PSVI-30 OmniGen-AF alters metabolic profile and blood cell populations in beef heifers subjected to repeated LPS challenges

摘要

Studies in cattle fed OmniGen-AF (OG, Phibro Animal Health, Teaneck, NJ) show OG modulates innate immunity and blood metabolites after 45 to 60 d of feeding. Recently, a shorter interval between measured changes in immune signaling following the onset of OG feeding have been measured. However, this work has been limited to cellular signals in healthy, unchallenged beef heifers. This study aimed to investigate immune and metabolic responses in beef heifers challenged with LPS after 28 and 56 d of feeding OG. Angus heifers were randomly assigned based on BW to one of two dietary treatments: TMR top dressed with OG (OG, 4g/45.36 kg BW, n = 7) or placebo (CON, 4g/45.36 kg BW, n = 7). After 28 and 56 d of feeding, heifers were administered an IV LPS bolus (0.125 µg/kg BW). Complete blood counts and serum metabolites were analyzed relative to LPS bolus (hour). Data was analyzed using the PROC Mixed procedure of SAS with hour, treatment, and the interaction evaluated as fixed effects. After 28 days of feeding, heifers fed OG had lower lymphocyte counts (P = 0.03) and a tendency to have higher monocyte counts (P = 0.07) relative to CON. Heifers fed OG also tended to have lower NEFA concentrations in the first LPS challenge (P < 0.10). Insulin concentrations tended to be lower in OG heifers during both LPS challenges (P ≤ 0.06). During the second LPS challenge, eosinophil counts were lower in OG fed heifers (P = 0.04), while lymphocyte counts were decreased in OG heifers over time (treatment x time P = 0.02) post LPS. Feeding OG altered blood cell populations and metabolism in LPS challenged beef heifers after 28 and 56 days of feeding. These data suggest beef heifers fed OG may be better suited to cope with immunological challenges at earlier feeding durations than previously reported.