1. Melan-A plays a key role in the development of the melanosome, making it a strong candidate for the pigmentation phenotype observed in animals. The main purpose of this study was to analyse the relationship between gene polymorphisms and tyrosinase (TYR) enzyme activity in skin tissues and melanin content in dorsal down feathers of Chinese yellow quail.2. The coding sequence region of mRNA was cloned and sequenced to detect polymorphisms. The melanin content in down feathers of 266 Chinese yellow quails was analysed by spectrophotometry, and TYR enzyme activity was measured in dorsal skin tissues. The expression of mRNA in skin tissues of individuals with different genotypes was analysed using RT-qPCR.3. One non-synonymous single nucleotide polymorphisms (NSSNP; c.218T/A) was identified, which resulted in a Leu36Val mutation in the transmembrane helix region of the MLANA protein. This NSSNP significantly reduced the expression level of mRNA and TYR enzyme activity in dorsal skin tissues, leading to a significant reduction in melanin content in down feathers.4. The c.218T/A locus of the gene is closely related to the pigmentation TYR of the down feathers in Chinese yellow quail and can be used as a molecular marker locus for breeding pure feather colour in quail.

1. This study evaluated the effect of acidified drinking water on the gastrointestinal function and intestinal health of broilers.2. A total of 630 one-day-old male broilers (Arbor Acre) were randomly assigned to one of three treatment groups: drinking water treatment (CON), drinking water + 0.5 ml Selko pH®/L (Selko pH), or + 0.85 ml Forticoat®/L (Forticoat) treated groups. Performance data, gut and digesta samples were collected from the broilers at the age of 21 and 42 d.3. The results showed that acidifying drinking water had no significant effect on body weight or average daily gain (ADG). However, addition of Forticoat significantly increased ( < 0.05) feed conversion ratio (FCR) throughout the experimental period and significantly increased ( < 0.05) pepsin activity on d 21. The Selko pH supplemented drinking water significantly increased ( < 0.05) the relative length of the duodenum and jejunum on d 21. The relative length of the jejunum and caecum on d 42 compared to birds receiving CON. The addition of the Forticoat to drinking water significantly increased ( < 0.05) the relative length of the jejunum and caecum on d 42 than for samples from birds in the CON group. In the caecal chyme, abundance of , , , and spp. on d 21 were significantly higher ( < 0.05) in the caecum of birds receiving Selko pH than those in CON group and the number of in Selko pH and Forticoat group were significantly lower ( < 0.05).4. Overall, adding Seiko pH and Forticoat to drinking water improved pepsin activity, reduced the number of caecal pathogens, increased the number of beneficial bacteria and improved intestinal health in broilers.

1. Clustered regularly interspaced short palindromic repeats (CRISPR)-associated proteins (Cas) systems have been highlighted for their potential applications in controlling the spread of mobile genetic elements, including antimicrobial resistance (AMR) genes. This study investigated the characteristics of CRISPR-Cas systems in from commercial broiler farms and assessed the impact of these systems on AMR.2. All isolates contained CRISPR2, and CRISPR1-Cas and CRISPR3-Cas were identified in 84 (56.4%) and 144 (96.6%) isolates. A combination of CRISPR2 and CRISPR3-Cas and a combination of CRISPR1-Cas, CRISPR2 and CRISPR3-Cas were each identified in 27 (96.4%) farms.3. There were significant differences between CRISPR-Cas systems for phenotypic AMR: CRISPR1-Cas and CRISPR3-Cas. The isolates without CRISPR1-Cas showed higher resistance to most antimicrobials and had a higher prevalence of multidrug resistance (MDR) than those with CRISPR1-Cas. However, the resistance rate against most antimicrobials and the prevalence of MDR did not differ significantly depending on the presence or absence of CRISPR3-Cas.4. The isolates without CRISPR1-Cas harboured higher levels of all AMR genes, except for , than those with CRISPR1-Cas. However, the isolates with CRISPR3-Cas showed a significant lower prevalence of gene and a significantly higher prevalence of and genes.5. In the distribution of families, the family was predominant, followed by , , and families. Only prevalence of the family was significantly higher in the isolates without CRISPR1-Cas (15.4%) than in those with CRISPR1-Cas (0%).6. This study is the first report on the characteristics of CRISPR-Cas systems in isolated from commercial broiler farm environments, and the results supported the hypothesis that the development of antimicrobial strategies requires an understanding of the distinctive capabilities between CRISPR1-Cas and CRISPR3-Cas and their underlying resistance mechanisms.

