Strains Of Laying Hens Research Articles

Transcriptional responses to diets without mineral phosphorus supplementation in the jejunum of two high-yielding laying hen strains

Phosphorus (P) is an essential mineral for all forms of life including laying hens, playing a crucial role in growth and efficient egg production. Recent studies suggest that current P recommendations might exceed the physiological demand, leading to unnecessarily high P excretions. This study on Lohmann Brown (LB) and Lohmann Selected Leghorn (LSL) laying hens (n=80; 10 replicates per strain, production period, and dietary group) investigates transcriptional changes in the jejunum, a critical intestinal segment for mineral absorption, in response to a diet either without (P-) or with (P+) a mineral supplement from monocalcium phosphate, administered over a 4-week period during the transition (15–19 weeks) or onset of laying (20–24 weeks). DESeq2 analysis of RNA sequencing data revealed that most differentially expressed genes (DEGs) varied between strains and age groups, with less pronounced effects from dietary mineral P content. The 19-week-old LB hens showed a stronger response to dietary mineral P removal, with transcripts affiliated with increased adaptation of the metabolism and decreased immune pathway activation. The identified pathways such as folate biosynthesis and p53 signaling, potentially link altered energy and amino acid metabolism (2-oxocarboxylic acid and arginine). Interestingly, genes involved in calcium transport (CALB1) and cellular signaling (PRKCA, STEAP4) along with tight junctions (CLDN2) were affected by complete removal of mineral P supplements, suggesting a promoted intestinal mineral uptake. Transcriptional regulation in the jejunum in response to low dietary mineral content is strain-specific when the laying phase begins, which may contribute to a physiological Ca:P ratio.

The effect of laying hen strain on perching biomechanics and keel deviations

The effect of laying hen strain on perching biomechanics and keel deviations

Betaine Alter SCFA-Producing Bacteria Population in Laying Pullet Reared in Tropical Climate

Short-chain fatty acids (SCFAs) are crucial products of microbial fermentation in the gut, known to play a significant role in maintaining gastrointestinal health and the overall well-being of animals. Betaine, a naturally occurring compound found in various plant and animal sources, has been widely used as a feed additive in poultry production due to its potential benefits, including improved growth, osmoregulation, and liver function. This study examines the possible effects of betaine supplementation on SCFA-producing bacteria in laying pullets raised in tropical climates, mainly focusing on SCFA-producing Lactobacillus and Bifidobacterium species. In total, 96 laying hens strain Lohmann aged three weeks were assigned to two dietary treatments. Dietary treatments included a basal diet (control) and a basal diet supplemented with 1.2 g.kg-1 betaine. The next-generation sequencing method of the 16S rRNA gene region V3–V4 was applied to view the bacteria abundance. Betaine supplementation showed significantly higher population levels of Lactobacillus_agilis, Lactobacillus_aviarius, Lactobacillus_ingluviei, Lactobacillus_johnsonii, and Lactobacillus_saerimneri compared to the control group (P<0.05). In Bifidobacterium_pullorum bacteria, betaine administration shows insignificant results compared to control. In conclusion, betaine supplementation appears to have a positive impact on promoting the growth of certain beneficial Lactobacillus species in laying pullets reared in tropical climates.

The Quality of Chicken Eggs Fed Black Pepper (Piper nigrum L.) Flour

The objectives of this study were to analyze the quality of laying hen eggs fed with feed containing black pepper (Piper nigrum L) flour. A total of 200 brown laying hens strain MB 402 (50 weeks-old) were used in this experiment. The research design used was Completely Randomized Design (CRD) and further analysis was conducted using Duncan’s Multiple Range Test. The Treatments given black pepper flour were 0%, 0.5%, 1%, 1.5%, and 2%. This research was conducted for 6 weeks. Parameters included egg weight (g/egg), egg yolk weight (g/egg), yolk index, and egg yolk color. The results showed that feeding chickens with up to 2 % BPF increased significantly the effect (P &lt; 0.01) on egg yolk weight, yolk index, egg yolk color but not significantly different (P &gt; 0.05) on egg weight. This research concluded that BPF diets can be fed to laying hens up to 2 % to produce eggs without negative effects on the egg quality.

Characterization of Qualitative and Quantitative Traits of Four Types of Indonesian Native Chickens as Ancestor of New Strains of Local Super Laying Hens

Characterization of Qualitative and Quantitative Traits of Four Types of Indonesian Native Chickens as Ancestor of New Strains of Local Super Laying Hens

Blood hematology and biochemical of four laying hen strains exposed to acute heat stress.

