Association Between Body Condition, Metabolic Parameters and Sperm Quality During Cold Storage in Purebred Spanish Stallions

This study evaluated the association of BCS and serum metabolic parameters with sperm quality during 72 h of refrigeration at 5 °C in 20 Purebred Spanish stallions. Motility, vitality, acrosome integrity, mitochondrial membrane potential, protamination and DNA fragmentation were assessed at 0, 24, 48 and 72 h. Storage time significantly affected most sperm parameters, confirming a progressive decline in quality during refrigeration. Two-way repeated measures ANOVA revealed that stallions with high BCS (7–8) showed a significantly lower percentage of sperm with normal acrosome integrity (p = 0.0426) than those with normal BCS (4–6), with no BCS × storage time interaction. Similarly, high triglyceride and cholesterol levels were each associated with reduced acrosome integrity throughout refrigeration. A few group × storage time interactions (vitality with glucose and cholesterol, progressive motility with cholesterol, acrosome integrity with leptin) were exploratory, without differences at individual times. These results indicate that the metabolic profile is associated with sperm membrane-related parameters during cooled storage. In contrast, the absence of fertility data and independent validation means that these results do not support metabolic profiling as a breeding soundness test and need confirmation in larger studies.