Animal Bioscience最新文献

Objective: Chicken embryos are typically incubated in complete darkness, overlooking the potential influence of rhythmic light exposure. This study aimed to investigate the effects of a 12-hour light/12-hour dark rhythmic light environment on liver development and lipid metabolism in chicken embryos, providing a foundation for regulating poultry physiology through light manipulation.

Methods: Fertile eggs were incubated under two lighting conditions: a 12 h light/12 h dark cycle (LD group) and constant darkness (DD group). Embryos or chicks were sampled at embryonic days 12 (E12), 14 (E14), 16 (E16), 18 (E18), 20 (E20), and day 1 post-hatch (D1). Body weight, liver weight, and residual yolk weight were recorded. Liver morphology and lipid accumulation were evaluated using H&E and Oil Red O staining. Hepatic levels of triglycerides (TG), total cholesterol (TC), free fatty acids, fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC) were measured. Expression of lipid metabolism-related genes was assessed by real-time quantitative polymerase chain reaction.

Results: Embryo weight, liver weight, liver index, and residual yolk weight did not differ significantly between groups. However, liver tissues in the LD group exhibited earlier maturation of liver plate structures and increased lipid droplet accumulation. TG concentration was significantly higher at E12 and D1, TC at E12 and E18, and ACC at E12, E16, and E18 in the LD group (p<0.05). Furthermore, lipid synthesis genes (ACC, FAS, SCD1, SREBP-1c, ELOVL6) were upregulated, while lipid degradation genes (CPT1, PPARα, MTTP) were downregulated at specific embryonic stages in the LD group (p<0.05).

Conclusion: Rhythmic light exposure under a 12 h light/12 h dark cycle promoted liver development and lipid accumulation by modulating expression of lipid metabolism genes such as ACC, FAS, and CPT1. These findings highlight the potential of light rhythm as a strategy to optimize embryonic development and lipid metabolism in poultry.

Objective: Dose-response curves were performed to explore the effect of eucalyptus essential oil nanoemulsion (EEONE) on the growth rate, feed efficiency, and health status of growing rabbits facing heat stress.

Methods: Sixty growing rabbits (6 weeks old), were randomly divided into four homogeneous groups, receiving diets supplements with 0, 100, 200, and 400 mg EEONE/kg diet (EEONE0, EEONE100, EEONE200, and EEONE400, respectively).

Results: Significant improvements were observed in growth performance, feed utilization, and physiological responses in the EEONE-treated groups compared to the control (p<0.05). Regression analysis revealed quadratic increases in red blood corpuscles and quadratic decreases in white blood cell counts in response to EEONE treatment, with optimal concentrations showed at 325 and 300 mg EEONE, respectively. Hemoglobin concentration, platelet count, blood protein and glucose levels linearly increased, while liver enzymes decreased significantly due to the EEONE treatment. The aberrant changes observed in liver tissues due to heat stress were effectively reversed, leading to a restoration of hepatic morphology closely resembling normal conditions, by co-administration of EEONE. Serum urea and creatinine concentrations decreased quadratically in the EEONE-treated groups, minimizing at 300 mg EEONE. Quadratic regression analysis indicated that the optimal doses were 300 mg EEONE for glutathione peroxidase and protein carbonyl, and 350 mg EEONE for total antioxidant capacity and malondialdehyde. Cellular and humoral immunity as well as pro inflammatory cytokinase significantly improved by the dietary treatment.

Conclusion: Supplementing the diet with EEONE at levels of 300-400 mg can effectively improve growth metrics and health status of fattened rabbits.

Objective: The objective of this study was to evaluate the effects of inactive (heat-killed) Clostridium butyricum (ICB) on gas production kinetics, fermentation parameters, and microbiota with varying media pH levels in batch culture.

