AUTHOR=Li Jiaming , Yan Liwen , Cao Xuehai , Luo Yueming , Peng Xintong , Wang Zirui , Zou Tiande , Chen Jun , You Jinming TITLE=Effects of rare earth as feed additive on production performance, egg quality, serum biochemical parameters, antioxidant capacity, intestinal morphology, and gut microbiota in late-phase laying hens JOURNAL=Frontiers in Sustainable Food Systems VOLUME=7 YEAR=2023 URL=https://www.frontiersin.org/journals/sustainable-food-systems/articles/10.3389/fsufs.2023.1155543 DOI=10.3389/fsufs.2023.1155543 ISSN=2571-581X ABSTRACT=

This study aimed to investigate the effects of dietary rare earth (RE) supplementation on production performance, egg quality, serum biochemical parameters, antioxidant capacity, intestinal morphology, and gut microbiota in late-phase laying hens. A total of 960 Lohmann Pink laying hens (380 d old) were randomly assigned to 1 of 5 dietary treatments in a 21-day feeding trial. There were 6 replicates in each treatment, with 32 hens per replicate. The five experimental diets were supplemented with 0, 150, 300, 450, and 600 g/t RE in the basal diet. Compared with the control group, hens fed the 150 g/t RE diet had a greater average egg weight during the third week of the experimental period (p < 0.05). However, dietary 150, 300, or 600 g/t RE supplementation decreased the eggshell thickness of laying hens compared to that of the control group (p < 0.05). No differences were observed in the serum biochemical parameters of laying hens among treatments except for the HDL-C concentration, which was higher in the 300 or 450 g/t RE-supplemented group than in the control group (p < 0.05). However, GSH-Px activity increased when hens were fed the 600 vs. 0 g/t RE diet (p < 0.05). But dietary supplementation with 600 g/t RE increased the ileum’s crypt depth in laying hens compared to the control group (p < 0.05). There were significant differences in beta diversity of cecum microbiota in laying hens fed a 600 g/t RE diet in place of the other 4 experimental diets (p < 0.05). Compared with the control diet, dietary 600 g/t RE supplementation significantly decreased the relative abundance of Fusobacteriota (phylum) and Fusobacterium (genus) while markedly increasing the relative abundance of Ruminococcus (genus) and Subdoligranulum (genus) (p < 0.05). A high RE dosage negatively affects egg quality and intestinal morphology and alters gut microbiota diversity and composition. In contrast, a moderate RE dosage has beneficial effects on production performance in late-phase laying hens. Further research is warranted regarding eggshell thickness to investigate whether dietary calcium levels must be adjusted when 150 g/t RE is supplemented for late-phase laying hens.