In vitro characterisation of fresh and frozen sex-sorted bull spermatozoa.

This study sought to compare the in vitro characteristics of fresh and frozen non-sorted (NS) and sex-sorted (SS) bull spermatozoa. Experiment 1: Holstein-Friesian ejaculates (n=10 bulls) were split across four treatments and processed: (1) NS fresh at 3×106 spermatozoa, (2) X-SS frozen at 2×106 spermatozoa, (3) X-SS fresh at 2×106 spermatozoa and (4) X-SS fresh at 1×106 spermatozoa. NS frozen controls of 20×106 spermatozoa per straw were sourced from previously frozen ejaculates (n=3 bulls). Experiment 2: Aberdeen Angus ejaculates (n=4 bulls) were split across four treatments and processed as: (1) NS fresh 3×106 spermatozoa, (2) Y-SS fresh at 1×106 spermatozoa, (3) Y-SS fresh at 2×106 spermatozoa and (4) X-SS fresh at 2×106 spermatozoa. Controls were sourced as per Experiment 1. In vitro assessments for progressive linear motility, acrosomal status and oxidative stress were carried out on Days 1, 2 and 3 after sorting (Day 0=day of sorting. In both experiments SS fresh treatments had higher levels of agglutination in comparison to the NS fresh (P<0.001), NS frozen treatments had the greatest PLM (P<0.05) and NS spermatozoa exhibited higher levels of superoxide anion production compared with SS spermatozoa (P<0.05). Experiment 1 found both fresh and frozen SS treatments had higher levels of viable acrosome-intact spermatozoa compared with the NS frozen treatments (P<0.01).