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1. The Wnt signalling pathway is centred on the fact that catenin beta-1(CTNNB1) participates in the regulation of ovarian follicle development. The aim of the following study was to identify polymorphisms in the 5ʹ regulatory region of the chicken CTNNB1 gene and evaluate the association between SNPs and egg production traits. 2. The study demonstrated that the 5ʹ regulatory region of the CTNNB1 gene has 10 SNPs in the investigated Jining Bairi chickens. After Bonferroni correction for multiple testing, five SNPs (rs315692306, 2:g43385123, rs735854102, 2:g43385457 and rs737907370) were significantly correlated with egg laying traits. 3. An association study of the haplotypes with egg laying traits revealed that both haplotypes in block 1 (consisting of rs735052881, rs740662190, rs315692306, and 2:43385123) and block 2 (consisting of rs735854102 and 2:g43385457) were associated with point of lay age and the number of eggs laid at 18–23 weeks. Prediction of transcription factor-binding sites showed that transcription factors changed after mutation in block 2. The luciferase assay revealed that the priming activity of the CA haplotype in block 2 was the highest. 4. Taken together, the rs315692306, 2:g43385123, rs735854102, 2:g43385457 and rs737907370 in the 5ʹ regulatory region of the CTNNB1 gene have significant impacts on egg production. [ABSTRACT FROM AUTHOR]

This study investigated the factors that caused the differences in egg production during the development of ovarian follicles in Leizhou black ducks. Leizhou black ducks population was divided into 2 groups as high-yield group (HG) and low-yield group (LG). The number of eggs (NE), age at first egg (AFE), weight at first egg, and egg weight (EW) of both groups were recorded, and differences were analyzed using the t test. The logistic model was used to simulate the egg production curves to analyze the production rules. The ovarian follicles of both duck groups were collected to count the number of different grades sized follicles, weigh the ovaries, and observe follicular sections to analyze the developmental differences. Ovarian transcriptomic sequencing was performed to investigate differentially expressed genes and signal pathways in both duck groups. The results revealed a significant difference (P

The aim of our study was to compare laying characteristics and egg weight of three different Oravka hen lines (OR 1, OR 2, OR 3) during two years. Hens were kept outdoor in a heatless hen-house with a covered yard. Feeding and watering were ad libitum. They were fed with a standard feed mixture with 11.7 MJ ME and 200.0 g NL. Basic statistics for average laying per hen and laying intensity (%) was done for each Oravka line indicating that these characteristics tended to be higher in year 2017 than in year 2018. The statistical model for egg weight included effects of line, month of laying and interaction line x month of laying. Data were analysed separately for each year. Only line (genotype) had significant effect on egg weight, the remaining effects were not significant. In year 2017 the highest egg weight had line OR 3 (58.61 ± 0.30 g), the lowest egg weight had line OR 1 (57.32 ± 0.31 g), (P = 0.010). In year 2018 the highest egg weight had line OR 1 (60.64 ± 0.33 g), the lowest egg weight had line OR 3 (58.72 ± 0.37 g), (P = 0.005). [ABSTRACT FROM AUTHOR]

Copyright of Journal of the Chinese Society of Animal Science is the property of Chinese Society of Animal Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of the Chinese Society of Animal Science is the property of Chinese Society of Animal Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of the Chinese Society of Animal Science is the property of Chinese Society of Animal Science and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present study was carried out with the aim of estimating genetic parameters as well as evaluating genetic improvement in Iranian native chickens to assess the effectiveness of selection programs performed in Azerbaijan native fowl breeding station. The data on pedigree and performance was collected through five consecutive generations consisted of 4400 hens and roosters. Considered traits were body weight at week 12 (BW12), total number of eggs laid during the first 12 weeks after flock maturity (EN), mean egg weight at 28, 30 and 32 weeks (MEW) and age at sexual maturity (ASM). The (co) variance components, heritabilities, correlations between traits as well as breeding values were estimated through univariate and bivariate animal models using WOMBAT software. Heritability estimates for BW12, EN, MEW and ASM, using four different univariate animal models, were 0.25±0.08, 0.18±0.05, 0.24±0.03 and 0.43±0.07, respectively. A bivariate animal model was applied to estimate genetic correlations between traits. Genetic correlations were in a range from-0.10 to -0.63. The highest and lowest genetic correlation were between ASM and MEW (0.30± 0.06) and ASM and EN (-0.63± 0.02), respectively. Regression coefficient of average breeding values on generation number were positive and significant for BW12 and EN, indicating positive trend that confirmed genetic progress in these traits. However, MEW as well as ASM responded negatively to genetic improvement. [ABSTRACT FROM AUTHOR]

A selective breeding program was implemented to improve the performance of indigenous chickens. Improved chicken from the 7th generation was compared with commercial layer, crossbred and unselected indigenous chickens both on-station and on-farm. A total of 870 chickens were used. More than 600 chickens ( n =150 and n =120 from each breed during growing and laying period respectively) arranged in completely randomized design were followed on-station, and 270 (90 from commercial, crossbred and improved during laying period) were evaluated on-farm in Ada ( n =6 farms) and Horro ( n =9 farms) districts in a split-plot design. Body weight, cumulative feed intake, and survival were recorded while feed conversion ratio was calculated at week 8, 12, 16 and 20 during the growing period on-station. Age at first egg and total egg number during lifetime were recorded once. Survival and hen housed egg production were recorded at month 3, 6, 9 and 12 of age both on-station and on-farm. Egg weight, and feed per egg were recorded and used to calculate feed conversion ratio during the laying period on-station. Significant effect of breed ( P <0.001) and interaction with time ( P <0.001) was observed for traits measured on-station during the growing and laying period. Similarly significant effect of breed, village and breed–village interactions were observed on-farm ( P <0.001). Improved indigenous chickens had higher performance than indigenous chickens for all traits measured on station ( P <0.05). 10 farmers out of 16 in the Ada district and 7 out of 16 in the Horro district dropped out after month 3 at different times either due to high chicken mortality or reduced motivation of the farmer. Improved chickens have been genetically improved as compared to unimproved, but their performance is still low compared to commercial chickens. [ABSTRACT FROM AUTHOR]

