LAUSR

Neonatal and weaning periods are the most challenging phases for enteric infections in dairy calves. While different approaches are used to minimize calf health issues, the neonatal diet remains the core approach to enhance pre- and post-weaning animal health and performance. Previous studies have shown that bioactive compounds, including oligosaccharides present in the diet of neonatal dairy calves, enhanced their growth performance post-weaning. However, the effects of oligosaccharides supplementation during the neonatal period and the impact on the health status of the calf remain to be elucidated. Thus, we aimed to evaluate blood biomarkers of inflammation in calves supplemented with condensed solubles from milk permeate (CS) during the neonatal period (from birth to 21 d) of dairy calves. Twenty-four newborn Holstein calves (n = 12/group) housed in individual hutches were used in a randomized complete block design study. Calves were blocked by birth date and sex. At 2-days old, calves were randomly assigned into two groups (n = 6 females and 6 males per group): control with no supplement; or treatment with 50 g/d of CS. Both treatment and control groups were fed pasteurized waste milk during the preweaning period. Calves were fed 2.83 L of pasteurized waste milk 2×/d during week 1 to 5, 1×/d in week 6, and weaned at week 7. At each milk feeding during week 1 to 5, 25 g of CS was added to the pasteurized waste milk for each calf on the CS treatment. Healthy scores were recorded daily. Calf growth measurements and blood samples were collected weekly. Data were analyzed using MIXED procedures of SAS 9.4 with repeated measures. Significant differences were declared at P < 0.05. Overall, body weight, fecal and respiratory scores were similar between groups during the preweaning period. During the first 3 weeks of age, a group×sex×time interaction was observed for the enzyme myeloperoxidase (MPO) expressed by neutrophils. Female calves on the CS treatment had decreased MPO concentrations in the blood relative to the female controls at week 3. Other biomarkers of inflammation (i.e., haptoglobin) or consequent liver response (i.e., albumin, paraoxonase) did not differ between groups. Based on these parameters, there was no evidence of systemic inflammation during the first 21 days of age. However, circulating MPO is an indicative of phagocytosis by neutrophils resulting in a local or systemic inflammatory responses. The decreased MPO in CS female calves can be associated with a lesser microbial infiltration in the gut. The latter suggests that oligosaccharides from the diet stimulate the growth of commensal microbiota on the host, which serve as decoy receptors to pathogenic microorganisms (i.e., blocking microbial infiltration). Overall, these findings suggest that bioactive molecules as feed supplements such as CS can help the local immune response in neonatal dairy calves.