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ABSTRACT: Salmonella Typhimurium (ST) infection in laying hens is a significant threat to public health and food safety. Host resistance against enteric pathogen invasion primarily relies on immunity and gut barrier integrity. This study applied the ST infection model and a dual live vaccine containing Salmonella Enteritidis (SE) strain Sm24/Rif12/Ssq and ST strain Nal2/Rif9/Rtt to investigate the cellular cytokine expression profiles and the differential community structure in the cecal microbiota of specific-pathogen-free (SPF) chicks and field-raised layers. The results showed that ST challenge significantly upregulated expressions of IL-1β in SPF chicks. Vaccination, on the other hand, led to an elevation in IFNγ expression and restrained IL-1β levels. In the group where vaccination preceded the ST challenge (S.STvc), heightened expressions of IL-1β, IL-6, IL-10, and IL-12β were observed, indicating active involvement of both humoral and cell-mediated immunity in the defense against ST. Regarding the cecal microbiota, the vaccine did not affect alpha diversity nor induce a significant shift in the microbial community. Conversely, ST infection significantly affected the alpha and beta diversity in the cecal microbiota, reducing beneficial commensal genera, such as Blautia and Subdoligranulum. MetagenomeSeq analysis reveals a significant increase in the relative abundance of Faecalibacterium prausnitzii in the groups (S.STvc and STvc) exhibiting protection against ST infection. LEfSe further demonstrated Faecalibacterium prausnitzii as the prominent biomarker within the cecal microbiota of SPF chicks and field layers demonstrating protection. Another biomarker identified in the S.STvc group, Eubacterium coprostanoligenes, displayed an antagonistic relationship with Faecalibacterium prausnitzii, suggesting the limited biological significance of the former in reducing cloacal shedding and tissue invasion. In conclusion, the application of AviPro Salmonella DUO vaccine stimulates host immunity and modulates cecal microbiota to defend against ST infection. Among the microbial modulations observed in SPF chicks and field layers with protection, Faecalibacterium prausnitzii emerges as a significant species in the ceca. Further research is warranted to elucidate its role in protecting layers against ST infection.

Nontyphoidal Salmonella infection was one of the predominant foodborne illnesses in humans. The medical burden and antimicrobial resistance of salmonellosis gained importance in public health and requested the poultry industry to seek effective measures to control the disease. The objective of this study was to evaluate the safety and effectiveness of a commercial bivalent live attenuated vaccine (AviPro Salmonella DUO) in specific-pathogen-free (SPF) chickens and field layers. It explored its safety and efficacy against medically important strains, Salmonella Enteritidis (SE) and S. Typhimurium (ST). The results demonstrated that ten vaccine doses in SPF chickens and regular doses in commercial layers showed desirable safety without affecting chicken health. Vaccinated layers demonstrated lower flock mortality and higher egg production performance than the unvaccinated layers during the raising and egg production periods. Additionally, no visceral colonization and egg contaminations were detected. Cloacal shedding of vaccine strains was noted, but the colonization of Salmonella disappeared within four weeks of the last vaccination. Regarding vaccine efficacy, one dose significantly reduced Salmonella cloacal shedding (P = 0.037 for SE and P = 0.027 for ST) and viable cell counts (P = 0.003 for SE and ST) on day 7 post the challenges. Significantly low Salmonella loads of cloacal samples on day 14 after the challenges were also determined in the vaccinated group (P = 0.006 for SE; P = 0.041 for ST). Triple immunizations effectively prevented layers from the cloacal shedding on either day 7 or day 14 post Salmonella challenges. Total viable counts of SE and ST in tissues of vaccinated layers were also reduced on day 14 after the challenges (P = 0.026 for SE; P = 0.002 for ST). To conclude, one dose of vaccine exhibited inhibitory effects on Salmonella shedding and tissue invasions in young layers. Following the regimen of triple vaccinations, Salmonella shedding was completely inhibited, and tissue invasions were significantly reduced. Incorporating this vaccine into a comprehensive Salmonella control program is promising to protect layers from the risks of contaminating the flocks and egg products.

