Katie Mason, PhD, Extension Beef Cattle Specialist, University of Tennessee Institute of Agriculture
I often get inquiries about how a producer should feed their cows. I go through a series of questions about stage of production, forage quality, feedstuff availability, and the like. To determine cattle needs, I use information from the beef cattle nutrient requirement tables published by the National Academies of Sciences, Engineering, and Medicine (NASEM), but often referred to as “NRC values” from the previous name, National Research Council. There are a whole host of spreadsheet tools and methods to perform ration calculations, and heck, sometimes I even pull out the trusty pen and paper (and a calculator!). Needless to say, I use several tools to deliver an informed and helpful answer. But I always try to remind the producer or agent of one very important tool that we all have access to: body condition score.
Body condition score (BCS), an indicator of relative fatness/condition/energy stores, can be visually assessed at any point in time to evaluate the nutritional status of cattle. Some critical times to evaluate BCS are 90 days prior to calving, before breeding, and at weaning. For beef cattle, the scale ranges from 1 to 9, with 1 being extremely thin and 9 being obese. The ideal range for beef cattle is right in the middle: 5 for mature cows and 6 for first-calf and two-year old heifers. Cattle that calve at a BCS of 5 or 6 have enough energy stores to have a productive lactation period and breed back in a timely fashion so that they maintain a yearly calving interval.
When evaluating BCS in cattle, start by looking at the ribs. A rule of thumb I follow is “4 ribs = 4 BCS.” If I can see 4 ribs, I estimate that animal at a 4 BCS, and then adjust up or down based on other areas of the body, like the back, hooks & pins, tailhead, and brisket. The publication, “Body Condition Scoring Beef Cows: A Tool for Managing the Nutrition Program for Beef Herds” – EC281, from UNL Extension provides a very through explanation of body condition scoring and its implications on cattle management.
If you do not have a lot of experience body condition scoring, do not get too caught up in assigning exact numbers. Start by evaluating and sorting cattle into groups of thin, moderate, and fat. Then refine your nutritional management and eye for BCS over time. Keep records of BCS on a whole-herd or group basis to see how it fluctuates throughout stages of production, but it is also important evaluate individual cows. Individual BCS can help you determine which cows may be more efficient or which ones have a harder time keeping condition, weaning good calves, or breeding back, which can help you making breeding and culling decisions.
Nutrition does not have a “one size fits all” answer. No matter how many spreadsheets I use or numbers I crunch, I always say no calculator can tell me as much as body condition score can. If you find that a ration is not keeping weight on your cows, it may be time to reevaluate and bump up the plane of nutrition. Make it a regular practice to body condition score your cows to make the most of your nutritional planning.