It's well-known that lame cattle can have reduced milk production and increased disease incidence, but the effects of lameness can also negatively affect fertility and reproduction.
Jeff DeFrain, research nutritionist at Zinpro Performance Minerals, says the link between lameness and fertility is what he considers as a “hidden transaction” in the profitability equation. “Checks are either written or cashed when it comes to milk income, hoof trimming and culling,” he says. “However, the true cost of poor fertility, especially as it relates to lameness, becomes difficult to assess in most cases.”
Relative to their healthy, non-lame herd mates, research indicates that lame cows have decreased conception rates, more services per conception, increased presence of ovarian cysts and an overall decrease in pregnancy rate.
“Lameness is a chronic stressor. Once a stress is detected by the animal, chemical signals are sent to the brain in the form of pro-inflammatory mediators,” DeFrain says.
The brain is constantly interpreting these signals and directing metabolic processes such as the release of reproductive hormones. In essence, the animal goes into “conservation mode” and puts strict limits on nutrient use until the problem is eliminated.
“Therefore, until the stressor is removed, levels of hormones such as progesterone will not return to normal,” DeFrain says. Because of this, poor reproductive performance should be expected if one chooses to inseminate lame cows.
Research shows that severely lame cows have lower maximum progesterone concentrations, responsible for maintenance of pregnancy, compared to non-lame cows. Research has also found:
• Cows with abscesses/sole ulcers or with two or more claw disorders had more days open than cows without claws.
• Cows that were clinically lame due to a claw disorder in the first 30 days postpartum had a 58.9 percent decrease in first service conception rates, a 125 percent increase in ovarian cysts, and an 8.2 percent decrease in pregnancy rate at 480 days postpartum.
• Low pregnancy rates in lame cows appear to be associated with failure of ovulation.
Just managing lame cows isn’t enough. Getting to the root of the problem is critical to reducing lameness. DeFrain says investigating lameness involves three steps:
1. Locomotion scoring.
Everyone on the dairy should be trained in locomotion scoring dairy cattle (see the scoring chart below). This scoring system forms the foundation for visual identification and recruitment of lame cows to be assessed by a qualified hoof trimmer. Hoof-trimming records, which include proper claw lesion diagnosis and recording, should be reviewed routinely during management meetings.