Vitellogenin (Vtg) is a large precursor molecule of the two major egg yolk phosphoproteins, namely; lipovitellin and phosvitin. All of the vitellogenic zinc is found in lipovitellin. Several reports had speculated into the probable relationships of Vtg with reproductive phenotype of Philippine Mallard duck (Anas platyrhynchos domesticus L.). Hence, it was hypothesized to use the Vtg profile as a nonlethal physiological index of reproductive performance in Philippine Mallard duck. Forty ducks, aged 16 weeks old, were randomly assigned into two treatment groups: 20 ducks fed with 30 ppm zinc-diet (zinc positive) and 20 ducks fed with no added zinc (zinc negative). All ducks were kept individually in cages. The circulating Vtg at sexual maturity (155.11±10.83 days old) was determined from the blood sera. The sera were assayed for Vtg in duplicate using 96-well microplate and the optical density was read at 415 nm. Results show that the circulating Vtg in the blood sera of ducks at sexual maturity was 0.69±0.07 µg Zn/dl. This circulating Vtg was identified to have negatively very weak to weak linear correlation with the majority of the laying traits (11 out of 17) in Philippine mallard duck. [ABSTRACT FROM AUTHOR]

Abstract: The objective was to characterize the potential laying traits and underlying transcripts expressed in the hypothalamus and pituitary gland that were associated with egg production variability in five genetic stocks of chickens: two commercial lines, Red- (n =12) and Black-feather (n =14) Taiwan country chickens (TCCs); two selected lines of TCCs, B (high body weight/comb size; n =17) and L2 (high-egg production; n =14); and a commercial single comb White Leghorn (WL; n =17). Six laying traits, age at first egg, clutch length, pause length, oviposition lag within clutch, follicle rapid growth period, and rate of yolk accumulation were measured. The significance of differential values among five chicken stocks and correlation coefficients between laying traits and number of eggs to 50 weeks of age or laying rate after first egg, and the expression level of 33 transcripts were determined. Longer clutch length and shorter oviposition lag within clutch contributed to a higher number of eggs to 50 weeks of age or laying rate after first egg in L2 (P <0.05) and WL strains (P <0.05). However, their rate of yolk accumulation (P <0.05) and follicle rapid growth period (P <0.05) were different, indicating the accumulation of different alleles after long-term, independent selection. Across all five strains, numbers of eggs to 50 weeks of age were positive correlated with average clutch length (P <0.05) as well as the rate of yolk accumulation (P <0.05). Expressions of PLAG1, STMN2, PGDS, PARK7, ANP32A, PCDHA@, SCG2, BDH and SAR1A transcripts contributed to number of eggs to 50 weeks of age (P <0.05) or laying rate after first egg (P <0.05). Analysis of correlation coefficients indicated that PLAG1 additionally played roles in decreasing average pause length. Two transcripts, PRL and GARNL1, specifically contributed to number of eggs to 50 weeks of age or laying rate after first egg by reducing oviposition lag within clutch (P <0.05) and/or increasing average clutch length (P <0.05), respectively. Expression level of NCAM1, contributed to laying rate after first egg by association with a shorter oviposition lag within clutch (P <0.05). The current study attributed egg production phenotype in five strains into several laying traits; correlations between these traits and expression levels of underlying transcripts expressed in the hypothalamus and pituitary gland were also established. [Copyright &y& Elsevier]

This study investigated the factors that caused the differences in egg production during the development of ovarian follicles in Leizhou black ducks. Leizhou black ducks population was divided into 2 groups as high-yield group (HG) and low-yield group (LG). The number of eggs (NE), age at first egg (AFE), weight at first egg, and egg weight (EW) of both groups were recorded, and differences were analyzed using the t test. The logistic model was used to simulate the egg production curves to analyze the production rules. The ovarian follicles of both duck groups were collected to count the number of different grades sized follicles, weigh the ovaries, and observe follicular sections to analyze the developmental differences. Ovarian transcriptomic sequencing was performed to investigate differentially expressed genes and signal pathways in both duck groups. The results revealed a significant difference (P < 0.01) in the NE laid, AFE, and EW between both groups. Comparatively, HG had significantly more (P < 0.01) large yellow follicles (LYF) than LG. The density of medullary layer cells of the follicle section was greater in HG than LG ducks. Transcriptome sequencing revealed a total of 1,027 differentially expressed genes between the HG and LG ducks of which 495 genes were upregulated, and 532 genes were downregulated. Fifty genes were related to reproduction and reproductive processes. Kyoto Encyclopedia of Genes and Genomes-enriched signaling pathways revealed 274 signal pathways enriched in these differentially expressed genes of which the steroid biosynthesis pathway was significantly enriched. Analysis (Q < 0.05) showed that HSD3β → gonadotropin-releasing hormone (GnRH) and estrogen receptor (ESR) → LHβ/ERK1/2 were enriched in the steroid biosynthesis signal pathway. Follicle-stimulating hormone signal pathway mediated by HSD3β → GnRH and ESR → LHβ/ERK1/2 may be involved in ovarian follicle development to regulate LYF reserve process and affect its ovulation cycle, which in turn influence the egg production of Leizhou black ducks., (Copyright © 2020. Published by Elsevier Inc.)