Supplementation of OmniGen-AF during the receiving period modulates the metabolic response to a lipopolysaccharide challenge in feedlot steers

Abstract Text:

The use of probiotic feed supplements to enhance animal health and growth are of great interest to the beef industry. Studies have demonstrated that some probiotic supplements may affect metabolism, and therefore influence an animal’s response to an immune challenge.  This study was designed to determine the effect of supplementing feedlot steers with OmniGen-AF during the receiving period on the metabolic response to a lipopolysaccharide (LPS) challenge.  Steers (n=18; 270±5 kg BW) were obtained and transported to the University of Nebraska Agricultural Research and Development Center feedlot. Upon arrival steers were processed and separated into 2 treatment groups (n=9/treatment): one group was fed a standard receiving  diet (Control; Cont) and the other group was fed the same receiving diet supplemented with OmniGen-AF at 4 g/45.4 kg BW/d for 29 d (OmniGen-AF).  On d 27 steers were fitted with indwelling jugular cannulas and placed in individual stalls.  On d 28, steers were challenged i.v. with LPS (0.5 µg/kg BW at 0 h) and blood samples were collected at 30-min intervals from -2 to 8 h and at 24 h post-challenge.  Serum was isolated and stored at -80^oC until analyzed for glucose, non-esterified fatty acids (NEFA) and blood urea nitrogen (BUN) concentrations.  Data were analyzed using the Mixed procedure of SAS specific for repeated measures. Glucose concentrations were affected by treatment (P=0.009) and time (P<0.001).  Glucose was greater in OmniGen-AF steers compared to Cont steers (76.4 ± 1.1 mg/dL vs. 72.4 ± 1.0 mg/dL). For NEFA concentrations, there was a treatment (P<0.001) and time (P<0.001) effect. Specifically, Cont (0.210 ± 0.007 mmol/L) steers had greater NEFA concentrations than OmniGen-AF steers (0.101 ± 0.010 mmol/L).  There was a tendency (P=0.07) for a treatment x time interaction such that NEFA concentrations were greater (P≤0.03) in Cont steers than OmniGen-AF steers from 3 to 8 hr after LPS challenge.  For BUN, there was a treatment (P<0.001) effect such that concentrations were greater in Cont steers (12.4 ± 0.1 mg/dL) than OmniGen-AF supplemented steers (11.5 ± 0.1 mg/dL) throughout the study, and were not affected by time (P=0.28). These data suggest that OmniGen-AF supplementation modulates the metabolic response to a LPS challenge and provides an indication that supplementation of feedlot steers with OmniGen-AF may prevent the breakdown of other substrates (e.g., protein and fat) for energy during an immune challenge.

Keywords: cattle, metabolism, OmniGen-AF