Autor: Janine Vögely

"Analysis of selected blood parameters of the energy metabolism in cattle with digital dermatitis" Digital Dermatitis (DD) is a multifactorial, infectious bovine claw disease, mainly affecting dairy cows that are kept in loose housing systems. DD usually manifests as a circumscribed inflammation of the skin just above the coronary band. The acute stage of these lesions causes a considerable reduction of animal-wellbeing and loss in production. In human medicine, an inflammation of the oral cavity- Periodontal Disease- shows noticeable similarities in etiological bacteria and in the influence of environmental risk factors on the course of the disease. Because of these similarities and with the fact that many patients with periodontal disease also suffer from "metabolic syndrome" (MS), this study analyzed selected blood parameters of the bovine energy metabolism in healthy animals, animals with DD and animals with claw diseases of non-infectious origin. A pilot study was carried out previously to the main study. In the main study, examination of claws and sampling of blood took place on five dairy farms in the German region of Brandenburg, to provide indications for the involvement of metabolism in the pathogenesis of DD, similar to the observations made in human periodontal disease and MS. Different stages of DD were diagnosed in 1075 of 1587 examined animals. Prevalence of disease varied between the different farms from 39.5% to 89.9%. The percentage of animals with one affected hind limb was 23.2% in total and varied between 19.1% and 32.7% on the different farms. The percentage of animals affected on both hind limbs was 44.6% in total and ranged between 18.5% to 66.7%, depending on the farm. Two of the five farms had concrete flooring walking pens and straw bedding in the cubicles, while the other three had rubber flooring walking pens and rubber mattresses in the cubicles. The farms with concrete flooring showed a prevalence of DD at 41.6%, while the farms with rubber flooring showed a prevalence of 86,2%. DD on both hind limbs was found in 21.7% and 60.7% of animals, respectively. In this study, the crude ratios for animals becoming infected with DD are 8.67 fold higher (p=0.000) when they are held in cubicle housing systems with rubber surface walking pens and beds than for animals that are kept on concrete floors and straw bedding. Blood samples from 300 animals were taken and analyzed to determine the serum concentration (SK) of non-esterified fatty acids (NEFA), ß-hydroxybutyrate (ß-HBS), glucose, triglycerides and cholesterol and to compare them between groups and farms. They were categorized in three groups (FG) regarding their claw health, as diagnosed in the trimming chute, and in four groups regarding their state of lactation. Claw health groups consisted of animals affected by DD in the acute M2-stage (FG 2 = DD-group), animals that showed lameness because of a non-infectious claw disease (FG 1=lame-group) and a group of animals with no claw disease at all (FG 3 =healthy-group). State of lactation was determined by days after calving (d p.p.) and categorized in groups of 14-70 d p.p., 71-150 d p.p., 151-250 d p.p. and over 250 d p.p. The comparison of mean values of SK revealed substantial differences for all blood parameters between the five herds. Also, the results of the generalized linear models showed that the factor "farm" significantly influenced the SK of all blood parameters analyzed. The mean values of SK for NEFA, triglycerides and cholesterol differed significantly between the different states of lactation (p=0.000; p= 0.033; p=0.000), which can be explained by the physiological changes in metabolism throughout the lactation period. In the pilot-study, the SK for NEFA were significantly higher (p=0,0) in the blood of cows within FG 2 (DD) compared to those of FG 1 (lame) and FG 3 (healthy) group. In the present study, SK for NEFA between 0.4 and 0.6 mmol/l is associated with a higher risk for lameness (OR=13.5 / p=0.006) an DD (OR=9.4 / p=0.012). Animals of FG 2 (DD) showed lower mean values for SK of Glucose (p=0.052) This difference was more pronounced in the group of animals in early lactation (p=0.011). Higher SK for NEFA and lower SK for Glucose in lame cows can be a result of reduced feed intake and reduced energy consumption due to lower activity. A pain-related stress reaction could also be a cause of higher SK for NEFA. Another cause for increased incidence of lameness and DD in animals with higher SK for NEFA and lower SK for Glucose could be the influence of negative energy balance (NEB) on the Immune system and healing of wounds. Animals of FG 2 (DD) had higher mean values for SK of cholesterol than healthy or lame animals, without being statistical significant. The cholesterol transport could be influenced by inflammatory conditions. The results of this study show no clear role of the selected blood parameters of the energy metabolism on the pathogenesis of DD. Further research is necessary to assess the results of this study. Overall there were remarkable differences in mean SK of the analyzed blood parameters and in DD prevalence between herds, that emphasize the importance of management practices and housing conditions for metabolism an animal health.