1. Avian () causes significant losses in livestock by inducing morbidity and mortality. Erythrocytes, the most abundant in blood, possess dual functions of oxygen transportation and immune regulation. In recent years, the interaction between erythrocytes and the complement system has gradually become a focal point of study. However, the transcription dynamics of the complement system in chicken erythrocytes post- invasion remains unclear.2. In this study, chicken erythrocytes and were co-cultured for 0.25-2 h to assess adhesion, analysed by indirect immunofluorescence (IIF) and scanning electron microscopy (SEM). Quantitative real-time PCR (qRT-PCR) examined differential expression of complement genes () using erythrocytes at 0.25-2 h and in using chicks at 1, 3 and 7 d post- infection.3. adheres to chicken erythrocytes, as observed using IF and SEM. Gene expression analysis revealed early downregulation of C4, C4A, MBL and late upregulation of CD93, C1q, C1s, C3, C3AR1, C5AR1, C6, with C5, C7, C8G downregulated at 7 dpi. C2 expression varied at each time point.4. This study first showed adhering to erythrocytes, which activated complement genes rapidly. recovery from chickens with colibacillosis favours classical pathway activation, while lectin pathway may be inhibited, suggesting early immune down-regulation.

1. It remains unclear whether slow-growing broilers actually represent an overall animal welfare improvement - a major knowledge gap for policymakers and animal welfare NGOs. This paper addresses this knowledge gap by using an economic model to produce an all-things-considered estimate of the welfare effects of slow-growing genotypes. A quantitative end-point welfare metric that accounts for welfare challenges throughout the production cycle used the Pain-Track method from the Cumulative Pain Framework.2. Longer lifespans of slow-growing broilers (relative to fast-growing broilers) typically caused an increase in the time spent in low-intensity negative affective states. However, despite the additional broilers being farmed and their longer growth period, switching to slow-growing genotypes caused a decrease in higher-intensity negative affective states - a major win for welfare.3. These results can be used to alleviate consumer and producer concerns that any transition causes a welfare risk and provide an optimistic understanding of the overall welfare impact of transitioning to slow-growing broilers.

1. This review was conducted to examine the nutritional composition of microalgae and their effects as a feed ingredient in poultry diets, delving into their influence on the production and quality of meat and eggs. Data collection focused on peer-reviewed scientific articles, with no limitation on the temporal horizon.2. Regarding nutritional composition, the collected papers indicated that certain microalgae species have a rich nutritional composition, with approximately 50% of their biomass composed of proteins. They contain a high concentration of EPA and DHA, important fatty acids that are found in low concentrations in conventional feedstuffs, and the presence of carotenoids such as beta-carotene.3. Incorporating microalgae into the diet of poultry can improve performance variables, such as mortality, live weight and feed conversion rate. It promotes benefits in meat and egg quality, with reduced cholesterol, increased EPA and DHA, intensified colour and higher concentration of carotenoids.

