based finishing tool is available to help in this planning process. To use this tool, you will need to account for
• Calving/weaning season
• Average weaning weights
• Realistic gains during the grazing season and winter feeding period
Through this process you will be able to determine if this production system is able to hit your targeted finishing period for this particular market. You will also get a better idea of the winter gains and pasture gains necessary to achieve this target finish date. You may find out that your particular breed/frame size and calving dates are not well-suited for your target market or that you will need to adjust your production practices.