In the case of E. coli, 99% of samples tested had counts < 102 cfu/ml and only 0.7% were > 103 cfu/ml ( Fig. 1). Pathogenic E. coli O157:H7 was not detected in any samples tested in this study (n = 296). In other studies published internationally, this pathogen has also been found to be at low prevalences in raw milk (0–0.2% of samples in most trials) with the exception being an American study ( Jayarao et al., 2006) in which 2.4% of samples were found to contain E. coli O157:H7. Crump et al. (2001) have credited New Zealand's system of pastoral agriculture and grass-fed herds for the delay of the appearance of this pathogen in local herds. Previous research has shown that healthy cattle are known reservoirs of such E. coli strains in New Zealand ( Cookson et al., 2006). Non-pathogenic E. coli O157 (i.e. non-H7, lacking Shiga toxins 1 and 2, eae and Hyl A genes) was detected in 1% of samples, but did not exceed 1 cfu/4 ml ( Table 3).