ABSTRACT: The objective of the current study was to evaluate increasing levels of manganese hydroxychloride (MHC) in 45-wk-old white leghorn laying hens, using yolk and shell manganese (Mn) content as a potential marker for Mn concentration. A total of 80, 45-wk-old white leghorns were assigned to 6 dietary treatments, each consisting of 14 individually caged laying hens, with the exception of the reference diet containing 10 individually caged laying hens. The experiment consisted of a reference diet that contained 70 ppm of supplemental inorganic Mn in the form of Mn oxide and 5 experimental treatments each containing 0, 15, 30, 60, and 90 ppm supplemental MHC. Experimental birds were subjected to a 21 D depletion phase in which no supplemental Mn was included in the diet; however, during this time reference fed birds were fed the control diet (70 ppm Mn). After the 21 D depletion phase, the depleted birds were fed experimental diets for a 35 D evaluation period. Yolk and shell Mn content were analyzed at the end of the depletion phase and during the experimental phase on day 5, 10, 15, 25, and 35. During the experimental phase, Mn was replenished in the yolk and shell in all experimental treatments containing supplemental Mn; however, dose and time impacted the rate of replenishment. The yolk tended to be more sensitive to variations in Mn level as increases in Mn inclusion significantly (P < 0.05) increased concentration. These data demonstrate the ability to deplete and replenish Mn, and the use of egg yolk Mn concentration as measurement for determining changes in dietary Mn. At the conclusion of the experiment at 35 D, 60 ppm of Mn hydroxychloride seemed to be adequate in replenishing Mn to the level of the reference.

ABSTRACT: Vitamin D is essential for the metabolism of calcium (Ca) and phosphorus (P) in birds. The objective of the study was to evaluate the effect of different isoforms of dietary vitamin D on Ca and P utilization, egg quality, and bone mineralization of laying hens. A total of 42 Lohmann white laying hens at 57 wk of age were randomly assigned to 7 dietary treatments for 6 wk. Dietary treatments were: 3,000 IU/kg Vit D3 as control, and control with additional 3,000 IU/kg 25-hydroxyvitamin D3 (T1), 9,000 IU/kg 25-hydroxyvitamin D3 (T2), 3,000 IU/kg vitamin D3 (T3), 9,000 IU/kg vitamin D3 (T4), 3,000 IU/kg of vitamin D2 (T5), or 9,000 IU/kg of vitamin D2 (T6). Egg production and egg quality were measured weekly. Fecal samples were collected at weeks 2 and 6 to measure Ca and P utilization. After 6 wk, the left tibia and femurs were collected to measure bone mineral density (BMD) and bone mineral content (BMC). A 1-way ANOVA with Tukey HSD means separation test was used for statistical analysis. There were no significant differences in egg production, egg quality, BMD, or BMC of tibia and femurs among the treatments (P > 0.05). T6 significantly reduced feed intake (P < 0.05). The apparent total tract digestibility (ATTD) of Ca was higher (P < 0.012) in treatments supplemented with additional vitamin D, irrespective of forms. The ATTD of P was higher (P < 0.0001) in T5 compared to the other treatments at both time points. The utilization of Ca and P by laying hens can be improved through the addition of different isoforms of vitamin D in diets. However, additional vitamin D supplementation to laying hens, regardless of forms, had no effect on either bone mineralization or measures of egg quality.

