Cryopreservation of dog spermatozoa: effect of bovine serum albumin on acrosomal integrity and pregnancy rates after artificial insemination

Abstract

The objective of the present study was
to compare the in vitro and in vivo profile of frozen
dog semen with Tris-bovine serum albumin (TB)
and Tris-egg yolk (TE) extenders. Twenty dogs
were used as donors. Each dog was stimulated by
penile massage and only the sperm-rich fraction
was collected weekly until 40 ejaculates were obtained.
After macroscopic and microscopic analysis,
equal parts of each ejaculate were diluted with TB
and TE by the one-step method at 37 ºC. The semen
was added to 0.5-mL French straws which presented
normal characteristics before freezing and
after thawing. Acrosomal integrity was evaluated by
double Trypan blue-Giemsa staining, in which alive
intact (LI), alive reacted (LR), dead intact (DI) and
dead reacted (DR) spermatozoa, were identified
by the time of thawing and up to 4 h of incubation
at 39 °C, the TE being significantly superior to TB
(P<0,01) in the LI and LR variables. The TB being
significantly superior to TE (P<0,01) in the DR variable.
Female dogs in natural heat were submitted to
artificial insemination, 20 receiving TE-semen and
20 receiving TB-semen with the Osiris probe (IMV,
L’Aigle, France) and the numbers indicate that TE
was significantly better than TB (P<0,01) to pregnancy
rate and number of puppies/delivery. We
concluded from this study, that TE was better than
TB, because this, induced an early acrossome reaction
in dog’s sperm.