Everywhere you turn – magazines, Extension publications, web sites, even previous issues of this newsletter – the message is the same: use cow body condition scores (BCS) as your indicator of herd nutritional status, and as a tool to direct your feeding programs. Research comparing performance of cattle on different planes of nutrition repeatedly shows strong relationships between BCS and key production measures. Calf viability, preweaning weight gains, conception rate and calving interval are all tied to the amount of condition, or energy reserves, that a cow has been able to lay down. But why does this correlation exist?
The key lies in how nutrients are allocated within the cow’s system. If nutrition is limited, the cow’s response is much more complex than “across the board” supply reductions for all body functions. Instead, needs are prioritized, and the nutritional demands of the most critical processes are fully met – at the expense of other activities. The chart below illustrates the basic flow of nutrient partitioning in a beef cow.
In other words, when nutrition is severely limited (and body condition has dropped to the low end of the scale), the cow by necessity directs everything available to her basic maintenance requirements. Animals that are underfed, but not actually starving, will expend energy for routine physical activity and, if they have not yet reached mature size, growth. If feed resources supply nutrients beyond what is needed for these functions, the cow will put down some basic energy reserves. Under these situations she would still be considered “thin,” and would have a BCS of 3 or less (10-point scale).
As long as a cow’s system can sense the presence of at least these basic energy reserves, she will direct any additional flow of nutrients towards maintaining pregnancy, and, if possible, milk production. But she has to have enough protein, energy, and other nutrients available to deposit additional energy reserves – and thus increase body condition to a moderate level – before estrus cycles can be triggered, and rebreeding take place. In practice, to ensure that cows are cycling at the start of the breeding season, we can manage feeding programs to supply everything necessary to take or keep the herd at the “Excess reserves” (BCS ~ 6) level at the top of the chart.
Even if we accept the strong ties between energy reserves and reproductive performance, it might seem that body condition scoring would be too subjective for a practical evaluation tool. But a number of scientists have conducted objective research to check for inconsistency and bias, and all have concluded that BCS is a reliable indicator of the body energy content of a beef cow. In fact, work done at Purdue (Houghton et al., 1990) showed that BCS plus body weight was a more accurate predictor of percent fat and protein in a beef animal than weight, weight-to-height ratio, or a combination of these factors. Additionally, OklahomaStateUniversity analysis (Vizcarra and Wettemann, 1996) statistically proved that the repeatability of BCS evaluations is precise enough for practical application.
As a management tool, body condition scoring not only passes the test for relevance and for accuracy, but also for practicality. Key benefits include:
ü Simplicity
ü No equipment required
ü Cattle do not have to be restrained
Visit with your QLF dealer, or local QLF representative, to see how QLF liquid supplements can effectively, and cost-effectively, work with available forages to supply your cowherd all the nutrients needed to keep body condition – and reproductive performance – at desirable levels.
Source: Dr. Cathy Bandyk, Quality Liquid Feeds