Bovine mastitis is one of the most important diseases in the dairy industry and has detrimental impact on the economy and welfare of the animals. Further, treatment failure results in increased antibiotic use in the dairy industry, as some of these mastitis cases for unknown reasons are not resolved despite standard antibiotic treatment. Chronic biofilm infections are notoriously known to be difficult to eradicate with antibiotics and biofilm formation could be a possible explanation for mastitis cases that are not resolved by standard treatment. This paper reviews the current literature on biofilm in bovine mastitis research to evaluate the status and methods used in the literature. Focus of the current research has been on isolates from milk samples and investigation of their biofilm forming properties in vitro. However, in vitro observations of biofilm formation are not easily comparable with the in vivo situation inside the udder. Only two papers investigate the location and distribution of bacterial biofilms inside udders of dairy cows with mastitis. Based on the current knowledge, the role of biofilm in bovine mastitis is still unclear and more in vivo investigations are needed to uncover the actual role of biofilm formation in the pathogenesis of bovine mastitis.

Cull dairy cows are typically transported to slaughter by road. Across different types of cattle, road transport is recognized as stressful. Cull dairy cows may have different injuries or weaknesses and may thus be more vulnerable to transport stress than other types of cattle. The aim of this study was to investigate whether the clinical condition of cull dairy cows deteriorates during transport (< 8 h), and to evaluate risk factors for potential deterioration of the clinical condition. A total of 411 dairy cows were clinically examined on farm before loading and again after unloading at the slaughter plant. The clinical examination included locomotion, presence of wounds, milk leakage, and general condition. One-fifth of the cows either became lame or more lame during transport, and there was a significant increase in the proportion of lame cows after transport (41% after vs. 31% before, P < 0.0001). A significant increase in the proportion of cows with milk leakage (17% vs. 1%, P < 0.0001) and wounds (34% after vs. 22% before, P < 0.0001) after transport were also found. Low body condition score (BCS) (< 2.75) (P = 0.001), early or late lactation [< 100 days in milk (DIM) or >300 DIM] (P = 0.01), digital dermatitis in the hind feet (P = 0.01), and pelvic asymmetry (P = 0.001) were identified as risk factors for the deterioration in lameness during transport. Early lactation (< 100 DIM) (P = 0.04) and transport distance (>100 km) (P = 0.006) were identified as risk factors for milk leakage. For wounds, no significant risk factors were found. The results demonstrate that cull dairy cows are vulnerable to the strains of transport, even journeys shorter than 8 h, to the extent that the occurrence of clinical findings were increased after transport in cows legally considered fit for transport. These results call for further research into the animal welfare implications and optimization of cattle transport.

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High mortality among dairy cows constitutes a problem both financially and in relation to animal welfare. Knowledge about causes of death is a fundamental step toward reducing cow mortality. Several studies have evaluated causes of dairy cow deaths. However, the vast majority of studies describing causes of death are based on questionnaires with farmers or veterinarians. It is uncertain to what degree such information is sufficient and reflects the true cause of death or euthanasia. In this study, proximate causes of death were evaluated based on a thorough necropsy of a random sample of 79 Danish dairy cows at an incineration plant. The necropsy was combined with information about the farmer's perception regarding the cause of death and information about disease treatments from the Danish Cattle Database. Pneumonia and locomotor disorders were found to be the most predominant proximate causes of death. Often the death occurred after a prolonged period during which the cow suffered several different disorders, even though this was often not noticed by the farmer. Causes of death stated by the farmers agreed with the necropsy results in 50 to 64% of cases. Information about disease treatments from the Danish Cattle Database agreed with the necropsy results in 34 to 39% of cases. All 3 sources of information about cause of death agreed in only 1 out of 4 cases, and even when the farmer and the disease recordings did agree with the necropsy results, the latter often gave additional information about the cause of death. In many situations, therefore, a necropsy may be a valuable tool when trying to control excessive cow mortality in a herd.

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