Ejaculates from each stallion
were collected once daily for 5 d, which was the time
period deemed sufficient to stabilize extragonadal sperm
reserves in these stallions and thus calculate daily sperm
output (DSO) for Miniature Horse stallions; this was
based on modification of previous DSO determination calculations
for full-sized stallions (Love et al., 1991). The
mean value for sperm output during the fi nal 2 d of semen
collection was used to represent actual DSO, as the numbers
of sperm no longer varied signifi cantly (Gebauer et
al., 1974; Thompson et al., 2004). No semen was collected
for at least 7 d before each DSO determination