Effects of kefir supplementation in a liquid diet on growth, diarrhea incidence, and antibiotic use in preweaning Holstein heifers

Our objective was to evaluate the effect of kefir supplementation in calves through 21 d of life under different management conditions on growth, diarrhea inci-dence, and antibiotic use. Holstein heifers (n = 148) at 3 commercial farms were randomized to receive a con-trol (CON; 60 mL of whole milk in farm A or nothing in farm B or C) or 60 mL of kefir (KEF) added to whole milk or milk replacer at the morning feeding until 21 d of life. Kefir was prepared as needed by trained personnel on each farm by fermenting salable whole milk with kefir grains for 24 h at 20 to 25°C. Each farm used a similar experimental design and was analyzed independently from the others. Daily feed intake and refusals, as well as health scores, were recorded in farm A. Growth performance was measured weekly at farm A and at wk 4 and 8 at farms B and C. An aggregated data set for all 3 farms was created to compare growth performance at wk 4 and 8 of age. A subset of serum samples (n = 24) collected on d 21 at farm A was analyzed for free fatty acid composition. Calves receiving KEF in farm A had significantly greater starter DMI at wk 8 com-pared with CON, as well as greater circulating linoleic acid concentrations, though feed efficiency, preweaning BW, ADG, and occurrence of health events were not dif-ferent. Improved BW before weaning, hip height, and hip width were observed with KEF supplementation in farm B compared with CON, but BW at weaning was not differ-ent among treatments across all 3 farms. However, calves receiving KEF at all 3 farms were 3 times more likely to double their birth weight by weaning than calves fed CON. Kefir supplementa-tion in early life may improve starter intake before wean-ing, but more work is needed to further understand other potential metabolic or physiological influences.