Abstract
Background
Porcine circovirus type 2 (PCV2) is commonly associated with several clinical syndromes and diseases collectively referred to as porcine circovirus-associated disease, which has a significant economic impact on the global swine industry. In Japan, PCV2 is endemic to most pig farms, and vaccination for piglets and/or sows has been implemented on most farms. The present study explored factors associated with piglets at elevated risk of PCV2 infection. Pre-vaccination serum samples were collected, from birth through 19 days, from 39 piglets born to five sows; these specimens were used to measure the titer of maternally derived antibody (MDA) against PCV2, immunoglobulin G concentration, and total protein concentration. Additionally, records of sow parity and piglet body weights were examined.
Results
Regarding anti-PCV2 MDA, the mean maximum sample-to-positive (S/P) ratios among litters born from the five sows differed significantly (p < 0.001). The half-life of the anti-PCV2 MDA was estimated to be 17.4 days (95% confidence interval: 16.2–18.9 days). The trend to lower antibody titers appeared to be attenuated in piglets born from sows with higher parities. Furthermore, among litters from sows with a large number of parities, litters with larger mean birth weights exhibited greater variability in antibody titers. Additionally, within litters of piglets with higher mean birth weights, piglets with lower birth weights or lower serum total protein concentrations exhibited lower antibody titers.
Conclusions
The present study aimed to evaluate the relationship between serum anti-PCV2 MDA titers and several indicators in suckling piglets and to identify characteristics of piglets at elevated risk of PCV2 infection. In the field, indicators such as sow parity, birth weight, and serum total protein concentration may facilitate the identification of piglets at elevated risk of PCV2 infection.