A Salmonella Pullorum outbreak with neurological signs in adult layers and outbreak investigation using whole genome sequencing.

RESEARCH HIGHLIGHTS: Cerebral granulomas are associated with nervous signs in Salmonella Pullorum outbreak.Bone marrow is also a recommended tissue for isolation of Salmonella Pullorum.Rapid plate agglutination test detects Pullorum antibodies in a vaccinated flock.Phylogenetic analysis showed clonality of isolates within the outbreak.

Effects of quercetin and genistein on egg quality, lipid profiles, and immunity in laying hens.

BACKGROUND: After the peak laying stage, laying hens become susceptible to lipid accumulation and inflammatory reactions. The objective of this experiment was to examine the impact of quercetin and genistein on egg quality and lipid profiles in laying hens. A total of 240 Hy-Line Brown hens were randomly assigned to three dietary treatments. Each treatment had eight replicates, with ten hens in each replicate, and the hens were aged between 46 and 56 weeks. The test diets consisted of a corn-soybean meal-based basal diet, a basal diet supplemented with 300 mg kg-1 quercetin, and a basal diet supplemented with 300 mg kg-1 quercetin and 40 mg kg-1 genistein. RESULTS: Results showed that, separately, supplemental quercetin significantly improved egg quality (eggshell strength, albumen height, and Haugh unit, P < 0.05) and reduced the deposition of abdominal fat (P < 0.05). Our findings also showed that, separately or as a combination, supplemental quercetin and genistein significantly increased eggshell thickness (P < 0.05), decreased the levels of lipids in serum (low-density lipoprotein cholesterol, total cholesterol, total triglycerides, and non-esterified fatty acids, P < 0.05) and significantly increased serum immunoglobulins A and G (P < 0.05), and promoted the expression of splenic immune-related genes (IgA and IL-4, P < 0.05). CONCLUSION: This study confirmed that supplemental quercetin and genistein, either separately or in combination, can enhance eggshell thickness, lipid profiles, and immune function in aging hens. Moreover, both quercetin alone and quercetin + genistein exhibited similar abilities to lower lipid levels and improve immune function. © 2023 Society of Chemical Industry.

Effects of a mixture of glycerol monolaurate and cinnamaldehyde supplementation on laying performance, egg quality, and antioxidant status in laying hens.

BACKGROUND: This study aimed to determine the effects of a mixture of glycerol monolaurate and cinnamaldehyde (GCM) supplementation on the laying performance, egg quality, antioxidant capacity, and serum parameters of laying hens. A total of 1120 14-week-old Jingfen-1 strain laying hens with similar performance were randomly allocated to four dietary treatments: control, and GCM groups supplemented with 250, 500, or 1000 mg kg-1 for 12 weeks. RESULTS: Compared with the control group, GCM-supplemented groups significantly reduced (P < 0.05) the rate of unqualified eggs of laying hens aged 17-24 weeks. Supplementation of GCM significantly increased (P < 0.05) yolk color and serum glutathione peroxidase (GSH-Px) activity but decreased (P < 0.05) the hydrogen peroxide (H2 O2 ) content in the serum of laying hens at the age of 20 weeks. Furthermore, groups supplemented with GCM showed a significant increase (P < 0.05) in Haugh unit, yolk color, activities of total superoxide dismutase and GSH-Px, and the glucose content in serum, and a decrease (P < 0.05) in the content of urea nitrogen and H2 O2 and malondialdehyde in serum of laying hens at the age of 24 weeks. 500 mg kg-1 GCM supplementation significantly increased (P < 0.05) the number of large white follicles and 1000 mg kg-1 GCM supplementation decreased the number of large yellow follicles in 28-week-old laying hens. CONCLUSION: These results indicated that GCM supplementation has positive effects on reducing egg loss and improving egg quality in the early laying period of laying hens. © 2023 Society of Chemical Industry.

Effect of limestone particle size and microbial phytase on phosphorus and calcium digestion kinetics along the gastrointestinal tract in laying hens.