This study is aimed at defining physiological responses to heat stress (HS) in four different lines to better understand the underlying mechanisms of various responses in these genotypes when exposed to heat for a short period. At the age of 30weeks, 176 laying hens (44 each from the Fayoumi, Golden Sabahia, White Leghorn, and Lohman Brown) were allotted to 2 groups (thermoneutral temperature (26.0 ± 1°C) and HS (35 ± 1°C) with relative humidity 55 ± 5% for 6h/day). Blood samples were collected after 6h of heat. According to the findings of this study, acute HS increased the concentration of LH in hens by 20.2% while decreasing the concentration of FSH by 4.24. Genotype was found to have a significant effect on blood hematology and most blood biochemical. Significant differences were found between heat stress and genotype in most of the blood parameters. Golden sabahia laying hens had significantly higher WBC, IgY, and LH levels than other groups under HS. The findings of the current study suggested that Lohman Brown was less tolerant to acute HS than another genotype.

Effects of full-fat high-oleic soybean meal in layer diets on nutrient digestibility and egg quality parameters of a white laying hen strain

This study was conducted to understand the impact of including full fat high-oleic soybean meal in layer hen diets on nutrient digestibility and added nutritional value in eggs. Forty-eight layers (∼36 wk old) were randomly assigned to one of 4 isonitrogenous (18.5% crude protein) treatment diets with 12 replicate birds per treatment in a 3-wk study. Treatments were 1) solvent extracted defatted soybean meal+corn diet, 2) dry extruded defatted soybean meal+corn, 3) full-fat soybean meal+corn, 4) high-oleic full-fat soybean meal+corn diet. Apparent ileal digestibility of crude fat (CF) and crude protein (CP) were determined using celite (∼2%) as an indigestible marker. Tibia strength and egg quality parameters (egg weight, shell strength, Haugh unit, shell color, and yolk color) were recorded during the study. Fatty acid profiles, including the monounsaturated fatty acid, oleic acid (C18:1, cis), in eggs and adipogenic tissue (liver, muscle, and fat pad) were measured using gas chromatography (GC-FID). Digestibility values of CF ranged from 71 to 84% and CP varied from 67 to 72% for treatment diets, with treatment mean values being no different (P > 0.05) between treatment diets. No differences between treatment diets in tibia strength or egg quality parameters (egg weight, shell strength, and Haugh unit) were observed (P > 0.05) except for yolk color. Similarly, there were no differences in the total lipids in egg yolk (P > 0.05) between treatment diets. However, oleic acid percentage of total lipid in egg and tissue was significantly higher (P < 0.001) in hens given the high-oleic full-fat soybean meal diet than in other treatment groups. No difference was observed in oleic acid percentage of total lipid in egg between the other 3 treatment diets (P > 0.05). Overall, the results exhibited that the eggs and tissue of layer hens fed the full-fat high-oleic acid soybean meal diet were higher in oleic acid while the CF and CP digestibility remained similar to the digestibility of the other diets.

The dynamics of molecular, immune and physiological features of the host and the gut microbiome, and their interactions before and after onset of laying in two hen strains

Aggregation of data, including deep sequencing of mRNA and miRNA data in jejunum mucosa, abundance of immune cells, metabolites, or hormones in blood, composition of microbiota in digesta and duodenal mucosa, and production traits collected along the lifespan, provides a comprehensive picture of lifelong adaptation processes. Here, respective data from two laying hen strains (Lohmann Brown-Classic (LB) and Lohmann LSL-Classic (LSL) collected at 10, 16, 24, 30, and 60 wk of age were analyzed. Data integration revealed strain- and stage-specific biosignatures, including elements indicative of molecular pathways discriminating the strains. Although the strains performed the same, they differed in the activity of immunological and metabolic functions and pathways and showed specific gut-microbiota-interactions in different production periods. The study shows that both strains employ different strategies to acquire and maintain their capabilities under high performance conditions, especially during the transition phase. Furthermore, the study demonstrates the capacity of such integrative analyses to elucidate molecular pathways that reflect functional biodiversity. The bioinformatic reduction of the multidimensional data provides good guidance for further manual review of the data.

