The effect of Coryne bacterium cutis lysate to control somatic cell counts in dairy cows

[摘要] English: The main aim of this study was to evaluate the effectiveness of repeated inoculations of a Corynebacterium cutis lysate (Ultra-Corn®) - a non-specific immune-stimulant, to reduce the milk SCC in commercial dairy cows. An additional aim was to evaluate if these inoculations had any detrimental effects on milk quality. This study was performed in two separate trials, using Holstein cows with SCC's over 250 000 cells/ml of milk at different stages of lactation from two commercial dairy farms in the Free State Province. On each farm, cows were paired according days in milk and SCC, in order to obtain two homogeneous groups of experimental animals. The two groups of cows in each farm were randomly allocated to a treatment or a control group. Both groups in the same farm were managed under the same conditions for the entire trial periods. The only difference was that cows from the treatment group received 3 weekly inoculations of Corynebacterium cutis lysate(Ultra-Corn® ), while those from the control group received distilled water for injection (the same volume as the cows in the treatment group). Two similar trials were conducted, using the same basic experimental design. Differences were only in the dose of the Corynebacterium cutis lysate inoculated per cow treated, number of experimental animals and duration of the observation periods. In Trial 1, cows from the treated group received 3 weekly vaccinations of Ultra-Corn® (4 ml per cow, thus 80mg of Corynebacterium cutis lysate per cow) injected subcutaneously (sc), while those from the control group received 3 weekly sc injections of 4 ml distilled water. This was followed by 8 weeks of observation of the effect of treatment on milk SCC and composition. In Trial 2, the three doses of Corynebacterium cutis lysate administered weekly per cow for the treated group was 2ml/100kg, thus 40mg Corynebacterium cutis lysate/100 kg per cow. This was followed by 8 weeks of observation of the effect of treatment on milk SCC and composition. Individual quarter milk samples were collected weekly from all cows and analysed for SCC and a combined milk sample (from the measuring bottle in the milk parlour) from each cow was also taken for butterfat, protein, lactose and urea content. The results were compared between the two groups per farm, using ANOVA procedures for repeated measures analysis, using the 95% confidence level (SAS, 2004). The two farms were evaluated separately, due to the possible differences between general management conditions, which could introduce serious confounding factors if the results from the two farms were combined. However, it can be considered that both dairy farms used an acceptable level of commercial dairy management practices and produced an acceptable yield per cow under South African commercial conditions. In general no significant differences were recorded between the treated and control groups of cows in both farms in both trials in terms of milk SCC, butterfat, protein, lactose and urea content of the milk. In this study, the immuno-stimulant effect of Ultra-Corn®, a Corynebacterium cutis lysate could not be confirmed in lactating cows. Although this inoculant does not seem to have any detrimental effects on the main solids of the milk, its use cannot be justified as it did not significantly reduce somatic cell counts in lactating cows. Further research is warranted to develop and evaluate the effectiveness of vaccines against mastitis causing organisms, in order to control SCC and mastitis in dairy cows. However, when such studies are conducted it is advisable to use very high number of experimental units and proper control trials should be conducted. All efforts should be done to ensure minimum environmental changes during these trials, which can introduce serious confounding effects in the experimental design.

[发布机构] University of the Free State