Effects of dietary octacosanol supplementation on laying performance, egg quality, serum hormone levels, and expression of genes related to the reproductive axis in laying hens

Theaflavin Reduces Oxidative Stress and Apoptosis in Oxidized Protein-Induced Granulosa Cells and Improves Production Performance in Laying Hens

This study aims to investigate the effects of theaflavins on production performance and egg quality in laying hens fed oxidized corn gluten meal while evaluating their antioxidant and anti-apoptotic effects on granulosa cells (GCs) from chicken follicles. In total, 600 Lohmann commercial laying hens, aged 64 weeks, were randomly assigned to four treatment groups: a control group, a theaflavin-supplemented group, an oxidized corn gluten meal group, and a combination group. After 8 weeks of feeding, production performance, egg quality, and antioxidant status, along with GC apoptosis and the antioxidant capacity of eggs, were measured. The results demonstrated that oxidized corn gluten meal significantly reduced production performance, antioxidant capacity, and egg quality in laying hens while increasing GC apoptosis. Theaflavin significantly enhanced egg production during weeks 5-8, along with superoxide dismutase activity in the liver, serum, and ovary, alongside egg white reducing power and egg yolk threonine content (p < 0.05). Additionally, theaflavin decreased feed conversion ratios during weeks 5-8 and 1-8, lowered egg white malondialdehyde content (p < 0.05), and inhibited GC apoptosis. In conclusion, oxidized protein reduced production performance, while theaflavin supplementation partially alleviated its adverse effects.

The Impact of Dietary Encapsulated Fennel Seed (Foeniculum vulgare Mill.) Essential Oil Inclusion Levels on Performance, Serum Hormone Profiles, and Expression of Reproductive Axis-Related Genes in the Early and Late Laying Phases of Hens

Fennel seed (Foeniculum vulgare Mill.) essential oil (FEO), which is rich in the phytoestrogenic compound trans-anethole, interacts with oestrogen receptors and influences molecular targets within cells and hormonal responses. This study examined the effect of dietary encapsulated FEO inclusion levels on performance, reproductive hormone profiles, and gene expression in laying hens during the early and late phases. The study was conducted in two independent trials, each involving 210 Atak-S laying hens that were randomly distributed into 3 experimental groups, each having 10 replicates with 7 hens. The dietary treatments included a basal diet without FEO (Control) and a basal diet supplemented with 175 (FEO175) or 350 mg (FEO350) of encapsulated FEO/kg for 12 weeks. The results showed that FEO350 treatment improved egg production, egg mass, and feed conversion ratio during both early and late phases (p < 0.05). Moreover, increasing FEO inclusion levels enhanced oestradiol, follicle-stimulating hormone, luteinizing hormone and progesterone concentrations in both early and late laying hens, reaching peak levels at FEO350 (p < 0.05). FEO supplementation upregulated the expression of oestrogen receptor 2 (ESR2) and follicle-stimulating hormone receptor (FSHR) (p < 0.05). Furthermore, FEO350 increased prolactin receptor (PRLR) expression during the early phase but decreased it during the late laying phase (p < 0.05). Positive correlations were observed between egg production and FSHR, ESR2 and steroidogenic acute regulatory protein (STAR) expression, with a negative correlation for PRLR (p < 0.05). In conclusion, 350 mg FEO/kg was found to be the most effective level for enhancing layer performance.

Kaempferol and Vitamin E Improve Production Performance by Linking the Gut-Uterus Axis Through the Reproductive Hormones and Microbiota of Late-Laying Hens

This study evaluated the effects of kaempferol (KAE), and vitamin E (VE) on the performance, reproductive hormones, and the composition of the cecum and uterus microbiota in late-laying hens. A total of 192 49-week-old Jinghong No. 1 laying hens were randomly divided into four groups, with six replicates in each group and eight laying hens in each replicate, pre-reared for one week and formally tested for ten weeks. The CON group was fed basal diets, the VE group, the KAE group, and the KAE + VE group were fed a basal diet to which was added 0.2 g/kg VE, 0.4 g/kg KAE, and 0.2 g/kg VE + 0.4 g/kg KAE, respectively. The results are as follows. Compared to the CON group, the VE group, the KAE group, and the KAE + VE group significantly increased the egg production rate, average daily egg weight and significantly decreased the feed-to-egg ratio. The VE + KAE group significantly improved the Haugh unit. The VE group, the KAE group, and the KAE + VE group considerably enhanced the eggshell strength, eggshell relative weight, eggshell thickness, yolk color, and relative yolk weight. The serum E2 and LH levels of the KAE group and the KAE + VE group and the serum FSH levels of the KAE + VE group were significantly higher. In the ovary, the KAE group and the KAE + VE group's ESR1 gene expression levels were significantly higher, and the KAE + VE group's FSHR gene expression levels were markedly higher. In the uterus, the KAE group and the KAE + VE group's ESR1 gene expression levels were dramatically higher, and the KAE + VE group's ESR2 and FSHR gene expression levels were significantly higher. 16S rRNA gene sequencing revealed a significant aggregation of cecum and uterus colonies in the Beta diversity PCoA. In the cecum, Firmicutes, Bacteroidetes, and WPS-2 were the dominant phylums. In the uterus, the Firmicutes, Proteobacteria, and Bacteroidetes were the dominant phylums. The KAE + VE group's F/B was significantly higher at the phylum level than in the CON group and the VE group. In summary, the addition of VE and KAE to the diet can improve the production performance of late-laying hens, increase the content of reproductive hormones, and stabilize the cecal and uterus microbiota, which may be related to the hormone and microbiota linkage of the gut-uterus axis.

Study on the changing patterns of production performance of laying hens and their relationships with environmental factors in a large-scale henhouse

The production performance of laying hens is influenced by various environmental factors within the henhouse. The intricate interactions among these factors make the impact process highly complicated. The exact relationships between production performance and environmental variables are still not well understood. In this study, we measured the production performance of laying hens and various environmental variables across different parts of the henhouse, evaluated the weight of each environmental variable, and constructed a laying rate prediction model. Results displayed that body weight, laying rate, egg weight and eggshell thickness of hens decrease gradually from WCA to FA (P < 0.05). Serum levels of FSH and LH, as well as antibody level of H5 Re-13, gradually decrease from WCA to FA (P < 0.05). Moreover, the values for temperature (T), temperature-humidity index (THI), air velocity (AV), carbon dioxide (CO2), and particulate matter (PM2.5) gradually increase from WCA to FA (P < 0.05). Conversely, the relative humidity (RH) value gradually decreases from FA to WCA (P < 0.05). Additionally, the weights of the environmental variables, determined using a combination of the grey relational analysis (GRA) and analytic hierarchy process (AHP), were as follows in descending order: RH, THI, T, light intensity (LI), AV, PM2.5, NH3, and CO2. When the number of decision trees in the laying rate prediction model was set to 2,500, the results displayed a high level of agreement between the model's predictions and the observed outcomes. The model's performance evaluation yielded an R2 value of 0.89995 for the test set, suggesting strong predictive effects. In conclusion, the current study revealed significant differences in both the production performance of laying hens and the environmental variables across different parts of the henhouse. Furthermore, the study demonstrated that different environmental factors have distinct impacts on laying rate, with humidity and temperature identified as the primary factors. Finally, a multi-variable prediction model was constructed, exhibiting high accuracy in predicting laying rate.

