In a mature cow, body condition score and plane of nutrition just prior to breeding often are highlighted as having a major impact on reproductive success, Dahlen says. However, management around the time of weaning also can be a major driver of a reproductive event that can occur more than six months in the future.
Producing milk for a calf requires a lot of energy, and once weaning occurs, a mature cow's nutrient requirements are the lowest they will be all year. A majority of fetal growth occurs during the third trimester of gestation and, thus, cow nutrient requirements begin to increase during late gestation.
"If heavy lactation or poor pasture growth has cows in low body condition, weaning calves prior to the third trimester of pregnancy may allow cows to put on body condition without supplemental feeding," Dahlen says.
As cows get further along in gestation, thin cows will need to consume more calories to gain weight prior to calving. The additional calories required to gain condition later in gestation translate to greater expense for producers to get cows into proper condition at the time of calving.
"Calving in good body condition is very important because most cows lose additional body condition after calving," Dalen says. "Gaining body condition after calving is difficult because of additional energy demands of milk production and repairing the body from the trauma of calving. Cows that are thin at calving may never reach the point where they have sufficient body condition to become pregnant during the next breeding season."
Characteristics of pastures being grazed and the condition of cattle grazing pastures can be major drivers of overall herd productivity, Sedivec says. If either is in a declining state, producers should take proactive steps to alleviate strain on the system and salvage future productivity.