Background Dietary essential oil (EO) supplementation can exert favorable effects on gut health in broilers. However, it is unknown whether EO could improve intestinal functions, consequently beneficial for egg performance and quality in late-phase laying hens. This study was aimed to investigate the potential effects of EO on production performance, egg quality, intestinal health and ileal microbiota of hens in the late phase of production. A total of 288 60-week-old Hy-line Brown laying hens were randomly divided into 4 groups and fed a basal diet (control) or basal diets supplemented with oregano EO at 100, 200 and 400 mg/kg (EO100, EO200 and EO400). Results Dietary EO supplementation resulted in a quadratic decrease (P < 0.05) in feed conversion ratio with lower (P < 0.05) feed conversion ratio in EO200 group than the control during weeks 9–12 and 1–12 of the trial. Compared to the control, EO addition resulted in higher (P < 0.05) eggshell thickness at the end of week. 4, 8 and 12 and higher (P < 0.05) chymotrypsin activity. There was a quadratic elevation (P < 0.05) in ileal chymotrypsin and lipase activity, along with a linear increase in villus height to crypt depth ratio. Quadratic declines (P < 0.05) in mRNA expression of IL-1β, TNF-α, IFN-γ and TLR-4, concurrent with a linear and quadratic increase (P < 0.05) in ZO-1 expression were identified in the ileum with EO addition. These favorable effects were maximized at medium dosage (200 mg/kg) of EO addition and intestinal microbial composition in the control and EO200 groups were assessed. Dietary EO addition increased (P < 0.05) the abundances of Burkholderiales, Actinobacteria, Bifidobacteriales, Enterococcaceae and Bacillaceae, whereas decreased Shigella abundance in the ileum. Conclusions Dietary EO addition could enhance digestive enzyme activity, improve gut morphology, epithelial barrier functions and modulate mucosal immune status by altering microbial composition, thus favoring feed efficiency and eggshell quality of late-phase laying hens.

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The objective of this study was to determine the effect of dietary lycopene supplementation on the growth performance, antioxidant enzyme activity of serum and liver, and gene expressions associated with Kelch-like ech-associated protein-1 (Keap1)/Nuclear Factor E2-related factor 2 (Nrf2) pathway in liver of Arbor Acres broilers. A total of 288 1-day-old male broilers were randomly divided into 4 treatments with 6 replicates and 12 chickens for each replicate. The control group was fed with the basal diet, while the treated groups were fed with the basal diet with 10, 20, and 30 mg/kg lycopene in powder. Feed and water were provided ad libitum for 42 days. Compared with the control group, (a) the average daily gain increased (p = 0.002 vs. p = 0.001) and the feed conversion ratio decreased (p = 0.017 vs. p = 0.023) in groups treated with lycopene in the grower and whole phases, and the average daily feed intake was quadratically affected (p = 0.043) by lycopene in the grower phase; (b) the serum superoxide dismutase content was linearly affected (p = 0.035) by lycopene at 21 days; (c) the serum glutathione peroxidase content, superoxide dismutase content, and total antioxidant capability were higher (p = 0.014, p = 0.003, and p = 0.016, respectively) in the 30 mg/kg lycopene group at 42 days; (d) the liver glutathione peroxidase and superoxide dismutase contents in groups treated with lycopene were higher (p ≤ 0.001 vs. p ≤ 0.001) at 21 days; (e) the liver glutathione peroxidase content was higher (p ≤ 0.001) in the 20 and 30 mg/kg lycopene groups, at 42 days; (f) the mRNA expression levels of Nrf2, superoxide dismutase 2, NAD(P)H quinone dehydrogenase 1, and heme oxygenase 1 genes were higher (21 days: p = 0.042, p = 0.021, p = 0.035, and p = 0.043, respectively; 42 days: p = 0.038, p = 0.025, p = 0.034, and p = 0.043, respectively) in the 20 and 30 mg/kg lycopene groups at 21 and 42 days. The 30 mg/kg lycopene concentration improved the growth performance, antioxidant enzyme activity in serum and liver, and gene expression in the Keap1-Nrf2 signaling pathway of Arbor Acres broilers.

Eggshell color is an important characteristic for poultry eggs. Eggs from aged hens usually have poor shell color that is unacceptable for the table egg market. The objective of this study was to examine effects of pigment synthesis and mitochondrial biogenesis on brown eggshell color of aged laying hens. In this trial, 8 hens laying eggs with darker shell color and 8 hens laying eggs with lighter shell color were selected from 300 62-week-old Hy-Line brown-egg laying hens. Results showed that egg weight ( P < 0.05), eggshell weight ( P < 0.01), protoporphyrin IX ( Pp IX ) content of the eggshell and the shell gland ( P < 0.001), and biliverdin content of the shell gland ( P < 0.001) were significantly declined in the light-shell group compared with the dark-shell group. Relative mRNA expression of δ-aminolevulinic acid synthase1 ( ALAS1 ) ( P < 0.05), coproporphyrinogen oxidase ( P < 0.01), ATP-binding cassette transporter ABCG2 ( P < 0.01), and mitochondrial transcription factor A ( P < 0.05) was reduced in hens laying lighter brown eggshell. Moreover relative mRNA expression of mitochondrial DNA copy number ( P < 0.01), mitochondrial NADH dehydrogenase subunit 4 ( P < 0.05), mitochondrial ATP synthase F0 subunit 8 ( P < 0.05), and mitochondrial cytochrome c oxidase 1 ( P < 0.01) was significantly decreased in the shell gland of the light-shell group. In addition, NAD + contents of the shell gland were increased in the dark-shell group ( P < 0.01). Brown eggshell depigmentation is a result of decreased Pp IX content in the eggshell and the shell gland. Decreased mitochondrial biogenesis may contribute to the depigmentation of brown eggshell by targeting ALAS1 and ALAS1-mediated Pp IX biosynthesis.

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