The more things change, the more they stay the same
By : Glenn Selk, Oklahoma State University Emeritus Extension Animal Scientist
For at least three decades, beef cattle scientists have studied body condition of cows and its impact on productivity. Cows in better body condition at calving time and breeding nearly always seem to out-perform counter parts that are in thinner body condition. However, some things do change. Some examples include cattle type changes, selection methods change, drought impacts on feed availability and prices. We therefore question whether the research would give the same answers in more modern times.
Research published in a recent issue of the Journal of Animal Science (Bohnert, et al. J. Anim. Sci. 2013, 91: 5485-5491) provides some insight into this discussion. Oregon State University, University of Nebraska, and USDA-ARS scientists combined on a two year study utilizing 120 mature, crossbred (Angus X Hereford) cows/year. The cows were fed in such a manner to expect half of the cows to be in a body condition score of 6 entering the last trimester, whereas the other half of the cows were fed to be in a body condition score of 4 at the same time. The actual outcome of their management schemes resulted in the high condition cows averaging a 5.7 body condition score (1243 lbs) and the low cows averaged 4.4 (1106 lbs.) They also subdivided each of these groups and fed half of each group the equivalent of 2 pounds/day of dried distillers grains with solubles (DDGS). The supplement was fed in appropriate amounts 3 times per week. All cows received access to 28 lb/day of the hay (6.4% crude protein) during the last trimester and then after calving the cows were placed together in a common pasture and exposed to a 60 day natural breeding season.
The small amount of DDGS had only a small effect on the productivity of the cows by increasing fall weaning weights in calves nursing supplemented cows. Body condition in the last trimester however had a more dramatic impact. High body condition cows had 10% more live calves at birth and weaning than did the low body condition cows. Birth weights of the calves were higher in the high body condition cows but certainly did not increase losses due to dystocia. The total weaned calf weight per cow in the herd was 57 lb greater for the cows in better body condition prior to calving. At today’s calf prices this represents a sizeable dollar difference in productivity and should more than pay for the additional nutrition that the cows received. The story does not stop at this point. The rebreeding percentage of the cows in better body condition (92%) was significantly greater than the percentage of the thin cows (79%). Cull cow weights were also greater at weaning time for the cows that were adequately fed the previous fall.
These scientists concluded …”our research further substantiates historical data that stresses the importance of maintaining cows in acceptable BCS (body condition score) entering the last third of gestation.”