A Deleterious Gene Mutation and the Downregulated Expression of the Glucose Transporter System (Glut) In the Gut is Associated with Poor Growth in Broiler Chickens

Understanding the mechanisms underpinning individual variation in growth is an important question to address uniformity and overall performance in broiler chickens. The robust association between feed intake and growth has been well established, and energy is one of the main drivers of feed intake (Roura and Navarro, 2018). However, the specific differences in feed intake mechanisms between slow- and fast-growing chickens remain poorly understood. The universal energy source in cell metabolism is glucose.

We hypothesized that broiler chickens with low compared to high feed intake and growth are less efficient in utilizing dietary glucose. A total of 580 day-old male chickens (Ross 308) were transferred to the Poultry Unit facilities of the University of Queensland (Gatton, Australia) and reared on floor pens. Chickens were provided with ad libitum water and standard feed commercial (Starter: 25.1% CP, 12.65MJ/kg; Grower: 21.6%CP, 13.2MJ/kg; Finisher: 19.29CP, 13.3MJ/kg). Performance parameters were measured weekly. After 3 weeks, all the birds were weighed, and the 48 heaviest and the 48 lightest were selected as fast-growing and slow-growing chickens, respectively. They were placed in individual cages to measure individual feed intake and body weight until week 6. At the end of week 6, we selected the six heaviest (3598g, FCR=1.81) and the six lightest birds (2828g, FCR=1.61) and tissues samples from the proventriculus and duodenum were collected. Transport and metabolism of glucose in the gut were compared between slow- and fast-growing chickens using transcriptomic (RNAseq), proteomic, and genomic analyses.

Results showed that the two biological pathways identified as ‘translocation of glucose transporter in membrane’ and ‘glycolysis’ were significantly (P< 0.05) downregulated in slowgrowing chickens. In addition, protein abundance of glucose transporter 2 (GLUT2), together with the gene expression of glucose transporters GLUT1 and GLUT10 were all downregulated in slow-growing chickens (P< 0.05). Furthermore, the SLC2A4RG, a transcription factor regulating the gene expression of glucose transporters (Oshel et al., 2000), carried a deleterious mutation only in slow-growing chickens. In conclusion, a deficiency in the cellular glucose uptake system and metabolism in proventriculus and duodenum may partially explain poor growth rate in broiler chickens.

ACKNOWLEDGEMENTS: This project was partially funded by AgriFutures Australia.