Novel insight into the feed conversion ratio in laying hens and construction of its prediction model

Feed efficiency (FE) is an important economic factor in poultry production, and feed conversion ratio (FCR) is one of the most widely used measures of FE. Factors associated with FCR include genetics, the environment, and other factors. However, the mechanisms responsible for FCR in chickens are still less well appreciated. In this study, we examined the pattern changes of FCR, then delved into understanding the mechanisms behind these variations from both genetic and environmental perspectives. Most interestingly, the FCR at the front section of henhouse exhibited the lowest value. Further investigation revealed that laying rate in the high FCR (HFCR) group was lower than that in the low FCR (LFCR) group (P < 0.05). Cortisol, total antioxidant capacity (TAOC), and IgG levels in the LFCR group were significantly lower than those in the HFCR group (P < 0.05), while BUN level was significantly higher than that in the HFCR group (P < 0.05). We identified a total of 67 and 10 differentially expressed genes (DEGs) associated with FCR in ovarian and small intestine tissues, respectively. Functional enrichment analysis of DEGs revealed that they might affect FCR by modulating genes associated with salivary secretion, ferroptosis, and mineral absorption. Moreover, values for relative humidity (RH), air velocity (AV), PM2.5, ammonia (NH3), and carbon dioxide (CO2) in the LFCR group were significantly lower than those in the HFCR group (P < 0.05). Conversely, value for light intensity (LI) in the LFCR group was significantly higher than that in the HFCR group (P < 0.05). Correlation analysis revealed a positive correlation between FCR and RH, AV, PM2.5, NH3, and CO2, and a negative correlation with LI. Finally, the FCR prediction model was successfully constructed based on multiple environmental variables using the random forest algorithm, providing a valuable tool for predicting FCR in chickens.

Effects of Different Photoperiods on the Transcriptome of the Ovary and Small White Follicles in Zhedong White Geese

Photoperiod can regulate the broodiness of geese and thus increase their egg-laying rate. The laying performance of geese is mainly determined by ovary and follicle development. To understand the effect of photoperiod on the ovary and small white follicles, sixteen 220-day-old healthy female Zhedong white geese were randomly divided into two groups for long photoperiods (15L:9D) and short photoperiods (9L:15D). The geese were euthanized after two months of feeding, and their ovaries and follicles were collected for transcriptome sequencing. RNA-seq analysis identified 187 and 448 differentially expressed genes in ovaries and small white follicles of different photoperiod groups, respectively. A long photoperiod promotes high expression of SPP1, C6, MZB1, GP1BA, and FCGBP genes in the ovaries, and increases the expression of SPP1, ANGPTL5, ALPL, ZP1, and CHRNA4 genes in small white follicles. Functional enrichment analysis showed that photoperiod could affect respiratory system development, smooth muscle cell proliferation in ovaries, and extracellular matrix-related function in small white follicles. WGCNA revealed 31 gene modules, of which 2 were significantly associated with ovarian weight and 17 with the number of small white follicles. Our results provide a better understanding of the molecular regulation in the photoperiod affecting goose reproduction.

Multi-functional application of octacosanol as a feed additive in animal and aquaculture: A review

Demand for sustainable animal and aquaculture production drives the exploration of novel feed additives. We highlight octacosanol, a long-chain alcohol from plant sources, as a promising multifunctional feed additive. The review comprehensively evaluates octacosanol's applications in animal and aquaculture nutrition, including its molecular properties and mechanisms of action. It elucidates how octacosanol affects lipid metabolism, energy utilization and immune modulation. Octacosanol enhances livestock growth, efficiency, carcass quality and stress resilience. We thoroughly discuss how it enhances feed utilization, disease resistance and overall performance in finfish and shellfish in aquaculture. The review also addresses the ecological and sustainability aspects of octacosanol utilization. We identify challenges and knowledge gaps in octacosanol research, prompting suggestions for future investigations. We address regulatory considerations, dosage optimization and potential interactions with other feed additives to ensure the safe and effective use of octacosanol. In conclusion, the review highlights octacosanol's potential as a versatile feed additive in the animal and aquaculture industries and urges further research to uncover its benefits and sustainability contributions, proposing a prospective research plan for this purpose. This thorough analysis is a valuable resource for researchers, nutritionists and industry professionals looking to find innovative methods to improve production practices and advance sustainable food systems.

Comparison of the In Vivo Efficacy of Cuban (Raydel®) and Chinese (BOC Science) Policosanol in Alleviating Dyslipidemia and Inflammation via Safeguarding Major Organs and Reproductive Health in Hyperlipidemic Zebrafish: A Twelve-Week Consumption Study

Policosanol is a blend of long-chain aliphatic alcohols (LCAAs) and is well-known for several health-beneficial activities; however, the functionality of policosanol varied substantially based on the composition of LCAAs. In this study, two distinct policosanols, Raydel® (extracted from Cuban sugarcane wax) and BOC Sciences (extracted from Chinese sugarcane wax), were dietarily supplemented (0.1% w/w) for 12 weeks in hyperlipidemic zebrafish to examine their influence on the blood lipid profile and functionality of the liver, kidney, and reproductive organs. The results demonstrated a noteworthy impact of both policosanols on preventing high-cholesterol diet (HCD, 4% w/w)-induced dyslipidemia by decreasing total cholesterol (TC) and triglyceride (TG) levels in the plasma. However, compared to BOC Sciences, the Raydel® policosanol exhibited a significantly (p < 0.05) higher efficacy in reducing HCD-induced TC and TG levels. A substantial effect was observed exclusively with the Raydel® policosanol in mitigating HCD-impaired low-density-lipoprotein cholesterol (LDL-C) and high-density-lipoprotein cholesterol (HDL-C) levels. Hepatic histology and immunohistochemistry (IHC) analysis revealed the higher efficacy of Raydel® policosanol over BOC Sciences policosanol to prevent HCD-provoked fatty liver changes, cellular senescence, oxidative stress, and interleukin (IL)-6 production. Consistently, a significantly higher effect of Raydel® over BOC Sciences policosanol was observed on the protection of kidney, testis, and ovary morphology hampered by HCD consumption. In addition, Raydel® policosanol exhibited a notably stronger effect (~2-fold, p < 0.05) on the egg-laying ability of the zebrafish compared to policosanol from BOC Sciences. Furthermore, Raydel® policosanol plays a crucial role in improving embryo viability and mitigating developmental defects caused by the intake of an HCD. Conclusively, Raydel® policosanol displayed a substantially higher efficacy over BOC Sciences policosanol to revert HCD-induced dyslipidemia, the functionality of vital organs, and the reproductive health of zebrafish.

