Meta-analysis of laying hen performance and egg quality characteristics in response to Spirulina supplementation

Because of its essential and beneficial nutritional content, the utilization of Spirulina in the layer chicken diet has
received more attention nowadays. The meta-analysis in this study aimed to ascertain the efficacy of dietary Spirulina on feed intake (FI), feed conversion ratio (FCR), laying rate (LR), and egg quality in laying hens, including egg weight, eggshell thickness, yolk weight, yolk colour, haugh unit, and yolk cholesterol concentration. The analysis drew upon nineteen publications identified across PubMed, Scopus, and Google Scholar databases, collectively utilizing the varied search mechanisms therein. The data from these 19 trials underwent analysis using random-effects models within the OpenMEE software. The standardized mean difference (SMD) with its accompanying 95% confidence interval was unveiled as the result. The findings revealed a significant improvement in FCR (SMD = -2.233; p<0.001), LR (SMD=2.290; p<0.001), egg weight (SMD=1.551; p<0.001), eggshell thickness (SMD=1.223; p<0.001), yolk colour (SMD=10.659; p<0.001), haugh unit (SMD=2.189; p<0.001), and a reduction in yolk cholesterol concentration (SMD=-0.964; p<0.001). The results for FI (SMD=0.776; p=0.074) and yolk weight (SMD=0.367; p=0.075) were compared to the control group (dosage 0% in reference studies). The meta-analysis unveiled considerable variation among the included papers, indicating high heterogeneity. The meta-regression uncovered that the factors scrutinized in the research—namely, a hen's age, inclusion level, and duration of treatment—greatly impacted the divergences observed in this meta-analysis and substantially accounted for its outcomes. The current meta-analysis concluded that dietary supplementation of Spirulina in laying hens could improve the performance and egg quality characteristics.