Location: Livestock Issues ResearchTitle: Dose response effect of NutriTek on leukocyte functionality during a dexamethasone challenge in Holstein steer calves. Author
|Sharon, Kate - Texas Tech University|
|Liang, Yu - Texas Tech University|
|Hudson, Rachel - Texas Tech University|
|Yoon, Iikyu - Diamond V Mills, Inc|
|Scott, Mark - Diamond V Mills, Inc|
|Carroll, Jeffery - Jeff Carroll|
|Ballou, Micheal - Texas Tech University|
Submitted to: Proceeding of Plains Nutrition Council Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 3/28/2016
Publication Date: 4/15/2016
Citation: Sharon, K.P., Liang, Y., Hudson, R.E., Yoon, I., Scott, M.F., Sanchez, N.C., Broadway, P.R., Carroll, J.A., Ballou, M.A. 2016. Dose response effect of NutriTek on leukocyte functionality during a dexamethasone challenge in Holstein steer calves.. Proceeding of Plains Nutrition Council Symposium. 2016 Plains Nutrition Council Spring Conference Proceedings 04/15-16/2016 San Antonio, TX: pg.125.
Technical Abstract: The objective of this study was to determine the dose response effects of supplementing NutriTek® on leukocyte functionality and ex vivo cytokine production during a dexamethasone (DEX) challenge. Holstein steers (125.1±8.16kg; N=32) were assigned to treatments including 0, 20, 40, or 60g/head/d of NutriTek® (n=8). Calves were housed in open, dry lot corrals with 4 calves per pen (2 pens/treatment). Calves were offered ad libitum access to a 50/50 total mixed ration of a commercially available 16% crude protein pelleted calf grower and chopped alfalfa hay. Treatments were top dressed for 21d. Orts were measured daily and the quantity of feed was adjusted for approximately 10% orts. After the 21d adjustment to diets, calves were jugularly catheterized and moved into individual stations (2.13×0.76'm) in an environmentally controlled barn and allowed 48h to adapt before the first DEX injection. Blood samples were collected at -24, -6, 0, 6, 12, 18, 24, 48, and 72h relative to the first DEX injection. DEX was administered via jugular catheter at 0.1 mg/kg BW at 0, 6, and 12h. Peripheral blood neutrophil (PMN) concentrations increased (P<0.001) at 6h and remained elevated through 72h in all steers. PMN L-selectin and PMN and monocyte (MONO) oxidative burst (OB) and phagocytosis (PHAG) of an environmental Escherichia coli decreased (P=0.059) at 6h in all steers. L-selectin returned to baseline at 72h while OB and PHAG failed to return to baseline by 72h. Total leukocytes counts (P<0.001) and PMN concentrations (P=0.001) increased linearly with NutriTek® dose. PMN L-selectin concentrations did not differ (P=0.684) among treatments. Oxidative burst intensity in PMN (P=0.025) and MONO (P=0.003) increased linearly with NutriTek® dose at 72h, as well as in MONO PHAG intensity (P=0.004) at 6 h. The percentage of PMN (P=0.012) and MONO (P=0.013) that were both PHAG and OB linearly increased with NutriTek® dose at 72h. Ex vivo whole blood lipopolysaccharide stimulated TNF-a concentrations tended to be greater (P=0.026) in NutriTek® steers than control steers at -24h. Ex vivo IFN-' production did not differ (P=0.695). Overall, these data demonstrate that the dexamethasone challenge induced severe leukocyte dysfunction, and NutriTek® supplementation influenced plasma neutrophil concentrations and may have increased recovery of neutrophil and monocyte function.