A 7-week feeding trial was conducted with Nile tilapia juveniles with an average body weight of 143.5 ± 3.1 g in a cage system in order to test the effect of different feed additives on growth performance, antioxidant defense system, and immune status of fish. For this reason, experimental diets were formulated with inclusion of two different additives containing bioactive compounds, namely Nannochlorophsis gaditana in 3.5% (diet EXP-A) and black soldier fly larvae meal (diet EXP-I) in 3.5%, and compared with a diet supplemented with a mixture of two different commercial compounds (Yang and Syrena Boost) in 0.4% (diet EXP-S). As a negative control, a commercially available feed (Nongteng, Laos) for tilapia was selected. At the end of the feeding trial, production parameters and expression of genes related to the antioxidant defense system and innate immune response were studied. Furthermore, following the feeding, air exposure stress for 5 min was administered to the fish, and similar parameters were assessed. Results indicated that all diets promoted adequate fish growth (SGR 1.67–1.81 g day⁻¹) and feed utilization (FCR 1.29–1.57 g g⁻¹) with no significant (p < 0.05) differences in these parameters between the dietary fish groups. Expression of genes sod, cat, and gpx significantly increased in the liver samples of the EXP-A group at the end of feeding. Following air exposure, the EXP-A group maintained a significantly higher level of antioxidant-related gene expression compared to other treatments. Subsequently, gpx upregulation was observed in the EXP-S group in the post-stress stage compared to pre-stress. Based on our results, we recommend the inclusion of any of the tested additives at the evaluated doses to enhance the non-specific immune response of Nile tilapia. Additionally, Nannochloropsis gaditana at a 3.5% inclusion level can be used to further improve antioxidant defense capacity.

Blood cortisol measurements may be confounded by sampling-induced handling and restraint, motivating the use of alternative matrices to assess adrenocortical activity in pigs. This narrative review examines the physiological time windows, collection requirements, analytical validation, and interpretive limitations of saliva, urine, feces, and hair. Saliva captures rapid responses but remains sensitive to collection conditions; urine integrates secretion over bladder filling and requires dilution correction; fecal glucocorticoid metabolites reflect delayed, integrated excretion and require a species-appropriate assay. Hair offers a potentially longer integration window, but controlled validation in pigs remains inconsistent, and clipping generally requires brief restraint. Antibody specificity, sample processing, and normalization constrain comparisons between studies. Published concentration benchmarks should not be interpreted as validated, production-stage-specific reference intervals. The practical matrix-selection framework presented here rests primarily on cross-study inference rather than direct comparisons of all four matrices under a common challenge. Cortisol indicates adrenocortical activation without establishing its cause or emotional valence. Interpretation therefore requires complementary behavioral, clinical, and production measures. A minimum reporting standard and priorities for paired-matrix validation, standardized sampling, and category-specific reference intervals are proposed. These matrices support comparative monitoring; none should be treated as a standalone diagnostic test of compromised welfare.