Abstract
Nineteen claudin-16 (CL-16) deficient Japanese Black cattle, as well as two Japanese Black cattle with renal failure due to other causes, were studied with regards to the dynamics of vitamin A (VA) and retinol binding protein (RBP) and the development of long hooves. All of the CL-16 deficient cattle, except for three calves that were between one and six months of age, had long hooves (84%). The CL-16 deficient cattle were divided into normal and long-hoof groups, each of which was then compared to a group of 36 normal Japanese Black calves. The CL-16 deficient, long hoof group showed a significant increase in RBP, VA, urea nitrogen (UN), and creatinine (Cre) levels, while the CL-16 deficient, normal hoof group showed a significant increase in VA levels only. The RBP levels significantly and positively correlated with VA, UN, and Cre levels. VA levels were markedly high in calves of ages between five and thirteen months, during which the calves received feed containing VA. The non-CL 16 deficient cattle (with pyelonephritis and renal hypoplasia, respectively) also had long hooves as well as high VA and RBP levels. Based on the fact that the CL-16 deficient, normal hoof cattle were either young or affected with mild nephropathy, it was considered that the development of long hooves was not a CL-16 deficiency specific symptom, but rather attributable to persistent, severe renal dysfunction.