The objective of the current study was to evaluate increasing levels of manganese hydroxychloride (MHC) in 45-wk-old white leghorn laying hens, using yolk and shell manganese (Mn) content as a potential marker for Mn concentration. A total of 80, 45-wk-old white leghorns were assigned to 6 dietary treatments, each consisting of 14 individually caged laying hens, with the exception of the reference diet containing 10 individually caged laying hens. The experiment consisted of a reference diet that contained 70 ppm of supplemental inorganic Mn in the form of Mn oxide and 5 experimental treatments each containing 0, 15, 30, 60, and 90 ppm supplemental MHC. Experimental birds were subjected to a 21 D depletion phase in which no supplemental Mn was included in the diet; however, during this time reference fed birds were fed the control diet (70 ppm Mn). After the 21 D depletion phase, the depleted birds were fed experimental diets for a 35 D evaluation period. Yolk and shell Mn content were analyzed at the end of the depletion phase and during the experimental phase on day 5, 10, 15, 25, and 35. During the experimental phase, Mn was replenished in the yolk and shell in all experimental treatments containing supplemental Mn; however, dose and time impacted the rate of replenishment. The yolk tended to be more sensitive to variations in Mn level as increases in Mn inclusion significantly (P < 0.05) increased concentration. These data demonstrate the ability to deplete and replenish Mn, and the use of egg yolk Mn concentration as measurement for determining changes in dietary Mn. At the conclusion of the experiment at 35 D, 60 ppm of Mn hydroxychloride seemed to be adequate in replenishing Mn to the level of the reference. [ABSTRACT FROM AUTHOR]

Vitamin D is essential for the metabolism of calcium (Ca) and phosphorus (P) in birds. The objective of the study was to evaluate the effect of different isoforms of dietary vitamin D on Ca and P utilization, egg quality, and bone mineralization of laying hens. A total of 42 Lohmann white laying hens at 57 wk of age were randomly assigned to 7 dietary treatments for 6 wk. Dietary treatments were: 3,000 IU/kg Vit D3 as control, and control with additional 3,000 IU/kg 25-hydroxyvitamin D3 (T1), 9,000 IU/kg 25-hydroxyvitamin D3 (T2), 3,000 IU/kg vitamin D3 (T3), 9,000 IU/kg vitamin D3 (T4), 3,000 IU/kg of vitamin D2 (T5), or 9,000 IU/kg of vitamin D2 (T6). Egg production and egg quality were measured weekly. Fecal samples were collected at weeks 2 and 6 to measure Ca and P utilization. After 6 wk, the left tibia and femurs were collected to measure bone mineral density (BMD) and bone mineral content (BMC). A 1-way ANOVA with Tukey HSD means separation test was used for statistical analysis. There were no significant differences in egg production, egg quality, BMD, or BMC of tibia and femurs among the treatments (P > 0.05). T6 significantly reduced feed intake (P < 0.05). The apparent total tract digestibility (ATTD) of Ca was higher (P < 0.012) in treatments supplemented with additional vitamin D, irrespective of forms. The ATTD of P was higher (P < 0.0001) in T5 compared to the other treatments at both time points. The utilization of Ca and P by laying hens can be improved through the addition of different isoforms of vitamin D in diets. However, additional vitamin D supplementation to laying hens, regardless of forms, had no effect on either bone mineralization or measures of egg quality. [ABSTRACT FROM AUTHOR]

Salmonella Typhimurium (ST) infection in laying hens is a significant threat to public health and food safety. Host resistance against enteric pathogen invasion primarily relies on immunity and gut barrier integrity. This study applied the ST infection model and a dual live vaccine containing Salmonella Enteritidis (SE) strain Sm24/Rif12/Ssq and ST strain Nal2/Rif9/Rtt to investigate the cellular cytokine expression profiles and the differential community structure in the cecal microbiota of specific-pathogen-free (SPF) chicks and field-raised layers. The results showed that ST challenge significantly upregulated expressions of IL-1β in SPF chicks. Vaccination, on the other hand, led to an elevation in IFNγ expression and restrained IL-1β levels. In the group where vaccination preceded the ST challenge (S.STvc), heightened expressions of IL-1β, IL-6, IL-10, and IL-12β were observed, indicating active involvement of both humoral and cell-mediated immunity in the defense against ST. Regarding the cecal microbiota, the vaccine did not affect alpha diversity nor induce a significant shift in the microbial community. Conversely, ST infection significantly affected the alpha and beta diversity in the cecal microbiota, reducing beneficial commensal genera, such as Blautia and Subdoligranulum. MetagenomeSeq analysis reveals a significant increase in the relative abundance of Faecalibacterium prausnitzii in the groups (S.STvc and STvc) exhibiting protection against ST infection. LEfSe further demonstrated Faecalibacterium prausnitzii as the prominent biomarker within the cecal microbiota of SPF chicks and field layers demonstrating protection. Another biomarker identified in the S.STvc group, Eubacterium coprostanoligenes , displayed an antagonistic relationship with Faecalibacterium prausnitzii , suggesting the limited biological significance of the former in reducing cloacal shedding and tissue invasion. In conclusion, the application of AviPro Salmonella DUO vaccine stimulates host immunity and modulates cecal microbiota to defend against ST infection. Among the microbial modulations observed in SPF chicks and field layers with protection, Faecalibacterium prausnitzii emerges as a significant species in the ceca. Further research is warranted to elucidate its role in protecting layers against ST infection. [ABSTRACT FROM AUTHOR]

