|Carroll, Jeffery - Jeff Carroll|
Submitted to: American Society of Animal Science Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 4/12/2004
Publication Date: 7/23/2004
Citation: Garcia, J.J., Schmidt, T.B., Berg, E.P., Cochran, E.M., Kleiboeker, S.B., Morgan, C.W., Drager, C.D., Carroll, J.A., Keisler, D.H., Larson, R., Olson, K.C., Rentfrow, G., Brown, M.S. 2004. Dietary supplementation of lipoic acid and its effect on circulating metabolic hormones and acute phase proteins of virus-challenged beef steers. American Society of Animal Science Annual Meeting. Journal of Animal Science. 82(1):407.
Technical Abstract: To determine the effect of lipoic acid (LA) supplementation on circulating metabolic hormones and acute phase proteins of virus challenged steers, 32 cross-bred steers (BW=308+/-27kg) were randomly assigned to control (CON), LA supplemented at 16mg/kg of BW (LA16), LA at 32 mg/kg of BW (LA32), and a negative control (NEG) treatments. Steers were allowed a 21 d adaptation period to adjust to treatment and environment. On d 22, blood samples, nasal swabs, BW, DMI, and rectal temperature were recorded. Control, LA16, and LA32 steers all received an intra-nasal dose of 2 ml/nostril of infectious bovine respiratory virus (Cooper stain, 1 X 10^6-7 PFU); NEG received a 2 ml/nostril saline dose. Blood samples, nasal swabs, BW, DMI, and rectal temperatures were collected on 23, 25, 27, 29, 36, and 43 d. Serum samples were analyzed for haptoglobin, amyloid-A, leptin, insulin, and serum-neutralization titer levels. Prior to challenge, DMI as percentage of BW was similar for all four treatments. Seven and 14 d post-challenge, DMI of LA32 was higher (P<0.05) than CON and LA16 (DMI as % BW; 1.35-7 d; 1.88-14 d vs. 0.95-7 d; 1.77-14 d, and 0.95-7 d; 1.67-14 d, respectively). As for maintaining body weight after viral challenge, all treatment groups experience BW loss. However by d 29, LA32 had rebounded and was gaining BW (+5.15 kg from previous BW; P<0.001), while NEG, CON, and LA16 continued to experience decreased BW (-3.45, -1.59, and -1.42 kg from previous BW, respectively). Haptoglobin concentrations were similar between all treatments pre-challenge (0.147, 0.133, 0.121, and 0.128 ng/ml for CON, LA16, LA32, and NEG, respectively). On d 27, LA32 had lower (P<0.04) serum concentrations compared to CON (0.311 vs. 0.592 ng/ml), and lower than CON and LA16 on d 29. Haptoglobin concentrations were at or below pre-challenge concentrations by d 36. Serum-neutralization titers for 30/32 steers were negative on d 22. However, by d 43 all animals were positive for IBRV antibodies. The geometric mean titer for LA32 was greater (P<0.001) compared to CON, LA16, and NEG (2^105, 2^25, 2^39, and 2^59, respectively). Results indicate that supplementation of LA at 32 mg/kg of BW can provide additional protection to steers facing a viral challenge associated with respiratory disease.