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Simple Summary: Autosexing based on sex-linked phenotypes of late feathering (LF) and early feathering (EF) was widely used in poultry production. Previous studies found that tandem duplication on the Z chromosome is responsible for LF. In this study, based on tandem duplication, we developed a multiplex PCR test for genotyping through reaction optimization. The genotyping result for feathering rate with the multiplex PCR test was consistent with the sex and phenotype records, and the result of homozygote and heterozygote tests of LF males were verified by test cross and tallied with offspring's phenotypes. The multiplex PCR test is stable and accurate for feathering rate genotyping, applicable to all LF chickens associated with tandem duplication, and has great significance for poultry breeding. Sex-linked phenotypes of late feathering (LF) and early feathering (EF) are controlled by a pair of alleles K and k+. Autosexing based on the feathering rate is widely used in poultry production. It is reported that a tandem duplication of 176,324 base pairs linked to the K locus is responsible for LF expression and could be used as a molecular marker to detect LF chicken. So far, there is no genotyping method that can accurately and stably identify the LF homozygote and heterozygote in all chicken breeds. In the present study, a multiplex PCR test was developed to identify EF, LF homozygote, and heterozygote according to electrophoretic bands and the relative height of the peaks by Sanger sequencing. We tested 413 chickens of six native Chinese breeds with this method. The identification was consistent with the sex and phenotype records of the chickens. Band density analysis was performed, and the results supported our genotyping using the new assay. In order to further verify the accuracy of this test in distinguishing homozygote and heterozygote males, 152 LF males were mated with EF females, and the results of the offspring's phenotypes were consistent with our expectations. Our results support tandem duplication as molecular markers of LF, and this new test is applicable to all LF chickens associated with tandem duplication. [ABSTRACT FROM AUTHOR]

Simple Summary: n-3 PUFA, selenium and lutein cannot be synthesized in the human body, but these substances are very important for human health. Consuming functional eggs enriched with nutrients can increase the body's intake of these substances. To efficiently produce functional eggs, selecting breeds that can deposit higher levels of these nutrients is necessary. Therefore, we investigated the types, dosages, and cycles of additives used in the production of functional eggs. In Trial 1, we investigated the differences in n-3 PUFA deposition among five breeds of eggs. The results showed significant variations in the ability of different breeds to deposit n-3 PUFA in eggs, with Dwarf Layer demonstrating a significant advantage. In Trial 2, we investigated the difference of n-3 PUFA, selenium and lutein deposition in eggs from two reeds in terms of their ability to deposit selenium and lutein in eggs. Additionally, the n-3 PUFA content in eggs from the two breeds was similar to the findings in Trial 1. Therefore, this experiment provides valuable insights for selecting different breeds in the production of functional eggs, ultimately improving the quality and economic benefits of the production process. The purpose of this study was to compare the differences in the content of functional nutrients in eggs, performance parameters, and egg quality parameters of different chicken breeds. In Trial 1, 150 41-week-old hens of each breed, including the Dwarf Layer, White Leghorn, Silky fowl, Beijing-you chicken, and Shouguang chicken, were randomly assigned to the control (CON) and 2.5% flaxseed oil (FSO) groups to compare the difference in n-3 polyunsaturated fatty acid (PUFA) content in eggs. The contents of α-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and total n-3 PUFA in eggs were increased (p < 0.05) in the FSO groups. The ALA (4.28%), DHA (2.03%), and total n-3 PUFA (6.46%) contents in eggs of Dwarf Layer were the highest among the five breeds (p < 0.05). To further verify if other functional nutrients also have such differences, 600 24-week-old White Leghorn and Dwarf Layer were allocated to four groups: CON, FSO, 0.02% selenium-enriched yeast (SEY), and 0.20% marigold flower extract (MFE), in Trial 2. The content of functional nutrients in eggs was significantly increased (p < 0.05) after feeding these additions. After feeding FSO, the eggs of the Dwarf Layer had a higher n-3 PUFA content than the White Leghorn (p < 0.05). However, no significant differences were found in selenium and lutein content in different breeds. Performance and egg quality were not negatively impacted by FSO, SEY, or MFE. [ABSTRACT FROM AUTHOR]

