All the Data, All the Time... as it relates to Optimal Cow Size
Part 1 – Is that 1100-lb cow really a 1100-lb cow?
Identifying the optimal mature cow size remains one of our industry’s most frequently cussed and discussed selection challenges. Mature weight (MW) and mature height (MH) impact cow herd profitability through maintenance requirements, reproductive rate, stocking rate, and cull cow value. These traits are moderate to highly heritable (≈.45 and ≈.62 respectively), so mistakes in bull selection have a good chance of showing up as undesired phenotypes in the cowherd. Furthermore, due to the high (≈.80) correlation between MH & MW, change in one trait typically comes with a corresponding change in the other. Some producers fear that unrestrained selection for growth will lead to increases in mature size and ultimately cows that eat their way out of environmental “fit”. On the other hand, the US sheep industry’s loss of 85% of its 1945 flock warns us that simply running more, smaller ruminants per acre is no guarantee of sustainability. One of the difficulties in selection for our "ideal" cow size is that, most producers only weigh cows when something bad has happened, i.e. she came up open. At Mushrush Red Angus, we capture a weight on each cow when her calf is weaned, but her weight alone doesn’t come close to telling if she fits our idea of optimal... For example: Cow A weighed 1100 lbs when her calf is weaned in the fall. Cow B lived in the same pasture all summer and also weighed 1100 lbs on the same day. So Cow A and Cow B are the same size, right?
Not so fast, we need more information. What if we dug a little deeper and found that: Cow A was a 9 year-old cow in Body Condition Score (BCS) 7, while Cow B was a 2 year-old cow in BCS 3?
If we adjust Cow A down to a BCS 5, we find she's probably closer to 1000 cow - albeit a fat one. Likewise, when we adjust Cow B up to a BCS of 5 and also adjust her age to that of a mature 5-year-old, we can easily imagine she is closer to a 1300 lb. cow. Our bull sale catalog provides Age of Dam (AoD), Cow Weight, and BCS (taken when her calf was weaned) for each bull. However, we also understand that adjusting those measures in one’s head on the day of the bull sale may not be the most user-friendly way for seedstock producers to present that data to ranchers.
Stay tuned… Our fall newsletter will discuss how cow weight/BCS data is used in genetic evaluation as well as evaluate new and more useful ways this data can be presented.
BIF to tour Mushrush Red Angus
Mushrush Red Angus has been selected for 2016 Beef Improvement Federation (BIF) seedstock tour to represent Red Angus and Kansas' Beef Industry.
Progress on the Prairie 2016 BIF Conference
June 14–17, Manhattan, Kansas • For more info visit: http://www.asi.k-state.edu/events/2016bif