Impact of adding different concentrations of IGF-I and insulin to the semen extender on bull sperm quality post-cryopreservation

This study aimed to evaluate the addition of different concentrations of IGF-I and insulin to egg yolk-based extender to improve bovine semen cryopreservation. Two experiments were developed to evaluate the effects of the additives in two commercial extenders, Botubov (R) (Experiment 1) and Triladyl (R) (Experiment 2), both with the same design. Three ejaculates from four bulls (n = 12) were used. Each ejaculate was divided into seven equal fractions for dilution (60x106 spermatozoa/mL) in the following treatments: CON: extender only; IGF100: IGF-I 100ng/mL; IGF200: IGF-I 200ng/mL; INS150: insulin 150 mu UI/mL; INS200: insulin 200 mu UI/mL; ASS1: IGF-I 100ng/mL + insulin 150 mu UI/mL; ASS2: IGF-I 200ng/mL + insulin 200 mu UI/mL. Semen was cryopreserved by an automated system. Post-thawed sperm were evaluated regarding motility by CASA (Computer-assisted sperm analysis), and membranes by fluorescent probes (H342, PI, FITC-PSA and JC-1). For Botubov (R) extender, INS150 was more efficient in preserving total and progressive motility, VCL, BCF, plasma and mitochondrial membranes. A similar response was seen when insulin was added to the Triladyl (R) extender, INS150 was more efficient in preserving sperm motility, plasma membrane integrity and mitochondrial potential. Thus, the addition of insulin 150 mu UI/mL, regardless of the composition of the extender, contributes to better preserving bovine sperm from the cryopreservation effects.