Progress 10/01/01 to 09/30/06
Outputs
The goals of the project were to (1) determine if infection by Mycoplasma hyopneumoniae (Mh) potentiates the effects of porcine reproductive and respiratory syndrome virus (PRRSV) on feed intake and protein accretion of pigs; (2) determine if decreased feed intake and protein accretion of pigs experimentally infected with Mycoplasma hyopneumoniae and porcine reproductive and respiratory syndrome virus is associated with increased expression of metabolically active cytokines; and (3) determine the circulating levels of several hormones and metabolically active cytokines in experimentally infected pigs prior to the onset of clinical signs of disease, during clinical disease, and during recovery. The important results showed that PRRSV but not Mh increased circulating inflammatory cytokines and inhibited feed intake and whole body protein accretion. Sickness behaviors were evident in pigs infected with PRRSV, and the reduction in protein accretion was associated with
increased expression of mysostatin, a negative regulator of muscle mass. Providing pigs diet high in vitamin E and selenium or water supplemented with plasma protein failed to mitigate the negative effects of PRRSV infection.
Impacts
Respiratory infections are common and reduce growth in swine. The results of this project indicate that sickness behavior and growth depression are closely associated with circulating inflammatory cytokines. Further, myostatin gene expression is increased in slow-growing PRRSV-infected pigs. Thus, this project revealed inflammatory cytokines and myostatin as viable targets for improving growth of pigs with clinical or subclinical infections. Providing pigs diets high in vitamin E and selenium or water supplemented with plasma protein did not mitigate the negative effects of PRRSV infection. Therefore, currently there are no data to support their use for this purpose.
Publications
- Escobar, J., Van Alstine, W.G., Baker, D.H. and Johnson, R.W. 2002. Growth performance and whole-body composition of pigs experimentally infected with Mycoplasma hyopneumoniae. J. Anim. Sci. 80:384-391.
- Johnson, R.W. 2002. The concept of sickness behavior: A brief chronological account of four key discoveries. Vet. Immunol. Immunopath. 87:443-450.
- Kelley, K.W., Bluthe, R.M. Dantzer, R., Zhou, J.H., Shen, W.H., Johnson, R.W. and Broussard, S.R. 2003. Cytokine-induced sickness behavior. Brain Behav. Immunol. 117:S112-S118.
- Escobar, J., Van Alstine, W.G., Baker, D.H. and Johnson, R.W. 2004. Decreased protein accretion in pigs with viral and bacterial pneumonia is associated with increased myostatin expression in muscle. J. Nutr. 134:3047-3053.
- Johnson, R.W. and Escobar, J. 2005. Immune system: Nutrition effects. In: Encyclopedia of An. Sci., Eds. Wilson Pond and Alan Bell, Marcel Dekker, Inc. pg 541-543.
- Escobar, J., Toepfer-Berg, T.L., Chen, J., Van Alstine, W.G., Campbell, J.M. and Johnson, R.W. 2006. Supplementing drinking water with Solutein did not mitigate acute morbidity effects of PRRSV in nursery pigs. J. Anim. Sci. 84:2101-2109.
- Escobar, J., Van Alstine, W.G., Baker, D.H. and Johnson, R.W. 2006. Behavior of pigs with viral and bacterial pneumonia. J. Appl. Anim. Behav. Sci. (In Press).
- Johnson, R.W., Escobar, J. and Webel, D.M. 2001. Nutrition and immunology of swine. In: A. J. Lewis and L. L. Southern (Eds.) Swine Nutrition. Butterworth-Heinemann, Stoneham, MA. pp. 545-562.
- Johnson, R.W. and Escobar, J. 2005. Cytokine regulation of protein accretion in growing animals. In: D. Burrins and H. Mersmann (Eds.) Biology of Metabolism in Growing Animals. Elsevier Science B. V., Amsterdam, The Netherlands. pp. 83-106.