The interaction between bird type (broilers and layers) and corn particle size (fine, medium, and coarse) on the coefficient of apparent ileal digestibility (CAID) of DM, nitrogen (N), starch, fat, gross energy (GE), calcium (Ca) and phosphorus (P), and AMEn was investigated in a 2 by 3 factorial study of 6 dietary treatments. Whole corn was ground in a hammer mill to pass through screen sizes of 2.0, 5.0, and 8.0 mm for fine, medium, and coarse grades, respectively. A corn-soybean meal diet, mixed using the same batch of ingredients, was fed to both bird types. Titanium dioxide was included in all diets for digestibility measurements. 35-day-old Ross 308 male broilers and 59-wk-old Hy-Line Brown layers were used in this study. For each bird type, 108 birds of uniform body weights were accommodated in 18 replicates (6 replicates per particle size and 6 birds per replicate). The treatment diets were offered ad libitum for 7 d prior to the collection of ileal digesta. A bird type by particle size interaction was observed (P < 0.001) for the CAID of DM, starch and GE. In broilers, CAID of DM, starch and GE was unaffected by particle size, whilst in layers, increasing the corn particle size to medium and coarse resulted in a greater (P < 0.05) CAID for DM, starch and GE compared to fine particles. The CAID of N and fat was greater (P < 0.05) in broilers than layers and the opposite was observed (P < 0.05) for Ca and P. Regardless of bird type, coarse and medium-ground corn resulted in a greater (P < 0.05) Ca digestibility compared to finely-ground corn. Overall, broilers had a greater digestibility of nutrients than layers, except for Ca and P. Feeding medium and coarse corn particles benefited the CAID of DM, starch and GE in layers, suggesting that digestive system in these birds is probably more sensitive to feed particle size than broilers. [ABSTRACT FROM AUTHOR]

Single-step genomic prediction method has been proposed to improve the accuracy of genomic prediction by incorporating information of both genotyped and ungenotyped animals. The objective of this study is to compare the prediction performance of single-step model with a 2-step models and the pedigree-based models in a nuclear population of layers. A total of 1,344 chickens across 4 generations were genotyped by a 600 K SNP chip. Four traits were analyzed, i.e., body weight at 28 wk (BW28), egg weight at 28 wk (EW28), laying rate at 38 wk (LR38), and Haugh unit at 36 wk (HU36). In predicting offsprings, individuals from generation 1 to 3 were used as training data and females from generation 4 were used as validation set. The accuracies of predicted breeding values by pedigree BLUP (PBLUP), genomic BLUP (GBLUP), SSGBLUP and single-step blending (SSBlending) were compared for both genotyped and ungenotyped individuals. For genotyped females, GBLUP performed no better than PBLUP because of the small size of training data, while the 2 single-step models predicted more accurately than the PBLUP model. The average predictive ability of SSGBLUP and SSBlending were 16.0% and 10.8% higher than the PBLUP model across traits, respectively. Furthermore, the predictive abilities for ungenotyped individuals were also enhanced. The average improvements of prediction abilities were 5.9% and 1.5% for SSGBLUP and SSBlending model, respectively. It was concluded that single-step models, especially the SSGBLUP model, can yield more accurate prediction of genetic merits and are preferable for practical implementation of genomic selection in layers. [ABSTRACT FROM AUTHOR]