1. The heritability (h) of liveweight (LW) in ostriches can be highly variable, depending on age at recording. The objective of this study was to consider random regression (RR) as an alternative to the multi-trait (MT) structure for the analysis of repeated measures of LW.2. The data included 74 683 LW phenotypes recorded from 10 052 birds aged between 20 and 410 days (d) of age. Statistical analysis included single trait (ST), MT and RR analysis in a linear mixed model framework using the ASREML V4.2 software.3. For ST and MT, six traits were defined to represent LW at 28, 77, 150, 230, 300 and 365 d of age. Random variance components included direct genetic and maternal permanent environment (PE) effects. A MT analysis including all six traits converged.4. For RR, the data was transformed (LW + 10) due to difficulty in dealing with large scale effects. The final RR model fitted direct genetic and animal PE components as third degree Legendre polynomials and heterogeneous residuals.5. The h estimates was in agreement across analysis, ranging from moderate (0.16-0.20) for W28 to high (0.41-0.51) for W230 to W365. Importantly, the genetic relationship between LW recorded as a chick and juvenile was only moderate (~0.35 to 0.55). The correlations between RR and MT EBVs for the six traits were 0.85, 0.54, 0.65, 0.75, 0.83 and 0.91, showing a considerable level of re-ranking.6. This study reaffirmed age dependent genetic variation when determining LW in ostriches. The RR structure was useful for overcoming the dimension problem of MT analysis, but was susceptible to scale effects present in the data, despite transformation. It remains unknown whether the need for cubic terms reflected scale or animal effects.

1. is an opportunist pathogen of animals, including food-producing ones and humans. Chickens may be a notable source of pathogenic and antimicrobial resistant for transmission to humans.2. This study compared virulence-associated genes (VGs) and antimicrobial resistance (AMR) in avian pathogenic (APEC) and extraintestinal pathogenic E. coli (ExPEC) isolates from broiler chickens, specifically APEC isolates in liver samples ( = 78) and ExPEC or non-ExPEC isolates in litter samples ( = 34). Virulence was evaluated by PCR for and genes, while AMR was evaluated by using antimicrobials from seven classes and detecting and genes.3. The APEC isolates were found in 100% of livers, while ExPEC and non-ExPEC isolates were found in 44% and 56% of the litter samples. The predominant VG was (100%), followed by (63%), (60%), (58%) and (43%). Surprisingly, and had higher prevalences in APEC isolates (85%, 96% and 96%, respectively) than in ExPEC isolates (73%, 87% and 73%, respectively) and non-ExPEC isolates (0% for all). The presence of all VG in 33% of isolates indicated high pathogenicity.4. The isolates were phenotypically resistant to ampicillin (93%), ceftazidime (72%) and nalidixic acid (82%). All APEC and ExPEC isolates (100%) were multidrug resistant (MDR), while 63% of non-ExPEC isolates were MDR. Genotypic AMR testing revealed that 53% and 52% of all isolates had and , respectively. No isolate was positive for or , which suggested the benefits of colistin for treating carbapenem-resistant enteric pathogens, due to the high resistance detected to meropenem (47%).5. Given the potential pathogenicity of isolates, improving biosecurity practices in chicken flocks should be prioritised to eliminate transmission to humans through the food chain.

1. This study investigated antimicrobial resistance, virulence factors and genotypic profiling among isolated from three sources (poultry farms, slaughterhouses and retail markets) in the poultry production chain in Zhejiang Province, China, to assess its potential risk to public health.2. A total of 112 strains were isolated from 409 samples, including 35 from poultry farms, 35 from slaughterhouses and 42 from retail markets. Antimicrobial susceptibility was tested using 18 antimicrobials in 9 categories, in which 110 (98.2%) strains were considered multidrug-resistant (MDR). These strains carried numerous antimicrobial resistance genes, with the sulphonamide resistance gene () having the highest rate (100%) and the polymyxin resistance gene () the lowest (3.6%).3. These isolates were validated to carry virulence genes , , , , , and with the high prevalence of 96.4, 92.9, 92.0, 85.7, 85.7, 57.1 and 46.4%, respectively. Genotyping results using the ERIC-PCR indicated that the genetic similarity of all the isolates was 68.6% to 100% which fell into 4 clusters.4. The isolates from the slaughterhouses exhibited higher levels of antibiotic resistance and a more pronounced MDR phenomenon than those from poultry farms and retail markets. The proportion of isolates carrying the most commonly detected resistant and virulence genes was higher in samples from poultry farms and slaughterhouses as opposed to retail markets. Importantly, there was genetic similarity and heterogeneity among isolates from the three sources and genotypic diversity was the highest among isolates from retail markets, followed by slaughterhouses and poultry farms.