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Progress 01/01/05 to 12/31/05
Outputs
A study was conducted to determine whether providing nursery pigs drinking water supplemented with spray-dried animal plasma (Solutein, American Protein Corporation, Inc., Ankeny, IA) would reduce the detrimental impact of porcine reproductive and respiratory syndrome virus (PRRSV) infection. Sixty-four pigs were subjected to one of four treatment combinations (2 x 2 factorial) of Solutein (0 or 2.5% w/w in drinking water) and PRRSV (5 ml of TCID50 of high-virulence strain ATCC VR-2385 or sterile medium). Pigs were provided the water treatments during a 1-wk period before inoculation as well as during a 2 wk period after inoculation. Growth performance was determined throughout the study, and several indicators of the immunological response to PRRSV and disease pathology were assessed in blood and tissue samples collected from pigs killed 7 or 14 d after inoculation. Before inoculation, pigs provided water supplemented with Solutein tended to eat less (P = 0.08), but
tended to gain more (P = 0.13) than pigs provided tap water. Thus, Solutein markedly improved G:F (P < 0.01). Inoculation with PRRSV reduced ADG and ADFI (P < 0.01) irrespective of water treatment; however, the beneficial effects of Solutein on G:F persisted. Infection with PRRSV also reduced villus height and crypt depth in proximal, medial, and distal segments of the small intestine, and increased lung and spleen weight, the number of leukocytes in lung lavage fluid, and serum concentrations of interferon gamma and IL-1 beta regardless of water treatment. Collectively, these results indicate that supplementing water with spray-dried animal plasma improved feed efficiency but did not afford nursery pigs protection from the effects of PRRSV on growth and certain hematological traits.
Impacts
Supplementing water with Solutein improved feed efficiency but did not afford pigs protection from the effects of PRRSV infection on growth and certain hematological traits. Thus, it may be difficult to overcome the morbidity effects of PRRSV with Solutein. However, it should be noted that this study focused on the acute response to PRRSV. Had the study been extended past 14 d after inoculation, it is possible that pigs provided Solutein might have recovered faster. Furthermore, pigs in this study were housed in a highly sanitized environment, so exposure to secondary pathogens was minimized. In commercial settings, pigs are subjected to multiple pathogens and are more likely to develop secondary infections that may be affected by Solutein. This may be particularly important if virulent gastrointestinal pathogens are present, because addition of spray-dried plasma to calf milk replacer was shown to reduce the duration of diarrhea and mortality in dairy calves.
Furthermore, others have shown that feeding spray-dried plasma reduced diarrhea and increased ADFI and ADG in nursery pigs orally inoculated with pathogenic E. coli bacteria.
Publications
- Toepfer-Berg, T.L., Escobar, J., Van Alstine, W.G., Baker, D.H., Salak-Johnson, J.L. and Johnson, R.W. 2004. Vitamin E supplementation does not mitigate the acute morbidity effects of porcine reproductive and respiratory syndrome virus in nursery pigs. J. Anim. Sci. 82:1942-1951.
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Progress 01/01/04 to 12/31/04
Outputs
Chronic respiratory infections reduce growth in pigs but protein accretion (PA) during an ongoing multi-factorial respiratory infection has not been determined, and the mechanisms underlying growth inhibition are largely unknown. The objectives of this study were to determine if viral and bacterial pneumonia in young pigs would decrease PA, increase serum interleukin (IL)-1b and IL-6, and increase myostatin (MSTN) mRNA in biceps femoris and triceps muscles. Mycoplasma hyopneumoniae (Mh) or medium was given intratracheally at 4-weeks of age, Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) or medium was given intranasally at 6-weeks of age, and pigs were killed 7 or 14 days after PRRSV inoculation for body composition analysis. PRRSV but not Mh induced a marked increase (P < 0.01) in IL-1b, IL-6, and MSTN mRNA, and a decrease (P < 0.01) in food intake (FI), daily weight gain, PA and lipid accretion. PRRSV also reduced (P < 0.01) myofiber area in the biceps
femoris. Food intake, weight gain, PA, and weight of biceps femoris and triceps muscles were negatively correlated (r=-0.4 to -0.8, P < 0.05) with serum IL-1b and IL-6, and with MSTN mRNA in muscle. These results suggest that the magnitude of increases in inflammatory cytokines during a respiratory infection may be predictive of decreases in PA and growth. They further suggest that, during infection, growth of skeletal muscle is limited, in part, by myostatin.
Impacts
Respiratory infections are a major cause of morbidity and mortality in swine. Pigs are commonly infected by more than one pathogen, but how the different pathogens interact and affect growth performance is poorly understood. Results from this study suggest that although Mh induces gross pulmonary lesions, PRRSV is more detrimental to growth performance in nursery pigs. Moreover, during infection muscle growth may be limited by increased expression of myostatin.