Study of Lactococcus lactis and Lactobacillus casei Probiotics Addition on Analysis of Laying Hens Strain Isa Brown Infected with E. coli

This study aims to determine the use of probiotics Lactococcus lactis and Lactobacillus casei. on the analysis of laying hens infected with Escherichia coli. A total of 120 laying hens aged 25 weeks were divided into 6 treatments. Each treatment included 4 repetitions, each of which included 5 laying hens. The treatments included factor a, namely infectious and non-infectious escherichia coli and factor B, namely AGP, basal feed and probiotics.. The result of this research shows that the use of probiotics Lactococccuslactis and Lactobacillus caseion the laying hens infected with bacteria Escherichia coli The results of the study that giving probiotics had a significant effect (P&lt;0.05) on variable costs, acceptance and profits. The infection factor had a significant effect (P&lt;0.05) on variable costs, revenues and profits. Based on the results of this research, it can be concluded that the addition of probiotic Lactococccuslactis and Lactobacillus casei on the laying hens infected with bacteria Escherichia coli can bacteri increases the income of laying hens.

Evaluation of Production Peak of Laying Hens Strain Lohman Brown in CV. Lawu Farm Malang

Background: The productivity of laying hens is a key measurement in the laying hens business. One of the targets for laying hens is to achieve peak production. The optimal peak production period is necessary to attain the maximum profit. Purpose: To determine the productivity of laying hens strain Lohman Brown aged 25-49 weeks at CV. Lawu Farm Malang Regency as an evaluation of the peak production period. Case Analysis: The descriptive method with the case study technique was used. Primary data were obtained from observations by participating in direct livestock activities, interviews, and documentation, and secondary data were obtained from literature studies. The variables observed in this study were Hen Day Production, Feed Conversion Ratio, egg weight, and mortality. Results: Observation of laying hens productivity in CV. Lawu Farm showed that 71.42% of Hen Day Production value of the full cages had met the target with HDP of more than 92%, while 28.58% did not reach the peak production target by only getting HDP less than 90%. The FCR value was 2.4 – 2.15, the average egg weight wais 63.03 grams/egg, and the mortality was ≤3%. Conclusion: The productivity of laying hens of the Lohman Brown strain aged 24-59 weeks at CV. Lawu Farm has met production standards in terms of HDP, FCR, egg weight, and mortality.

Multi-Omics Reveals Different Strategies in the Immune and Metabolic Systems of High-Yielding Strains of Laying Hens

Lohmann Brown (LB) and Lohmann Selected Leghorn (LSL) are two commercially important laying hen strains due to their high egg production and excellent commercial suitability. The present study integrated multiple data sets along the genotype-phenotype map to better understand how the genetic background of the two strains influences their molecular pathways. In total, 71 individuals were analyzed (LB, n = 36; LSL, n = 35). Data sets include gut miRNA and mRNA transcriptome data, microbiota composition, immune cells, inositol phosphate metabolites, minerals, and hormones from different organs of the two hen strains. All complex data sets were pre-processed, normalized, and compatible with the mixOmics platform. The most discriminant features between two laying strains included 20 miRNAs, 20 mRNAs, 16 immune cells, 10 microbes, 11 phenotypic traits, and 16 metabolites. The expression of specific miRNAs and the abundance of immune cell types were related to the enrichment of immune pathways in the LSL strain. In contrast, more microbial taxa specific to the LB strain were identified, and the abundance of certain microbes strongly correlated with host gut transcripts enriched in immunological and metabolic pathways. Our findings indicate that both strains employ distinct inherent strategies to acquire and maintain their immune and metabolic systems under high-performance conditions. In addition, the study provides a new perspective on a view of the functional biodiversity that emerges during strain selection and contributes to the understanding of the role of host–gut interaction, including immune phenotype, microbiota, gut transcriptome, and metabolome.

Effects of genotype and age on eggshell cuticle coverage and color profile in modern laying hen strains