1. As one of the most widespread poultry species in the world, pigeons have been bred primarily for meat production due to their high nutritional value and good taste. Their breast muscle is an important economic product as it determines the yield and quality of meat from pigeons.2. Long non-coding RNA (lncRNA) plays an important role in transcription and post-transcriptional regulation, but research on the molecular mechanisms of this process in pectoral muscle development in pigeon squabs is lacking.3. Herein, RNA sequencing was used to analyse these mechanisms in pigeon squabs at different ages: 3(D3), 14 (D14) and 25 d (D25). A total of 56 169 differentially expressed (DE) lncRNA and 29 939 DE mRNA were identified among the three age groups, of which 483 were differentially co-expressed. A lncRNA-mRNA interaction network was constructed, and cis-trans identification, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed.4. The results showed that lncRNA affected muscle development through the cell cycle, cytoskeleton in muscle cells, motor proteins, extracellular matrix (ECM) receptor interaction, focal adhesion, and other signalling pathways. Five DE lncRNA and mRNA were selected (, , , , , , , and ). Their expression patterns were validated by reverse transcription-quantitative polymerase chain reaction (RT-QPCR), which were consistent with the high-through sequencing results.

1.During transport of broilers from farms to slaughterhouses, the interior of crates may become contaminated with faeces. When these crates are not cleaned and disinfected adequately, they pose a potential risk for the dissemination of pathogens, including spp., between slaughterhouses and farms.2. The aim of the trial was to compare the efficacy of immersion-based crate washing systems with a spray-based washing system in reducing spp. Therefore, the crate washing systems in two slaughterhouses were sampled. In one of these two slaughterhouses, the immersion-based crate washing system was replaced by a new spray-based system which was sampled. Samples were collected from the slaughterhouse equipment, the crate washing system as well as from the crates both before and after cleaning and disinfection (C&D). All samples were screened for the presence of spp.; water and crate samples were used for enumeration. Molecular typing was performed to investigate the source and routes of contamination.3. In all cases, crates were contaminated with spp. prior to washing. However, only the spray-based system achieved a significant reduction after C&D Molecular typing revealed that the same strains were present on the crates after C&D as before cleaning. Additionally, crates could become contaminated by previously cleaned crates wash water in the immersion-based crate washing system.

1. Lighting is a crucial environmental factor in poultry production. This study evaluated the effects of light-emitting diodes (LED) on performance and several bone characteristics, including bone mineralisation, morphometry, histology and selected gene expression in broiler breeders.2. A total of 800 one-d-old female broiler breeder chickens (Ross 308) were randomly allocated to one of 20 light-proof pens and reared under green (GL) or white (WL) LED light for two photophases (8 or 12 h) in a 2 × 2 factorial experiment and compared to a control group (incandescent lamp at 8 L:16D duration; CON). Weight gain, feed consumption and feed conversion ratio (FCR) were calculated. Femoral and tibial characteristics were measured.3. The LED colour affected feed intake during the rearing period, being higher for birds under white compared to green light. Tibial calcium (Ca) concentration in WL birds was lower than for green LED lighting regimens but not different from the CON group ( ≤ 0.05). Birds under 12 h lighting had greater tibia bone dry matter and trabecular separation (mm) than those in the 8 h groups. However, bone volume fraction and trabecular number per mm in 8 h birds were higher than in 12 h groups ( ≤ 0.01). There was greater expression of the gene under WL compared with CON. expression in WL8 was 4.63 times greater than in the CON group ( ≤ 0.05). The gene expression in WL12 was higher than in the CON group ( ≤ 0.05).4. Exposure to white and green LED spectra enhanced bone gene expression and mineralisation, respectively, without adverse effects on bird performance. Thus, LED light may be beneficial to broiler breeder bone traits.