Publications
- Escobar, E., Van Alstine, W.G., Baker, D.H. and Johnson, R.W. 2004. Decreased protein accretion in pigs with viral and bacterial pneumonia is associated with increased myostatin expression in muscle. J. Nutr. 134:3047-3053.
- Johnson, R.W. and Escobar, J. 2005. Immune system: Nutrition effects. In: Encyclopedia of An. Sci., Eds. Wilson Pond and Alan Bell, Marcel Dekker, Inc. pg 541-543.
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Progress 01/01/03 to 12/31/03
Outputs
The overall goal of this project is to investigate the underlying mechanisms responsible for growth inhibition in pigs with respiratory infections. A study was conducted to determine if porcine respiratory syndrome virus (PRRSV) and Mycoplasma hyopneumoniae (Mh)- alone or in combination - induce gross pulmonary lesions and decrease growth performance and protein accretion in nursery pigs. Mh or medium was given intratracheally at 4-weeks of age, PRRSV or medium was given intranasally at 6-weeks of age, and pigs were killed 7 or 14 days later. Pigs inoculated with Mh had gross pulmonary lesions affecting 8% and 15% of the lung area 7 and 14 days after PRRSV inoculation, which corresponded to 21 and 28 days after Mh inoculation, respectively. Lung lesions induced by Mh were markedly exacerbated by PRRSV. Mycoplasma lung lesions in pigs inoculated with both Mh and PRRSV affected 39% and 43% of lung area 7 and 14 days after PRRSV inoculation. PRRSV but not MH induced a
marked decrease in feed intake, weight gain, and protein accretion. And despite the significant interaction between Mh and PRRSV with regard to the development of gross pulmonary lesions, the depression in feed intake, growth and protein accretion was explained by PRRSV alone.
Impacts
Respiratory infections are a major cause of morbidity and mortality in swine. Pigs are commonly infected by more than one pathogen, but how the different pathogens interact and affect growth performance is poorly understood. Results from this study suggest that although Mh induces gross pulmonary lesions, PRRSV is more detrimental to growth performance in nursery pigs.
Publications
- No publications reported this period
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Progress 01/01/02 to 12/31/02
Outputs
A study was conducted to determine if porcine respiratory syndrome virus (PRRSV) and Mycoplasma hyopneumoniae (Mh)-alone or in combination-decrease protein accretion, increase serum interleukin (IL)-1 and IL-6, and increase steady-state levels of myostatin mRNA in biceps femoris and triceps muscles of pigs. Mh or medium was given intratracheally at 4-weeks of age, PRRSV or medium was given intranasally at 6-weeks of age, and pigs were killed 7 days later. PRRSV but not MH induced a marked increase in IL-1, IL-6 and myostatin mRNA, and a concomitant decrease in food intake, weight gain, and protein accretion. Food intake, weight gain, protein accretion, and weight of biceps femoris and triceps muscles were negatively correlated to serum levels of IL-1 and IL-6 and with myostatin mRNA. These data showed that when IL-1, IL-6 and myostatin were increased during disease, feed intake, weight gain and protein accretion were decreased.
Impacts
Respiratory infections increase inflammatory cytokines and markedly depress growth in animals, but it was not known if myostatin-a negative regulator of muscle mass-is increasingly expressed by muscle during infection. The results showed that inflammatory cytokines and myostatin mRNA were increased in slow-growing PRRSV-infected pigs. Thus, cytokines may induce myostatin expression, which acts to reduce growth in sick animals. Understanding why animals with clinical or sub-clinical infections grow poorly is important for minimizing the impact of endemic pathogens.
Publications
- No publications reported this period
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Progress 01/01/01 to 12/31/01
Outputs
Studies have been initiated to investigate the effects of Mycoplasma hyopneumoniae and porcine reproductive and respiratory syndrome virus on protein accretion in nursery pigs.
Impacts
Mycoplasma hyopneumoniae and porcine reproductive and respiratory syndrome virus are highly prevalent in U.S. swine herds. Infected pigs have reduced appetites and grow poorly, but little is known about how the pathogens or the pig's immune system inhibits growth performance. This study will help understand how pathogens and the immune system decreases growth.
Publications
- No publications reported this period
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