233 NaturSafe® supplementation mitigates some aspects of the acute phase immune response to a lipopolysaccharide (LPS) challenge in weaned beef calves

Abstract

Abstract This study was conducted to determine if feeding calves NaturSafe would reduce the acute phase response (APR) to lipopolysaccharide (LPS) challenge. Crossbred steers (n=32; 274±2 kg) were randomly allotted to two treatment diets: 1) Control, fed a standard receiving ration, and 2) NaturSafe, fed the Control ration supplemented with NaturSafe at 12 g/hd/d (NaturSafe®, Diamond V). On d22, steers were fitted with indwelling jugular catheters and rectal temperature monitoring devices and placed in individual stalls. On d23, steers were challenged i.v. with 0.25 µg/kg BW LPS. Serum samples were collected and sickness behavior scores (SBS) recorded at 0.5-h intervals from -2 to 8h and at 24h relative to LPS challenge. Rectal temperatures were greater (P=0.01) in NaturSafe compared to Control steers for the following time intervals following LPS challenge: 6 to 11h, 13h, 15 to 20h, and 22 to 24h. Additionally, SBS were reduced (P< 0.01) in NaturSafe compared to Control steers. White blood cell concentrations were greater (P=0.05) in NaturSafe compared to Control steers prior to the LPS challenge, yet the response to LPS did not differ between treatments (P >0.05). A treatment × time interaction for serum cortisol concentrations (P< 0.01) showed an increase at 0.5 and 2h post-challenge but a reduction at 3h in NaturSafe compared to Control steers. Additionally, fibrinogen was greater (P< 0.01) in NaturSafe compared to Control steers. There was a treatment × time interaction (P< 0.01) for TNF-α where concentrations were reduced from 1 to 2h post-challenge in NaturSafe compared to Control steers. Serum IL-6 tended (P=0.09) to show a reduction in serum concentrations in NaturSafe compared to Control steers. There was a tendency (P=0.07) for a treatment × time interaction for IFN-γ. Overall these data suggest a priming effect of NaturSafe on the innate immune system of steers, resulting in an attenuated APR to the LPS challenge.