Supplementation of the Combination of Quercetin and Vitamin E Alleviates the Effects of Heat Stress on the Uterine Function and Hormone Synthesis in Laying Hens

Chickens are sensitive to heat stress because their capacity to dissipate body heat is low. Hence, in chickens, excessive ambient temperature negatively influences their reproductive performance and health. Heat stress induces inflammation and oxidative stress, thereby rendering many reproductive organs dysfunctional. In this study, we evaluated the effects of the supplementation of dietary quercetin and vitamin E on the uterine function, eggshell quality via estrogen concentration, calcium metabolism, and antioxidant status of the uterus of laying hens under heat stress. The ambient temperature transformation was set at 34 ± 2 °C for 8 h/d (9:00 am-5:00 pm), which was followed by 22 °C to 28 °C for 16 h/d. Throughout the experiment, the relative humidity in the chicken's pen was at 50 to 65%. A total of 400 Tianfu breeder hens (120-days-old) were randomly divided into four dietary experimental groups, including basal diet (Control); basal diet + 0.4 g/kg quercetin; basal diet + 0.2 g/kg vitamin E; and basal diet + the combination of quercetin (0.4 g/kg) and vitamin E (0.2 g/kg). The results show that the combination of quercetin and vitamin E significantly increased the serum alkaline phosphatase levels and the antioxidant status of the uterus (p < 0.05). In addition, the combination of quercetin and vitamin E significantly increased the concentrations of serum estrogen and progesterone, as well as elevated the expression of hypothalamic gonadotropin-releasing hormone-1 and follicular cytochrome P450 family 19 subfamily A member-1 (p < 0.05). We also found that the calcium levels of the serum and uterus were significantly increased by the synergistic effects of quercetin and vitamin E (p < 0.05), and they also increased the expression of Ca2+-ATPase and the mRNA expression of calcium-binding-related genes in the uterus (p < 0.05). These results are consistent with the increased eggshell quality of the laying hens under heat stress. Further, the combination of quercetin and vitamin E significantly increased the uterine morphological characteristics, such as the height of the uterine mucosal fold and the length of the uterine mucosa villus of the heat-stressed laying hens. These results collectively improve the uterine function, serum and uterine calcium concentration, eggshell strength, and eggshell thickness (p < 0.05) in heat-stressed laying hens. Taken together, we demonstrated in the present study that supplementing the combination of dietary quercetin and vitamin E alleviated the effects of heat stress and improved calcium metabolism, hormone synthesis, and uterine function in the heat-stressed laying hens. Thus, the supplementation of the combination of quercetin and vitamin E alleviates oxidative stress in the eggshell gland of heat-stressed laying hens, thereby promoting calcium concentration in the serum and eggshell gland, etc., in laying hens. Hence, the combination of quercetin and vitamin E promotes the reproductive performance of the laying hens under heat stress and can also be used as a potent anti-stressor in laying hens.

Dietary supplementation of osthole and icariin improves the production performance of laying hens by promoting follicular development

Osthole (Ost) and icariin (Ica) are extracted from traditional Chinese medicine Cnidium monnieri and Epimedii Folium, respectively, and both exhibit estrogen-like biological activity. This study aimed to determine the efficacy and safety of combining Ost with Ica on the production performance of laying hens and to explore their possible mechanisms. The production performance, egg quality, residues of Ost and Ica in eggs, serum reproductive hormone levels, expression of ovarian reproductive hormone receptor, proliferation of granulosa cells in small yellow follicles (SYF), and progesterone secretion in large yellow follicles (LYF) related genes and proteins expression were detected. The results showed that adding 2 mg/kg Ost + 2 mg/kg Ica to the feed increased the laying rate, average egg weight, Haugh unit, and protein height of laying hens. Serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), and progesterone (P4) levels increased, and the expression of ovarian estrogen receptor (ER), follicle-stimulating hormone receptor (FSHR), and progesterone receptor (PGR) mRNA was up-regulated. Additionally, the mRNA and protein levels of steroidogenesis acute regulatory protein (StAR), cytochrome P450 side-chain cleavage (P450scc), and 3β-hydroxysteroid dehydrogenase (3β-HSD) increased in LYF. Furthermore, mRNA and protein levels of proliferating cell nuclear antigen (PCNA), cyclin E1, and cyclin A2 were up-regulated in SYF. The residues of Ost and Ica in egg samples were not detected by high-performance liquid chromatography (HPLC). In conclusion, dietary supplementation of Ost and Ica increased granulosa cells proliferation in SYF and increased P4 secretion in granulosa cells of LYF, ultimately improving the production performance of laying hens.

Effects of different stocking densities on the development of reproductive and immune functions in young breeder pigeons during the rearing period

1. Stocking density (SD) is closely related to animal performance. This experiment was designed to evaluate the development of reproductive and immune functions of young pigeons under different SDs.2. A total of 288 (half male and half female) 40-day-old pigeons (body weight 400 ± 15 g) were allocated into four groups: High stocking density (HSD; 0.308 m3/bird), standard stocking density (SD; 0.616 m3/bird), and low stocking density (LSD; 1.232 m3/bird) and a caged (control; 0.04125 m3/bird). Every group had six replicates of the same sex.3. The results showed that caged male pigeons had the highest testis index, testosterone content, and gene expression of the androgen receptor gene. LSD treatment induced the highest concentrations of oestradiol, progesterone and mRNA levels of reproductive hormone receptor genes in female pigeons. In male pigeons, the spleen index (organ weight calculated as a percentage of total body weight) showed a peak level (0.09 ± 0.020) in the LSD group, and the thymus index peaked (0.23 ± 0.039) in SD group. However, the index for ovary, spleen, thymus and bursa of Fabricius in female pigeons showed no significant changes among different groups.4. The IL-1β, IL-8, IFN-γ, TGF-β and toll-like receptor 2 (TLR-2) mRNA levels reached their maximum values in both male and female pigeon spleens in the LSD group.5. Young male pigeons housed in cages showed increased testicular development while low stocking density increased the development of reproductive function in young female pigeons. A larger activity space could help enhance the immune function of both male and female pigeons.

Effects of enzymolysis and fermentation of Chinese herbal medicines on serum component, egg production, and hormone receptor expression in laying hens

OBJECTIVE

In the present study, we aimed to investigate the effects of enzymolysis fermentation of Chinese herbal medicines (CHMs) on egg production performance, egg quality, lipid metabolism, serum reproductive hormone levels, and the mRNA expression of the ovarian hormone receptor of laying hens in the late-laying stage.

METHODS

A total of 360 Hy-Line Brown laying hens (age, 390 days) were randomly categorized into four groups. Hens in the control (C) group were fed a basic diet devoid of CHMs, the crushed CHM (CT), fermented CHM (FC), and enzymatically fermented CHM (EFT) groups received diets containing 2% crushed CHM, 2% fermented CHM, and 2% enzymatically fermented CHM, respectively.

RESULTS

Compared with crushed CHM, the acid detergent fiber, total flavonoids, and total saponins contents of fermented CHM showed improvement (p<0.05); furthermore, the neutral and acid detergent fiber, total flavonoids, and total saponins contents of enzymatically fermented CHM improved (p<0.05). At 5 to 8 weeks, hens in the FC and EFT groups showed increased laying rates, haugh unit, albumin height, yolk color, shell thickness, and shell strength compared with those in the C group (p<0.05). Compared with the FC group, the laying rate, albumin height, and Shell thickness in the EFT group was increased (p<0.05). Compared with the C, CT, and FC groups, the EFT group showed reduced serum total cholesterol and increased serum luteinizing hormone levels and mRNA expressions of follicle stimulating hormone receptor and luteinizing hormone receptor (p<0.05).

CONCLUSION

These results indicated that the ETF group improved the laying rate and egg quality and regulated the lipid metabolism in aged hens. The mechanism underlying this effect was likely related to cell wall degradation of CHM and increased serum levels of luteinizing hormone and mRNA expression of the ovarian hormone receptor.

