ICAR Technical Series no. 7 - Nitra Proc.

Different diagnostic measures for mastitisIntroductionThe early identification of mastitic quarters is essential for all dairy farmers,to ensure animal welfare, milk quality and farm productivity. The mostprecise diagnostic categorization in this respect can be obtained bycyto-bacteriological analysis of quarter milk samples (Table 1).Nevertheless, this procedure is not economic for a continuous screeningof udder health. For this reason, alternative parameters, which howeverindicate an inflammation only, are used for an assessing categorization ofthe udder health. In this context, most systems employed in milking devicesup to today (especially automatic milking systems), measure the electricalmilk conductivity and milk yield at quarter level. This study offers thepossibility for a retrospective assessment of the diagnostic quality of theparameters mentioned above, by using the cyto-bacteriological and clinicalexaminations parallel.Material andmethodsNinty-six German Holstein cows, originated in two different productionsystems (loose house system and fixed stanchion barn) were sampled overat least one lactation. During lactation, sampling was carried out 18 times.The sampling pattern included weekly survey for the first eight and thelast three weeks of lactation, and monthly intervals for the period inbetween. At morning milking, cows were milked with a quarter milkingmachine, after foremilk sampling had occurred for cyto-bacteriologicalanalysis. In addition to this, all udders were clinically examined.Bacteriological examination was performed according to IDFrecommendations (IDF, 1981). Somatic cell count (SCC) was determinedby fluorescent microscopy (Fossomatic ® , Foss Electric TM , Denmark,precision: Cv < 5%; Schmidt-Madsen, 1975). The quarter milk yield wasdetermined by weighing electronically (DNP15 SNR 2116076262, Ohaus TM ;precision: Cv 0,5 %). Furthermore, electrical conductivity was measuredin quarter machine samples (LF 539, WTW, precision: Cv < 0,5 %). Udderhealth was determined according to the categorization scheme shown intable 1. Physiological ranges on quarter level were determined (Figure 1),using data from cows, healthy on all four quarters throughout the wholelactation. Milk yield data could be corrected lactation-related, with theseranges (Grabowski, 2000). The statistic processing of diagnostic data wascarried out by means of the procedure Freq (SAS, 1987). The thresholdsTable 1. Mastitis definition* (DVG, 1994).Cell contentPathogens[cells/ml milk] Not identified Identified< 100.000 Normal secretion (NS) Latent infection (LI)> 100.000 Unspecific mastitis (UM) Mastitis (M)*based on cyto-bacteriological examination of udder quarter foremilksamples64Conference on "Physiological and technicalaspects of machine milking"