Source-specific modeling of selenium requirements to enhance sperm quality in aged broiler breeders

The environmental impact of selenium (Se) pollution from overfeeding poultry, particularly roosters, is a critical concern due to the narrow margin between its nutritional benefits and toxicity. Accumulation of Se in manure can lead to soil and water contamination, especially in regions with seleniferous soils. This study evaluates various Se sources, including nanoparticles and organic Se, to optimize Se intake for reproductive health while emphasizing the importance of environmentally responsible Se supplementation to mitigate potential pollution risks. This study aimed to determine the optimal dietary Se requirements for enhancing sperm quality parameters in aged broiler breeder roosters using linear (LBL) and quadratic broken-line (QBL) regression models. Three Se sources—sodium selenite (SS), selenium nanoparticles (SeNPs), and selenium-enriched yeast (SelPlex)—were evaluated for their effects on sperm volume, viability, motility, morphology, concentration, membrane integrity, and oxidative stress biomarkers (malondialdehyde [MDA] and glutathione [GSH]). Overall, the LBL model provided a better fit across most parameters, with the exception of sperm viability in the SeNPs group, where the QBL model performed better fit than the LBL models. SeNPs consistently yielded the highest model accuracy for sperm volume (0.265 ± 0.015 mg/kg; R2 = 0.999), morphology (0.300 ± 0.129 mg/kg; R2 = 0.954), and concentration (0.274 ± 0.159 mg/kg; R2 = 0.900). SS demonstrated optimal responses for motility (0.341 ± 0.121 mg/kg; R2 = 0.914) and membrane integrity (0.300 ± 0.103 mg/kg; R2 = 0.918). SelPlex was most effective for sperm viability (0.300 ± 0.090 mg/kg; R2 = 0.935), MDA reduction (0.300 ± 0.138 mg/kg; R2 = 0.864), and GSH enhancement (0.300 ± 0.315 mg/kg; R2 = 0.797), although it exhibited greater variability across other traits. Despite equal estimated optimal levels (0.300 mg/kg) for several parameters, Sy.x values revealed substantial variation in model precision between sources. The results of this study indicate that the selection of Se sources in the diets of aged breeder roosters should be trait-specific, and that nanoparticles and organic forms of Se are more effective than inorganic Se.