1. This study assessed the effect of limestone particle size and microbial phytase incorporation on the fate of phosphorus (P) and calcium (Ca) along the gastrointestinal tract in 72 laying hens.2. Four experimental diets were formulated according to a 2 × 2 factorial arrangement to evaluate the effect of two coarse limestone (CL) inclusion. This included a mix (MIX) of 75% CL (2 - 4 mm) and 25% fine particles (FL, <0.5 mm) or 100% FL, in two different basal diets formulated without (MIX0 and FL0) or with 300 FTU of microbial phytase/kg (MIX300 and FL300).3. Contents of the crop, gizzard, duodenum, jejunum and ileum were collected to determine the mean retention time (MRT) of dry matter (DM), the recovery rate of Ca and P in each segment of the gastrointestinal tract and the apparent fractional digestibility coefficient (AD) of Ca and P in each intestinal segment.4. In hens fed FL, microbial phytase decreased the MRT of DM along the intestine (p < 0.05). In the crop and the gizzard, Ca recovery increased with MIX incorporation to a greater extent in hens fed without microbial phytase (p < 0.05). The mixed particle size incorporation decreased absorption kinetics of Ca in hens fed microbial phytase. The AD of P and the absorption kinetics of P were significantly decreased in hens receiving FL300, probably due to complex formation between Ca and phytic acid.5. This study showed that coarse limestone particles incorporation improved mineral utilisation along the digestive tract.

Effects of graded levels of dietary microbial 6-phytase on performance, intestinal histomorphology, caecal microbial population and short-chain fatty acid composition of Lohmann white-classics.

1. This study was conducted to determine the effects of graded levels of phytase on the performance, egg quality and gut health of white laying hens.2. Treatments consisted of a negative control (NC) diet containing 0.14% available phosphorus (avP), positive control (PC) diet containing 0.35% avP provided via dicalcium phosphate (DCP) and DCP replaced in the PC by with three graded levels of phytase derived from Komagataella phaffii at 500 (PC-500), 750 (PC-750) and 1000 (PC-1000) FTU/kg which provided 0.176%, 0.188% and 0.200% of avP, respectively.3. Egg production, feed intake, feed conversion ratio and jejunal morphometry were negatively affected in NC-fed birds (p < 0.05). Considering the whole period, birds fed a diet supplemented with graded levels of phytase shared the same egg production and feed intake levels with PC birds (p < 0.05). Feed conversion ratio was significantly lowered by 4.9%, 1.6% and 7.6% in hens fed on diets PC-500, PC-750 and PC-1000, respectively compared to those fed the PC (p < 0.05).4. Neither of the dietary treatments affected cracked eggs, dirty eggs, eggshell breaking strength and eggshell thickness. Dietary supplementation of phytase significantly increased villus surface area by 15%, 36% and 40% in PC-500, PC-750 and PC-1000 birds, respectively compared to PC (p < 0.05).5. A significant increase in lactobacillus count was observed in line with increasing the level of phytase (p < 0.05). Dietary treatments had no effect on the caecal coliform or aerobic populations. Furthermore, phytase supplementation significantly increased the concentrations of total caecal short-chain fatty acid (SCFA; p < 0.01).6. In conclusion, along with improving performance parameters, the inclusion of phytase in laying hen diets can ameliorate intestinal morphology and stimulate caecal microflora and increase SCFA concentrations.

The effect of thermostable and enteric-coated multi-protease on the performance and digestibility of laying hen fed low-protein diets.

This study evaluated the efficacy of a multi-protease on the performance, egg quality and digestibility of laying hen. The study had four treatments: Control (without multi-protease, CON), Pro 1.2 (CON + 0.1% multi-protease), Pro 2.4 (CON + 0.2% multi-protease) and Pro 3.6 (CON + 0.3% multi-protease). Each treatment was replicated six times (replicate = experimental unit = one pen with 15 hens) to give a total of 360 layer hens of the Hy-line breed. The study lasted for a total of 3 months (14 day adaptation period + 84 days experimental period). The effects of the additive were assessed on: the performance variables, egg quality and ileal amino acid (AA) digestibility. At the end of the study, dietary supplementation with Pro 2.4 and Pro 3.6 improved (p < 0.05) hen-day egg production, egg mass and eggshell thickness compared with CON at the peak phase. Further improvements (p < 0.05) were observed in the digestibility of crude protein and AAs such as isoleucine, lysine, threonine and cysteine at Pro 2.4 and Pro 3.6 protease supplementation levels compared with CON, while arginine and alanine were higher (p < 0.05) at Pro 3.6 compared with CON. No differences were reported for other performances such as body weight, average daily feed intake, average egg weight, feed conversion ratio, eggshell hardness and all the egg qualities measured. Overall, the results from this study showed better efficacy at Pro 2.4 and Pro 3.6 on the performance of laying hen during the peak phase.

