Marcela Vyletělová, Oto Hanuš, Lucie Hasoňová, Petr Roubal, Ivan Manga, Ludmila Nejeschlebová

The incidence of mastitis pathogens is a persistent problem not only in dairy cows but also for other dairy animals. For breeders it always presents the economic losses. Rajala–Schultz et al. (1999) studied the effect of mastitis dissease on milk yields and found that the daily loss during the first 2 wk after the occurrence of mastitis varied from 1.0 to 2.5 kg, and the total loss over the entire lactation varied from 110 to 552 kg. The milking hygiene control, which is directly associated with the development disease caused by environmental microorganisms, often sticking mainly to time and financial cost of laboratory tests. The higher incidence of environmental microorganisms, which include S. aureus and S. uberis, can be explained by the development and change of milking technology, when the pipeline milking equipment in stall occurred more frequent contamination of the udder by hands of nursing staff or by handling with milking equipment. Therefore, the milking equipment influences whole row of indicators by its function and use, for instance by overmilking (Pařilová et al., 2010, 2011), and can be factor and vector of mastitis origination. Aggravated function grows up mastitis occurrence and subsequently also somatic cell count (Hanuš and Ticháček, 1997). The current types of milking parlours provide better comfort and hygiene of milking (Vyletělová et al., 2009; Janštová et al., 2011). Beside good quality of milking equipment function also other ways of reduction of mastitis occurrence are looking for as cow vaccination for instance (Toušová et al., 2011).
One of the respected indicators of health status of the mammary gland (Sava and Piwczynski, 2002; Berry et al., 2006; Heck et al., 2009) is the somatic cells count (SCC) similarly as mammary associated isotype of serum amyloid A (Kováč et al., 2011). Golebiewski et al. (2011) found the higher average SCC value in long–term observation for Polish Holstein–Friesian as compared to Montbéliarde breed (642 and 455 ths.ml-1). Similar conclusion published Frelich and Šlachta (2011) for Holstein and Czech Fleckvieh without interaction to farm and seasonal effect. The permissible SCC limit value in a pool sample is < 400 thousands in 1 ml of raw cow´s milk. As a healthy mammary gland is generally taken to mean that, where the SCC is around 100 ths.ml-1 in one quarter. Sheldrake et al. (1983) determined the number of somatic cells in uninfected mammary gland from 83 ths.ml-1 (from the 35th day after calving) to 160 ths.ml-1 (285th day). The higher values indicate a possible infection of the mammary gland. Reneau (1986) in his work provides the value of SCC 283 ths.ml-1 as a limit value suitable for the determination of suspicion from subclinical mastitis occurrence. The less numbers of SCC (250 and 228 ths.ml-1) indicate also Andrews et al. (1983) and Dohoo et al. (1981) as the threshold for selection in the case of treatment of mastitis in cows. The similar relationship (but in the case of the bulk milk samples) describe in their work Benda et al. (1997). They estimated 1.7% mastitis diseases incidence caused by Staphylococcus aureus at the somatic cells count 160 ths in 1 ml, and 43.5% incidence at the SCC 410 ths.ml-1. In the case of streptococcal mastitis caused by Streptococcus agalactiae estimated 1% incidence of mastitis at SCC 160 ths.ml-1, and 24.6% at SCC 400 ths.ml-1.
In time of areal application of antibiotic mastitis therapy in dairy cows and increase of pathogen strain resistance against these medicaments the topicality of return to selective cure and also importance of methods which support this kind of therapy is growing up. At present, much attention is given to methicillin–resistant staphylococci strains, especially S. aureus (MRSA), which represent a serious problem in human and veterinary medicine (Holmes and Zadoks, 2011). These strains, which are associated with livestock, are called as LA–MRSA.
The spread of resistant strains in cattle can be problematic in the case of farms with breeding of dairy and meat animals. Because the transfer of resistance going horizontally, the spread of resistant strains is also possible through working staff (Holmes and Zadoks, 2011). An improvement of methods for support of selective cure could be effective in terms of cost saving and mentioned risk reduction as well.
Aim of this work was to assess the relationship between mammary gland pathogen occurrence and somatic cell count (SCC) and possibility to find SCC discrimination limit for estimation of start for subclinical mastitis treatment according to SCC under current conditions.

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Bentley Czech s.r.o. Českomoravská společnost chovatelů, a.s. Mendelova univerzita v Brně Výzkumný ústav mlékárenský s.r.o. Výzkumný ústav živočišné výroby, v.i.i. Výzkumný ústav veterinárního lékařství, v.v.i.