Methods: The in vitro experiment was designed as a completely randomized factorial arrangement, with 2 media pH levels (5.8 and 6.5)×2 Clostridium butyricum (CB) products (active and inactive)×4 dosages of CB. Two lactating dairy cows with ruminal fistulas, fed a diet comprising 40% forage and 60% concentrate, served as donors for rumen inoculum. Following 24 h of incubation, the gas production, dry matter disappearance (DMD), volatile fatty acid (VFA), ammonia nitrogen (NH3-N) and microbial profile were measured to determine the effect of treatment on fermentation.

Results: The gas volume (GV), DMD, total VFA concentration, NH3-N concentration, acetate concentration and microbial alpha diversity were inhibited when the media pH decreased from 6.5 to 5.8. Increasing the supplemental doses of ICB linearly increased the GV, DMD (trend) and butyrate proportion at media pH 6.5. Moreover, the increasing supplemental dose of active Clostridium butyricum (ACB) linearly increased GV, butyrate proportion and NH3-N concentration (trend) regardless of media pH, and linearly increased DMD, total VFA concentration and A:P ratio at media pH 6.5. Supplementing ICB decreased the relative abundance of Actinobacteria and Butyrivibrio in the fermentation fluid.

Conclusion: Increasing media pH promotes rumen fermentation and alter bacterial community. Although both ACB and ICB have the potential to stimulate rumen fermentation in a dose-dependent manner, their effects change depending on media pH levels. Furthermore, both ACB and ICB rarely altered the rumen bacterial community.

Objective: This study explored the effects of different dietary crude protein (CP) levels on the cecal transcriptome and microbial composition in weaning pigs.

Methods: Ninety-six weaning pigs were randomly assigned into three groups designated as H, M, and L groups. The H, M, and L groups were administered 20% and 18%, 18% and 16%, and 16% and 14% CP during the early (1-14 days) and late phases (15-28 days), respectively.

Results: The final body weight and average daily gain in the L group were significantly lower than those in the other groups (p = 0.008). The feed conversion ratio was lower in the H and M groups than in the L group (p = 0.01). Cecal transcriptome analysis revealed that heatmap and principal component analysis of differentially expressed genes indicated the presence of distinct clusters among the groups. Genes associated with cell proliferation and differentiation and inflammation were down-regulated in the M and L groups, compared with corresponding genes in the H group (p<0.001). Pathway enrichment analysis suggested that genes related to IL-17 signaling pathway was down-regulated in the M and L groups (p<0.05). Beta diversity analysis and heatmap for microbial composition and function indicated the presence of distinct clusters among the groups. Carbohydrate-fermenting bacteria, such as Megasphaera elsdenii DSM 20460 and Blautia luti DSM 14534, exhibited higher levels in the M and L groups compared with the H group (p≤0.05). The abundance of Lactobacillus amylovorus DSM 20531 was significantly greater in the M group than in the other groups (p≤0.05). The abundance of L. amylovorus DSM 20531 was positively correlated with growth performance. Integrated multi-omics analysis suggested significant similarities between the cecal transcriptome and microbiota (p<0.01).

Conclusion: Reducing CP levels modulates cell growth and alleviates inflammation in the cecum. A low CP diet causes cecal microbiota composition shift and promotes the proliferation of carbohydrate-fermenting bacteria. Overall, 18% CP in an early phase and 16% CP in a late phase can substantially improve growth and gut health in weaning pigs.

Objective: This study aimed to compare the effects of natural palygorskite (Nat-Pal) and crystal bundles disaggregated palygorskite (Dis-Pal) supplementation on the growth performance, intestinal health, and digestive function of young broilers.

Methods: A total of 400 male Arbor Acres broilers (one-day-old) were randomly assigned to five experimental groups with eight replicates over a 14-day experimental period. Chicks were fed a basal diet (Control group), the basal diet supplemented with 10 g/kg Nat-Pal or 2.5, 5, and 10 g/kg Dis-Pal, respectively.

