UNIVERSITY PARK, Pa. -- The Effects Of Lameness On The Reproductive Performance Of Dairy Cattle Should Not Be Underestimated, According To An Extension Expert In Penn State's College Of Agricultural Sciences, Who Warns That Lame Cows Are Generally Less Likely To Engage In Mounting Activity.

"Cows need sound feet and legs to seek out cows in heat, mount them or be mounted if they are in heat themselves," says Mike O'Connor, professor of dairy science. "If this basic requirement is compromised, then efficiency and accuracy of heat detection will be low. On average, cows are in heat for seven to eight hours. This is a narrow window of opportunity to detect healthy cows in heat and presents a real challenge to detect lame cows in heat."

O'Connor cites the impact of lameness on reproductive performance shown by a British study involving 770 cows with nearly 1,500 lactations. The research showed that lameness caused by lesions on the hoof was associated with a seven-day increase in days to first service and 11 more days open, compared with herd mates without lameness.

"These differences were greater for cows with sole lesions that developed between 36 and 70 days postpartum, the time when cows should first be detected in heat," O'Connor explained. "For those cows, the interval to first service and days open increased 17 and 30 days, respectively. Data from a study in Florida involving 837 cows, 30 percent of which were diagnosed as lame, most with claw lesions, showed that the number of services per conception was significantly higher in lame cows than healthy (nonlame) cows. The median time to conception for lame cows with claw lesions was 140 days compared to 100 days for healthy cows."

New information recently published in the Journal of Dairy Science (December 2004) by a team of researchers at the University of Florida reported the results of a study, which examined the relationship between lameness and the onset of cycling during the first 60 days of lactation (Garbino et al. J. Dairy Science, 2004).

Using the new modified six-point locomotion scoring system, cows in a large commercial dairy were examined weekly during the first 35 days of lactation for diagnosis of lameness. "In addition, blood samples were obtained to determine the concentrations of progesterone, which indicate the onset of the first estrous cycle," says O'Connor. "Cows classified as lame were 3.5 times more likely to have delayed ovarian activity, compared to nonlame cows. Furthermore, it was determined that ketosis was a factor that delayed resumption of estrous cycles.

"The researchers suggested that lameness and ketosis might interact to delay onset of estrous cycles," he continues. "As shown in several other studies, lameness depresses dry matter intake, causing negative energy balance and production of ketone bodies. If cows are in pain due to lameness they spend less time eating and ruminating and more time lying down. Consequently, dry matter intake will be reduced, which may likely delay the onset of cycling during early lactation."

Lameness is a significant factor affecting reproductive performance by inhibiting estrous behavior as well as delaying ovarian activity, O'Connor stresses. "It is a complex problem," he says. "Dairy producers should develop the skill of scoring locomotion so cows can be evaluated for lameness on a routine basis and problems can be identified and treated early."

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EDITORS: Contact Mike O'Connor at 814-863-3913 or by e-mail at mlo@psu.edu.

Jeff Mulhollem Office 814-863-2719 FAX 814-863-9877