ABSTRACT
The purpose of this study was to concurrently estimate the effect of different digital dermatitis (DD) treatment regimens and herd management practices on the occurrence of a new DD lesion. A controlled clinical trial was conducted and involved 4678 dairy cows from 52 French dairy farms where DD was endemic. Farms were allocated by minimisation to one of 4 treatment regimens, varying through the mode (footbath or collective spraying) and the frequency of application (2 days every 4 weeks or fortnightly). They were visited 7 times every 4 weeks by 14 trained investigators. Frailty Cox proportional hazards models were used to estimate the relative effect of potential risk factors and treatment practices on the time until the first occurrence of a DD lesion. At herd level, high initial DD prevalence strongly increased the risk for DD occurrence (HR=1.93, CI 1.23-3.04), as well as absence of hoof-trimming (HR=1.75, CI 1.36-2.27) and poor leg cleanliness (HR=2.44, CI 1.80-3.31). At animal level, Holstein breed (HR=1.92, CI 1.35-3.57) and high-productive cows (HR=1.26, CI 1.01-1.56) were identified to be at higher risk for DD compared to Normande breed and low-productive cows, respectively. Compared to individual topical antibiotic treatments alone, collective treatments tended to decrease the risk of DD occurrence only when applied over 2 days at least every fortnight (HR range=0.64-0.73).
Subject(s)
Anti-Bacterial Agents/therapeutic use , Baths , Cattle Diseases/prevention & control , Digital Dermatitis/prevention & control , Disinfectants/therapeutic use , Foot Diseases/veterinary , Oxytetracycline/therapeutic use , Animals , Baths/veterinary , Cattle , Cattle Diseases/genetics , Cattle Diseases/microbiology , Chelating Agents/therapeutic use , Copper/therapeutic use , Dairying/methods , Digital Dermatitis/genetics , Digital Dermatitis/microbiology , Female , Foot Diseases/genetics , Foot Diseases/microbiology , Foot Diseases/prevention & control , France , Hoof and Claw/microbiology , Hoof and Claw/pathology , Proportional Hazards Models , Risk Factors , Time Factors , Treponema/drug effects , Zinc/therapeutic useABSTRACT
A combination of a removal and fertilization experiment in the field and a replacement experiment in containers in a cold frame was carried out to investigate the role of nutrient supply in the interactions between Calluna vulgaris and Molinia caerulea. It is concluded that the growth of Calluna as well as that of Molinia increased with increasing nutrient availability. However, the increase in biomass of Molinia was much larger than that of Calluna. It is also concluded that increased nutrient availability favours the competitive vigour of Molinia in interaction with Calluna.