Results: Dis-Pal linearly increased average body weight and average daily gain, and decreased feed-to-gain ratio of broilers from days 1 to 14, with the 5-10 g/kg Dis-Pal showing the most pronounced effects (p<0.05). An addition of Dis-Pal linearly increased glucose level, and decreased triglyceride level in serum (p<0.05). Compared to the control group, 5 g/kg Dis-Pal increased the digestibility of crude protein and dry matter, enhanced trypsin, lipase, and amylase activities in jejunal digesta, and elevated the ratio between villus height and crypt depth in jejunum and ileum (p<0.05). Dis-Pal linearly increased ileal mucosal glutathione and total antioxidant capacity levels, as well as total superoxide dismutase and catalase activities, with 10 g/kg Dis-Pal addition showing the best effects (p<0.05). The 2.5-10 g/kg Dis-Pal decreased the interferon-γ and tumor necrosis factor-α levels in ileal mucosa compared to the control group (p<0.05). Moreover, Dis-Pal supplementation linearly increased interleukin-10, secretory immunoglobulin A, and immunoglobulin M levels, and decreased the interferon-γ level, quadratically increased total superoxide dismutase and catalase activities in jejunal mucosa (p<0.05).

Conclusion: Dietary Dis-Pal supplementation could improve growth performance, intestinal health, and enhance the nutrient digestibility of young broilers. Supplementation with Dis-Pal was more advantageous for broilers than with Nat-Pal, and its optimal dosage was 5 g/kg.

Objective: Germ cell identity is regulated by the coordinated action of multiple key transcription factors during embryonic development, which includes the induction and control of germ-line-specific gene expression. The expression of DEAD-box helicase 4 (DDX4) and deleted in azoospermia-like (DAZL) genes in chickens plays a pivotal role in germplasm formation and the specification of germ cell lineage from a totipotent genome. This study aimed to investigate the regulatory mechanisms underlying germ cell fate determination.

Methods: Large-scale gene expression profiling was conducted to screen and select critical transcription factors. This analysis identified differentially expressed genes in chicken primordial germ cells (PGCs), comprising 1,020 transcription factors. Additionally, we generated a chicken DF1 cell line featuring an enhanced green fluorescent protein (eGFP) reporter precisely knocked into the transcriptional start site of the DAZL gene using the CRISPR-Cas9 system, enabling real-time monitoring of DAZL expression during reprogramming.

Results: Through analysis of transcription factor binding sites within approximately 10 kb upstream regions of DDX4 and DAZL, resulting in the selection of 10 candidate transcription factors for germ cell induction. Subsequently, the ten transcription factors identified as regulators of germ cell identity were transduced into the DAZL-knock-in eGFP DF1 cells. This approach led to the successful induction of eGFP-expressing cells in vitro, driven by the endogenous DAZL promoter. We conducted further characterization of these cells to confirm their germ cell-specific properties.

Conclusion: Our findings offer new insights into the transcriptional regulation of chicken germ cells by identifying key factors that activate DAZL expression. These results indicated valuable opportunities for advancing germ cell induction from somatic cells, with potential applications of in vitro models for studying germ cell-specific gene regulatory pathways in avian species.

Objective: The ovary, as an important reproductive organ, tightly regulates the litter size of rabbits through its complex network of genes. This study aims to identify candidate genes related to litter size in rabbits through RNA sequencing and to analyze the regulatory effects of C-X-C motif chemokine ligand 12 (CXCL12) on granulosa cells (GCs).

Methods: This study used ovarian transcriptome sequencing to identify differentially expressed genes between the ovarian tissues of New Zealand female rabbits with high (H) and low (L) litter sizes. In addition, a new candidate gene which was highly expressed in group H, namely the chemokine ligand CXCL12, was selected for further verification of biological functions.