The aim of this research was to investigate the effects of laying hen genotype and age on eggshell cuticle deposition. A total of 4,320 brown eggs were obtained from 3 modern hen strains (A, B, and C), currently used worldwide for commercial egg production, at different intervals of age (20–30, 40–50, and 60–70 wk). Four samplings of 120 randomly collected eggs were carried out for each genotype/interval of age. Eggs were individually weighed and cuticle blue staining was used to assess quality and degree of cuticle coverage. On each egg, the eggshell color profile was assessed before and after staining using the CIE L*a*b* system and these values were used to calculate ΔE*ab. A 4-point scale visual score (VS) system was also applied to estimate the degree of cuticle coverage after staining (0 = no coverage, 1 = partial coverage, 2 = total coverage - low degree, 3 = total coverage - high degree). The effects of genotype and age and their interaction on eggshell color attributes were assessed by means of factorial ANOVA, while omnibus Chi-Square and Chi-squared Automatic Interaction Detector algorithm were applied for the analysis of VS data. Overall, both genotype and age affected the eggshell color profile as well as the degree of cuticle coverage. Hen strain A showed better cuticle deposition in comparison with B and particularly C one, being ΔE*ab values significantly higher. The VS evaluation revealed that eggs with impaired cuticle coverage degree increased with the hen age (23, 34, and 37%, respectively for 20–30, 40–50, and 60–70 wk; P < 0.05). However, a significant interaction between genotype and age was observed: transition from early to late hen age resulted in a significantly different pattern of ΔE*ab changes in each genotype. The classification tree analysis confirmed that the hen genotype has a greater effect than the age on cuticle deposition. In conclusion, considering the importance of the cuticle in table egg production, these results highlight the crucial role exerted by the genotype on eggshell cuticle coverage.

Efficacy of Using Lactic Acid Bacillus on Productive Parameters of Babcock B300 Laying Hens Strain

This research was carried out in the Research Center of the Faculty of Agriculture in Al-Muslimiya, 240 hybrid Babcock B300 female laying hens were randomly distributed since the first day of the experiment into four independent groups. Each group included 60 birds according to three replicates (20 birds in each replicate). Lactic acid bacillus was added to the feed mixture according to three levels (50 mg/kg; B group, 100 mg /kg; C group and 150 mg/kg; D group), while the first group was considered as a control group (A group) and was without additions. During the production period, the results showed that the addition of lactic acid bacillus led to significant differences (p<0.03) in the egg production and shell thickness compared with the control group. The additions did not affect the egg weight and feed consumption rate as well as the feed conversion ratio. The birds of the third group (C group) showed clear superiority in various productive traits compared to others in the other groups throughout the productive period followed by the birds of group D and then group B. The current study concluded that adding 100 mg /kg lactic acid bacillus to the feed mixtures for laying hens will contribute to raising the productive efficiency of laying hens and improving egg specifications.

Effect of Different Proportions of Probiotics on Immunological Blood Parameters of Babcock Laying Hens Strain

The research was conducted at the Research Center of Agriculture Faculty of the University of Aleppo. 240 chickens of Babcock B300 strain were used and distributed randomly from day one into four independent groups. Each group included 60 birds distributed into three replicates (20 birds). The control group (A group) was fed a balanced standard feed mixture (1-18 weeks) without additives, while lactic acid bacillus was added to treatments groups according to three levels (50 mg/kg feed; B group, 100 mg/kg feed; C group and 150 mg/kg feed; D group). Haematological analyzes were performed over two- time intervals (1-21 weeks and 22-32 weeks). In the first time interval, results showed that a rise in blood albumin (P<0.001) was also observed in C and D groups compared to the A group. The rates of blood globulin increased (P<0.02) in the D group compared with the rest of the groups. No significant differences were noticed across the various groups for the total number of white blood cells and lymphocytes rates. In the second time interval (productive stage), significant differences (P<0.01) were noticed across the various groups in the percentages of the total protein (the highest value was 4.75 g/dl; B group) and serum albumin (the highest value was 3.26 g/dl; D group). It is concluded from the current study that the addition of probiotics to the mixtures of laying hens had a significant improvement in the immune parameters in the blood.

Effect of housing environment and hen strain on egg production and egg quality as well as cloacal and eggshell microbiology in laying hens

