PSV-18 - Host transcriptional changes detected in the feces of dairy calves supplemented with condensed solubles from milk permeate

Abstract: Newborn dairy calves are exposed to an environment characterized by multiple challenges, such as pathogen load and nutrient delivery adaptations. Nutritional strategies can help young animals to face these challenges. Hence, we proposed that feeding a type of oligosaccharides (condensed solubles from milk permeate – CS) to dairy calves from birth to postweaning will improve their inflammatory response. This study aimed to perform real-time (RT)-qPCR in RNA isolated from fecal samples to assess the molecular changes relative to inflammation in dairy calves. To address this, 2-days old (d) Holstein calves were randomly assigned into two groups (n=12/group): control with no supplement; or treatment with 50 g/d of CS/d. Both groups were fed pasteurized waste milk during the preweaning period. Calves were fed pasteurized waste milk 2×/d during week 1-5, 1×/d in week 6, and weaned at week 7. For the CS-treated calves, at each milk feeding during week 1-5, 25 g of CS was added to the pasteurized milk. At week 6, 25 g of CS was added to the milk morning feeding and 25g were top-dressed on the starter pellets. Starting at week 7 until the end of the trial at week 12, 50g of CS were top-dressed on the starter pellets offered to CS calves. Healthy scores were recorded daily. Fresh fecal samples were collected weekly and immediately frozen until RNA extraction. Statistical analysis was performed using MIXED procedures (SAS 9.4) with repeated measures. Significant differences were declared at P < 0.05. The average fecal score postweaning was lower in the CS calves relative to the control. Overall, the mRNA expression of the transcription factor of inflammation, NFKB, was lower in the feces of the CS group compared to the control. However, the membrane receptor for gram-positive bacteria, TLR2, was upregulated in CS calves relative to control during the postweaning stage (week 8). The fecal gene expression of the membrane receptor for gram-negative bacteria, TLR4, and the proinflammatory cytokines, IL1B and TNFA, did not differ between groups. In summary, the lack of difference in the gene expression of proinflammatory cytokines IL1B and TNFA, along with the TLR4 expression in the feces of the calves, indicate that there was no severe inflammation during the trial. In contrast, TLR2 gene expression findings suggest that some mild local infection might have affected those calves. In conclusion, feeding oligosaccharides to dairy calves might improve the response to inflammation.