Two groups of 70 cows, including 51 identical twin sets, were grazed at either an unrestricted (14 kg dry matter intake/day; DMI/d) or restricted (6 kg DMI/d) daily pasture allowance for two weeks after drying off (DO). Incidence of new intramammary infection (IMI) and teat open/closed status was assessed at 7, 14 and 21 days after DO. Keratin plug formation was determined on a subset of 40 cows at 7 and 14 days after DO. Number of clinical mastitis (CM) cases and total new IMI did not differ between cows maintained on unrestricted or restricted DMI. However Streptococcus uberis was isolated from more new IMI in unrestricted animals than restricted animals (11.7% vs. 4.6 % of quarters respectively; P <0.01). At 7 and 14 days after DO, more teats were classified as open in the unrestricted group compared to the restricted animals (57% vs. 43% of quarters respectively; P <0.01). However weight of keratin collected from teat canals did not differ between nutritional treatments. Results suggest that unrestricted nutrition after DO did not increase risk of CM but does increase risk of S. uberis infection.