Supplementation of OmniGen-AF® improves the metabolic response to a glucose tolerance test in beef heifers

Authors: Sanchez, Nicole; Carroll, Jeffery - Jeff Carroll; Broadway, Paul; SCHELL, TYLER - Phibro Animal Health Corporation; PUNTENNEY, STEVE - Phibro Animal Health Corporation; MCLEAN, DERECK - Phibro Animal Health Corporation

Submitted to: Translational Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2019
Publication Date: 7/30/2019
Citation: Sanchez, N.C., Carroll, J.A., Broadway, P.R., Schell, T.H., Puntenney, S.B., McLean, D.J. 2019. Supplementation of OmniGen-AF® improves the metabolic response to a glucose tolerance test in beef heifers. Translational Animal Science. 3:1521-1529. https://doi.org/10.1093/tas/txz130.
DOI: https://doi.org/10.1093/tas/txz130

Interpretive Summary: The immune system requires a large amount of energy in order to fight off infections. While there are many non-antibiotic supplements available to cattle producers that boast claims of improving the immune response, the mechanism behind how they work is unclear. Previous data from our laboratory found that the immune-stimulating supplement, OmniGen-AF improved the immune response to a toxin possibly by increasing the available energy that could be used to fight off the infection. To explore this idea more completely, scientists from the USDA-ARS Livestock Issues Research Unit and Phibro Animal Health Corp. Conducted a study to determine if OmniGen-AF was truly changing available energy in cattle. Data from the study found that heifers supplemented with OmniGen-AF were more responsive to changes in energy in the form of glucose. Specifically, increases in the stress hormone, cortisol, as well as increases in the energy hormone insulin were observed in heifers supplemented with OmniGen-AF for 42 days. The data from this study suggests that OmniGen-AF is affecting the storage and/or availability of energy within the body, which may help reduce the severity of an infection and speed up recovery. This information will be of interest to cattle producers as well as scientists who are seeking alternatives to antibiotics in livestock production.

Technical Abstract: This study determined whether feeding OmniGen-AF® to feedlot heifers would alter metabolic profiles to a glucose tolerance test. Heifer calves (n = 184; 216 ± 1 kg) were allocated into 2 treatment diets: 1) Control, fed a standard receiving ration, and 2) OmniGen, fed the Control diet supplemented with OmniGen-AF at 4.54 g-1·cwt-1·d. Heifers were fed in a commercial feedlot for 42 d, after which a subset of 16 heifers per treatment were selected for a glucose tolerance test. Heifers were housed in outdoor pens according to treatment and fed respective diets until processed through a working facility for placement of indwelling jugular catheters and vaginal temperature recording devices. After these procedures, heifers were moved into individual stanchions in an enclosed barn and all heifers were fed their treatment diets at 1400 h. All orts were removed at 2000 h to allow for a 12-h fast prior to first blood collection. The following day, heifers were administered 0.5 mL/kg BW of a 50% dextrose solution at 0900 h (0 min). Blood samples were collected for serum isolation at -60, -45, -30, -15, 0, 10, 20, 30, 45, 60, 90, 120, and 150 min relative to bolus dextrose infusion. Serum was stored at -80oC until analyzed for cortisol, glucose, insulin, NEFA and urea nitrogen (SUN) concentrations. Vaginal temperature was not affected by treatment (P = 0.80) but decreased post-infusion (P < 0.01). There was a treatment x time interaction for cortisol (P < 0.01) such that cortisol was greater in OmniGen heifers than Control heifers from 10 to 45 min post-infusion. Glucose concentrations increased post-infusion (P < 0.01) and were reduced in OmniGen compared to Control heifers at 10, 45, and 90-min post challenge (treatment x time P < 0.001). There was no treatment effect for serum insulin (P = 0.61). There was a treatment x time interaction (P = 0.006) for NEFA concentrations such that they were reduced in OmniGen-supplemented heifers from -60 to -30 min prior to the challenge, and 10 to 30 min following the glucose tolerance test. Additionally, SUN concentrations tended (P = 0.06; 89 vs. 98 ± 3 mg/dL) to be reduced in OminGen heifers compared to Control heifers. Insulin sensitivity, measured via RQUICKI, was greater (P < 0.002) in OmniGen heifers than Control heifers (0.36 vs. 0.35 ± 0.002). These data suggest that OmniGen heifers were more responsive to changes in glucose, perhaps affecting the storage and/or redistribution of energy deposits, and provide further evidence for altered metabolism in OmniGen-AF supplemented cattle.