1. This study investigated the impact of different lairage duration on physiology, metabolism and meat quality in commercial broilers.2. A total of sixty, one-d-old Vencobb broilers were reared until 42 d of age and subjected to five lairage treatments (T0-T5), with the control with no lairage and then each timepoint increasing by 2 h.3. Head, eye and feet temperature increased progressively (P˂0.05), from 21 to 42 d. During lairage, temperature for the head, eye and feet were significantly higher in birds held until T3-T4 (P˂0.05), than at T0-T2 and T5 treatments.4. Serum total protein, creatinine, lipase and TBARS showed no variation due to lairage ( > 0.05). Glucose levels were highest at T4 ( < 0.05) than at T1-T3 or T5 and serum albumin increased only at T4 as compared to T5 ( < 0.05). Higher levels for blood triglycerides were recorded for T0, T1 and T5 ( < 0.05), than at T2-T4 and total blood antioxidants were significantly higher at T1 ( < 0.05), than at T0 and T2-T5 treatments, respectively.5. There was no significant difference for meat pH, ERV and WHC ( > 0.05), while, higher tyrosine levels ( < 0.05) were noted for birds in T5 than for the rest of the lairage treatments (T0-T4). On the same trend, TBA concentration was highest for birds in T5, as compared to T4 ( < 0.05).6. In conclusion, lairage over eight hours for commercial broilers is not recommended, as there are drastic changes in physiology, metabolism and deterioration of meat, reducing meat quality.

1. Valgus-varus deformity (VVD) is a disease that severely affects leg function in broilers and for which there is no effective control method current available. Although DNA methylation has an important impact on most physiological and pathological processes, its involvement in skeletal muscle growth and development in VVD broilers is unknown. In this study, genome-wide DNA methylation was analysed in VVD-affected and normal broilers using whole genome resulphite sequencing.2. The results showed that in the cytosine-phosphoric acid-guanine (CG) sequence environment there was a methylation rate of about 55% and 4,265 differentially methylated regions (DMRs) were found in the CG. Of these, 550 were located in the promoter, 547 in the exon region, and 1,718 in the intron region.3. All differentially methylated genes (DMGs) were analysed for enrichment of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. The GO was enriched in pathways related to protein degradation such as proteasome complex, endopeptidase complex and extracellular region. The KEGG pathways were enriched in signalling pathways related to protein degradation and catabolism such as proteasome, nitrogen metabolism, adherens junction and alanine.4. Protein interactions analysis revealed that FOS, MYL9, and FRAS1 had a high degree of interactions, in which the DNA methylation level of the promoter region was negatively correlated with mRNA expression level. Further studies showed that 5-azacytidine (5-AzaC) inhibited and gene expression and promoted expression.5. This study systematically investigated overall DNA methylation patterns in the leg muscle of VVD and normal broilers. It screened common differential genes in conjunction with transcriptomic data to further identify genes associated with muscle growth and development. This study provides new insights to better understand the pathogenesis of VVD from an epigenetic perspective.

1. This study aimed to investigate the effect of the first and third parities and one male: four females (1 M:4F) and 1 M:6F sex ratios of White Roman geese on their reproductive performance and biochemical parameters in an environmentally controlled house.2. Ganders ( = 136) and geese ( = 656) from the first and third parity were randomly placed into eight pens. These eight pens were assigned to one of four treatments in a 2 × 2 factorial arrangement (two sex ratio groups × two parity groups). The first and third parity treatment groups had 1 M:4F (each pen containing 20 ganders and 80 geese) and 1 M:6F (each pen containing 14 ganders and 84 geese) sex ratio treatment groups, respectively, replicated twice.3. Blood samples were collected from the geese at different time points: upon entering the house (ST), the beginning of the lighting regime of 7 L:17D for six weeks (LC6W), lighting adjustment to 9 L:15D for 6 weeks (9C6W), the peak of egg production (PEP) and the end of egg production (EEP).4. The first parity group had a longer laying period than the third parity (274 vs.191 days). First parity had a lower egg production rate than third parity during whole stage (18.7 vs. 25.4%). Fertility in 1 M:4F group was significantly higher than in 1 M:6F rate group (54.7 vs. 45.1%) at all periods.5. Plasma levels of total protein, albumin, globulin, triglycerides, calcium and phosphorus concentrations were significantly higher for whole laying period in first parity geese compared to third parity birds.

