The effects of the leptospiral infection on reproductive performance in sows

A serologic survey was conducted among 76 sows randomly selected from a single farrow-to-finish swine herd, located on the Ibiúna municipality, state of São Paulo, Brazil, to investigate associations between Leptospira spp. seropositivity and reproductive performance. For detection of anti-leptospires antibodies, the microscopic agglutination test (MAT) was carried out using live cultures of 22 pathogenic and two saprophytic Leptospira spp. serovars. Questionnaires with open and closed questions were administered to the manager of the herd for collection of information about the sows included in the study and the reproductive performance of the subsequent offspring. The following variables were evaluated: age of sows, total number of piglets born, number of piglets born alive, number of weak piglets, number of weaned piglets, number of mummified fetuses, number of stillbirths, mass of piglets at birth, mass of piglets at weaning, weaning to service interval (WSI), and occurrence of return to heat, mummified fetuses and stillbirths. The frequency of seropositivity for at least one Leptospira spp. serovar was 18.4%. The reactant serovars and respective frequencies were Bratislava (33.3%), Hardjobovis (33.3%), Shermani (19.1%), Icterohaemorrhagiae (9.5%) and Grippotyphosa (4.8%). Seropositivity for Leptospira spp. was associated with prolonged WSI (P<0.001), decreased number of piglets born (P = 0.001), decreased number of piglets born alive (P<0.001), decreased number of weaned piglets (P = 0.003), low mass of the piglets at birth (P<0.01), and increased number of stillbirths (P = 0.001). Seropositive sows had also significant relative risk (P = 0.003) of stillbirths.