This study was conducted to examine the influence of supplementation of sodium butyrate, sodium monensin or calcium propionate in a starter diet on the performance and selected plasma metabolites (plasma glucose, non-esterified fatty acids and β-hydroxybutyrate) of Holstein calves during pre- and post-weaning periods. Twenty-four newborn Holstein calves were housed in individual hutches until 10 weeks of life, receiving water free choice, and fed four liters of milk daily. Calves were blocked according to weight and date of birth, and allocated to one of the following treatments, according to the additive in the starter: (i) sodium butyrate (150 g/kg); (ii) sodium monensin (30 mg/kg); and (iii) calcium propionate (150 g/kg). During 10 weeks, calves received starter ad libitum, while coast cross hay (Cynodon dactylon (L.) pers.) was offered after weaning, which occurred at the 8th week of age. Weekly, calves were weighted and evaluated for body measurements. Blood samples were taken weekly after the fourth week of age, 2 hours after the morning feeding, for determination of plasma metabolites. No differences were observed among treatments for starter or hay intake, BW and daily gain of the animals. Mean concentrations of selected plasma metabolites were similar in calves fed a starter supplemented with sodium butyrate, sodium monensin and calcium propionate. There was significant reduction in the concentrations of plasma glucose as calves aged. The inclusion of sodium butyrate, calcium propionate or sodium monensin as additives in starter feeds resulted in equal animal performance, before and after weaning, suggesting that sodium monensin may be replaced by organic acid salts.
