Early embryo mortality in Buffalo (Bubalus bubalis) during the spring period.

Embryo development is linked to several factors, such as intrinsic defects within the embryo, an inadequate maternal environment or failure of the mother to respond appropriately to embryonic signals. Reproductive seasonality in buffalo species (Bubalus bubalis) is responsible of lower reliability of the pregnancy diagnosis by progesterone assay in the spring, probably due to high incidence of early embryo mortality (EEM) for hormonal causes. The aim of the study was to identify the causes of EEM in buffaloes inseminated during the spring period. Italian Mediterranean Buffalo cows (n=209) in a good status of health were synchronized using the Ovsynch-TAI Program and were inseminated 16 and 40 hours after the second administration of GnRH. Artificial inseminations were performed by the same technician. Ten to 20 days after the first insemination two blood samples were collected from each animal for assessing P4 levels by RIA. 24 and 40 days after the first insemination pregnancy diagnosis was assessed by rectal ultrasonography (Aloka SSD-500) with a 5 MHz sector scanner. In animals with EEM a uterine flushing was carried out and recovered fluid was analysed for the principal infectious agents. Microbiological analysis were carried out according to Clinical Veterinary Microbiology and a PCR analysis was performed only for BUHVI, Toxoplasma and Neospora. Statistical analysis was assessed by Student t test. The incidence of cyclic buffaloes after synchronization treatment (94%) and pregnancy rate at 40 days (34.4%) were similar to those reported in a previous study. EEM between 24 and 40 days was 45% and only in 9 buffaloes (15.3%) these results correlated with the presence of infectious agents (Streptococcus spp., Enteriobacteriacee spp., Proteus spp., Staphylococcus spp. and BUHVI). P4 levels on day 10 were higher (P<0.05) in pregnant (P) buffaloes than in those with EEM. On day 20, P4 levels were higher (P<0.01) in P buffaloes than in those with EEM and those not pregnant. It is hypothesized that the reduced activity of hypophysis, correlated with an increase in hours of light which may be resposible for decreased P4 concentrations and EEM in buffalo.