Thin cows can be economically devastating as beef producers head into spring calving season, said Purdue Extension beef specialist Ron Lemenager.
"Spring calving cows need to be in moderate body condition at the time of calving because it has a pretty significant effect on how quickly these cows will return to estrus after calving and, subsequently, when or if they conceive," he said. "If cows are thin at calving, producers can expect long postpartum intervals, which means they will calve later the following season."
That means instead of having a 365-day calving interval, producers may face 13-14 month intervals and, ultimately, a loss of productivity.
Thin cows also tend to have lower colostrum quality, which means calves aren't able to develop the passive immunity they need to protect them against disease, cold stress and other stress factors.
"In addition, these thin cows are going to have lower milk production, resulting in lighter weaning weights of their offspring," Lemenager said.
Ideally, cows should be carrying a moderate body condition score, which falls at 5-6 on the 1-9 BCS system. In order to evaluate whether cows are at a healthy BCS, Lemenager said producers need to look past the winter hair coat the animals are carrying right now.
"There are three places on the cow that are the best indicators for body condition, starting along the top line. If you can see bone structure along the top line right under the hide, the cow is probably pretty thin," he said. "The second place is in the rib section. If the cow shows the 12th and 13th rib, she's borderline. If you can see more ribs – the 10th, 11th, 12th and 13th, the cow is too thin.
"The third place to look, and it's the least affected by muscle, fill and hair, is right along the loin edge between the 13th rib and the hooks. If a producer can see bone structure at the edge of the loin, the cow is too thin."
At this time of year, spring calving cows have advanced into the last trimester of pregnancy. Because of fetal nutrient requirements, correcting low body condition scores can be a challenge, but it's not impossible if producers can strategically supplement the animals.
Because corn prices are so high right now, Lemenager recommends beef producers look at some alternative feeds such as soybean hulls, distillers grains and corn gluten feed, which may be more economical. A chart to help producers make those decisions is available at www.thebeefcenter.com. Also included on the site is a how-to video for checking body condition scores.
"Producers should be looking at cows monthly and using BCS as a wake-up call," he said. "They are a good indicator of nutrition and reproduction. If cows look to be gaining or losing BCS, producers need to evaluate and adjust rations to optimize performance and minimize expenses."