Exploration of a novel indicator for duck egg quality (yolk weight-to-albumen height ratio): Its impact on egg quality and serum parameters, and correlation analysis

This study introduced a novel indicator of duck egg quality - the yolk weight to albumen height ratio (YAR) - and investigated its relationships with egg quality traits, serum biochemical indices, and antioxidant parameters. A total of 1,215 eggs were collected from 450 Shanma ducks (43 weeks old) over three consecutive days. Based on egg quality results, 60 ducks with the highest YAR (HYAR group) and 60 ducks with the lowest YAR (LYAR group) were selected for comparative analysis. Correlation analysis showed that YAR was positively correlate with YW (r = 0.61, P < 0.01) and negatively correlated with AH (r = -0.79, P < 0.01) and HU (r = -0.84, P < 0.01). The HYAR group displayed an altered serum metabolite profile, characterized by elevated total cholesterol (TC), triglycerides (TG), low density lipoprotein cholesterol (LDL-C), and malondialdehyde (MDA), along with reduced uric acid (UA), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), and catalase (CAT). Accordingly, YAR was positively correlated with TC (r = 0.27, P < 0.05), TG (r = 0.26, P < 0.05), LDL-C (r = 0.42, P < 0.01), and MDA (r = 0.65, P < 0.01), and negatively correlated with SOD (r = -0.32, P < 0.05), CAT (r = -0.32, P < 0.05), and T-AOC (r = -0.38, P < 0.01). In conclusion, YAR is a valuable comprehensive indicator for evaluating both internal egg quality and physiological status in laying ducks. However, breeding or feeding programs that excessively increase YAR may compromise metabolic health and long-term productivity, underscoring the need for an optimal balance between egg quality and animal welfare.