Culling in cows is a complicated condition. Many factors such as, age (parity), milk production, fertility, health, season, feed price, and other variables may influence severity of this condition. Infectious foot diseases are common in dairy herds, causing welfare reduction and financial losses. Interdigital Necrobacillosis (INB) which is a painful condition is one of the most important infectious causes of lameness. Fusobacterium necrophorum has been isolated from over 90% of clinical cases of INB in cattle. When the organism enters subcutaneous tissue through interdigital skin after traumatic damage or the action of irritant agents in slurry this condition may happen. Lack of micronutrients, genetics and disturbances in the local immune system are known as predisposing factors.The overall incidence of INB is probably less than 5%, but in epidemic outbreaks the incidence of the disease can be as high as 20% of the milking cows in a herd. This current study was done in a dairy herd with 910 productive cows (including milking and dry cows), during 12 month period started from March 2014 till February 2015. All cows housed in free stall barns and milk three times a day. The average production of the cows during this period recorded as 36.5 lit/day. Hoof care programs including regular hoof trimming by veterinary practitioners and skilled hoof trimmers was done as the cows at least trimmed two times a year and total 4 times including different inspections and treatments referred to hoof trimming chute. Days in milk (DIM), milk production, parity recorded in all cows in addition to the records of the diseases. The INB located in zone 0 of the hooves selected as treatment group and in addition to the above mentioned records culling rate in these animals in comparison to the control (the cows without any digital disorder 6 month before to 6 month after case occurrence) were recorded. In treatment group total of 94 cases recorded and 40.42% of them were culled in average of 8.97 days after detection. This number were significantly higher than culling rate of the control group (23.3%)(Chi square test, P=0.009). No significant difference between culling rate of the cows with lower production (less than 30 Lit/day) and higher production (more than 30 lit/day) recorded (P>0.05). Thirteen cows were culled in treatment group (32.5%) with days in milk less than 150 days that did not show any significant difference with days in milk over 150 days (49%)(P>0.05). It seems that despite of a very intensive care of the affected animals still culling rate in INB animals is higher than normal cows that need special attention to control the hygiene and other predisposing factors. Days in milk and milk production record of the cow’s do not affect the culling rate following INB.

Keywords