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, PhD, Dipl. ACAN, 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.”
The 2007 National Animal Health Monitoring System survey found that 16% of cows are culled for lameness, and lameness may increase the number of cows culled due to reproductive failure. Generally speaking, non-infectious claw lesions, such as sole ulcers or white line disease, tend to be more damaging to reproductive performance than would infectious claw disease, most notably digital dermatitis (hairy heel warts), DeFrain explains.
AGE AND LAMENESS
DeFrain says throughout the United States and abroad, Zinpro has conducted numerous herd lameness investigations using hoof-trimming records, and routinely observes an increase in infectious claw lesions in the first 60 days in milk. “Generally speaking, after 60 days in milk, the infectious claw lesions tend to trend downward and we begin to find more non-infectious lesions,” DeFrain says.
The increase in infectious claw disease in the first 60 days in milk coincides with the immunosuppression typically observed in transition cows. “Activation of the immune system to overcome these infectious challenges, both in the claw and the uterine environment, comes at a significant energetic cost,” DeFrain says.
It should be noted that optimal reproductive function is only possible after the energetic needs for maintenance (including immune function), growth and milk production have been met. “Therefore, herds which focus on minimizing lameness in early lactation tend to have greater reproductive performance,” DeFrain adds.
Similar modes of action will apply to both heifers and cows when it comes to the impact of lameness on reproductive performance. Research clearly shows older cows are at greater risk for lameness, especially the more complex, more painful, non-infectious claw lesions. “Therefore, by default, older cows will be at greater risk for compromised reproductive function compared to their younger herd mates,” DeFrain says. ”However, it should be noted that we have been finding greater levels of digital dermatitis in replacement heifers returning to the dairy.”
THE PHYSIOLOGICAL EFFECTS OF LAMENESS
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.
DeFrain says that research shows severely lame cows have lower maximum progesterone concentrations, which is responsible for maintenance of pregnancy, compared to non-lame cows. “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.”
The brain is constantly interpreting these signals and directing metabolic processes such as the release of reproductive hormones from the hypothalamic-pituitary-adrenal (HPA) axis. In essence, the animal goes into “conservation mode” and puts strict limits on nutrient use until the problem/stressor 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.
Some of the other effects of lameness on fertility include:
• Cows with abscesses/sole ulcers or with two or more claw disorders had more days open than cows without claws disorders (Hernandez, et al, 2000).
• Cows that were clinically lame due to a claw disorder in the first 30 days postpartum had a 58.9% decrease in first service conception rates, a 125% increase in ovarian cysts and an 8.2% decrease in pregnancy rate at 480 days postpartum (Melendez, et al, 2003).
• Lower pregnancy rate in lame cows appears to be associated with failure of ovulation (Morris, et al, 2011).
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 sidebar). 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.
“It should be noted that measurable success in reducing lameness and improving reproductive performance has been realized on dairies approaching lameness as a team of people including the management/owner, veterinarian, nutritionist, hoof trimmer and breeding team,” DeFrain says.
Locomotion scoring and hoof trimming records should be used together to formulate a plan to address the trigger factors causing lameness within each individual dairy. Incorporating this approach on a routine basis will provide for greater levels of reproductive performance.
2. ANALYSIS OF CLAW LESIONS PRESENT IN THE HERD
Proper diagnosis of claw lesions at the trim chute forms the foundation for a solid investigation into lameness and reproductive performance. The veterinarian and/or hoof trimmer should work to establish a baseline of current levels of claw lesions present within each herd, work with the management/owners to make changes to address the lesions expressed in greatest quantity. Lastly, with the veterinarian’s help, they should monitor the reproductive performance of the herd over time.
3. ASSESSMENT OF THE MANAGEMENT, ENVIRONMENTAL, AND NUTRITIONAL COMPONENTS OF THE DAIRY KNOWN TO BE ASSOCIATED WITH EITHER NON-INFECTIOUS OR INFECTIOUS CLAW LESIONS PRESENT IN THE HERD
Historically, mistakes in nutritional formulations may have played a significant role in lameness on dairies, DeFrain says. “Today, it seems the majority of claw lesions present are not directly related to nutrition. Most of the nutritionally-related factors become manifested through how we group and manage cows and how feed deliveries are managed.”
The majority of diets fed today are well-balanced, however, the eating and resting/rumination behavior of the cows becomes affected by how the feed is mixed, delivered and pushed up and how pen stocking densities are managed, all of which significantly affects how the cow consumes the diet and ultimately contributes to compromised rumen function.
Lame cows should be addressed immediately. This includes proper functional and corrective trimming technique and isolating these cows to a pen which has a soft, forgiving walking/resting surface, is not overstocked, has ample water supply and a pen which is close to the milking center, DeFrain recommends. “Typically, the diet for this pen is formulated for a reduced level of intake and is fortified with key nutrients known to affect the growth, healing and repair of the claw such as highly bioavailable forms of trace minerals.”