Preliminary results on the composition of oviductal fluid in buffalo species.

Although the multi-step process of IVEP has been successfully used for producing morulae/blastocysts and pregnancies in buffalo, the efficiency, in terms of transferable embryos (TE) and development to term, is still very low. We believe that IVEP efficiency in buffalo may be greatly improved by minimizing the stress before IVM and identifying the causes of the lower cleavage rate. It is still not clear if the lower cleavage rate is due to problems occurring during IVM or IVF. Furthermore it is advisable to carry out new studies in order to better understand the physiology and the metabolism of buffalo embryos, that may have different culture requirements compared to bovine embryos. The characterization of buffalo oviductal fluid in different stages of the estrus cycle would allow the optimization of the IVEP system, because the oviduct represents the microenvironment in which the processes of fertilization and early embryo development happen. The production of oviductal fluid is affected by the phase of the estrous cycle. In fact, when progesterone levels are higher, the oviductal fluid volume is lower than 1ml, whereas definitely higher values are recorded during the follicular phases of the cycle. Anyway, the volume of oviductal fluid collected in buffalo, both in follicular and luteal phases of the cycle, is greatly lower than those reported in bovine and in swine. The concentration of this metabolite assessed during the estral phase (0.06 mmol/L) resulted similar to that recorded in bovine. A different trend is recorded for lactate and pyruvate: in fact similar values were observed both in luteal and estral phases. Few differences were observed regarding to the ionic components of the Ampullary fluid. The levels of sodium, potassium and calcium did not show any significant differences among the phases, but resulted highly correlated to the typical levels recorded in the blood in buffalo. These preliminary results on the quantity and the characteristics of the oviductal fluid in buffalo underlined that this species is different from others, although the trend reported for several substances is similar. The lower production of oviductal fluid and metabolites recorded in the ampulla may be due to anatomic-functional causes. However, further studies are needed in order to better evaluate the protein composition and concentration. These studies would be furthermore utilized for the preparation of laboratory media specific for buffalo species.