Smectite supplementation to preweaning female dairy calves: Effects on passive immunity, morbidity, and mortality

Objective Our objective was to evaluate the effects of supplementing preweaning dairy calves with smectite (montmorillonite bentonite clay) on serum immunoglobu-lin G (IgG), morbidity, and mortality. Materials and Methods Holstein and Jersey female calves were assigned to control (CON; force-fed 50 mL of water; n = 100) or smectite supplementation (SMECT; force-fed a paste made of 2.5 g of smectite and 5 mL of water followed by 50 mL of water; n = 100) daily from 1 (after colostrum feeding) to 10 d of age. Jugular blood samples were collected at d 1, 4, 8, 12, and 16 of age for determination of serum total protein, IgG, and blood he-matocrit from 44 calves. Researchers assessed fecal consis-tency, appetite, and respiratory disease daily up to 20 d of age. Calves’ therapeutic treatment and mortality records were collected up to 30 d of age. Results and Discussion Serum IgG concentrations tended to be greater for SMECT compared with CON calves during the supplementation period (22.0 ± 2.07 vs. 17.0 ± 1.98 g/L). Serum total protein and blood hemato-crit were similar among SMECT and CON calves. No ef-fects were detected on health and therapeutic treatments. However, mortality within 1 mo of age (3% vs. 8%) and risk of death tended to be less for SMECT compared with CON calves (risk ratio = 0.37; 95% CI = 0.10 to 1.32). Implications and Applications Low-dose smectite supplementation may help to maintain passive immunity while supplemented and reduce mortality within 1 mo of age.