1. Loop-mediated isothermal amplification (LAMP) assays were developed to detect subspecies serotypes Enteritidis and Heidelberg in poultry farms. These serotype-specific methods were evaluated in comparison with PCR in the analysis of different spp. serotypes from a culture collection and poultry farm samples.2. The results demonstrated the specific amplification of the genetic targets A in all . Enteritidis ( = 10) and in all . Heidelberg ( = 36) isolates from the culture collection. The remaining isolates from other spp. serotypes ( = 84) and bacterial species ( = 8) were negative in both LAMP assays.3. The methods detected DNAs from . Enteritidis and . Heidelberg after a single-step pre-enrichment in buffered peptone water of the poultry samples, which agreed with previously developed PCR methods to detect these same two serotypes.4. In conclusion, LAMP assays were useful for rapid serotype-specific detection, being suitable for surveillance purposes in resource-limited environments such as poultry farms.

1. Modern broiler chickens are among the most efficient livestock in terms of resource requirements and production time. To maintain and improve production efficiency and meat quality and account for welfare problems, early interventions, such as incubation temperature, require investigation2. In this study, Ross 308 broiler eggs were incubated at either 36.5°C or 38.5°C on embryonic days (ED) 4-7. The control group eggs were incubated at a constant temperature of 37.5°C. and samples were taken for the investigation of muscle physiology, and the tibia was sampled for bone strength analysis from chickens aged 35 and 36 d. In addition, meat quality was analysed and gait scoring was performed.3. The performance of chickens in the 36.5°C group was inferior to those in the other groups up to d 10 post-hatch, but compensatory growth was seen by d 35 of age. Meat quality was unaffected, but significant differences between sexes were observed. Males had lighter meat colour than females. Muscle glycogen and intramuscular fat were unaffected by the incubation temperature, but the and intramuscular fat contents were greater in males than in females, accompanied by the increased expression of enzymes involved in lipolysis. In the 38.5°C group, males had less bone elasticity than females, and the inverse was observed in the other groups. Gait scores were affected by sex but not incubation temperature.4. The results of this study showed a stronger effect of sex than incubation temperature on broiler muscle physiology, bone strength, performance and meat quality.

1. Improving resistance against disease is important in the animal and poultry industry. Besides drugs and vaccines, genetic selection for improved immune systems may be an effective approach.2. Traits related to the immune system were studied in a 938 pedigreed Japanese quail population infected by sheep red blood cells (SRBC). Besides body weight at 35 d of age (BW35), weight of the gizzard (G), liver (Li), lungs (Lu), bursa (Bu), spleen (S), heart (H), and digestive track (D) and length of ileum (I) and caecum (C) were recorded. Total antibody (TA), mercaptoethanol-resistant (IgG), mercaptoethanol-sensitive titres (IgM), the number of monocyte (M), basophil (B) and eosinophil (E) and the ratio of heterophil to lymphocyte (H/L) were measured. Co-variance components were estimated Gibbs sampling using GIBBS3F90 software. Five univariate animal models, including simple forms, were used for genetic parameter estimations, and the best model was determined by the deviance information criterion (DIC). Genetic and environmental correlations were estimated using a bivariate animal model.3. Direct heritability estimates for internal organs ranged from 0.06 (Lu) to 0.57 (G) and for immune system traits from 0.05 (IgM) to 0.17 (IgG). Negative genetic correlations were found between BW35 and internal organs (-0.22 to -0.80).4. Including one of the internal organs, such as the spleen, in the selection index improved the immune response in heavier birds. Additionally, because of the moderate heritability of IgG (0.17) and its effect on lasting immunity, selecting for higher IgG concentration may improve the resistance of Japanese quail against pathogens.