Effect of monosodium glutamate supplementation in diet on fatty acid profiles, genes expression related to lipid metabolism and egg yolk cholesterol in late phase of production in laying hens.

In an experiment with four treatments and five replicates, the effects of adding monosodium glutamate (MSG) to the diet in late phase of egg production was studied on performance, and lipid metabolism in laying hens. Dietary treatments included the control basal diet without MSG and the other treatments adding 0.4%, 0.8% and 1.2% MSG in the control diet respectively. The effect of supplementation of MSG on egg weight, egg production, feed conversion ratio and egg mass was insignificant (p < 0.05). Adding MSG to the diet significantly increased feed intake and blood polyunsaturated fatty acids concentration (p < 0.05). Intake of 0.8% and 1.2% MSG in the diet up regulated the mRNA expression of acetyl-coenzyme A carboxylase, fatty acid synthase and lipoprotein lipase in the abdominal and liver tissues in comparison to the control group. Blood very low-density lipoprotein-cholesterol, triglycerides and cholesterol concentration were increased in treatment fed with a diet containing 0.8% MSG compared to the control group (p < 0.05). The effect of MSG on total egg yolk cholesterol concentration was not significant. In conclusion, the results of the present experiment indicated that adding MSG increased feed intake and blood polyunsaturated fatty acid concentration.

Assessing the influence of micelle silymarin on laying hens' performance, egg quality, water loss and blood profile.

Micelle silymarin (MS) is known for its various beneficial properties, including antiswelling, antioxidant, hepatoprotective and antidiabetic effects. The primary goal of this research was to investigate how MS impacts the performance, egg quality, water loss and blood profile of laying hens. 288 Hy-Line brown laying hens, 28 weeks in age, were utilized for this experiment. The hens were randomly allocated into three dietary treatment groups, with each group comprising eight replicates of 12 hens, each housed in individual pens with access to feed and water. Over a 12-week feeding trial, the hens were provided with a basal diet supplemented with different levels of MS: 0%, 0.03% and 0.06%. The results indicated that the inclusion of MS in the hens' diet did not have a significant impact on their performance (p > 0.05). However, Haugh units, egg weight and eggshell strength showed a linear improvement (p < 0.05) throughout the entire trial period with MS supplementation. Furthermore, there was a linear decrease in egg yolk colour and eggshell thickness showed linear improvements (p < 0.05), particularly during Week 8, with MS supplementation. Moreover, layers fed diet supplemented with MS showed a linear increased (p < 0.05) in albumen height and eggshell thickness in Week 12. In addition, egg water loss during Week 12, the third day of incubation, linearly decreased as an effect of the increasing level of the MS in the laying hen's diet (p < 0.05). Regarding blood profile parameters, the study revealed a tendency for alkaline phosphatase to decrease, whereas aspartate aminotransferase and cholesterol levels were linearly decreased (p < 0.05). In summary, increasing the level of MS supplementation in the diet of laying hens appeared to be beneficial in improving egg quality, slight improvement for egg water loss and certain aspects of blood profile parameters, without adversely affecting the hens' growth performance.

Heavy metal contamination in eggs on poultry farms and ecological risk assessment around a gold mine area in northern Thailand.

The aim of this study was to analyze and compare the Hg, Pb, Cd, and Mn levels in egg feed, soil, and water among laying hens, laying ducks, and free-grazing duck farms in contaminated and uncontaminated areas. This study revealed that the Hg concentration in the eggs of free-grazing ducks was significantly greater than that in the eggs of laying hens and ducks in both contaminated and uncontaminated areas. However, the Pb and Mn levels in the eggs of laying ducks and free-grazing ducks were significantly greater than those in the eggs of laying hens in the contaminated area. Unfortunately, the Hg, Pb, Cd, and Mn concentrations in the feed, soil, and water from these three farms in both areas were not significantly different (P > 0.05). Hg and Cd were confirmed to be enriched in the egg albumin fraction, while Pb and Mn were found mainly in the egg yolk. However, egg consumption from free-grazing duck farms was the riskiest to Hg, Pb, and Mn contamination in the contaminated area. Additionally, the ecological risk factor (ER) in the soil revealed that all the farms were at considerable to high environmental risk for Cd except for Hg and Pb. Although the potential ecological risk index (RI) indicated a moderate risk for all farms in both contaminated and uncontaminated areas, these results were not consistent with our hypothesis. Therefore, the information gained in this study could be useful for setting up mitigation strategies and making decisions about public health concerns related to health hazards, especially for ecological risk assessments of heavy metal contamination.