This study was conducted to determine the effect of housing environment and laying hen strain on performance, egg quality, and microbiology of the cloaca and eggshell. A total of 1,152 Hy-Line Brown (HB) and Hy-Line W-36 White Leghorn (W-36) hens were used. All hens were kept in conventional cages (CC) from 18 to 32 wk of age and then moved to either enriched colony cages (EC) or free-range (FR) pens or continued in CC. Hens were randomly allocated into a 2 × 3 factorial arrangement of 2 laying hen strains (brown and white) and 3 housing environments (CC, EC, and FR) in a split plot in time (hen age) design. The experiment was conducted from 32 to 85 wk of age. The experiment was divided into 2 phases: early phase (32–51 wk of age) and late phase (52–85 wk of age). A 3-way interaction was observed for hen day egg production (HDEP) among housing environments, hen strain, and bird age in the early phase (P = 0.004) as well as in the late phase (P < 0.0001). In both of the phases, HDEP was higher in CC and FR than in EC. Hy-Line W-36 hens raised in EC had the lowest HDEP compared to other treatments. A 3-way interaction was observed for feed intake (FI; P = 0.017) and feed conversion ratio (FCR) in the late phase (P < 0.0001). The lowest FI and highest FCR were observed in EC for W-36 hens. Free-range hens performed in-between for eggshell quality when compared to CC and EC while HB had better egg quality than W-36. Free-range hens had higher cloacal bacterial counts for aerobes, anaerobes, and coliforms than CC and EC. Higher eggshell bacterial contamination was observed in eggs from FR versus eggs from CC and EC. These results indicate that both housing environment and laying hen strain affect performance and egg quality as well as cloacal and eggshell microbiology. Further studies should be conducted to determine food safety and economic impacts when using different hen strains and housing environments.

The effect of betaine supplementation on performance of laying hens in the tropical climate during the starting period

The study investigated the effects of dietary betaine on the growth performance of laying hens in a tropical climate during the starting period. In total, 192 laying hens strain Lohmann aged three weeks were assigned to four dietary treatments, each consisting of six replicates of eight birds. The dietary treatments included a basal diet (T0) and a basal diet supplemented with betaine at 6 mg/kg (T1), 12 mg/kg (T2), 18 mg/kg (T3). The treatments lasted for eight weeks. Temperature and relative humidity were measured with Hobo-U12, while the wet-bulb temperature was measured using Lutron HT-3027SD. The effect of betaine was not consistent where T3 decreased feed intake (FI) in week 2 but increased FI in weeks 4 and 5. Furthermore, T2 showed higher FI in weeks 6 and 7 than T0 (p<0.05). Accordingly, T2 and T3 led to lower weight gain in week 2, but they compensated with higher weight gain in week 4 when ambient temperature above 30°C occurred for 42 hours in a week. Overall, weight gain and body weight in week 8 was not affected by the treatment. It is concluded that the effect of betaine was more apparent when the birds were exposed to high ambient temperature.

Different Non-cage Housing Systems Alter Duodenal and Cecal Microbiota Composition in Shendan Chickens.

Housing systems are among the most important non-genetic factors affecting hen production performance and intestinal microbes. With increased interest in animal welfare, cage-free laying hen housing systems have become common, providing behavioral freedom and health benefits. The present study aimed to compare the effects of plastic net housing system (NRS) and floor litter housing system (LRS) on the composition and function of the duodenal and cecal microbiota in Shendan chicken, one of the most popular laying hen strains in China. The associations between the differential microbiota abundance and production traits and intestinal morphological parameters were determined. Compared with the LRS, the NRS improved the laying rate (p < 0.05) and increased the villus height (VH) of the duodenum (p < 0.05) and the VH-to-crypt depth ratio (VCR) of the cecum (p < 0.05). Alpha diversity analysis showed that LRS chickens had a significantly higher diversity and richness than NRS chickens. Beta diversity analysis demonstrated differences in the microbiota composition based on housing systems. Within the cecum, Proteobacteria and Kiritimatiellaeota were significantly more abundant in the LRS than in the NRS (p < 0.05), while Bacteroidetes were significantly less abundant in the LRS (p < 0.05). Phascolarctobacterium and Ruminococcaceae_UCG-005 were significantly less abundant in the LRS (p < 0.05) compare to the NRS. Within the duodenum, Lactobacillus was significantly less abundant in the LRS (p < 0.05) than in the NRS, while Pseudomonas was significantly more abundant in the LRS (p < 0.05). Cecal Phascolarctobacterium and Ruminococcaceae_UCG-005 were significantly positively correlated with eggshell strength (R = 0.608, p < 0.01) and egg weight (R = 0.526, p < 0.05), respectively. Duodenal Lactobacillus was significantly positively correlated with VH and VCR (R = 0.548 and 0.565, p < 0.05), while Pseudomonas was significantly negatively correlated with the Haugh unit (R = −0.550, p < 0.05). In conclusion, there are differences in the cecal and duodenal microbiota compositions of Shendan laying hens reared in different non-cage housing systems, and the NRS was superior to the LRS in improving the laying performance and intestinal morphology and microecological environment.