When laying hen diets are enriched with omega-3 polyunsaturated fatty acids to generate value-added eggs for human consumption markets, concentrations of alpha-linolenic (ALA), eicosapentaenoic (EPA), and docosahexaenoic acids (DHA) in the yolk can reach 250 mg/50 g whole egg. Flaxseed, a rich source of ALA, is commonly used for omega-3 enrichment; however, the impact of dietary flaxseed source (extracted oil vs. milled seed) on fatty acid transfer to egg yolk in laying hens is unknown. Therefore, transfer of ALA, EPA, and DHA into egg yolk from extracted flaxseed oil or milled flaxseed was evaluated in Hy-Line W-36 laying hens over an 8-week feeding period (25 to 33 wk old). Hens (n = 132) were randomly housed with 3 birds/cage (4 replicates/treatment) for each of the 11 treatment groups. Diets were isocaloric and consisted of a control diet, 5 flaxseed oil diets (0.5, 1.0, 2.0, 3.0, or 5.0% flaxseed oil), and 5 milled flaxseed diets (calculated flaxseed oil concentration from milled flaxseed 0.5, 1.0, 2.0, 3.0, 5.0%). Increasing dietary concentrations of flaxseed oil and milled flaxseed resulted in increased ALA, EPA, and DHA concentration in egg yolk, and fatty acid deposition from flaxseed oil was 2 times greater compared to milled flaxseed when fed at the same dietary inclusions (P < 0.01). Egg yolk EPA and DHA concentrations were not different due to oil or milled source (P = 0.21); however, increasing dietary inclusion rates of flaxseed oil from either source increased yolk EPA and DHA (P < 0.01). Hens fed either flaxseed oil or milled flaxseed resulted in reduced BW change as dietary concentrations increased (P = 0.02). Feed efficiency increased as flaxseed oil increased in concentration, while feeding milled flaxseed decreased feed efficiency (P = 0.01). Analysis of the nitrogen corrected apparent metabolizable energy of flaxseed oil resulted in 7,488 kcal/kg on an as-fed basis. Dietary flaxseed oil improved feed efficiency and increased ALA deposition into yolk compared to a milled source, demonstrating flaxseed oil to be a viable alternative for ALA egg enrichment. [ABSTRACT FROM AUTHOR]

A survey on the prevalence of Salmonella (S.) species was carried out on 39 layer farms in Kosovo between April and September 2012. In total 367 samples, comprising feces, dust, eggs, and internal organs from dead birds, were investigated using bacteriological culture methods. Additionally, data on the location of the farm, the total number of birds on the farm, age of birds, and laying performance were collected. Salmonella were isolated from 38 samples obtained from 19 (49%) farms. The most common serovar identified was Salmonella enteritidis, found on 18 farms. The most common S. enteritidis phage type was PT29 followed by PT6, PT7, PT21, PT13a, PT8, PT14b, and PT4. One S. enteritidis isolate was not typable. Six farms had more than one phage type. Furthermore, serovar S. Bovismorbificans also was found in samples from 3 farms. Flock size or production stage was not associated with the probability of isolating Salmonella. The only flock factor found to be significantly associated was percent hen/day production: It was 2.8 times more likely to isolate Salmonella from flocks with production above 80% hen/day production compared to flocks producing at a lower level. Analysis of antimicrobial resistance patterns of 30 isolates revealed that all isolates were sensitive to gentamicin, ampicillin, sulphamethoxazole trimethoprim, and oxytetracycline, and 29 (97%) were sensitive to ciprofloxacin. All isolates showed intermediate resistance or were resistant to minocycline and cloxacillin. Twenty-six isolates (86%) had intermediate resistance to amoxicillin and 27 isolates (90%) were fully resistant to streptomycin. The present survey revealed a high prevalence of Salmonella enteritidis in layer flocks in Kosovo, indicating that table eggs have to be suspected as an important source of human salmonellosis. [ABSTRACT FROM AUTHOR]