Antimicrobial resistance characteristics and phylogenetic relationships of pleuromutilin-resistant Enterococcus isolates from different environmental samples along a laying hen production chain.

Antimicrobial resistance in the laying hen production industry has become a serious public health problem. The antimicrobial resistance and phylogenetic relationships of the common conditional pathogen Enterococcus along the laying hen production chain have not been systematically clarified. 105 Enterococcus isolates were obtained from 115 environmental samples (air, dust, feces, flies, sewage, and soil) collected along the laying hen production chain (breeding chicken, chick, young chicken, and commercial laying hen). These Enterococcus isolates exhibited resistance to some clinically relevant antibiotics, such as tetracycline (92.4%), streptomycin (92.4%), and erythromycin (91.4%), and all strains had multidrug resistance phenotypes. Whole genome sequencing characterized 29 acquired antibiotic resistance genes (ARGs) that conferred resistance to 11 classes of antibiotics in 51 pleuromutilin-resistant Enterococcus isolates, and lsa(E), which mediates resistance to pleuromutilins, always co-occurred with lnu(B). Alignments with the Mobile Genetic Elements database identified four transposons (Tn554, Tn558, Tn6261, and Tn6674) with several ARGs (erm(A), ant(9)-la, fex(A), and optrA) that mediated resistance to many clinically important antibiotics. Moreover, we identified two new transposons that carried ARGs in the Tn554 family designated as Tn7508 and Tn7492. A complementary approach based on conventional multi-locus sequence typing and whole genome single nucleotide polymorphism analysis showed that phylogenetically related pleuromutilin-resistant Enterococcus isolates were widely distributed in various environments on different production farms. Our results indicate that environmental contamination by antimicrobial-resistant Enterococcus requires greater attention, and they highlight the risk of pleuromutilin-resistant Enterococcus and ARGs disseminating along the laying hen production chain, thereby warranting effective disinfection.

An exploratory study on the prevalence of neoplasms in two strains of laying hens during an extended production cycle.

There is a trend towards extended periods of lay in the laying hen industry. Extended cycles without a moulting stage gives the opportunity to obtain more eggs from a single hen. However, appropriate management and care for older laying hens is needed. In this trial we assessed the prevalence of conditions in old laying hens with a focus on neoplastic diseases. In total 150 ISA Brown and 150 Dekalb white laying hens were selected at 86 weeks of age. Of each hen line, 75 hens were necropsied at 86 weeks of age; the other half were monitored for 44 weeks after which they were necropsied. At week 86, 15.3% of the hens suffered from a neoplasm, ISA Brown being the most affected. During the follow up period, 50 birds died because of a natural cause of which 20 hens showed signs of a neoplasms. At the end of the follow up period, 43% of the hens were affected by a neoplasm. Adenocarcinoma was the most prevalent neoplasm and equally distributed among both hen lines. Leiomyomas were most frequently observed in ISA brown hens. Among causes of death, 19.05% of ISA brown and 20.69% of Dekalb White was attributed to a neoplasm. Furthermore, link with ovarian activity and other pathologies were made with significant correlations between adenocarcinomas and inactive ovaries. In conclusion, this study shows that the prevalence of adenocarcinoma and leiomyoma is a factor to be considered in longer laying cycles with 1/5th of the mortality caused by these processes.RESEARCH HIGHLIGHTSAt 86 weeks of age, the prevalence of neoplasms was 15.3%, mainly in brown hens.At 130 weeks of age, 43% of the hens were affected by a neoplasm.Adenocarcinoma was the most prevalent neoplasm equally distributed among hen lines.Leiomyoma was the second most prevalent neoplasm, mainly found in brown hens.

The Gordon Memorial Lecture: Laying hen welfare.