Transcriptome Analysis of Granulosa Cells Reveals Regulatory Mechanisms Related to Chicken Follicle Development

In this study, we aimed to better understand the difference between the functions of the two types of granulosa cells and sought to discover more key genes involved in follicle development and follicle selection. Herein, we separately collected pre-hierarchical follicle granulosa cells (PHGCs) and preovulatory follicle granulosa cells (POGCs) for RNA extraction; the transcriptomes of the two groups were compared via RNA-seq. A total of 5273 differentially expressed genes (DEGs) were identified between the PHGCs and POGCs; 2797 genes were up-regulated and 2476 were down-regulated in the PHGCs compared with the POGCs. A qPCR analysis confirmed that the expression patterns of 16 randomly selected DEGs were highly consistent with the RNA-seq results. In the POGCs, many of the genes with the most significant increase in expression were related to steroid hormone synthesis. In addition, the genes with the most significant decline in expression, including AMH and WT1, were related to the inhibition of steroid hormone synthesis. These results suggest that steroid hormones play a key role in follicle development. Furthermore, a Gene Ontology (GO) analysis revealed that these DEGs were mainly involved in the primary metabolic process, the carbohydrate metabolic process, the cellular process, ribosomes, the cytoplasm, and intracellular processes. A Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that the DEGs were mainly enriched in steroid biosynthesis, the cell cycle, ribosomes, the TGF-beta signaling pathway, focal adhesion, and so on. We also observed the morphology of the follicles at different developmental stages, and the results showed that the thickness of the granular layer of the small yellow follicles (SYFs) decreased significantly with further development. In addition, we also found that the thickness of the granulosa layer of hens over 300 days old was significantly lower than that of 200-day-old hens. In short, these data indicate that the tissue morphology and function of granulosa cells change throughout follicle development.

Dietary Canthaxanthin Supplementation Promotes the Laying Rate and Follicular Development of Huaixiang Hens

Canthaxanthin(CX) is a ketocarotenoid, which is widely used in poultry production as a lipophilic antioxidant. Huaixiang chickens are a local breed in China famous for their excellent meat quality; improving their laying rate via nutritional regulation has attracted extensive attention. The aim of this study was to evaluate the effects of dietary CX on the laying rate and follicular development in Huaixiang hens. A total of 180 Huaixiang hens were randomly divided into five groups with six replicates, and six chickens per replication. The control group (CON) were fed a basal diet, and the treatment group (NT) were fed a basal diet supplemented with 4, 6, 8 and 10 mg/kg CX. All chickens were 26 weeks old, living at an average environmental temperature of 25 ± 2 °C with a relative humidity of 65-75%. The results showed that supplementing the CX improved the laying rate and large white follicles (LWF) number (p < 0.05) and increased the concentration of reproductive hormones (LH, FSH, E2 and Prog) (p < 0.05), and the basal diet supplemented with 6 mg/kg CX worked best. Moreover, CX could increase the activities of antioxidant enzymes SOD and GSH-Px (p < 0.05) and reduce the content of the lipid peroxidation product MDA in Huaixiang chickens (p < 0.05); again, 6 mg/kg CX was best. In conclusion, dietary CX had positive effects on the laying rate, ovarian structure, reproductive hormone secretion, follicle development, and the antioxidant capacity of Huaixiang hens, and 6 mg/kg CX was recommended to be added to the diet of Huaixiang chickens.

Dietary replacement of soybean meal by fermented feedstuffs for aged laying hens: effects on laying performance, egg quality, nutrient digestibility, intestinal health, follicle development, and biological parameters in a long-term feeding period

This study aimed to investigate the effects of dietary supplementation with fermented soybean meal (FSM) or fermented miscellaneous meal (FMM, cottonseed meal: coconut meal = at a 1:1 ratio) on the intestinal health, laying performance, egg quality, and follicle development of laying hens. A total of 1,008 54-wk-old laying hens were randomly divided into 7 treatment groups and fed a corn-soybean base diet in addition to 2%, 4%, and 8% FSM or FMM. The results showed that fermentation increased the contents of crude protein, amino acids (Ser, Gly, Cys, Leu, Lys, His, and Arg), and organic acids (butyric acid, citric acid, succinic acid) and decreased the contents of neutral and acid detergent fiber in the soybean and miscellaneous meals (P < 0.05). Compared with the results found for the control group, feeding with 4% FSM increased the egg production, egg mass and average daily feed intake (ADFI), and feeding with 4% FMM increased the ADFI of laying hens (P < 0.05). Furthermore, feeding with 8% FMM reduced the productive performance and laying performance, supplementation with 4% FSM increased the eggshell strength and weight, and 2 to 4% FSM increased the egg albumen height and Haugh unit (P < 0.05). Moreover, 2 to 8% FSM or 2 to 4% FMM enhanced the apparent digestibility of dry matter, crude protein, and NDF for laying hens (P < 0.05). The relative weight, villus height, crypt depth, and villus:crypt ratio of the jejunum were higher in the 4% FSM- and FMM-fed groups (P < 0.05). Moreover, diamine oxidase (DAO) activity, transepithelial electrical resistance (TEER), and the expression of tight junction proteins (ZO-1, Occluding, and Claudin1), the intestinal stem cell marker Lgr5, and the proliferation cell marker proliferating cell nuclear antigen (PCNA) was upregulated in the jejunum of laying hens fed 4% FSM and FMM (P < 0.05). The relative weight of the ovaries, and the number of small yellow follicles and large white follicles were elevated after 4% FSM or FMM supplementation. Furthermore, the levels of serum follicle-stimulating hormone and luteinizing hormone were increased in the 4% FSM and FMM groups (P < 0.05). In conclusion, the supplementation of laying hen feed with FSM and FMM improved the laying performance, egg quality, intestinal barrier function, and follicle development of aged laying hens, and 4% FSM supplementation was optimal.

Dietary naringin supplementation on laying performance and antioxidant capacity of Three-Yellow breeder hens during the late laying period

In this study, the effects of 3 graded dietary levels (0.1%, 0.2%, and 0.4%) of naringin were studied in Three-Yellow breeder hens during the late laying period (55-62 wk). A total of 480 Three-Yellow breeder hens (54-wk-old) were randomly divided into 4 groups (6 replicates of 20 hens): basal diet group (C), and basal diets supplemented with 0.1%, 0.2%, and 0.4% of naringin (N1, N2, and N3), respectively. Results showed that dietary supplementation with 0.1%, 0.2%, and 0.4% of naringin for 8 wk increased the laying rate and egg mass, enhanced egg yolk color, and decreased the feed egg ratio (P < 0.05). Meanwhile, compared with hens in C group, there were more preovulatory follicles and higher ovarian index as well as an enhanced ovarian somatic cell proliferation in hens of N2 and N3 groups (P < 0.05). With 0.2% and 0.4% naringin, glutathione concentration, the activity of catalase and total superoxide dismutase, and the total antioxidant capacity of ovarian tissues and serum increased (P < 0.05), while the contents of malondialdehyde and hydrogen peroxide decreased (P < 0.05). Moreover, compared to C group, the transcription levels of antioxidant genes in ovarian tissues increased in hens from N2 and N3 groups (P < 0.05). In conclusion, supplementation with 0.2% and 0.4% naringin both could improve the laying rate, ovarian and serum antioxidant capacity of Three-Yellow breeder hens during the late laying period.