Nontyphoidal Salmonella infection was one of the predominant foodborne illnesses in humans. The medical burden and antimicrobial resistance of salmonellosis gained importance in public health and requested the poultry industry to seek effective measures to control the disease. The objective of this study was to evaluate the safety and effectiveness of a commercial bivalent live attenuated vaccine (AviPro Salmonella DUO) in specific-pathogen-free (SPF) chickens and field layers. It explored its safety and efficacy against medically important strains, Salmonella Enteritidis (SE) and S. Typhimurium (ST). The results demonstrated that ten vaccine doses in SPF chickens and regular doses in commercial layers showed desirable safety without affecting chicken health. Vaccinated layers demonstrated lower flock mortality and higher egg production performance than the unvaccinated layers during the raising and egg production periods. Additionally, no visceral colonization and egg contaminations were detected. Cloacal shedding of vaccine strains was noted, but the colonization of Salmonella disappeared within four weeks of the last vaccination. Regarding vaccine efficacy, one dose significantly reduced Salmonella cloacal shedding (P = 0.037 for SE and P = 0.027 for ST) and viable cell counts (P = 0.003 for SE and ST) on day 7 post the challenges. Significantly low Salmonella loads of cloacal samples on day 14 after the challenges were also determined in the vaccinated group (P = 0.006 for SE; P = 0.041 for ST). Triple immunizations effectively prevented layers from the cloacal shedding on either day 7 or day 14 post Salmonella challenges. Total viable counts of SE and ST in tissues of vaccinated layers were also reduced on day 14 after the challenges (P = 0.026 for SE; P = 0.002 for ST). To conclude, one dose of vaccine exhibited inhibitory effects on Salmonella shedding and tissue invasions in young layers. Following the regimen of triple vaccinations, Salmonella shedding was completely inhibited, and tissue invasions were significantly reduced. Incorporating this vaccine into a comprehensive Salmonella control program is promising to protect layers from the risks of contaminating the flocks and egg products. [ABSTRACT FROM AUTHOR]

This research examined the effects of infrared beak treatment on layer chicks. Seventy-two layer chicks were assigned to hot-blade trimming (HB), infrared treatment (IR), or a control treatment. Day-old chicks were pair-housed by treatment. Beak photographs, behavior, and production indices were obtained at intervals for 9 wk posttreatment. All beaks were normally shaped at the onset of the study, and no perceptible treatment- related differences in shape occurred over time (P > 0.05). Posttreatment, HB birds had shorter beaks relative to the other 2 groups (P < 0.05). Control and IR beaks remained comparable in length until tissue eroded in IR beaks at 1 to 2 wk posttreatment. Thereafter, beak length increased in all treatments over time (P < 0.01). Two weeks posttreatment, beaks were longest in control birds, intermediate in HB birds (P < 0.001), and shortest in IR birds (P < 0.001). The HB birds had abnormal deviations from a normal upper-to-lower mandible length ratio than the IR or control birds (P < 0.05). Notable effects of treatment on production emerged by +2 d and persisted for 5 wk. Growth and feed intake were lower in HB and IR birds compared with control birds (P < 0.05), with IR birds performing least well until the fourth week of the study (P < 0.05). Thereafter, they performed similarly to the HB group. Feed waste was lowest in the IR group and ~as generally greatest in the control group (P < 0.05). There was an overall effect of trimming, irrespective of method, on behavior, particularly eating and drinking behaviors (P < 0.05). Specifically, IR birds were less active (P < 0.01) and spent less time eating (P < 0.01) and drinking (P < 0.05) than did control birds. Behavior in FIB birds often ranked intermediate in duration and incidence, but Was not significantly different compared with behavior measured in the control and IR groups. Effects of treatment on behavior were not present after 1 wk posttrimming. Results indicate that acute pain occurred with both trimming methods. Although the impact of trimming appeared to be greatest in the IR birds initially, these differences disappeared relatively quickly, and subsequent performance was similar in both trimmed groups. [ABSTRACT FROM AUTHOR]