Preference tests remain a useful tool in the assessment of laying hen welfare and have been used to establish what types of resources and enrichments are most likely to meet the birds' needs. Evidence on the underlying structure of bird preference suggests that hens make stable and reliable choices across time and context. This means that their preferences can also be used as a benchmark in the validation of other welfare indicators. Hens have sophisticated cognitive abilities. They are quick to form associations between events and they are flexible in how they apply their knowledge in different contexts. However, they may not form expectations about the world in the same way as some mammalian species. Limited research in this area to date seems to show that hens judge situations in absolute terms rather than evaluating how a situation may be improving or deteriorating. The proportion of hens housed in cage-free systems is increasing globally, providing birds with greater behavioural freedom. Many of the problems associated with cage-free systems, such as keel bone fractures, mortality and injurious pecking, are slowly reducing due to improved experience and appropriate changes in rearing practices, diet, housing design and alignment of breeding goals. However, much remains to be done. The design and performance of veranda-based systems which provide hens with fresh air and natural light is a promising avenue for future research aimed at optimising hen welfare and improving sustainability.

Amino acid digestibility of insect meals and effects on key bacterial groups in excreta of caecectomised laying hens.

The chemical composition and amino acids (AA) digestibility were determined in insect meals from mealworms, crickets, black soldier fly (BSF) larvae and BSF prepupae, and soybean meal. Six caecectomised laying hens were individually housed in metabolism cages and fed either a basal diet or one of five assay diets. Diets and hens were arranged in a 6 × 6 Latin square design with 6 subsequent periods. In each period, the laying hens were fed their respective diet for 9 d, and excreta samples were quantitatively collected twice daily from day 5 to 8. On day 9, a sterile plastic bag was attached to the cloaca of each hen to collect excreta for microbiota analysis. The AA digestibility of the insect meals and soybean meal were calculated using a linear regression approach. Crude protein (CP) concentrations in crickets and mealworms were higher than the value in soybean meal, BSF prepupae and BSF larvae. Ether extract concentrations were high in the insect meals and low in the soybean meal. The digestibility of most essential AA in soybean meal was higher (p < 0.05) than in crickets and BSF prepupae and not different from AA digestibility in mealworms and BSF larvae (except for arginine and histidine). The gene copy number of Escherichia coli in excreta from hens fed with BSF prepupae was lower (p < 0.05) than those fed with BSF larvae, whereas the gene copy number of Bacillus spp. and Clostridium spp. in excreta from hens fed with crickets was lower (p < 0.05) than those fed with BSF larvae. In conclusion, the chemical composition and AA digestibility varied among insect meals based on insect species and life stage. The high level of AA digestibility of insect meals supports the assessment that insect meals are a suitable feed component for laying hens, but differences in AA digestibility should be considered in diet formulation.

Effects of turmeric (Curcuma longa) powder supplementation in laying hens' diet on production performance, blood biochemical parameters and egg quality traits.

This study aimed to evaluate the effect of turmeric powder (TP) supplementation on laying hens' performance, blood biochemical parameters and egg quality parameters. In total, 144 laying hens (Hy-line W36) ageing 53 weeks were used in this study. Birds were randomly assigned to three treatments (6 replicates, 8 birds in each). The diets contained 0 (control), 0.25, and 0.5% TP based on the maize-soybean meal. It was found that the TP supplementation significantly reduced egg production, weight and mass throughout the experiment (p < 0.05). However, the feed conversion ratio increased (p < 0.05), whereas feed intake remained unaffected. Yolk percentage, height and index reduced, and the yolk colour, accompanied by the egg-shell percentage, increased (p< 0.05) during the first 4 weeks of the experiment. Interestingly, only the albumen pH was affected by TP supplementation during the second 4 weeks (p < 0.05). The serum malondialdehyde level reduced significantly, and the total antioxidant capacity increased in the groups fed on the diets supplemented with TP (p < 0.05). Serum lipids levels, including triglyceride, cholesterol and very-low-density lipoprotein (VLDL), and the yolk triglyceride level reduced due to TP supplementation (p < 0.05). The interactive effect of all three independent factors on the internal quality traits of the stored eggs was significant only for yolk pH (p < 0.05). Thus, TP could be a potential lipid reducing factor, especially triglycerides, and a natural antioxidant in laying hens' diet. However, it may significantly impair the productive performance of laying hens under normal environmental conditions.

Effects of supplemental dried wild leek (Allium scorodoprasum L. subsp. rotundum) leaves on laying performance, egg quality characteristics, and oxidative stability in laying hens.

