Prevalence of digital dermatitis in Canadian Holsteins classified as high, average or low antibody and cell-mediated immune responders

Abstract Text:

Lameness is one of the major issues affecting production and animal welfare in the Canadian dairy industry, with digital dermatitis being the most common lesion.  Studies have shown dairy cattle classified as high immune responders have lower incidence of disease, therefore it may be possible the immune response (IR) plays a role in preventing hoof lesions. The objective of this study was to compare the prevalence of digital dermatitis in Canadian dairy cattle that were classified for antibody (AMIR) and cell-mediated immune response (CMIR). Cattle (n = 341) from five commercial dairy farms in Ontario were evaluated for IR using a protocol that captures both AMIR and CMIR. They were classified as high, average and low responders based on standardized residuals for AMIR and CMIR. Residuals were calculated using a SAS general linear model that included the effects of herd, parity, stage of lactation and stage of pregnancy. Hoof health data was collected in 2012 by the farm’s hoof trimmer using Hoof Supervisor software.  Only the first trim date for each animal was included and multiple lesions per cow were considered.  Trimmers scored each lesion for severity with 1 = least, 2 = moderate, 3 = most. Hoof health data was analyzed using a SAS general linear model which included the effects of herd, stage of lactation (at trim date), parity (at trim date) and IR category (high, average and low).  Data is presented as prevalence within IR category. Preliminary results showed that high (17% of highs) AMIR cattle had a trend (P = 0.098) towards lower prevalence of digital dermatitis then average (28% of averages) AMIR cattle. It was observed that high (17% of highs) CMIR cattle had a trend (P = 0.081) towards lower prevalence of digital dermatitis compared to average (27% of averages) CMIR cattle and significantly (P= 0.04) lower digital dermatitis compared to low (30% of lows). Similarly high CMIR cows also had significantly lower (P=0.03) prevalence of the most severe type of digital dermatitis lesion compared to low CMIR cows. Since digital dermatitis is primarily caused by extracellular bacteria which is typically associated with AMIR these results still indicate that having a more robust or high IR is associated with lower prevalence of infectious hoof lesions.  Therefore by breeding animals for high IR it is likely that improvements in hoof health can be made.

Keywords:

Digital Dermatitis, Immune response, Dairy cattle