Beiranvand, H., Khorvash, M., Ghorbani, G. R., Homayouni, A., Bachmann, L. and Kargar, S. 2014. Evaluation of ketogenic vs. glucogenic substrates as energy sources in starter diets for Holstein dairy calves. Can. J. Anim. Sci. 94: 717-723. The objective of this study was to investigate the influence of the inclusion of granular sugar and sodium propionate as ketogenic and glucogenic substrates, respectively, in calf starter diets on the performance, weaning age, rumen fermentation characteristics and plasma β-hydroxybutyrate (βHBA). Twenty-one newborn male Holstein calves were housed in individual pens until 10 wk of age, receiving starter ad libitum, fresh water free choice, and fed four liters of pasteurized waste milk daily until weaning. Calves were randomly assigned to one of the following treatments: (1) no supplemental additive (Control); (2) granular sugar (5% of dietary DM; Sugar); and (3) sodium propionate (5% of dietary DM; Propionate). Overall, no differences were observed among treatments for starter intake, average daily gain, feed efficiency, day of weaning, body weight at weaning and at the end of the study. Body measurements including body length, hip height, hip width, and heart girth were remained unchanged among treatments. Ruminal fluid pH (5.36 to 5.58) and concentrations of total volatile fatty acids (93.1 to 101.6 mM), acetate (43.6 to 53.1 mM), propionate (30.5 to 35.1 mM), and ratio of acetate to propionate (1.42 to 1.89) were not affected by treatments over the experimental period. However, the concentration of butyrate was greater at 35 and 70 d of age in calves receiving Sugar compared with calves receiving Propionate, but not compared with the Control. Greater blood βHBA at 45, 60 and 70 d of age was noticed in calves fed Sugar compared with those fed Control and Propionate. In conclusion, according to the concentrations of supplemental ketogenic and glucogenic substrates used in the current experiment, sugar and sodium propionate in starter diets did not improve calf performance.