This study aimed to examine the effect of dietary supplementation of dried wild leek (Allium scorodoprasum L. subsp. rotundum) leaves on laying performance, egg traits, antioxidant status, and oxidative stability in laying hens. For this purpose, a total of 96 Lohmann White laying hens aged 22 weeks allocated into four treatment groups each containing 24 hens. Hens were fed a diet supplemented with 0 (control), 1 (WL1), 2 (WL2), and 3 (WL3) g/kg dried wild leek (DWL) leaves. During the 10-week trial, egg weight was increased and feed efficiency was improved with 2 and 3 g/kg DWL leaves. No significant differences were observed among groups for egg production, feed intake, internal and external egg quality characteristics, and egg yolk cholesterol concentration. Levels of malondialdehyde and total antioxidant-oxidant status of egg yolk were not affected from DWL supplementation. However, 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity was increased and oxidative stress index was decreased in egg yolk. Superoxide dismutase enzyme activity was increased in the group of WL3, and total antioxidant status levels were increased in the groups of WL2 and WL3 in serum. DWL supplementation reduced serum cholesterol concentration significantly. No marked changes were observed in other blood parameters. In conclusion, DWL is considered to be high antioxidant supplement due to having high antioxidant capacity and important bioactive compounds. Dietary supplementation of DWL leaves at 3 g/kg could be a viable and beneficial feed additive to improve egg weight and feed efficiency, increase DPPH radical scavenging activity in egg yolk and antioxidant status of hen. Therefore, the usage of DWL leaves in the laying hen diets will be beneficial for egg producers and poultry nutritionists to produce functional eggs having low cholesterol and high antioxidants.

Bone quality and composition are influenced by egg production, layer line, and oestradiol-17ß in laying hens.

Keel bone fractures are a serious animal welfare problem in laying hens. The aim of the current study was to assess the influence of egg production, oestradiol-17ß, and selection for high laying performance on bone quality. Hens of two layer lines differing in laying performance (WLA: 320 eggs per year, G11: 200 eggs per year) were allocated to four treatment groups. Group S received a deslorelin acetate implant that suppressed egg production. Group E received an implant with the sexual steroid oestradiol-17ß. Group SE received both implants and group C did not receive any implant. In the 63rd week of age, composition and characteristics of the tibiotarsi were assessed using histological analysis, three-point bending test, thermogravimetric analysis, infrared spectroscopy, and two-dimensional X-ray diffraction, respectively. Non-egg-laying hens showed a higher total bone area and a higher relative amount of cortical bone compared to egg-laying hens. Hens of layer line G11 showed a higher relative amount of medullary bone and a higher degree of mineralization of the cortical bone compared to hens of layer line WLA. These differences in bone composition may explain different susceptibility to keel bone fractures in non-egg-laying compared to egg-laying hens as well as in hens of layer lines differing in laying performance. The effect of exogenous oestradiol-17ß on bone parameters varied between the layer lines indicating a genetic influence on bone physiology and the way it can be modulated by hormone substitution.

Size-segregated physicochemical properties of inhalable particulate matter in a tunnel-ventilated layer house in China.

This study investigated the physicochemical properties of the particles in a typical commercial laying hen barn in Southeast China. Mass concentrations and size distributions of the particulate matter (PM) and the key components (incl. organic carbon (OC), element carbon (EC), and the water-soluble inorganic ions (WSIIs)) were analyzed. The result shows that the mass concentrations of PM accumulated along with the airflow inside the house, with the total mass of the sampling particles increasing from 843.66 ± 160.74 µg/m3 at the center of the house to 1264.93 ± 285.70 µg/m3 at the place close to exhaust fans. The particles with the aerodynamic equivalent diameter, Dp > 9 µm, coarse particles (2.1 µm < Dp ≤ 9 µm), fine particles (Dp ≤ 2.1 µm) accounted for around 50%, 40%, and 10% of the total mass of the sampling particles, respectively. Mass closure analysis shows secondary inorganic ions (NH4+, SO42- and NO3-) were abundant in the fine-mode fraction and OC accounted for more than 40% of the coarse particles. Size distribution analysis shows that the three secondary inorganic ions were bimodally distributed, and the rest tested components were unimodally distributed. The ratios of OC/EC in fine particles were smaller than those in the coarse particles. The equivalent concentration of WSIIs indicated that fine particles were slightly acidic, and the large size particles were slightly alkaline. Knowledge gained from this study will lead to a better understanding of physicochemical properties, sources, and formation of PM.

Effect of dietary flaxseed meal supplemented with dried tomato and grape pomace on performance traits and antioxidant status of laying hens.

