Bayesian analysis of herd-level risk factors for bovine digital dermatitis in New Zealand dairy herds

Abstract

Background: Bovine digital dermatitis (BDD) is considered the most important infectious cause of lameness in dairy cattle worldwide, but has only recently been observed in New Zealand. Although many studies have investigated the risk factors for BDD in confined dairy systems, information on risk factors in pasture-based system is limited. Therefore a cross-sectional study including 59,849 animals from 127 dairy herds in four regions of New Zealand was conducted to identify the herd-level factors associated with the probability of a herd being BDD-lesion positive and with within-herd BDD prevalence. Results: Purchasing heifers was associated with increased odds of a herd being BDD-lesion positive (odds ratio [OR]: 2.33, 95% probability interval [PI]: 1.26-4.42) and a cow being BDD affected (OR: 3.76, 95%PI: 1.73-8.38), respectively. Higher odds of a herd being BDD-lesion positive (OR: 2.06, 95%PI: 1.17-3.62) and a cow being BDD affected (OR: 2.87, 95%PI: 1.43-5.94) were also seen in herds where heifers co-grazed with cattle from other properties. In addition, using outside staff to treat lameness was associated with higher odds of a cow being BDD affected (OR: 2.18, 95%PI: 0.96-4.98). Conclusion: This study highlighted that movements of heifers are significantly associated with the spread of BDD within and between dairy herds in New Zealand. To minimise the risk of disease introductions in herds where moving heifers cannot be avoided, it is best to purchase heifers only from herds where BDD-freedom has been confirmed and, if heifers have to graze-off a farm, they should be reared as a single biosecure management group, especially since animals may be BDD-infected without having clinically obvious lesions.

Risk factors for digital dermatitis in free‐stall‐housed, Canadian dairy cattle

“…42,43 Increased prevalence has been associated with the use of outside staff for hoof trimmers, 44,45 implying that these bacteria can be transmitted between herds. A higher DD prevalence has also been reported on farms that lacked boots for visitors and farm staff working at other dairy farms, 15 and farms that purchase cows and heifers, 9,43,46 emphasizing the importance of good hygiene practices.…”

Impact of Nutrients on the Hoof Health in Cattle

“…Grazing systems have a preventive effect on infectious diseases of the hooves (dermatitis digitalis and interdigitalis, erosion of the heel), but this is due to a lower probability of traumatic lesions and the absence of direct contact of infectious lesions with contaminated manure. Dermatitis digitalis is surprisingly the most common lesion reported in many studies in grazing cattle in Brazil [ 46 , 78 ].…”

“…Lesions that cause lameness in cows can be of infectious or non-infectious origin [15,16,28,78,79]. The prime infectious lesions causing lameness are digital dermatitis [15,16,37,78,80] and interdigital phlegmon [16].…”

“…Lesions that cause lameness in cows can be of infectious or non-infectious origin [15,16,28,78,79]. The prime infectious lesions causing lameness are digital dermatitis [15,16,37,78,80] and interdigital phlegmon [16]. Non-infectious lesions are associated with the loss of tissue integrity due to traumatic events, excessive wear, nutritional deficiencies, or unduly hoof modification, which may provide the primary gateway for infection.…”

Modelling the transmission dynamics of bovine digital dermatitis in New Zealand pastoral dairy production systems

“…In pasture-based systems, such as those that predominate in New Zealand, DD lesions are typically less commonly seen than in housed cattle [11]. Furthermore, clinical lameness was rarely associated with DD under New Zealand conditions [12], it is therefore likely that DD will have only limited impacts on herd-level production [13]. However, routine monitoring of DD is still recommended to identify early cases of the disease and to make sure DD remains manageable at the herd level [14].…”