1. Building on established understandings regarding hormonal and metabolic-driven processes of avian embryo's growth and development, this paper proposes a novel method, focusing on sex-related dimorphism. Such processes involve crucial activities, . nutrition delivery, gas exchange and waste disposal. These are influenced by interactions among various structures within embryonic compartments, whose sequential patterns between males and females have been proven different.2. The embryonic compartments, having undergone physiological changes during d 8-12, were acquired from candled images. Their temporal appearance model was developed from a non-linear classifier. It was hypothesised that if there is any distinctive pattern associated with the embryonic compartments between embryo sexes, then the classifier can be trained to recognise the dimorphism.3. The results revealed that the proposed method could separate sexes with accuracy, recall, precision and balance accuracy of 94.71, 93.47, 95.92 and 94.72%, respectively. Error analyses found 4.82% false discovery and 9.78% false omission rates. The method was expected to enhance farming resource management and leads to better animal welfare.

1. Six pelleted diets with different ratios of whole oats to dehulled oats, ground either finely (2 mm) or coarsely (6 mm), resulting in 0.05% (LOH), 6.5% (MOH) and 11.4% (HOH) OH inclusion, were fed to broilers to study gizzard functionality and its influence on passage of large oat hull (OH) particles. The hypothesis was that coarse OH would be selectively retained in gizzard for grinding, but higher levels would increasingly result in passage of unground OH.2. In experiment 1, gizzard and small intestinal contents were sampled from 78 birds at 28-29 d of age. Neutral detergent fibre (NDF) of gizzard contents was over three times higher than that of diets, indicating selective retention. An interaction effect of OH and screen size was seen for large particles (>1.6 mm) in the upper ileum, which was higher for MOH and HOH than LOH and only for coarse diets. This indicated that passage of unground coarse large particles from the gizzard increased when it exceeded a maximum retention level.3. In experiment 2, pre-weighed amount of HOH 2 mm and HOH 6 mm diets were fed to 80 birds for 2 h and were sampled on d 30 at 0, 2, 4, 8 and16 h to study OH degradation and flow. Contents were sampled from the crop, gizzard, small intestine, colon/cloaca and excreta. Unrecovered NDF in gastrointestinal tract plus excreta increased with more time and coarseness. An interaction effect between time and screen size was found for large particles in excreta, which was higher for 6 mm diets than 2 mm diets at 16 h.4. The presence of large OH particles in excreta challenged the previous assumption that particles are ground in the gizzard to a certain critical size before passing down further down the digestive tract. Some OH seemed to escape grinding in gizzard and this was higher for coarser particles.

1. The cuticle acts as a barrier to prevent microbial penetration of the eggshell. The reduction in the oviposition interval with selection for egg production and the activity of clock genes in the oviduct led to testing the hypothesis that the interval between successive oviposition of eggs would be related to the deposition of the cuticle.2. There was oviposition interval and cuticle deposition data from 2140 eggs from 5 White Leghorn pure lines for over 7 d. The association between oviposition interval and cuticle deposition was assessed using a random slopes model for each hen.3. The time of oviposition was 05:37 h:m, about 2.5 h after lights on. Differences in oviposition time between lines were significant (P=0.025). Oviposition interval was slightly greater than 24 h at 24:06 h:min with significant differences between lines (P = 0.003). The variance was low and the maximum difference between lines for oviposition interval was only 11 min. Cuticle deposition was 28.87ΔE*ab with no differences between lines.4. The number of eggs a hen laid had an effect on the oviposition interval (P = 0.004), being shortest in hens laying seven eggs (24:01 h:m) than those laying six (24:08) or five eggs (24:14).5. There was a significant positive association between cuticle deposition and oviposition interval (P = 0.007) with a minimal increase of 0.79 ΔE*ab in cuticle deposition for each additional hour of oviposition interval. Heritability for cuticle deposition in this study was 0.48 but heritability was not measurable for oviposition interval and was not different from zero for oviposition time.6. Combined with a difference between the top and tail of the distribution for cuticle deposition, there was evidence for a significant but relatively small relationship between oviposition interval and deposition of cuticle on the egg. This may have contributed to some reduction in cuticle coverage as the oviposition interval approached 24 h, but it seems unlikely that it was a major component.