Effect of dietary octacosanol concentration extracted from triticale sprout on laying performance, egg quality, and blood parameters of laying hens

This study was conducted to investigate the effect of dietary supplementation of octacosanol (OCT) extracted from triticale sprout on laying performance, egg quality, and blood parameters of laying hens. A total of 192, Hyline brown laying hens aged 43 weeks were divided into 4 dietary groups of 48 birds each and they were randomly subjected to one of the experimental diets containing OCT at the levels of none, 10, 20, and 30 mg/kg of diet. All birds were fed with isoenergetic and isonitrogenous mash diets for 6 weeks. The result showed that hens supplemented with 20 and 30 mg/kg OCT in diet significantly increased (p < 0.05) egg production than those fed with the basal diet. OCT concentration in the egg yolk of hens fed with 20 and 30 mg/kg OCT was significantly higher than in those fed the control diet. Hens fed 20 and 30 mg/kg OCT exhibited greater high-density lipoprotein (HDL) cholesterol and interleukin (IL) concentrations and reduced serum concentrations of cholesterol and triglyceride compared to those fed with 0 and 10 mg/kg OCT. This study indicates that supplementing the diet of laying hens with 20 and 30 mg/kg of OCT can improve the performance, egg quality, and health status of laying hens.

Use of Maca Powder (Lepidium meyenii) as Feed Additive in Diets of Laying Quails at Different Ages: Its Effect on Performance, Eggshell Quality, Serum, Ileum, and Bone Properties

Using additives can reduce the negative effects of aging on factors affecting profitability, such as the availability of nutrients, production, and egg quality. Maca is an herbaceous plant rich in protein, crude oil, essential acids, and pharmacological compounds. Maca has positive effects on different health parameters. In this study, the effect of adding Maca powder to the diets of young and old laying quails at the end of the 10-week trial was investigated. In total, 150 laying Japanese quails (Coturnix japonica) (209.1 ± 10.0 g) were randomly distributed to a 2 × 3 factorial arrangement with two ages (10 weeks and 30 weeks) and three Maca powder levels (0, 1, or 2 g/kg), with five subgroups per treatment. According to the study, eggshell quality, total cholesterol, triglyceride, progesterone, and testosterone concentrations of serum were lower in old quail than in young quail, while egg weight, feed intake, and follicle-stimulating hormone increased significantly as quail aged. (p < 0.05). Furthermore, aging negatively affected the histomorphology of the ileum and cortical bone thickness (p < 0.05). Additional findings show that adding 1 g/kg Maca powder to the diet of quail significantly improved eggshell, ileum, and bone traits that deteriorate with age, without affecting performance, and adding 2 g/kg Maca powder to the diet significantly reduced serum total cholesterol levels (p < 0.05). Incorporating Maca powder into the diet of aged birds could reduce the negative effects of aging.

Effects of Zinc Methionine Hydroxy Analog Chelate on Laying Performance, Serum Hormone Levels, and Expression of Reproductive Axis Related Genes in Aged Broiler Breeders

Inorganic zinc (Zn) supplements are commonly used in poultry feeds, but their low utilization results in the increase of Zn excretion. Thus, to provide a new perspective for the substitution of inorganic Zn, a novel Zn methionine hydroxy analog chelate (Zn-MHA) was studied in the present study to evaluate its effects on laying performance, serum hormone indexes and reproductive axis-related genes in broilers breeders. A total of 480 Hubbard breeders (56-week-old) were fed a basal diet (containing 27.81 mg Zn/kg) without Zn addition for 2 weeks, and then allocated to 4 groups with 6 replicates (each replicate consisting of 10 cages and 2 breeders per cage) for 10 weeks. Four treatment diets given to broiler breeders included the basal diet added with 25, 50, and 75 mg/kg of Zn-MHA and 100 mg/kg of Zn sulfate (ZnSO₄). The laying rate, egg weight and feed conversation ratio increased in the 75 mg/kg Zn-MHA group compared to the ZnSO₄ group. The eggshell thickness was not decreased with the addition of 50 mg/kg and 75 mg/kg Zn-MHA in the diet compared to the 100 mg/kg ZnSO₄ group. There was a significant improvement in the reproductive performance of breeders in the 75 mg/kg Zn-MHA group, including the fertility and 1-day-old offspring weight. Besides, serum sex hormone levels including FSH and P₄ increased significantly in 75 mg/kg Zn-MHA group. No significant effect on the ovarian weight or the number of follicles in broiler breeders was observed by supplementing Zn-MHA. Compared to the 100 mg/kg ZnSO₄ group, dietary supplementation with 75 mg/kg of Zn-MHA showed an up-regulation of the FSHR mRNA in the granular layer of follicles. However, dietary supplementation of Zn-MHA had no effects on mRNA expressions of the ovarian LHR and PRLR genes. These findings reinforce the suggestion that Zn-MHA (75 mg/kg) could replace ZnSO₄ (100 mg/kg) as a Zn supplement in diet of broiler breeders, which resulted in better laying and reproduction performances by regulating the expression levels of reproductive axis related genes and serum hormone levels.

Natural Products of Plants and Animal Origin Improve Albumen Quality of Chicken Eggs

Albumen quality is recognized as one of the major yardsticks in measuring egg quality. The elasticity of thick albumen, a strong bond in the ovomucin-lysozyme complex, and excellent biological properties are indicators of high-quality albumen. The albumen quality prior to egg storage contribute to enhance egg’s shelf life and economic value. Evidence suggests that albumen quality can deteriorate due to changes in albumen structure, such as the degradation of β-ovomucin subunit and O-glyosidic bonds, the collapse of the ovomucin-lysozyme complex, and a decrease in albumen protein-protein interaction. Using organic minerals, natural plants and animal products with antioxidant and antimicrobial properties, high biological value, no residue effect and toxicity risk could improve albumen quality. These natural products (e.g., tea polyphenols, marigold extract, magnolol, essential oils, Upro (small peptide), yeast cell wall, Bacillus species, a purified amino acid from animal blood, and pumpkin seed meal) are bio-fortified into eggs, thus enhancing the biological and technological function of the albumen. Multiple strategies to meeting laying hens’ metabolic requirements and improvement in albumen quality are described in this review, including the use of amino acids, vitamins, minerals, essential oils, prebiotics, probiotics, organic trace elements, and phytogenic as feed additives. From this analysis, natural products can improve animal health and consequently albumen quality. Future research should focus on effects of these natural products in extending shelf life of the albumen during storage and at different storage conditions. Research in that direction may provide insight into albumen quality and its biological value in fresh and stored eggs.

Effects of stocking density on ovarian development and maturation during the rearing period in Shan-ma ducks

Stocking density critically affects the growth and subsequent performance of animals in modern poultry production. This study investigated the effects of stocking density on ovarian development, ovarian maturation, and the mRNA expression of key genes in the reproductive axis during the rearing period of Shan-ma ducks. The experiments involved 180 healthy 7-wk-old Shan-ma ducks and randomly divided into low stocking density (LSD; n = 30, density = 5 birds/m²), medium stocking density (MSD; n = 60, density = 10 birds/m²) and high stocking density groups (HSD; n = 90, density = 15 birds/m²), for rearing. After examining ovarian development and measuring hormone levels in the plasma and expression levels of key regulatory genes in the reproductive axis at 19 wk of rearing, analysis of the gonad index analysis, reflecting stocking density, uncovered statistically significant differences. The gonad index of the LSD group was significantly higher than those of the MSD and HSD groups (P < 0.01), while no significant difference was observed between the MSD and HSD groups. pre-ovulatory follicles (POFs) and small yellow follicles (SYFs) development was only apparent in the LSD group, with the large white follicles (LWFs) number of this group being significantly higher than that of the MSD group (P < 0.05). The blood levels of E2 (estradiol), P4 (progesterone), and T (testosterone) were significantly higher in the LSD group than in the MSD and HSD groups (P < 0.05 or 0.01). Also, the levels of both P4 and T were significantly higher in the MSD group than in the HSD group (P < 0.01). The gene expression levels of GnRHR, FSH, AMHR, and FSHR were significantly increased in the LSD group compared to the MSD and HSD groups (P < 0.05 or 0.01), while the expression levels of GnIHR and GDF9 were significantly decreased in the LSD and MSD groups compared to the HSD group (P < 0.05 or 0.01). Steroid biosynthesis pathway genes such as StAR, CYP11A1, 3β-HSD, CYP19A1, and BMP15 were significantly downregulated at greater stocking densities (P < 0.05 or 0.01). Likewise, the protein expression of StAR, 3β-HSD, and CYP19A1 was also significantly decreased (P < 0.05 or 0.01). These results demonstrate that both medium and high stocking densities suppressed the expression of the key reproduction-promoting factors, while the expression level of the key reproductive inhibitory factors was enhanced. Therefore, rates of ovarian development and maturation could be reduced by a high stocking density leading to a delay in reproduction performance during the rearing period of Shan-ma ducks.

