Location: Livestock Issues ResearchTitle: Zinc source and concentration altered physiological responses of beef heifers during a combined viral-bacterial respiratory challenge Author
|Word, Alyssa - Texas Tech University|
|Carroll, Jeffery - Jeff Carroll|
|Roberts, Shelby - West Texas A & M University|
|Kaufman, Emily - West Texas A & M University|
|Fontenot, Lauren - West Texas A & M University|
|Richeson, John - West Texas A & M University|
|Brown, Michael - Global Animal Products, Incorporated|
|Ridenour, Ken - Global Animal Products, Incorporated|
Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 11/21/2016
Publication Date: 12/23/2016
Citation: Word, A.B., Broadway, P.R., Sanchez, N.C., Carroll, J.A., Roberts, S.L., Kaufman, E.L., Fontenot, L.R., Richeson, J.T., Brown, M.S., Ridenour, K. 2016. Zinc source and concentration altered physiological responses of beef heifers during a combined viral-bacterial respiratory challenge. Journal of Animal Science Supplement. 2017. J.Anim.Sci.95(Supplement 1):18.
Technical Abstract: Three treatments were evaluated in feedlot heifers to determine the effects of zinc supplementation on the immune response to a combined viral-bacterial respiratory disease challenge. Thirty-two beef heifers (255+/-15 kg) were subjected to a 30d period of Zn depletion, then randomly assigned to one of three treatment diets fed for 30d before the challenge: 1) Supplementation with 100 mg of Zn from Zn sulfate/kg of DM (Zn100), 2) Supplementation with 200 mg of Zn from Zn sulfate/kg of DM (Zn200), and 3) Supplementation with 80 mg of Zn/kg of DM from zinc methionine (ZinMet® Global Animal Products, Inc., Amarillo, TX) and 20 mg of Zn from Zn sulfate/kg of DM (ZinMet). All heifers were fitted with indwelling vaginal temperature (VT) devices and intra-nasally challenged with 1x10^8 PFU bovine herpesvirus-1 on d -3, and then allowed to rest in outdoor pens for 3d. On d0, each heifer was challenged intra-tracheally with an average dose of 2.38 x 10^7 CFU Mannheimia haemolytica (MH), fitted with an indwelling jugular catheter, then moved into individual stanchions in an environmentally-controlled enclosed barn. Whole blood samples were collected at 1-h (serum) or 2-h (complete blood counts) intervals from 0 to 8h, and at 12, 24, 36, 48, 60, 72, 168 and 360h relative to MH challenge. Data were analyzed using the MIXED procedure of SAS specific for repeated measures with fixed effects of treatment, time and their interaction. There was a treatment effect (P<0.01) for VT such that Zn200 heifers had greater VT than Zn100 and ZinMet heifers. There was a trend (P=0.10) for a serum cortisol treatment effect with Zn100 heifers having greater cortisol than ZinMet heifers. Total leukocytes and lymphocytes were greater (P=0.008) in Zn100 heifers than Zn200 and ZinMet heifers, while monocytes were less (P=0.05) in ZinMet heifers than Zn100 and Zn200 heifers. Concentrations of IL-6 were greater (P=0.02) in ZinMet heifers than Zn100 and Zn200 heifers. Concentrations of IFN-' were greater in Zn200 heifers than ZinMet heifers at 0h, and Zn100 heifers from 0 to 12h post-MH challenge (trt x time P=0.02). Serum haptoglobin was not affected by treatment or treatment x time (P=0.36), but increased over time (P<0.001). There was a trend (P=0.11) for ZinMet heifers to have less severe nasal lesion scores than Zn100 heifers. The observed differential physiological responses in this study indicate that zinc source and concentration may alter the response to a bovine respiratory challenge in heifers.