Background: For laying hens in the late stage of peak production, dysregulated liver lipids are one of the leading causes of declining egg production. Glucuronolactone (D-Glu) is used as a functional beverage additive in human food products and has been reported to play a role in lipid metabolism. However, its use with laying hens is rarely reported. This study integrated in vitro avian hepatocyte culture (LMH) models and in vivo laying hen trials to investigate the regulatory effects of D-Glu on hepatic lipid deposition.
Results: D-Glu significantly reduced intracellular lipid deposition in hepatocytes both in vivo and in vitro models, while also improving the production performance of laying hens. Liver lipidomic profiling revealed that D-Glu supplementation increased hepatic phospholipid abundance and reduced triglyceride (TG) accumulation, particularly by decreasing TG species enriched with polyunsaturated fatty acid (PUFA). This reduction in hepatic lipids is achieved by downregulating genes associated with fatty acid (FA) synthesis (FASN, ACSL, and PPAR-γ) and transport (FABP1 and CD36) pathways in the liver. Notably, D-Glu administration modulated the relative abundance of specific bacteria, particularly Bacteroides, CHKCI001, and Angelakisella, during hepatic lipid reduction mediation. Furthermore, D-Glu modified the composition of FA in the yolk, increasing the deposition of PUFA. Correlation analyses strongly supported the involvement of the enterohepatic axis in the lipid-lowering mechanism of D-Glu.
Conclusion: D-Glu mediates lipid redistribution via the enterohepatic axis, effectively reducing hepatic lipid deposition while promoting the deposition of PUFA in egg yolk, ultimately alleviating the decline in production performance during the late peak laying period.
The early life gut microbial colonization in pre-weaning calves plays a pivotal role in shaping their health, growth, and productivity. This review delves into the dynamic changes of intestinal microbiota during early life, emphasizing key factors such as colostrum management, feeding strategies, roughage supplementation, and microbial interventions including probiotics, prebiotics, and fecal microbiota transplantation (FMT), and non-nutritional stressors that can shape the early life microbial colonization. We highlight the microbiota's critical functions in nutrient metabolism, immune development, gut barrier integrity, and gut-brain axis regulation. Additionally, the consequences of microbial dysbiosis on calf health and its long-term effects on production performance in beef and dairy cattle are discussed. While current research has provided valuable insights, understanding causal mechanisms remains a challenge. This review aims to guide practical strategies for targeted microbial management, offering a pathway to optimize early-life interventions for improved calf health and productivity.

