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