Effect of guanidinoacetic acid on the growth performance, serum biochemical indices and metabolites, intestinal morphology, and intestinal flora of Cherry Valley broiler ducks

Guanidinoacetic acid (GAA) is a direct precursor for creatine synthesis in animals. Because of its great biological value and chemical stability, it can be used as a feed ingredient. The aim of this study was to investigate the effects of GAA on the growth performance, serum biochemical indices and metabolites, intestinal morphology, and intestinal flora of Cherry Valley broiler ducks. The growth performance of broiler ducks in the treatment group was significantly higher than that in the control group. Alanine aminotransferase and total protein were significantly lower in the treatment group than in the control group, while high-density lipoprotein and immunoglobulin A were significantly higher in the treatment group than in the control group. The gut microbial community richness was higher in the treatment group. There were 149 metabolites found in all. The most important pathways through which GAA influences the serum of broiler ducks are fatty acid degradation, Cushing syndrome, fat digestion and absorption, cortisol synthesis and secretion, lipid accumulation and atherosclerosis, alpha-linolenic acid metabolism, and the folate biosynthesis metabolic pathway, according to an enrichment analysis of metabolic pathways. Spearman's correlation analysis showed that microorganisms were closely associated with metabolites. In summary, adding GAA to the diet of Cherry Valley broiler ducks can enhance their growth performance, improve intestinal villi formation, improve digestion and absorption, boost immunoglobulin secretion, and improve immune function. It also optimises lipid metabolism and reduces the burden on the liver, promoting efficient energy utilisation and anti-inflammatory and antioxidant properties. Additionally, GAA alters the blood metabolites and cecal flora of Cherry Valley broiler ducks.