The Ovsynch protocol and its modifications are generally
aimed to obtain the best possible conception rate with
minimal need of labour. In circumstances explained
above, one of the goals is to optimize the number of offspring
per AI dose, since the target is to import new and
valuable genetic material into the herd rather than conceive
all animals per AI. In practice, the conception rate
could be improved by selecting the involved animals
according to the known facts that affect fertility. In addition,
the selection method should be easy enough to
apply in field conditions. Vasconcelos et al. [15] have
shown that cows having low progesterone concentrations
at the time of the administration of PGF2α in the Ovsynch
protocol had significantly lower conception rate when
compared to that of those cows having high progesterone
concentration. The probability that included animals
have high progesterone concentration at the time of the
treatment can be increased in field conditions by detection
of a corpus luteum by palpation of ovaries per rectum
[16]. Instead Gümen et al. [17] have shown that anovulatory
cows react well to Ovsynch protocol. Thus, on the day
of the first GnRH injection of the Ovsynch protocol, there
are not any clear criteria to select the cows into the program