Nutritional modulation of the immune system of beef cattle

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Title: Nutritional modulation of the immune system of beef cattle
Author: Reuter, Richard Ryan
Abstract: Experiments were conducted related to measuring and modulating the acute -phase immune response in beef cattle . In Exp . 1 , bacterial lipopolysaccharide (LPS ) was administered to 9 steers in doses of 0 .5 , 1 .0 , or 2 .0 ¦Ìg /kg of body weight (BW ) and the resulting serum cortisol concentration and rectal temperature (RT ) were measured . Cortisol increased linearly (P = 0 .01 ) with LPS dose , but RT increased independent of dose . In Exp . 2 , 2 .5 ¦Ìg /kg of BW of LPS was administered to 9 Angus steers . Serum concentrations of cortisol , interleukin (IL ) -1¦Â , IL -6 , tumor necrosis factor -¦Á (TNF¦Á ) , interferon -¦Ã (INF¦Ã ) , and serum amyloid -A (SAA ) , rectal temperature (RT ) , ruminal temperature , and respiration and perspiration rates were all increased following LPS challenge (P < 0 .10 ) . Rump perspiration rate , IL -4 , and IL -2 were not changed (P > 0 .24 ) by LPS challenge . In Exp . 3 , a device was developed to automatically monitor RT in cattle . The autonomous device recorded RT at 1 -min intervals in cattle in Exp 2 . Rectal temperature measured with the device was related (P ¡Ü 0 .02 ) to IL -6 and TNF¦Á concentration following LPS challenge . In Exp 4 , two non -nutritive feed additives (Sucram , an artificial sweetener ; Omni -GenAF , an immunomodulatory yeast product ) were fed to newly received heifers for 44 d . Overall health and growth performance of the cattle were better than expected for heifers of the type and background used , and feed additives had no effect on growth , intake , or health . Nonetheless , the combination of Sucram and Omni -Gen AF decreased haptoglobin concentration on d 16 (P = 0 .001 ) . Deleterious effects of the additives on marbling score were evident (P = 0 .05 ) , and a long feeding period , relatively free of handling stress , mitigated negative effects of animal temperament on performance . In Exp 5 , 70 % and 30 % concentrate diets were fed ad libitum to beef steers for 28 d (70AL and 30AL , respectively ) to test the effects of energy source and energy intake on immune response . A third dietary treatment (70RES ) consisted of the 70 % fed in an amount restricted to equal the net energy for gain (NEg ) intake of the 30AL treatment . Two days before an LPS challenge , 4 steers in each diet treatment were injected with tilmicosin phosphate (1 mL /30 kg of BW ) , and 4 steers were injected with an equal volume of saline . Steers were catheterized in the jugular vein and then challenged with 2 .0 ¦Ìg LPS /kg of BW . Both energy source and energy intake affected the pro -inflammatory immune response ; the 30 % concentrate diet increased (P ¡Ü 0 .05 ) TNF¦Á and INF¦Ã response to LPS compared with the 70 % concentrate diet , and 70RES increased IL -6 (P = 0 .003 ) response compared with 70AL . Tilmicosin accelerated the febrile response (P = 0 .01 ) across all diets , and tilmicosin interacted with energy intake to increase pre -challenge levels of TNF¦Á , INF¦Ã , and IL -6 , and SAA response to the challenge , in 70RES compared with 70AL (P ¡Ü 0 .05 ) . Nutrition and management practices have immunomodulatory effects in beef cattle . More precisely measuring the acute -phase response , and correlating responses to challenge models with clinical health performance in commercial environments will help researchers make more effective recommendations to cattle producers . Benefits to animals , producers , and the public can be realized when nutrition and management are effectively used to decrease morbidity in beef cattle .
URI: http : / /hdl .handle .net /2346 /17696
Date: 2007-12

Citation

Nutritional modulation of the immune system of beef cattle. Doctoral dissertation, Texas Tech University. Available electronically from http : / /hdl .handle .net /2346 /17696 .

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