Simple Summary: Cage size is an essential environmental factor affecting the well-being and performance of hens and thus it is necessary to determine the extent of its contribution. The present study investigated the effects of four different-sized cages, i.e., huge, large, medium, and small cages, on the productive performance, serum biochemical indices, and caecal microbiota composition of Roman laying hens. The results indicated that enlarging cage size has some positive effects on the productive performance, lipid metabolism, and antioxidant capacity of laying hens, while medium cages were superior to large cages in feed conversion efficiency and caecal microflora composition. The effects of four different-sized cages—huge (HC), large (LC), medium (MC), and small (SC) cages—on the productive performance, serum biochemical indices, and caecal microbiota composition of Roman laying hens were investigated. At 44 weeks of age, a total of 450 hens were selected and allocated to the four groups, with six replicates each. Equal stocking density (0.054 m2 per bird) was maintained among the four groups throughout the experiment, and number of birds/cage changed for each treatment. After 2 weeks of preliminary trial, the formal experiment was performed from 46 to 60 weeks of age. The laying rate and feed conversion ratio (FCR) were determined daily, antibody titres were measured every 3 weeks, and serum biochemical parameters and caecal microbiota composition were analysed at 60 weeks of age. Compared to HC and SC, the higher laying rate and lower FCR in MC and LC indicated positive effects on egg production and feed efficiency, while SC showed the highest body weight gain (p < 0.05). With increasing cage size, the serum triglycerides (TG) and total cholesterol (T-CH) levels were reduced, and serum glutathione peroxidase (GSH-Px) activity improved, where birds raised in HCs had the lowest serum TG and T-CH and the highest GSH-Px activity. Twenty-nine different phyla and 301 different genera were detected in the caecal microbiota of birds in the four groups. Methanobrevibacter was significantly higher in the SC than in the other groups (p < 0.05). Faecalibacterium was most abundant in the MC compared with the other groups (p < 0.05) and was significantly positively correlated with serum GSH-Px concentration (R = 0.214, p = 0.0017). Lactobacillus was significantly less abundant in the LC and MC than in the HC and SC groups (p < 0.05) and was significantly positively correlated with body weight (R = 0.350, p = 0.0009) but negatively correlated with laying rate and FCR. In conclusion, MC were superior to HC and LC in improving feed conversion efficiency and caecal microflora composition compared to the SC. An appropriate increase in cage size is beneficial to laying hen production and health. [ABSTRACT FROM AUTHOR]

Simple Summary: The lipid deposition and health status of egg-laying hens is crucial to the development of the poultry industry. This study aimed to evaluate the effects of genetic variations in the flavin-containing monooxygenase 3 (FMO3) on the lipid metabolic diseases of laying hens during the late laying period. The results showed that the T329S mutation in FMO3 moderated the lipid parameters and decreased the atherosclerotic lesions and hepatic steatosis in laying hens with homozygous T329S mutation. In conclusion, the T329S mutation in FMO3 is closely associated with the improvement of lipid metabolic diseases in laying hens during the late laying period. The results of this study may contribute to overcoming the challenge of lipid metabolic diseases in laying hens during the late laying period. The T329S mutation in flavin-containing monooxygenase 3 (FMO3) impairs the trimethylamine (TMA) metabolism in laying hens. The TMA metabolic pathway is closely linked to lipid metabolic diseases, such as atherosclerosis and fatty liver disease. We aimed to evaluate the effects of the T329S mutation in FMO3 on lipid metabolism in chickens during the late laying period. We selected 18 FMO3 genotyped individuals (consisting of six AA, six AT, and six TT hens) with similar body weight and production performance. The lipid metabolism and deposition characteristics of the laying hens with different genotypes were compared. The T329S mutation moderated the serum-lipid parameters in TT hens compared to those in AA and AT hens from 49 to 62 weeks. Furthermore, it reduced the serum trimethylamine N-oxide concentrations and increased the serum total bile acid (p < 0.05) and related lipid transporter levels in TT hens. Moreover, it significantly (p < 0.01) decreased atherosclerotic lesions and hepatic steatosis in TT hens compared to those in the AA and AT hens. Our findings may help improve the health status in laying hens during the late laying period. [ABSTRACT FROM AUTHOR]

