Embryonic mortality in artificially inseminated buffaloes during the breeding season.

The aim of this study was to evaluate the embryonic mortality (EM) rate in Italian Mediterranean buffaloes artificially mated during a period of decreasing daylight length. The study was conducted between October and December on 133 multiparous Italian Mediterranean Buffaloes. The animals were selected by clinical examination before AI and synchronized by the Ovsynch-TAI Program, which consists of administration of a GnRH agonist on day 0, a PGF2a analogue on day 7 and GnRH agonist again on day 9. Artificial inseminations were performed by the same operator and each buffalo was inseminated twice, 16 and 40 h after the second injection of GnRH agonist. Twenty-five and 45 days after AI, buffaloes underwent transrectal ultrasonography to assess embryonic development and buffaloes pregnant on day 25, but not on day 45 were considered to have undergone EM. Pregnancy rate on Day 25 after AI was 54.9% (73/133) and declined to 48.1% (64/133) by Day 45, which represented an EM rate of 12.3% (9/73). This value is definitely lower than those reported during the transition period (passage from decreasing to increasing daylight length) by our research group. In conclusion this trial represents a further confirmation of buffalo sensitivity to seasonality.