H-FABP gene expression and genetic association with meat quality traits in domestic pigeons (Columba livia)

The Identification of Functional Genes Affecting Fat-Related Meat Traits in Meat-Type Pigeons Using Double-Digest Restriction-Associated DNA Sequencing and Molecular Docking Analysis

The Chinese indigenous Shiqi (SQ) pigeon and the imported White King (WK) pigeon are two meat-type pigeon breeds of economical and nutritional importance in China. They displayed significant differences in such meat quality traits as intramuscular fat (IMF) content and fatty acid (FA) compositions in the breast muscles. In this study, we aimed to screen candidate genes that could affect fat-related meat quality traits in meat-type pigeons. We investigated the polymorphic variations at the genomic level using double-digest restriction-associated DNA (ddRAD) sequencing in 12 squabs of SQ and WK pigeons that exhibited significant inter-breed differences in IMF content as well as FA and amino acid compositions in the breast muscles, and screened candidate genes influencing fat-related traits in squabs through gene ontology analysis and pathway analysis. By focusing on 6019 SNPs, which were located in genes with correct annotations and had the potential to induce changes in the encoded proteins, we identified 19 genes (ACAA1, ACAA2, ACACB, ACADS, ACAT1, ACOX3, ACSBG1, ACSBG2, ACSL1, ACSL4, ELOVL6, FADS1, FADS2, HACD4, HADH, HADHA, HADHB, MECR, OXSM) as candidate genes that could affect fat-related traits in squabs. They were significantly enriched in the pathways of FA metabolism, degradation, and biosynthesis (p < 0.05). Results from molecular docking analysis further revealed that three non-synonymous amino acid alterations, ACAA1(S357N), ACAA2(T234I), and ACACB(H1418N), could alter the non-bonding interactions between the enzymatic proteins and their substrates. Since ACAA1, ACAA2, and ACACB encode rate-limiting enzymes in FA synthesis and degradation, alterations in the enzyme-substrate binding affinity may subsequently affect the catalytic efficiency of enzymes. We suggested that SNPs in these three genes were worthy of further investigation into their roles in explaining the disparities in fat-related traits in squabs.

Dietary Supplementation of Chitosan Oligosaccharide–Clostridium butyricum Synbiotic Relieved Early-Weaned Stress by Improving Intestinal Health on Pigeon Squabs (Columba livia)

According to a previous study, we had found that early weaning causes harm to growth performance, intestinal morphology, activity of digestive enzymes, and antioxidant status in pigeon squabs (Columba livia). Chitosan oligosaccharides (COS) and Clostridium butyricum have been reported to have great potential to improve the growth performance and intestinal health of early-weaned animals. Therefore, the aim of this study is to explore whether dietary supplementation with COS-C. butyricum synbiotic could relieve early-weaned stress by evaluating its effects on growth performance and intestinal health in pigeon squabs. A total of 160 squabs (weaned at 7 days of age) were randomly divided into 5 groups: the control group, fed with artificial crop milk; the COS supplementation group, fed with artificial crop milk + 150 mg/kg COS; and three synbiotic supplementation groups, fed with artificial crop milk + 150 mg/kg COS + 200, 300, and 400 mg/kg C. butyricum. The results showed that a diet supplemented with COS-C. butyricum synbiotic benefitted the growth performance of early-weaned squabs; even so the differences were not significant among the five groups (p > 0.05). In addition, dietary supplementation of 150 mg/kg COS + 300~400 mg/kg C. butyricum significantly improved the intestinal morphology (especially villus surface area and the ratio of villus height to crypt depth), the activity of digestive enzymes (lipase, trypsin, and leucine aminopeptidase) in duodenum contents, and the production of total short-chain fatty acids and acetic acid in ileum content (p < 0.05). Additionally, dietary supplementation of 150 mg/kg COS + 400 mg/kg C. butyricum benefitted gut health by improving the antioxidant capacity (glutathione peroxidase and total antioxidant capacity) and cytokine status (IL-4 and IL-10) (p < 0.05), as well as by improving the intestinal microbiota diversity. In conclusion, our results revealed that dietary supplementation with synbiotic (150 mg/kg COS + 300~400 mg/kg C. butyricum) could relieve early-weaned stress by maintaining intestinal health in pigeon squabs.

Effects of early weaning on intestinal morphology, digestive enzyme activity, antioxidant status, and cytokine status in domestic pigeon squabs (Columba livia)

The aim of this study was to explore the effects of early weaning on growth performance, intestinal morphology, digestive enzyme activity, antioxidant status, and cytokine status in domestic pigeon squabs (Columba livia). The conclusion is based on body weight (BW) and average daily gain (ADG), length index and weight index of small intestine, small intestinal morphology, activity of digestive enzymes in duodenum content, the concentrations of jejunal antioxidant status and cytokines. A completely randomized design with 2 treatments, the control group (CON) and early weaning (EW) group, was utilized. Eight squabs per treatment were sampled at the age of 25 d. The results showed that early weaning reduced BW (P < 0.05), ADG (P < 0.05), ileac length index (P < 0.05), and weight index (P < 0.01). Compared with the CON group, small intestinal morphology was altered in the EW group. Ileac crypt depth (CD) increased significantly (P < 0.01). The villus area was decreased in the duodenum (P < 0.05), jejunum (P < 0.01), and ileum (P < 0.05). The ileac ratio of villus height to crypt depth (VCR) in the EW group was lower than the ileac ratio of villus height to VCR in the CON group (P < 0.01). The activity of trypsin (P < 0.05), sucrase (P < 0.01) and aminopeptidase-N (APN) (P < 0.01) in the duodenum was reduced. Jejunal malondialdehyde (MDA) (P < 0.01) was increased and total superoxide dismutase (T-SOD) (P < 0.01) was reduced significantly. Early weaning decreased the concentrations of interferon-γ (IFN-γ) (P < 0.01), interleukin-4 (IL-4) (P < 0.05) and interleukin-10 (IL-10) (P < 0.01) but induced significant upregulation of interleukin-2 (IL-2) (P < 0.05). In conclusion, our results suggested that early weaning did harm the BW and ADG, intestinal length index and weight index, intestinal morphology, activity of digestive enzymes, and antioxidant and cytokine status.