Presents abstracts of several studies on animal behavior and well being. "Effects of Photoperiod on the Immune Function of Multiparous Gestating Sows," by S. R. Niekamp, M. A. Sutherland, G. E. Dahl, T. L. Auchtung and J. L. Salak-Johnson; "Farrowing Performance and Injury in a Group Housing System for Gestating Sows," by T. M. Widowski and D. Barney; "Application of Guar Hull By-Product as a Full-Fed Molting Supplement," by C. Zhang, A. L. Cartwright, J. B. Carey and C. A. Bailey; "A Comparison of the Behavior of Broiler Chickens Raised on Two Different Bedding Types," by S. J. Shields, J. P. Garner and J. A. Mench.

Vitamin D is essential for the metabolism of calcium (Ca) and phosphorus (P) in birds. The objective of the study was to evaluate the effect of different isoforms of dietary vitamin D on Ca and P utilization, egg quality, and bone mineralization of laying hens. A total of 42 Lohmann white laying hens at 57 wk of age were randomly assigned to 7 dietary treatments for 6 wk. Dietary treatments were: 3,000 IU/kg Vit D 3 as control, and control with additional 3,000 IU/kg 25-hydroxyvitamin D 3 (T1), 9,000 IU/kg 25-hydroxyvitamin D 3 (T2), 3,000 IU/kg vitamin D3 (T3), 9,000 IU/kg vitamin D 3 (T4), 3,000 IU/kg of vitamin D 2 (T5), or 9,000 IU/kg of vitamin D 2 (T6). Egg production and egg quality were measured weekly. Fecal samples were collected at weeks 2 and 6 to measure Ca and P utilization. After 6 wk, the left tibia and femurs were collected to measure bone mineral density (BMD) and bone mineral content (BMC). A 1-way ANOVA with Tukey HSD means separation test was used for statistical analysis. There were no significant differences in egg production, egg quality, BMD, or BMC of tibia and femurs among the treatments (P > 0.05). T6 significantly reduced feed intake (P < 0.05). The apparent total tract digestibility (ATTD) of Ca was higher (P < 0.012) in treatments supplemented with additional vitamin D, irrespective of forms. The ATTD of P was higher (P < 0.0001) in T5 compared to the other treatments at both time points. The utilization of Ca and P by laying hens can be improved through the addition of different isoforms of vitamin D in diets. However, additional vitamin D supplementation to laying hens, regardless of forms, had no effect on either bone mineralization or measures of egg quality., (Copyright © 2019 The Author(s). Published by Elsevier Inc. All rights reserved.)

An abstract of the article "Effects of inorganic and organic selenium on the performance and egg composition of laying hens fed cottonseed meal," by V. Stanley, D. Wiley. O. Taylor, V. Vaughan, S. Woldesendent and A. Sefton is presented.

An abstract of the article "The Effects of Quantum Phytase on Egg Production and Shell Traits in Hyline W36 Hens," by M. S. Lilburn and C. Wyatt is presented.

An abstract of the article "The performance of layers fed Azolla (Azolla pinnata) meal in diets," by O. A. Alalade, E. A. Iyayi, and T. O. Alalade, is presented.

An abstract of the article "Effects of reducing dietary protein on performance of White Leghorn layers during the second production cycle," by H. M. Yakout, D. Hoehler, and C. Novak is presented.

An abstract of the article "Development of a high-throughput modified atmosphere chamber for the on-farm euthanasia of spent hens," J. S. Church, N. J. Cook, D. B. Haley and D. Slingerland is presented.

An abstract of the article "Effect of Bio-Mos in replacement pullets and layers," by R. J. Balander is presented.