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Phytogenic feed additives have been gaining considerable interest due to their ability to improve gut health and thereby performance of broiler chickens. The impact of Glycyrrhiza glabra (licorice) extract (GE) on expression of genes coding for tight junction proteins and gut protection and Campylobacter jejuni colonization in broilers has not been discussed until now. Thus, the current study assessed the effective dose of GE for maximum growth in broiler chickens, clear-cut molecular mechanisms related to integrity and health of intestine, and controlling C. jejuni colonization. Over a 35-day feeding period, a total of 500 Ross broiler chicks were allocated to five groups; the first group was fed a control diet without GE and the second group to the fifth group were fed a control diet with GE (0.25, 0.5, 1, and 2 g/kg of diet); each group comprised 100 chicks with 10 replicates (10 birds/replicate). Birds fed GE had an improved body weight gain and feed conversion ratio. Furthermore, the highest body weight gain was observed in the group that received 1 g/kg of GE (P < 0.05). The expression of genes coding for tight junction proteins [occludin and junctional adhesion molecules (JAM)] was upregulated in all groups supplemented with GE. Moreover, birds fed 1 g/kg of GE exhibited the maximum gene expression of occludin and JAM [0.2 and 0.3 fold change, respectively (P < 0.05)]. In relation to enterocyte protective genes [glucagon-like peptide (GLP-2) and fatty acid-binding protein (FABP-6)], use of GE significantly upregulated expression of GLP-2 gene with 0.8 fold change in 2 g/kg of the GE supplemented group (P < 0.05) while the expression of FABP-6 gene was not affected by GE supplementation (P > 0.05). After challenge with C. jejuni, the expression of mucin (MUC-2) gene was upregulated and the inflammatory markers such as Toll-like receptors (TLR-4) and interleukin (IL-1β) were downregulated with increasing level of supplemented GE (P < 0.05). The mean log10 count of C. jejuni in cecal samples after 7 days post-infection by culture and real-time qPCR was decreased in groups fed GE in a dose-dependent manner (P < 0.05). In addition, the highest reduction of C. jejuni count in cecal samples by culture and real-time qPCR was observed in the group fed 2 g/kg of GE (2.58 and 2.28 log10 CFU/g, respectively). Results from this study suggested that G. glabra extract (1 g/kg) improved growth performance of broiler chickens, as well as influenced the maintenance of intestinal integrity and reduced C. jejuni shedding from infected birds.

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Fish meal (FM) is a significant source of protein, but the high cost has limited its use in feeds. Hence, alternative, economic and available FM substitutes should be found. In this study, the consequences of replacing FM with rice protein concentrate (RPC) on the growth parameters, proximate body composition, digestive and absorptive capabilities, biochemical parameters and the expression of appetite‐related gene (ghrelin) in Nile tilapia, Oreochromis niloticus, were investigated. Fish (27.8 ± 0.1 g) were randomly organized into four groups and fed on experimental diets having four replacement percentages of FM with RPC: 0%, 25%, 50% and 75% (RPC0, RPC25, RPC50 and RPC75) for 5 months. The results cleared that RPC25 group exhibited linearly and quadratically the highest values for growth parameters, growth hormone level, and activities of protease, amylase as well as proximal intestinal villus length, width, the goblet cells count and ghrelin gene expression among all groups. From overall results, RPC could be used as an economically and beneficial ingredient to replace up to 25% of dietary FM in Nile tilapia diet with enhancing the growth performance, digestive and absorptive capability, and health status, but with the supplementation of synthetic amino acids.

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Blood samples were obtained from 28 mature healthy male Muscovy ducks for screening of a partial sequence of Growth hormone gene (GH gene) for single nucleotide polymorphisms using PCR amplification of the extracted DNA. The results of our research revealed one locus of exon 2 of growth hormone gene and its partial flanking intron. Polymorphisms in this locus were investigated by using direct sequencing and single strand conformational polymorphism (SSCP) technique. One unique pattern of SSCP was detected. Nucleotide sequencing was performed to endorse the current result which proved the absence of single nucleotides' polymorphisms (SNPs) or any other type of polymorphisms in the studied locus. The DNA sequencing and PCR-SSCP patterns confirmed that there was no polymorphism in all studied birds. In turn, it is spelled that PCR-SSCP failed to produce electrophoresis patterns capable of discriminating between the GH gene loci in Muscovy duck breed revealing no polymorphism in all studied individuals. Also, we compared our sequences with the published sequence on the gene bank of GH gene in Mallard ducks under the following accession number AB158762.1. Three SNPs were detected between Muscovy and Mallard breeds which are (94 A-G, 271 C-T and 298 G-A) these SNPs led to change of two amino acids proline and valine amino acids in GH protein in mallard ducks into serine and isoleucine in Muscovy ducks. In conclusion, these changes in the nucleotide sequence, amino acid and protein chain may be the main cause of differences of the phenotypic features, productive and reproductive traits between Muscovy and mallard duck breeds.