Results: The cell counting kit-8 assay and flow cytometry analysis showed that CXCL12 can promote GCs proliferation but inhibit their apoptosis. Furthermore, quantitative reverse transcription polymerase chain reaction and western blotting indicated that CRABP1 regulated genes (PCNA, CCND1, CDK2, Bcl-2 and Bax) and proteins (CCND1, PCNA, Bcl-2 and Bax) related to cell cycle and cell proliferation. In addition, it can also regulate the expression levels of genes (TAF4B, CITED1, WNT2, WNT10B, and HSD17B1) and proteins (CITED1 and WNT10B) related to follicle development and litter size. Finally, it was found that CXCL12 targeted the CXCR4 receptor to activate the JAK/STAT signaling pathway.

Conclusion: We utilized bioinformatics to screen 184 genes potentially associated with litter size in New Zealand female rabbits. Among these, CXCL12 plays a role in regulating the expression of cell cycle-related genes, promoting GCs proliferation. As a result, CXCL12 emerges as a promising candidate marker for selecting high litter size female rabbits in future breeding and production practices.

Objective: The aim of this experiment was to integrate production indices with omics sequencing to elucidate the systemic perturbations between hepatic metabolism and the gut microbiota during overfeeding.

Methods: A total of 120 seven-week-old male Landes geese were floor-reared in a pen environment. Overfeeding commenced at week 8 using a corn-based diet containing 5% soybean oil. The feeding regimen consisted of three daily meals (150-180 g/meal) initially, gradually increasing to five meals (300-500 g/meal) after two weeks, and was maintained for a total overfeeding period of four weeks.

Results: The results demonstrated that overfeeding significantly increased liver weight and serum lipid levels, accompanied by intracellular lipid droplet accumulation. Concurrently, the downregulation of taurine-conjugated bile acids and the upregulation of free bile acids disrupted cholesterol homeostasis. Crucially, overfeeding triggered gut microbial dysbiosis characterized by Escherichia-Shigella enrichment and norank_o_Clostridia_UCG-014 depletion.

Conclusion: Our work demonstrated that the identification of the "gut microbiota‒bile acid‒liver axis" could serve as a pivotal signaling pathway driving overfeeding-induced foie gras formation while providing a theoretical foundation for overfeeding strategies to mitigate metabolic pathologies in waterfowl production.

Objective: Body conformation traits directly impact carcass performance in the meat goat industry. This study explored the population genetics of two Chinese goat breeds and identified the genomic variants associated with their body conformation traits.

Methods: The Guizhou black goat (GBG, n = 104) and Hezhang black goat (HBG, n = 100) underwent genotyping through whole-genome sequencing and phenotyping by measuring their body height (BH), body length (BL), chest depth (CD), chest width (CW), chest girth (CG), rump width (RW), rump height (RH), and cannon circumference (CC).

Results: The relatedness analysis showed that these goats exhibited low genetic kinship-related, with the GBG and HBG being relatively independent, albeit with some genetic introgression present. The lambda values showed that the reliability of the genome-wide association studies (GWAS) model, identifying a total of 33, 1, 6, 2, 5, 10, 21, and 13 single nucleotide polymorphisms (SNPs) as significantly correlated (p<8.33e-8) with BH, BL, CD, CW, CG, RW, RH, and CC, respectively. The GWAS for BH and RH identified the greatest number of significant SNPs, with a substantial overlap among them, mainly located in four regions: chr13_63286230-69784740 (10 SNPs), chr14_60354209-60376549 (six SNPs), and chr15_65605417-73873841 (five SNPs), and chr23_42819635-43332716 (nine SNPs). Individuals with a greater number of these SNPs displayed elevated BH and RH values. Following the annotation of all significant SNPs, 102 genes within a ±100 Kb region were identified. The most significantly enriched KEGG pathway was "Olfactory transduction", while the most significantly enriched GO terms included "cellular process" and "molecular transducer activity".

Conclusion: This study investigated the population genetics of two prominent Chinese goat breeds and identified several SNPs that are significantly associated with body conformation traits. These findings offer biological insights into enhancing growth performance and hold significant potential for practical application in the genomic selection of meat goats.