Do lame cows go thin or do thin cows go lame?
A study by researchers at Cornell University examined the association between claw horn lesions and the depth of the digital cushion evaluated by ultrasound examination of the sole at the typical sole ulcer site.
Prevalences of claw horn lesions in 192 first lactation and 309 second-plus lactation cows were observed in the study.
The prevalence of sole ulcers and white line lesions was significantly associated with thickness of the digital cushion; cows in the upper quartile of digital cushion thickness had an adjusted prevalence of lameness that was 15 percentage points lower than the lower quartile (24.4% versus 8.6% prevalence). Body condition scores were positively associated with digital cushion thickness.
As illustrated in the graph below, digital cushion thickness decreased steadily from the first month of lactation and reached a nadir 120 days after parturition, matching the typical pattern seen for body condition scores. These results give support to the concept that sole ulcers and white line lesions are related to contusions within the claw horn capsule which are a consequence of the lower capacity of the digital cushion to dampen the pressure exerted by the third phalanx (pedal bone) on the soft tissue beneath.
Jon Huxley of Nottingham University is also monitoring digital cushion dept. In a presentation to The Cattle Lameness Academy he reported on this work
The longitudinal study was conducted across four UK herds over an 18 month period. Animals were condition and mobility scored every 13-15 days by a single observer. In total, 6889 observation from 731 cows were analysed in a multilevel multistate discrete time event history model to investigate the transition of lameness (assessed by mobility score) over time. Animals with a low BCS at calving (≤2.25) had a higher probability of becoming lame, and if they were already lame, they were less likely to recover. Similarly, when the BCS at the current visit was compared to the BCS at calving, cows which had lost condition had a higher probability of becoming lame, and if they were already lame, they were less likely to recover. Interestingly the converse effect was also identified, an increase in BCS from calving was associated with a lower probability of becoming lame, and if animals were already lame, they were more likely to recover. The study also identified that the longer an animal stayed lame the less likely she was to recover i.e. once lameness become chronic it is less likely to resolve.