Wild animal genetic resource banking (GRB) represents a valuable tool in conservation breeding programs, particularly in cases involving endangered species such as the golden‐headed lion tamarin (Leontopithecus chrysomelas). Thus, we aimed to assess a sperm freezing protocol for golden‐headed lion tamarins using two different exenders: BotuBOV® (BB) and Test Yolk Buffer® (TYB). Ejaculates were collected by penile vibrostimulation from animals housed at São Paulo Zoological Park Foundation, São Paulo, Brazil, and after immediate analysis, two aliquots were diluted in BB and TYB. Postthawing samples were evaluated for total and progressive motility, plasma membrane and acrosome integrities, mitochondrial activity, suscept- ibility to oxidative stress, and sperm–egg‐binding. No differences between BB and TYB were found for most seminal parameters, except for acrosome integrity and susceptibility to oxidative stress (in both cases BB showed higher values). However, in spite of these differences and regardless of the extender used, postthaw sperm motility and viability with the described protocol were encouraging (on average >50% and >80%, respectively), indicating that sperm cryopreservation may be a short‐term measure for the conservation of golden‐headed lion tamarins.
The golden-headed lion tamarin (Leontopithecus chrysomelas) is an endangered primate that, according to timing of births, there seems to have seasonal reproductive patterns in captive populations inhabiting the Southern Hemisphere. The extent to which male tamarins have cir- cannual cyclic fluctuations in testicular functions, however, remains unknown. Changes in testis size and seminal variables, therefore, were evaluated during the rainy and dry seasons of the year in seven males. There was estimation of mating and birth seasons from the breeding colony using a 27 year database (229 birth records). Births were distributed throughout the year with peaks occurring in August-October and January-March (39.7 % and 30.5 % of all births, respectively). Semen collection using penile vibrostimulation was successfully induced in more than 96 % of the attempts regardless of the season (total of 75 ejaculates). Body mass did not vary significantly between seasons, but relative testes size was larger during the dry season. Values for none of the seminal variables (total sperm count, total and progressive motility, plasma membrane and ac- rosome integrity, and total sperm defects), however, were different during the rainy and dry seasons. These results indicate that testicular function in golden-headed lion tamarins may not be affected by daylength changes, and that seasonal patterns of female reproduction is perhaps more relevant for the reproductive timing of the species. Furthermore, the possibility of year-round production of ejaculates containing viable sperm broadens our perspective of preserving genetic diversity within the species because there is a greater opportunity for semen collection and freezing.