Dietary hawthorn-leaves flavonoids improves ovarian function and liver lipid metabolism in aged breeder hens

Hawthorn-leaves flavonoids (HF), extracted from hawthorn leaves, were reported to exert antioxidant, anti-inflammatory and hypolipidemic properties. The aim of our study was to investigate the effects of dietary HF on the reproduction performance and liver lipid metabolism of aged breeder hens. A total of 270 aged Qiling breeder hens (60-wk-old) were randomly divided into 3 treatments: 1) basic corn-soybean diet (CON); 2) basic corn-soybean diet supplemented with 30 mg/kg HF (LHF); 3) basic corn-soybean diet supplemented with 60 mg/kg HF (HHF). The results showed that supplemented HF significantly improved the egg-laying rate and hatching rate of aged breeder hens (P < 0.05). HF treatment reduced the serum TG, T-CHO and L-LDL levels (P < 0.05), and upregulated the mRNA expressions of ESR1, ESR2, VTGⅡ, ApoB, and ApoVI in the liver (P < 0.05). Serum estrogen levels in HF treated groups were elevated compared with the CON group (P < 0.05). In the HHF group, the number of the primordial follicles was higher in comparison with the CON group (P < 0.05). Furthermore, dietary supplementation with HF improved the activity of antioxidant enzymes (T-AOC, GSH-Pχ) (P < 0.05), following with the reversed ovarian apoptosis and morphological damage. In addition, 60 mg/kg dietary HF upregulated the protein expression of PCNA and Nrf2 in the ovary (P < 0.05). In summary, dietary supplementation with HF could improve the reproduction performance through regulating liver lipid metabolism and improving ovarian function in aged breeder hens.

Effects of Dietary Indole-3-Acetate Sodium on Laying Performance, Egg Quality, Serum Hormone Levels and Biochemical Parameters of Danzhou Chickens

This study was conducted to investigate the effects of indole-3-acetate sodium (IAA-Na) inclusion in diets on the egg production performance, egg quality, intestinal tissue morphology, serum hormone levels and biochemical parameters of Danzhou chickens to preliminarily explore the efficacy of IAA-Na as a feed additive. A total of 192 Danzhou chickens (50 weeks old) were randomly assigned to 2 groups of 96. The diets for the treatment group consisted of the basal diets, supplemented with IAA-Na (200 mg/kg). The formal feeding trial lasted for four weeks. The results showed that the feed supplemented with IAA-Na not only increased the laying rate (p < 0.05) and egg yolk ratio (0.05 < p < 0.1), but also significantly reduced the feed:egg ratio (p < 0.05). In addition, the dietary supplementation of IAA-Na significantly increased the serum estradiol levels (p < 0.05) and decreased serum alkaline phosphatase activity (p < 0.05). Compared with the control group, the addition of IAA-Na to the diet had no significant effect on the intestinal tissue morphology or serum antioxidant capacity of Danzhou chickens. This study preliminarily provides evidence that dietary IAA-Na can improve laying performance, indicating that IAA-Na is a potentially effective feed additive for laying hens, but further studies are required before arriving at definite conclusions.

Chronological Expression of PITX2 and SIX1 Genes and the Association between Their Polymorphisms and Chicken Meat Quality Traits

Meat quality is closely related to the development of skeletal muscle, in which PITX2 and SIX1 genes play important regulatory roles. The present study firstly provided the data of chronological expression files of PITX2 and SIX1 genes in the post-hatching pectoral muscle and analyzed the association of their polymorphisms with the meat quality traits of Wuliang Mountain Black-bone (WLMB) chickens. The results showed that both PITX2 and SIX1 genes were weakly expressed in the second and third weeks, and then increased significantly from the third week to the fourth week. Furthermore, there was a significant positive correlation between the expression levels of the two genes. Twelve and one SNPs were detected in the chicken PITX2 and SIX1 genes, respectively, of which four SNPs (g.9830C > T, g.10073C > T, g.13335G > A, g.13726A > G) of the PITX2 gene and one SNP (g.564G > A) of the SIX1 gene were significantly associated with chicken meat quality traits. For the PITX2 gene, chickens with the CT genotype of g.9830C > T showed the highest meat color L*, shear force (SF), pH, and the lowest electrical conductivity (EC), and drip loss (DL) (p < 0.05 or p < 0.01); chickens with the CC genotype of g.10073C > T had the lowest L*, pH, and the highest DL (p < 0.01). For the SIX1 gene, chickens with the GG genotype of g.564G > A had the highest (p < 0.05) SF and pH. Furthermore, pH had a significant correlation with all the other meat quality traits. The current study could contribute to the research of regulatory mechanisms of meat quality and lay the foundation for improving meat quality based on marker-assisted selection in chickens.

Effects of Macleaya cordata extract on laying performance, egg quality, and serum indices in Xuefeng black-bone chicken

The abuse of antibiotic growth promoters (AGPs) in feed has led to drug resistance and ecological damage would threaten human health eventually. Natural plants have become a hotspot in the research and application of substituting AGPs because of their advantages of safety, efficiency, and availability. This study was conducted to investigate the effects of Macleaya cordata extract (MCE) in the diet of Xuefeng black-bone chicken on laying performance, egg quality, and serum indices. In this study, 576 birds (47-week-old) were evenly distributed between 4 treatments with 6 replicates of 24 hens each. The control group was fed a basal diet without MCE and the remaining groups received 100, 150, or 200 mg/kg MCE for 84 d. Results revealed that the strength and thickness of the eggshell increased significantly with the dietary addition of MCE (P < 0.05). The serum concentrations of glutathione peroxidase increased in the MCE groups (P < 0.01). Simultaneously, progesterone, follicle stimulating hormone, estradiol as well as serum luteinizing hormone levels also increased with the addition of MCE (P < 0.05). Compared with the control group, supplementation of MCE significantly decreased the tumor necrosis factor-α and interleukin-6 levels (P < 0.01). In summary, it was concluded that diet addition of 200 mg/kg MCE ameliorated egg quality, enhanced anti-oxidation and immune activity, and regulated hormone secretion of Xuefeng black-bone chicken.