Potensi Dedak Padi yang Difermentasi dengan Enzim Fitase dalam Pakan Basal Terhadap Kolesterol Total Darah Ayam Petelur

This study aimed to evaluate the potential of rice bran fermented by the enzyme phytase in basal feed to the total blood cholesterol level of laying hen. This research use an experimental method in vivo with a completely randomized design consisting of six treatments and four replications in each treatment. The experimental animals used 24 48-week-old female laying hen strain Isa Brown. The treatment wa given basal feed substituted with different percentage of fermented rice bran by phytase enzyme and 2% lemuru fish oil supplementation. In this research the amount of fermented rice bran by phytase enzyme substituted on basal feed was: treatment P0 (-) (0%), P0 (+) (0%), P1 (5%), P2 (10%) P3 (15%) and P4 (20%). The results of the statistical analysis showed that there are no significant differences (p&gt; 0.05) on total blood cholesterol levels in all treatments. The conclusion of the research is that rice bran fermented by phytase enzymes tends to decrease total blood cholesterol levels in laying hen.

Immune parameters in two different laying hen strains during five production periods

During life, the number and function of immune cells change with potential consequences for immunocompetence of an organism. In laying hens, studies have primarily focused on early development of immune competence and only few have investigated systemic and lymphatic distribution of leukocyte subsets during adolescence and the egg-laying period. The present study determined the number of various leukocyte types in blood, spleen, and cecal tonsils of 10 Lohmann Brown-Classic and 10 Lohmann LSL-Classic hens per wk of life 9/10, 15/16, 23/24, 29/30, and 59/60, encompassing important production as well as developmental stages, by flow cytometry. Although immune traits differed between the 2 hen strains, identical patterns of age-related immunological changes were found. The numbers of all investigated lymphocyte types in the spleen as well as the numbers of blood γδ T cells increased from wk 9/10 to 15/16. This suggests an ongoing release of lymphocytes from primary lymphoid tissues and an influx of blood lymphocytes into the spleen due to novel pathogen encounters during adolescence. A strong decrease in the number of CTL and γδ T cells and an increase in innate immune cells within blood and spleen were found between wk of life 15/16 and 23/24, covering the transition phase to egg-laying activity. Numbers of peripheral and splenic lymphocytes remained low during the egg-laying period or even further decreased, for example blood CD4+ T cells and splenic γδ T cells. Functional assessments showed that in vitro IFN-γ production of mitogen-stimulated splenocytes was lower in wk 60. Taken together, egg-laying activity seems to alter the immune system toward a more pronounced humoral and innate immune response, with probable consequences for the immunocompetence and thus for productivity, health and welfare of the hens.

Transcriptional responses in jejunum of two layer chicken strains following variations in dietary calcium and phosphorus levels

BackgroundCalcium (Ca) and phosphorus (P) are essential nutrients that are linked to a large array of biological processes. Disturbances in Ca and P homeostasis in chickens are associated with a decline in growth and egg laying performance and environmental burden due to excessive P excretion rates. Improved utilization of minerals in particular of P sources contributes to healthy growth while preserving the finite resource of mineral P and mitigating environmental pollution. In the current study, high performance Lohmann Selected Leghorn (LSL) and Lohmann Brown (LB) hens at peak laying performance were examined to approximate the consequences of variable dietary Ca and P supply. The experimental design comprised four dietary groups with standard or reduced levels of either Ca or P or both (n = 10 birds per treatment group and strain) in order to stimulate intrinsic mechanisms to maintain homeostasis. Jejunal transcriptome profiles and the systemic endocrine regulation of mineral homeostasis were assessed (n = 80).ResultsEndogenous mechanisms to maintain mineral homeostasis in response to variations in the supply of Ca and P were effective in both laying hen strains. However, the LSL and LB appeared to adopt different molecular pathways, as shown by circulating vitamin D levels and strain-specific transcriptome patterns. Responses in LSL indicated altered proliferation rates of intestinal cells as well as adaptive responses at the level of paracellular transport and immunocompetence. Endogenous mechanisms in LB appeared to involve a restructuring of the epithelium, which may allow adaptation of absorption capacity via improved micro-anatomical characteristics.ConclusionsThe results suggest that LSL and LB hens may exhibit different Ca, P, and vitamin D requirements, which have so far been neglected in the supply recommendations. There is a demand for trial data showing the mechanisms of endogenous factors of Ca and P homeostasis, such as vitamin D, at local and systemic levels in laying hens.