Simple Summary: With the increased interest in animal welfare, poultry housing systems have been a concern for the last decade, and conventional cages have been replaced by non-cage systems or enriched cages. However, the environmental conditions in non-cage housing systems and their association with hens' production performance and health have not been studied extensively. Therefore, the present study compared the indoor environmental microbial content in two different non-caged systems, namely, a plastic-net housing system and floor-litter housing system, and investigated its effects on the production performance, serum parameters and intestinal morphology of hens during the peak laying period. The results indicated that the NRS resulted in better indoor environmental air quality and ground hygiene than the LRS and enhanced the production performance, antioxidant capacity and intestinal health of hens, represented by positive changes in the laying rate, serum parameters and intestinal morphology. This study investigated the effects of plastic-net housing system (NRS) and floor-litter housing system (LRS) on the production performance, serum parameters and intestinal morphology of Shendan laying hens. A total of 1200 30-week-old hens were randomly allocated to the NRS and LRS groups, each of which included five replicates with 120 chickens in each replicate. The experiment was conducted from 32 to 40 weeks of age. Indoor airborne parameters were measured every 2 weeks, and indoor ground contamination was measured monthly. The laying rate and mortality of hens were recorded daily, and egg quality traits and serum parameters were measured every 2 weeks. At 40 weeks of age, four birds per replicate from each experimental group were selected for intestinal morphological observation. The results showed that the airborne bacteria number in the LRS was significantly higher than that in the NRS (p < 0.05) for most of the experimental period (except at 32 and 38 weeks of age), and the bacterial numbers on the surfaces of the floor and floor eggs in the LRS were approximately 10 times higher than those in the NRS (p < 0.05). Compared with the LRS, the NRS improved the laying rate (p < 0.05), reduced serum malondialdehyde (MDA) (p < 0.05) and corticosterone (CORT) concentrations and increased serum glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities, indicating favourable effects on antioxidative status. The NRS was significantly associated with an increased villus height (VH), villus height to crypt depth ratio (VCR) in the small intestine (p < 0.05) and increased VCR in the caecum (p < 0.05). Overall, the lower rate of bacterial contamination in the NRS than in the LRS indicated better environmental hygiene. The NRS enhanced the laying performance and antioxidant capacity of hens and was superior to the LRS in improving intestinal health. The current findings support the advantages of the NRS for the health and welfare of Shendan chickens during the peak laying period. [ABSTRACT FROM AUTHOR]

Simple Summary: Although there is an established understanding of the nutritional requirements for poultry production, the evaluation of the feed form for chickens still needs to be further examined. It is generally believed that a pellet diet has a positive effect on chicken growth, but there are some studies that have reported no difference between pellet and mash on chicken's performance. The present study indicated that pellet diets improved the production performance and nutrition metabolism through positive changes in the laying rate, feed intake, egg albumen quality and apparent digestibility of laying hens. One of the most important factors that determine feed utilization by chickens is the feed form. Although it is generally believed that pellet diets have a positive effect on chicken growth, there are some studies that have indicated no difference between pellet and mash on chickens performance. This study was conducted to assess the effects of feed form on production performance, egg quality, nutrient metabolism and intestinal morphology in two breed laying hens. Two hundred and sixteen 25-week-old Hy-Line brown (n = 108) and Hy-Line grey (n = 108) hens were selected. Each breed was randomly allocated into two treatments with 6 replications (9 birds in each replication), which were fed mash and pellet diets, respectively. Production performances were recorded daily and egg quality traits were measured every two weeks. At 42 weeks of age, one bird per replication from each experimental group was selected for metabolism determination and intestine morphology observation. Compared with mash diets, pellet diets improved laying rate (p < 0.05), ADFI (average daily feed intake, p < 0.05), egg weight, shell strength, yolk proportion and Haugh unit (p < 0.05) in both breeds and reduced the FCR (feed conversion ratio, p < 0.05) in Hy-Line grey. The apparent digestibility of DM% (dry matter) and CP% (crude protein) were significantly higher (p < 0.05) in both breed laying hens fed pellet than those fed mash. The apparent digestibility of P% (phosphorus) and Ca% (calcium) was higher in Hy-Line grey fed pellet and was higher in Hy-Line brown fed mash. Compared to mash diets, pellet diets increased the VH (villus height), CD (crypt depth) and VCR (ratio of villus height to crypt depth) of the small intestine of Hy-Line grey, and increased the VH and CD of duodenum and ileum of Hy-Line brown. Overall, pellet diets improved production performance and nutrition metabolism through positive changes in the laying rate, feed intake, egg albumen quality and apparent digestibility of laying hens. The current findings provided support for the advantages of feeding pellets during the peak egg laying period for the two popular laying hen strains, Hy-Line brown and Hy-Line grey. [ABSTRACT FROM AUTHOR]