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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #132488
Title: THE EFFECT OF DIETARY SOY DAIDZEIN ON PIG GROWTH AND VIRAL REPLICATION DURING A VIRAL CHALLENGE

Author
item GREINER, L - IOWA STATE UNIVERSITY
item STAHLY, T - IOWA STATE UNIVERSITY
item Stabel, Thomas

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/31/2001
Publication Date: 12/20/2001
Citation: N/A

Interpretive Summary: Continuous exposure or low level infection with disease-causing bacteria or virus can cause a reduction in body growth, desire to eat, and ability to properly digest food. It has been shown that factors that minimize the presence of virus in pigs result in improved pig growth. We chose to measure the effect of dietary daidzein, a primary compound found in soybeans, on pig growth and the immune response during a viral infection. To mimic a naturally occurring viral infection, we experimentally infected pigs with porcine reproductive and respiratory syndrome (PRRS) virus, an economically important and widespread viral disease in the pork industry. Serum PRRS virus and interferon peaked at 4 d postinoculation (PI) and then declined steadily. Serum alpha1- acylglycoprotein (AGP) concentration peaked at 12 d PI. Dietary daidzein additions did not alter the serum concentration after inoculation of PRRS virus or AGP. Dietary daidzein additions resulted in improvement in daily pig gain, daily feed intake, and gain/feed during periods of peak viremia, but not in periods when systemic virus concentrations were minimized. These data indicate that soy daidzein at dietary concentrations of 200 to 400 ppm is a weak enhancer of body growth in virally challenged pigs. Application of scientifically proven practices will have immediate economic benefits to the pork producer and eventually the American consumer since new control measures for disease will allow a continued supply of inexpensive, wholesome pork and pork products. This will benefit scientists, practitioners, producers, and FDA.

Technical Abstract: Pigs were randomly allotted to one of four dietary soy daidzein concentrations (0, 200, 400, and 800 ppm) to quantify the effect of daidzein on growth and immune response during a porcine reproductive and respiratory syndrome (PRRS) viral challenge. Pigs were oronasally inoculated with PRRS virus and blood was collected every 4 d from d 0 to 24 postinoculation (PI) and analyzed for serum PRRS virus, interferon, and alpha1-acylglycoprotein (AGP) concentrations. Serum virus and interferon peaked at 10**5.3 virus/ml and 79% protection, respectively, at 4 d PI and then declined steadily. Serum AGP concentration peaked at 12 d PI. Each log increase in serum virus was associated with an increase in serum interferon, which resulted in a decrease of pig ADG and daily feed intake. Dietary daidzein additions did not alter the serum concentration after inoculation of PRRS virus or AGP. Dietary daidzein additions resulted in improvement in daily pig gain, daily feed intake, and gain/feed during periods of peak viremia, but not in periods when systemic virus concentrations were minimized. Based on these data, the magnitude of the growth responses that occur in pigs infected with a virus is quantitatively related to the animal=s serum concentration of the virus and interferon, and dietary soy daidzein at 200 or 400 ppm is a weak enhancer of body growth in virally challenged pigs.