João Pedro Barbas

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1. Introduction Semen cryopreservation preserves semen quality for future use [1,2]. However, there is a loss of 40–50% in sperm viability after thawing [3], and optimization protocols are needed. Freezing and thawing procedures expose spermatozoa (SPZ) to adverse conditions and oxidative stress caused by the excessive formation of reactive oxygen species (ROS) [4,5].

Abstract : Simple Summary This study mainly aimed to evaluate the seasonal and breed effects on spermatozoa (SPZ) traits of ten Portuguese sheep breeds, cryopreserved and stored in the Portuguese National Germplasm Bank. The mean volume and SPZ concentration of the ejaculate was 0.77 mL and 5039 ± 51 × 106/mL, respectively, and were affected by breed but not by season.