Measurement of joint angles for the objective assessment of limb conformation in dairy calves

Poor limb conformation in cattle is believed to be closely associated with claw and limb disorders. Limb conformation is part of genetic evaluation and is assessed visually. In this descriptive study, the assessment of conformation in calves was evaluated objectively using joint angle measurements. A total of 100 Brown Swiss (n = 50) and Holstein (n = 50) heifer calves, aged 30 to 90 d old, were photographed from both sides and from the front and rear. Carpal, tarsal, autopodium, and fetlock joint angles of the fore- or hind limbs were measured on the images using anatomic reference points and the ImageJ Fiji program. Each angle was measured 3 times, and the mean was used for analysis. Values from both sides were pooled. Deviations from defined standard angles were classified as slight or moderate. The positions of the front and hind feet were measured and scored. On average, the calves had moderate knock-kneed carpal conformation, and the autopodium of the front limb had a slight lateral deviation. In the rear view, the calves had slight, but close to moderate, cow-hocked tarsal conformation, and the autopodium of the hind limbs was parallel, but close to slightly deviated. Holstein calves were moderately and Brown Swiss calves slightly cow-hocked. A moderate lateral deviation occurred in the metacarpal-digit angle in the front view, and a slight lateral deviation occurred in the metatarsal-digit angle in the rear view. The front feet position score was >17° in 69% of the calves, and the hind feet position score was <17° in 90% of the calves. In the side views, the calves were slightly over at the carpus and slightly straight-hocked and had average fetlock conformation. In the mean values, most measured joint angles did not correspond to the straight or parallel classifications in our calves; moderate knock-kneed and slight cow-hocked and toed-out classifications were most common. The limb angles measured were based on anatomical features and therefore are unlikely to change substantially with increasing age. These aspects should be considered when assessing linear traits and investigating the relationship between limb conformation and claw diseases.