Effects of photoperiod on performance, ovarian morphology, reproductive hormone level, and hormone receptor mRNA expression in laying ducks

We investigated the effect of photoperiod on performance, ovarian morphology, reproductive hormones levels, and their receptors mRNA expressions in laying ducks. After adaption, 300 252-day-old Jinding laying ducks were randomly allocated to 5 groups, receiving 12L:12D, 14L:10D, 16L:8D, 18L:6D, or 20L:4D, respectively. Each treatment had 6 replicates of 10 birds each. The feeding trial lasted 8 wk. Egg production, egg mass, and ADFI increased linearly and quadratically with increasing photoperiods (P < 0.05), and the higher values of them occurred in photoperiods ≥ 16 h, compared with 12L:12D (P > 0.05). Initial and bare stroma weight increased quadratically, while total large white follicle (LWF) number and weight increased linearly and quadratically, with increasing photoperiods (P < 0.05). The higher values of them occurred in 16L:8D and 18L:6D treatments as well as the higher total LWF weight also occurred in 20L:4D, compared with 12L:12D (P > 0.05). Besides, 16.93 and 16.93 h were the optimal photoperiods for bare stroma (follicles ≥ 2 mm in diameter removed) weight and total LWF weight, respectively, calculated from reliable regression equations (R² ≥ 0.5071). Compared with 12L:12D, the higher levels of estradiol, progesterone, follicle-stimulating hormone (FSH) as well as the higher expressions of estrogen, luteinizing hormone (LH) and progesterone receptors were observed in ≥16 h photoperiods (P < 0.05), while the higher LH level and FSH receptor expression only occurred in 16L:8D and 18L:6D (P < 0.05). In the hypothalamus, higher mRNA expression of gonadotropin-releasing hormone occurred in 16L:8D and 18L:6D groups (P < 0.05). Meanwhile, gonadotropin-inhibitory hormone and prolactin increased in 20-hour photoperiod (P < 0.05), and the latter may be due to theup-regulation of vasoactive intestinal peptide expression (P < 0.05). To sum up, an appropriate photoperiod could improve the performance and reproductive organ and ovarian follicles development through reproductive hormones and their receptors, and 16.56 to 10.93 h is an adequate photoperiod for laying ducks.

Effects of manganese and Bacillus subtilis on the reproductive performance, egg quality, antioxidant capacity, and gut microbiota of breeding geese during laying period

This experiment was conducted to investigate the effects of manganese (Mn) and Bacillus subtilis (BS) on the production performance, egg quality, antioxidant capacity, and gut microbiota of breeding geese during laying period. A total of 120 forty-six-week-old breeding geese (Wulong) were randomly assigned to 1 of 6 treatment diets formulated to supply 10, 20, and 30 mg/kg Mn with 5 × 109 CFU/kg or 2.5 × 109 CFU/kg BS for a 10-wk trial. Results showed that dietary supplementation with 20 and 30 mg/kg Mn could decrease the daily feed intake (DFI) of geese. Moreover, 30 mg/kg Mn significantly increased the laying rate. Besides, although Mn addition had no obvious effect on egg quality, 5 × 109 CFU/kg BS was found to elevate the hatching egg hatching rate and eggshell thickness. For the serum hormones, 30 mg/kg Mn promoted estradiol secretion, while 5 × 109 CFU/kg BS increased the level of follicle-stimulating hormone. Furthermore, 20 and 30 mg/kg Mn and 5 × 109 CFU/kg BS significantly enhanced the total antioxidant capacity by increasing the activity of total superoxide dismutases or decreasing the content of malondialdehyde. Dietary supplementation with 5 × 109 CFU/kg BS also increased the intestinal villus height and upregulated the abundance of Fusobacteria, Fusobacteriaceae, Fusobacterium, and Faecalibacterium in cecal content. In addition, 20 and 30 mg/kg Mn elevated the levels of Bacteroidetes, Bacteroidaceae, Bacteroides, and Ruminococcaceae but decreased Streptococcaceae. Importantly, an interaction effect was observed between Mn and BS on the DFI, egg mass, average egg size, and the abundance of Bacteroides as well as Faecalibacterium. In conclusion, dietary inclusion of Mn and BS could improve the production performance, egg quality, antioxidant capacity, intestinal structure, as well as gut microbiota. Supplementation of 30 mg/kg Mn and 5.0 × 109 CFU/kg BS provided the optimal effect.

Investigation of the CEBPA gene expression pattern and association analysis of its polymorphisms with meat quality traits in chickens

Meat quality is closely related to the fat deposition which is regulated by a cascade of transcription factors. As a transcription factor, the CCAAT/enhancer binding protein alpha (CEBPA) is considered as one of the key molecules regulating adipogenesis. Therefore, the objective of this study was to detect the expression pattern of the CEBPA gene and evaluate whether its single nucleotide polymorphisms (SNPs) were associated with the meat quality traits in Wuliang Mountain Black-bone (WLMB) chickens. The results showed that the chicken CEBPA mRNA was widely expressed in the 11 tissues, and the expression pattern of it might be tissue- and time-specific different. The locus of g.74C > G was not significantly associated with chicken meat quality. For the locus of g.552G > A, chickens with the GG genotype showed higher pH (p < 0.01), lower drip loss (p < 0.01) and higher intramuscular fat (p < 0.05) than those with other genotypes. It suggested that polymorphisms of the CEBPA gene were significantly associated with the meat quality traits of WLMB chickens. The results of this study contribute to the functional research of the CEBPA gene and lay the foundation for improving meat quality based on the marker-assisted selection in chickens.

Expression Analysis of the PITX2 Gene and Associations between Its Polymorphisms and Body Size and Carcass Traits in Chickens

Simple Summary

The Wuliang Mountain Black-bone chicken is a Chinese indigenous breed with good meat quality and strong resistance to disease. Like most of the other Chinese domestic breeds, it has a much slower early growth rate compared with foreign chicken breeds. Therefore, the genetic selection of body size and carcass traits is still the focus of Chinese indigenous chicken breeding. The paired-like homeodomain transcription factor 2 (PITX2) gene, an important transcription factor, plays an important role during the development of the eye, heart, skeletal muscle and other tissues in mammals. In chicken, the PITX2 gene affects the late myogenic differentiation of the limb. The objectives of this study were to detect the expression of the PITX2 gene and analyze the associations between the polymorphisms in the exons of the PITX2 gene and body size as well as carcass traits in chickens. The results could contribute to Chinese chicken breeding based on marker assisted-selection.

Abstract

PITX2 is expressed in and plays an important role in myocytes of mice, and it has effects on late myogenic differentiation in chickens. However, the expression profile and polymorphisms of PITX2 remain unclear in chickens. Therefore, the aim of the present study was to detect its expression and investigate single nucleotide polymorphisms (SNPs) within its exons and then to evaluate whether these polymorphisms affect body size as well as carcass traits in chickens. The expression analysis showed that the expression level of chicken PITX2 mRNA in the leg muscle and hypophysis was significantly higher (p < 0.01) than those in other tissues. The results of polymorphisms analysis identified two SNPs (i.e., g.9830C > T and g.10073C > T) in exon 1 and 10 SNPs (i.e., g.12713C > T, g.12755C > T, g.12938G > A, g. 3164C > T, g.13019G > A, g.13079G > A, g.13285G > A, g.13335G > A, g.13726A > G and g.13856C > T) in exon 3, including four novel SNPs (i.e., g.9830C > T, g.12713C > T, g.12938G > A and g.13856C > T). In the loci of g.10073C > T and g.12713C > T, chickens with the CT genotype had the highest (p < 0.05 or p < 0.01) breast depth and breast angle, respectively. For the locus of g.13335G > A, chickens with the GG genotype had the highest (p < 0.05 or p < 0.01) breast angle and shank circumference. For the locus of g.13726A > G, chickens with the GG genotype had the highest breast width, fossil keel bone length and shank circumference. The locus of g.12713A > G had significant effects on the PITX2 mRNA expression level in leg muscle. The H1H7 diplotype showed the highest shank circumference, and the H2H8 diplotype showed the highest breast muscle rate. The present research suggested that polymorphisms of the exons of the PITX2 gene were significantly associated with the body size and carcass traits of Wuliang Mountain Black-bone chickens and the PITX2 gene could be a potential candidate gene for molecular marker-aided selection in Wuliang Mountain Black-bone chickens and other chicken breeds.

