THE INFLUENCE OF AGE AND HEALTH-STATUS ON THE SERUM ALPHA1-ACID GLYCOPROTEIN LEVEL OF CONVENTIONAL AND SPECIFIC PATHOGEN-FREE PIGS

Serum alpha-1-acid glycoprotein (alpha1AG) was measured in 212 Land-ra ce White pigs between birth and finishing age. The alpha1AG level of h ealthy pigs five to ten months of age was 338 +/- 79 mug/mL, and the u pper normal limit in mature swine has been established as 500 mug/mL. In both specific pathogen-free (SPF) and conventional pigs, the alpha1 AG level within one day of birth was 14,263 +/- 2,393 mug/mL, 40 times the normal adult value, but rapidly decreased to 699 +/- 186 mug/mL b y four weeks of age. In conventional pigs, alpha1AG began to increase after four weeks, averaged 1,428 mug/mL by eight weeks, but gradually decreased to adult levels by 20 weeks of age. In comparison, alpha1AG of SPF pigs was only 800 mug/mL at eight weeks and decreased more rapi dly to normal by 16 weeks of age. The conventional pigs had a high inc idence of clinical pneumonia and specific antibodies to Actinobacillus pleuropneumoniae and Mycoplasma hyopneumoniae at the age of eight wee ks. As the clinical pneumonia disappeared, serum alpha1AG level also g radually declined. In contrast, SPF pigs had little clinical illness, low alpha1AG, and little serological evidence of microbial infection. Conventional pigs with nonrespiratory infections, encephalitis, or wit h hernias had increased alpha1AG. While the very high alpha1AG level o f the neonatal pig may be due to genetic influences, increases later i n life are likely in response to stimuli from its external environment . Monitoring of serum alpha1AG in several herds aided in the recogniti on of disease processes and may have potential use in swine herd healt h management.