This study was carried out to determine the effect of dietary flaxseed meal (FSM) supplemented with dried tomato pomace (DTP) and dried grape pomace (DGP) on performance, egg quality, biochemical parameters traits and antioxidant status of laying hens. Birds (1825 ± 87 g of body weight) were divided into 12 dietary groups with six replicates per group (eight birds per replicate), under a completely randomized design with factorial arrangement 2 × 3 × 2 consisted of two levels of DTP (0 and 15%), three FSM levels (0, 4 and 8%) and two levels of DGP (0 and 5%). As a result of this study, there were no significant differences in egg production and weight as well in feed conversion ratio (FCR) among treatments (p > 0.05). Feeding of DGP reduced significantly feed intake and egg mass when compared to control group (p < 0.05). There was no effect (p > 0.05) of dietary treatment on shell thickness and strength, shape index, Haugh unit and egg specific gravity. Hens consuming 15% DTP and 5% DGP revealed a significantly higher yolk color compared to the other dietary treatments (p < 0.05). Moreover, there was no difference among dietary treatments in terms of serum low-density lipoprotein cholesterol (LDL) and high-density lipoprotein cholesterol (HDL) cholesterol, atherogenic index, triglycerides, total cholesterol levels (p > 0.05). Serum antioxidant parameters as glutathione peroxidase (GSH-Px) activity, malondialdehyde (MDA), total superoxide dismutase (TSOD) and total antioxidant capacity (T-AOC) were not influenced by treatments (p > 0.05). Based on findings, FSM and DTP supplements did not significantly impact most of hens' performance indicators and egg quality parameters, whereas significant improvements were observed by feeding of 15% DTP and 5% DGP on egg traits, in particular on egg-yolk color that plays a key-role in consumer's choice. However, the supplementation of FSM and DTP or DGP even in laying hen diet is still controversial and further research is needed.

Sodium butyrate reduces ammonia emissions through glutamate metabolic pathways in cecal microorganisms of laying hens.

Ammonia emission is an important problem that needs to be solved in laying hen industries. Sodium butyrate (SB) is considered to have potential for reducing ammonia production because of its ability to improve nitrogen metabolism. In this in vitro fermentation study, we presented a correlation analysis of the metatranscriptome and metaproteome of lay hen cecal microorganisms, in order to identify important proteins and pathways involved in ammonia production reduction due to sodium butyrate supplementation. The results showed that sodium butyrate supplement decreased the production of ammonia by 26.22% as compared with the non-sodium butyrate supplementation (CK) group. The SB group exhibited a lower concentration of ammonium nitrogen (NH4+-N) and a decreased pH. Sodium butyrate promoted the uric acid concentration and lowered the uricase activity in the fermentation broth of laying hens cecal content. Notably, the 'alanine, aspartate and glutamate metabolism' category was more abundant in the SB group. The addition of sodium butyrate increased the expression of glutamate dehydrogenase (GDH) gene in cecal microbiota (e.g., Ruminococcus sp. and Bacteroides sp.) in vitro. The metaproteome analysis results showed that the expression of GDH with NADPH as coenzyme (NADPH-GDH) was up-regulated in cecal microbiota by sodium butyrate supplement. Our results indicate that sodium butyrate can affect glutamate metabolism through regulating the expression of glutamate dehydrogenase in cecal microorganisms, thereby reducing ammonia production. This study reveals that glutamate dehydrogenase-mediated glutamate metabolism play a key role in ammonia emission reduction in laying hen and provide theoretical basis for further developing ammonia production reduction approach.

Genetic background and production periods shape the microRNA profiles of the gut in laying hens.

There is growing evidence of the importance of miRNAs for intestinal functional properties and nutritional uptake. Comparative miRNAs profiles of the jejunal mucosa were established against two genetic backgrounds (Lohmann Brown-Classic (LB) and Lohmann LSL-Classic (LSL), which are similar in egg production but differ in physiological traits including mineral utilization, along the production periods of laying hens. The target genes of miRNAs higher expressed in LB vs. LSL (miR-126-3p, miR-214, miR-24-3p, miR-726-5p, miR-29b-3p) were enriched for energy pathways at all stages. The target genes of the miRNAs higher in LSL (miR-1788-5p, miR-103-3p, miR-22-5p, miR-221-3p, miR-375) were more enriched for immune and the bone signalling pathways. The most prominent expression differences were between 16 and 24 weeks of age before and after onset of laying. Our results evidence central roles of intestinal miRNAs as regulators of gene expression, influencing intestinal homeostasis and adaptation to environment in different strains and production phases.