Aspects of the transmission of protection against Mycoplasma hyopneumoniaefrom sow to offspring

The aims of this study were to describe the variation in concentration of a ntibodies to Mycoplasma hyopneumoniae in the serum and colostrum of seas, a nd to compare the amount of antibodies in colostrum with that obtained in t he serum of the smallest piglets in a litter. In addition, the efficacy of the passive immunity in natural conditions was studied. The study was perfo rmed in a sow pool herd (600 sows) that was endemically infected with M. hy opneumoniae. Blood samples were collected from sows 19 days (n = 25) before and 3 days (n = 15) after farrowing, and a colostrum sample (n = 25) was c ollected on the day of farrowing. All samples were analysed for antibodies to M. hyopneumoniae with a monoclonal blocking enzyme-linked immunosorbent assay (ELISA). Twelve sows (48%) were high-responders with respect to antib ody concentration in colostrum. The amount of blocking decreased in serum d uring the last weeks of pregnancy and 3 days post-farrowing it was only 53% of the level found in colostrum. At the age of 14 days, 30 of the smallest piglets were weaned. They were divided into three experimental groups, bei ng the offspring of high-responding sows, low-responding sows, or a mix of high- and low-responding sows. The groups were transported to three separat ed isolation units and were followed until slaughter. At slaughter, lung le sions were not found. Nor could M. hyopneumoniae be demonstrated either by cultivation or by polymerase chain reaction. However, a significant increas e in absorbance values, assessed by an indirect-ELISA, was demonstrated in groups established from low-responding sows. It was concluded that a high a ntibody level in colostrum appeared to protect piglets from M. hyopneumonia e.