Effect of photoperiod on ovarian morphology, reproductive hormone secretion, and hormone receptor mRNA expression in layer ducks during the pullet phase

We evaluated the effect of photoperiod on ovarian morphology, reproductive hormone secretion, and hormone receptor mRNA expression in layer ducks during the pullet phase. A total of 480 71-d-old Jinding layer ducks were randomly divided into 5 groups that received 6L (hours of light):18D (hours of darkness), 8L:16D, 10L:14D, 12L:12D, or 14L:10D, respectively. Each group had 6 replicates with 16 birds each. The photoperiod feeding trial lasted 80 d until 150 d of age. The age at first egg (AFE), the total number, and weight of eggs increased linearly with increasing photoperiods (P < 0.05); lower values of AFE occurred with photoperiods ≥8 h, whereas a higher total number and weight of eggs occurred with photoperiods ≥10 h, compared with 6L:18D (P > 0.05). Oviduct weight, ovary percentage, and initial and bare stroma (weight and percentage) increased quadratically with increasing photoperiods (P < 0.05), and 10.24, 10.01, and 10.10 h were the optimal photoperiods for oviduct weight, bare stroma (follicles ≥2 mm in diameter removed) weight, and bare stroma percentage, respectively, as calculated from reliable regression equations (R2 ≥ 0.5791). Compared with 6L:18D, 10L:14D had a higher total large white follicle weight, small yellow follicle number, and weight (P < 0.05). In addition, higher serum levels of follicle-stimulating hormone, luteinizing hormone, and progesterone were observed with ≥10-h photoperiods (P < 0.05), as were levels of hormone receptor mRNA expression in ovarian follicles (P < 0.05), with the highest values for both measures at 10L:14D. In the hypothalamus, mRNA expression of gonadotropin-releasing hormone increased in ≥8-h photoperiods, with the highest value at 10L:14D. In contrast, gonadotropin-inhibitory hormone increased in photoperiods ≥12 h (P < 0.05). In conclusion, an appropriate photoperiod led to early sexual maturity and improved the development of reproductive organs and ovarian follicles through effects on reproductive hormones and their receptors; 10 to 10.24 h is an adequate photoperiod for layer ducks during the pullet phase.

Effect of Lactobacillus Plantarum Supplementation on Production Performance and Fecal Microbial Composition in Laying Hens

The present study was performed to investigate the effects of dietary supplementation with Lactobacillus plantarum (CGMCC1.557) on egg production and fecal microbiota composition in laying hens. Sixty Hy-Line Brown laying hens (18 weeks old) were randomly divided into two groups. The control group was fed a basal diet only, and the test group was fed basal diet supplemented with a final concentration of 1.0 × 109 CFU/mL during the 10-week experimental period. Egg production and fecal microbiota composition were both assessed in 28-week-old hens using high-throughput sequencing technology. The results showed that, compared with the control group, the test group exhibited increased laying and feed intake rates (p < 0.05). At the genus level, Lactobacillus was more abundant in the test group compared with the control group (p < 0.05). Conversely, Romboutsia was more abundant in the control group compared with the test group (p < 0.05). This study provides us with an insight into the potential use of L. plantarum as a food supplement in the laying hen industry. the study also provides us with a better understanding of the interplay between L. plantarum and the fecal microbiota of laying hens.

Effects of rearing systems on reproductive hormones secretion and their receptors gene expression in Xianju chickens under summer conditions

Previous study in our lab showed that indigenous Xianju chickens from free-range system (FRS) under summer conditions had lower egg production than those from conventional cage rearing system (CRS). The objective of this study was to preliminarily determine the FRS-dependent mechanism of depressing laying performance according to determining the effect of rearing systems on reproductive hormones secretion and their receptors mRNA expression in Xianju chickens reared under summer conditions. A total of 360 indigenous Xianju chickens were randomly allocated to CRS and FRS groups, each of which included 5 replicates of 36 hens. The experiment lasted between 21 and 29 wk of age. We found that the ovarian weight, numbers of small yellow follicles, and large white follicles in the FRS group were lower than those in the CRS group (P < 0.05). Changing from CRS to FRS increased serum concentrations of prolactin and decreased serum-luteinizing hormone and progesterone levels (P < 0.05). Gene expressions in the preovulatory follicles from FRS hens were upregulated for prolactin receptor and downregulated for luteinizing hormone receptor and progesterone receptor, compared to those from CRS hens (P < 0.05). It can be concluded that changing from CRS to FRS in the current experimental conditions depressed egg production traits in Xianju chickens by inducing a synergistic activity of reproductive hormones and the gene expressions of their receptors.

Interferon-γ acts as a regulator in the trade-off between phagocytosis and production performance in dwarf chickens

Background

Interferon-γ (IFN-γ) is critical for innate and adaptive immunity against viral and bacterial infections. IFN-γ reportedly affects the phagocytic ability of monocytes and macrophages as well as regulates pituitary function in humans and mice. The present study analyzed the impact of IFN-γ on monocyte and macrophage phagocytosis, production performance, and pituitary function in vivo and in vitro (in dwarf chickens). IFN-γ was injected into dwarf chickens through a vein, and then, the laying rate, average egg weight, and levels of follicle-stimulating hormone (FSH) and IFN-γ were measured in treatment and control groups. For the in vitro experiment, the pituitary tissues were supplemented with IFN-γ, and the mRNA expression levels of follicle-stimulating hormone beta subunit (FSH-β), interferon gamma receptor 1 (IFNGR1), and interferon gamma receptor 2 (IFNGR2) in the pituitary were assessed.

Results

Monocyte and macrophage phagocytosis product (PP) was decreased by IFN-γ treatment in a dose-dependent manner in vitro. In the in vivo experiment, the level of IFN-γ in the treatment group was higher than that in the control group at 7 d (P < 0.05), 14 d (P < 0.01), and 21 d (P < 0.01) post-injection. Compared with the control group, monocyte and macrophage PP was lower in the treatment group after injection (P < 0.01). The laying rate was higher in the treatment group than in the control group at 2 and 3 wk post-injection (P < 0.05). There was a significant difference between the treatment and control groups in the levels of FSH at 1, 3, 7, and 14 d post-injection (P < 0.01). In the in vitro experiment, increased mRNA expression levels of FSH-β, IFNGR1, and IFNGR2 were observed in the treatment group after stimulation with 100 U/mL IFN-γ for 24 h compared to those in the control group (P < 0.05).

Conclusions

IFN-γ inhibited the phagocytosis of monocytes and macrophages; up-regulated the mRNA expression levels of the FSH-β, IFNGR1, and IFNGR2; enhanced the secretion of FSH; and improved the laying rate. IFN-γ might be an important regulator in the trade-off between the immune effect and production performance in dwarf chickens.