It has been reported that bovine colostrum (BC) supplementation improves buffer capacity (beta) during exercise, but whether the improvement results from changes in tissue and/or blood buffer systems has not been determined. The purpose of the present study was to examine the effect of supplementation with BC on blood buffer systems. Thirteen elite females rowers were supplemented with 60 g.day(-1) of either BC ( n=6) or whey protein (WP, n=7) during 9 weeks of pre-competition training in a randomised, double-blind, placebo-controlled, parallel design. All subjects undertook the study as a group and completed the same training program. Resting haemoglobin (Hb) concentration and plasma buffer capacity (pbeta) (determined by titration with HCl) were measured pre- and post-supplementation. There were no differences in macronutrient intakes ( P>0.56) or training volumes ( P>0.99) between BC and WP during the study period. There were no differences in Hb [BC 13.28 (0.28) mg.dl(-1), WP 13.70 (0.26) mg.dl(-1); P=0.45] or pbeta [BC 14.8 (1.1) nmol HCl.ml(-1).pH(-1), WP 14.8 (0.5) nmol HCl.ml(-1).pH(-1); P=0.68] between groups at week 0. pbeta increased in both groups during the study period ( P<0.001), but the increases were not significantly different between groups ( P=0.52). Hb did not change significantly in either group ( P=0.35). These data indicate that supplementation with BC does not affect pbeta or Hb. We therefore suggest that adaptations in tissue buffer systems are responsible for the previously reported increases in buffer capacity that result from BC supplementation.