One hundred ninety-one Holstein and x-bred cows were used to study the effect of feeding OmniGen-AF (OG, Phibro Animal Health, Quincy, IL) from dry-off to 150 d in milk (DIM) on health, milk yield (MY) and milk components for making Parmigiano Reggiano cheese. Cows were assigned randomly to either a control (C, n = 95) or a group fed 55g/h/d of OG (n = 96). Groups were balanced on parity, breed, expected calving date, BCS and previous MY. Cows were housed in comparable pens during the dry and lactation phases with diets fed as TM rations. Cows were milked 2× and MY recorded daily using Afimilk. Individual cow milk was sampled at dry-off, once between DIM 4 and 10 and then every 4 wk to 150 DIM and analyzed for fat, casein, protein, lactose, somatic cell count (SCC), acidity and lactodynamographic analysis (LDG). Health events were recorded. Treated or culled cows (n = 43) were excluded from the statistical analysis for milk production and quality. Milk was analyzed by ANOVA-Repeated Measures, SCC by Kruskal-Wallis test and all data processed using Statsoft Statistica v.10. Significance declared at P ≤ 0.05. MYs were not different, although OG cows tended (P = 0.25) to produce more milk (+1.39kg/d) with a lower SCC linear score (−0.06, P < 0.10) than C cows. A higher % of milk samples (23%) in C group had SCC > 300,000 cells/mL (P < 0.10) compared with OG cows (18.2%). The same trend was observed in cows with 2 or more samples > 300,000 cells/mL (C = 32.4%, OG = 22.9%, P = 0.27). Milk composition did not differ between C and OG cows, except milk from OG cows had a tendency (P = 0.12) for a better LDG score (OG = 18.24, C = 19.24). Culling rates were higher in the C cows group (12.6%) compared with OG (7.4%) and culling tended to occur sooner (DIM) for C cows than OG cows (57.3 vs. 102.6, P < 0.10). Incidence rates (%) of mastitis and metritis were higher in the C (18.9, 17.9) versus the OG cows (10.4, 15.6). In this study, cows fed OG from dry-off to 150 DIM tended to have fewer diseases and culls, plus a tendency for improved MY and properties associated with quality Parmigiano Reggiano cheese.