## 4 Discussion
It follows that it is of utmost importance to detect the residues and the best place to undertake that is at the production site, in the milk of the bulk tank of the farm, before the milk reaches the dairy. For such a task the required test should be able to detect the residues in relatively low concentrations and it should be relatively simple, sensitive to a large range of antibiotics and reliable. In other words, a suitable test should be able to detect the residues at concentrations above the MRL (Maximum Residue Level) values as they are stated in the legislation, it should be simple enough to be performed by a relatively unskilled person belonging to the personnel of the farm (or with a minimal training) and it should be performed by a low-cost method (the equipment included) [23; 43]. In the present study, group A has significantly more true positive samples than group B by a factor of 3 (\(\chi^{2}\) = 8.825, \(p\) = 0.002971, df = 1) (Table 2). Since all farms from which the milk originates are in the same rural ecosystem, factors attributed to the farming management are responsible for this differentiation (OR = 3.624, CI 95%: 1.484-8.847, \(p\) = 0.0047). The false positive samples in both groups are in similar percentages (26.67% for group A and 29.17% for group B) and can be attributed to substances (e.g., peptides) from the grazing plants with antibacterial properties which exert inhibition of bacterial growth, to bacteriocins produced by the milk's natural flora, to high count of somatic cells or to disinfectants producing thus a false positive score. In April and in May SCC were higher in the milk samples of group B, but the numbers of positive and true positive samples were lower in that group in comparison with group A. The hypothesis that various substances originating from the pasture are the causes of these results cannot be a strong point as both groups share the same ecosystem. The same holds for the bacteriocin hypothesis. The possibility that--for some reasons attributable to the microenvironment of some farms of the group A--some strains of the microbiota of the milk exerted exceptional bacteriocin production cannot be ruled out. This point is rather weak, since most farms showed true positive samples in random order and not every month or even most months of the milking period (which would be the case if these exceptional bacteriocin producing populations dominated the milk microbiota throughout the milking period). It is known that the milk microbial populations vary seasonally, but strains with such powerful bacteriocins would survive through competition in most circumstances. Somatic cells count (SCC) represents a measurement for the evaluation of the quality of the milk, as well as a strong indication for inflammation of the udder. There is no legal threshold provided by the EU legislation concerning SCC in the raw milk of sheep and goats. [PERSON] et al. (2021) propose bulk tank cut off limits 2.5 \(\times\) 10\({}^{6}\) cells/mL for sheep and 3.5 \(\times\) 10\({}^{6}\) cells/mL for goats [44]. In our study average SCC ranged from 5.05 \(\times\) 10\({}^{6}\) cells/mL to 5.42 \(\times\) 10\({}^{6}\) cells/mL for group A and from 5.04 \(\times\) 10\({}^{6}\) cells/mL to 5.77 \(\times\) 10\({}^{6}\) cells/mL for group B. These measurements are the arithmetic means of the counts of each of the 20 different milk tanks for each group and are close to the geometric average counts reported by [PERSON] et al. (2021) in Greek flocs, that is 0.488 \(\times\) 10\({}^{6}\) cells/M [45]. Besides bacterial mastitis, other factors contribute to higher SCC in milk bulk tanks. Higher counts are observed in the beginning and in the end of the milking period and are not associated with mastitis [46]. The body condition is negatively correlated to the SCC counts because of the effects of the malnutrition [45]. Imbalanced nutrition leads to deficiencies in minerals and vitamins and can predispose to inflammation of the mammary gland and thus affect the SCC in sheep [47].