Analysis of the Osmolarity of the Liquid Fraction of Squirrel Monkey's Semen ( Saimiri collinsi Osgood, 1916) in Fattening and Non‐Fattening Conditions

ABSTRACT Background The aim was to determine seminal osmolarity in S. collinsi and evaluate whether it, along with seminal parameters, varies between fattening and non‐fattening conditions and across age groups. Methods Biometric and seminal parameters were evaluated in nine S. collinsi males across conditions. Mixed‐effects models assessed reproductive parameters and seminal quality. Results Seminal osmolarity ranged from 300 to 500 mOsm/L and varied with age and fattening condition. Testicular volume was lower during non‐fattening. Seminal osmolarity showed linear and quadratic associations with reproductive biometry and sperm quality. Seminal volume decreased with increasing osmolarity, whereas sperm morphology and vigor showed non‐linear associations. Age was negatively associated with plasma membrane integrity and sperm morphology, while sperm concentration and motility were not significantly affected. Conclusion Seminal osmolarity and age are associated with reproductive and sperm functional parameters, establishing the first baseline for seminal osmolarity in this species and supporting reproductive biotechnology and conservation strategies.