It may seem like most university focus during the winter months is on body condition scoring – and you may be right, says Warren Rusche, cow/calf specialist with South Dakota State University. But there's a reason, he adds – because it's still the best indicator of nutrition.
"Right now most spring calving herds are either in or are approaching the last trimester," Rusche says, noting that managing body condition in the last three months ahead of calving is important for two very big reasons:
1. Thin cows tend to produce poorer quality colostrum with lower levels of immunoglobulins. They also tend to have calves that take longer to stand and are less able to produce enough body heat to maintain their temperature under cold conditions; and
2. Cows that are thin at calving are less likely to breed back in the first 21 days of the breeding season and are more likely to be open in the fall.
Between those two factors, body condition influences the size of the next two calf checks. That's the reason for the focus, because body condition can have such a sizeable impact on a rancher's bottom line, Rusche says.
There are a number of checklists and visual guides that have been developed to condition score cows, and it's not complicated: if you can see more than one or two ribs and the outline of the spine is visible, then that cow is below the optimum body condition score.
In a group of cows, the key factor is how many cows in the group are below that optimum line. If there's only a small number, there is little reason to be concerned. These cows may simply be cattle that don't fit their environment.
"Spending a lot of extra money on the entire group to pick up the handful at the bottom isn't likely to be profitable," Rusche says.
It would be more feasible to sort this group and manage them separately, he advises.
Larger percentages of thin cows, however, indicate that additional inputs will be required or that changes to the production system need to be made, or both. If additional feed energy needs to be supplied, the sooner that process begins the easier it will be to put on the necessary weight.
Rusche says that to change a cow one body condition score in 90 days requires about 20% more energy; 30% more energy is required if that change needs to happen in 60 days.
To put it another way, feeding a cow in late gestation an alfalfa-grass mixed hay diet should add about one body condition score in 90 days.
"A sixty day period would require something similar to straight alfalfa as far as energy content. Adding that much weight in 30 days would require a diet similar to corn silage," he adds.