Effect of dietary Dendrobium nobile Lindl. On production performance, immune function and caecal microbiota of Chishui black-bone hens.

The objective of this study was to investigate the effects of dietary supplementation of Dendrobium nobile Lindl. (DNL) on production performance, immune function, and caecal microbiota of Chishui black-bone hens. A total of one hundred and eighty 600-day-old Chishui black-bone hens were randomly allocated to two experimental groups, with six replicates of 15 chickens per group. The control group was fed a basal diet, and the experimental group was supplemented with 2100 mg/kg DNL in the basal diet. The results demonstrated that compared with the control group, the addition of 2100 mg/kg DNL to the diet significantly (P < 0.05) increased the average egg production rate of Chishui black-bone hens from 38.97 to 44.95%. Interferon-gamma (IFN-γ) levels were significantly lower in the experimental group than in the control group, whereas serum immunoglobulin A (IgA) levels were significantly higher (P < 0.05). However, adding DNL exerted no significant effect on egg quality. Asp, Ser, Gly, Leu, Phe, His, Pro, TAA, EAA, and NEAA levels in the eggs of the experimental group were significantly higher (P < 0.05) than in those in the control group. Additionally, the EAA/TAA in the control and experimental groups were 40.38% and 40.76%, respectively, and the EAA/NEAA was 76.62% and 74.72%, both of which were higher than the 40% and 60% thresholds specified in the WHO/HAO ideal protein guidelines. The results also indicated that eggs in the experimental group had significantly higher contents of palmitic acid (C16:0), stearic acid (C18:0), palmitic acid (C16:1), oleic acid (C18:ln9c), behenolic acid (C22:0), palmitic acid (C16:), oleic acid (C18:ln9c), saturated fatty acids (SFA), and monounsaturated fatty acids (MUFA) (P < 0.05). In contrast, the contents of hexadecenoic acid (C15:0), heptadecanoic acid (C17:0), α-linolenic acid (C18:3n3), arachidonic acid (C20:0), C10 heptadecanoic acid (C17:1), linoleic acid (C18:2n6c), α-linolenic acid (C18:3n3), eicosapentaenoic acid (C20:2), Docosapentaenoic Acid (DPA), polyunsaturated fatty acid (PUFA), and n-6PUFA were significantly reduced (P < 0.05). Moreover, when 2100 mg/kg DNL was added to the diet of Chishui black-bone hens, the composition of the intestinal flora was altered. Specifically, the relative abundances of Bacteroides, Lactobacillus, Subdoligranulum, and Parabacteroides increased, whereas those of Desulfovibrio, Lachnoclostridium, Ruminococcaceae, Fournierella, Faecalibacterium, and Oribacterium decreased. In conclusion, adding 2100 mg/kg DNL to the feed can increase serum IgA and reduce IFN-γ content in Chishui black-bone hens during the late laying period. Furthermore, it can enhance the laying rate and types of amino acids in eggs, as well as the ratio of ideal proteins. Simultaneously, it improved the caecal microbial community of Chishui black-bone hens and increased the relative abundance of beneficial bacteria.