ovulation by per rectum guidance of a long flexible pipette, even though it is
not yet clear whether this is strictly necessary. Indeed, the fact that mares
often conceive twins to bilateral ovulations following AI in the tip of just one
horn suggests that deep intrauterine AI is often unnecessary. Moreover, while
low dose AI is fine for some stallions, it is clearly not for others. Indeed, for
some stallions attempts to reduce the AI dose are disastrous and reveal a
pretty clear threshold (number of sperm/straws) below which the likelihood of
pregnancy drops dramatically, e.g. 4 straws may offer a good chance of
pregnancy whereas two straws is rarely successful. It is possible that deep
horn AI is similarly superfluous for some stallions but useful for others. The
problem is that the only way to generate the information required to identify
the limits for each individual, is trial and error; if semen availability and cost
are not an issue, it is therefore sensible to err on the side of caution.
Conclusions
Management of mares for AI with chilled or frozen semen can be pretty
straightforward, if sufficient semen is available. It becomes more challenging
when chilled semen is to be imported and has to be ordered far in advance of
planned AI; frozen semen AI becomes challenging when the amount of semen
available is limited or the semen is expensive and paid for on a per straw or
per dose basis. In such situations, ovulation induction is a routine part of most
AI protocols. And while practitioners still differ in their preferences with regard
to the intensity of monitoring, it is definitely possible to design perfectly
adequate protocols for frozen semen AI that do not require examining mares
more than twice (or even once) a day. This involves either strategic timing of
ovulation induction and/or deliberately planning to AI more than once in an
oestrus. Indeed, in the author’s opinion, there is more scope for improving
results by getting a clearer picture of individual st