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The Utrerana chicken is an endangered egg-producing breed native to Spain with four feather varieties that display productive seasonality. To fill the gap in knowledge on the seasonal variation in egg quality, 378 eggs were collected during the entire first laying period, between March and August, from an experimental flock of hens of the Partridge variety of the Utrerana breed and subsequently analysed to assess the effect of the laying month on external and external egg quality traits. The eggs, with an average weight of 61.66 g and sharp shape (shape index: 70.77), had 31.64% yolk, 56.59% albumen, and 11.77% white-coloured shell 0.43 mm in thickness. The egg yolk was light orange in colour (Roche fan score: 10.56) with a yolk index of 37.78%, whereas the albumen was moderately firm (Haugh units: 69.12). The egg yield was seasonal and peaked in the second month of the laying period, with a hen-day egg production of 61.4%. Throughout the first laying period, egg weight and eggshell content remained invariable and yolk content increased, whereas its quality and colour intensity worsened, and albumen content and quality decreased as a consequence of aging and increasing ambient temperature. In conclusion, the Partridge variety of the Utrerana chicken breed can be considered suitable for alternative farming systems because it lays good-quality eggs at a moderate seasonal laying rate.

ABSTRACT: Incubation behavior in chickens is closely associated with hypothalamus. Here, RNA sequencing of hypothalamus from Changshun green-shell laying hens, an indigenous chicken breed from China, in egg-laying period (LP) and incubation period (BP) was conducted to identify critical pathways and candidate genes involved in controlling the incubation behavior in hypothalamus. A total of 637 up-regulated and 305 down-regulated differently expressed genes (DEGs) were identified in chicken hypothalamus between LP and BP groups. Gene ontology term (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis further revealed that neuroactive ligand-receptor interaction, hippo signaling pathway, and focal adhesion were significantly enriched. Five candidate genes (POMC, IGF1R, CHAD, VCL, and MYL9) were suggested to play crucial roles in the regulation of chicken incubation behavior. Our results further indicated the complexity of reproductive behavior of different chicken breeds.

Abstract Background Incubation behaviour, an instinct for natural breeding in poultry, is strictly controlled by the central nervous system and multiple neuroendocrine hormones and neurotransmitters, and is closely associated with the cessation of egg laying. Therefore, it is essential for the commercial poultry industry to clarify the molecular regulation mechanism of incubation behaviour. Here, we used high-throughput sequencing technology to examine the pituitary transcriptome of Changshun green-shell laying hen, a local breed from Guizhou province, China, with strong broodiness, in two reproductive stages, including egg-laying phase (LP) and incubation phase (BP). We also analyze the differences in gene expression during the transition from egg-laying to incubation, and identify critical pathways and candidate genes involved in controlling the incubation behaviour in the pituitary. Results In this study, we demonstrated that a total of 2089 differently expressed genes (DEGs) were identified in the pituitary, including 842 up-regulated and 1247 down-regulated genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that steroid biosynthesis pathway and neuroactive ligand-receptor interaction were significantly enriched based on DEGs commonly identified in pituitary. Further analysis revealed that SRC, ITGB4, ITGB3, PIK3R3 and DRD2 may play crucial roles in the regulation of incubation behaviour. Conclusions We identified 2089 DEGs and the key signaling pathways which may be closely correlated with incubation in Changshun green-shell laying hens, and clarified the molecular regulation mechanism of incubation behaviour. Our results indicate the complexity and variety of differences in reproductive behaviour of different chicken breeds.

Background: Incubation behaviour, an instinct for natural breeding in poultry, is strictly controlled by the central nervous system and multiple neuroendocrine hormones and neurotransmitters, and is closely associated with the cessation of egg laying. Therefore, it is essential for the commercial poultry industry to clarify the molecular regulation mechanism of incubation behaviour. Here, we used high-throughput sequencing technology to examine the pituitary transcriptome of Changshun green-shell laying hen, a local breed from Guizhou province, China, with strong broodiness, in two reproductive stages, including egg-laying phase (LP) and incubation phase (BP). We also analyze the differences in gene expression during the transition from egg-laying to incubation, and identify critical pathways and candidate genes involved in controlling the incubation behaviour in the pituitary. Results: In this study, we demonstrated that a total of 2089 differently expressed genes (DEGs) were identified in the pituitary, including 842 up-regulated and 1247 down-regulated genes. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that steroid biosynthesis pathway and neuroactive ligand-receptor interaction were significantly enriched based on DEGs commonly identified in pituitary. Further analysis revealed that SRC, ITGB4, ITGB3, PIK3R3 and DRD2 may play crucial roles in the regulation of incubation behaviour. Conclusions: We identified 2089 DEGs and the key signaling pathways which may be closely correlated with incubation in Changshun green-shell laying hens, and clarified the molecular regulation mechanism of incubation behaviour. Our results indicate the complexity and variety of differences in reproductive behaviour of different chicken breeds. [ABSTRACT FROM AUTHOR]

1. Laying performance is an important economic trait in poultry. The blood is essential in transporting nutrients to the yolk and albumen and is necessary for egg formation. 2. This study calculated the phenotypic relationships of duck egg quality, egg production efficiency and 22 serum parameters in the egg-laying stage. Using a variety of methodologies, a genome-wide association study (GWAS) was carried out to uncover the genetic foundations of the 22 serum biochemical markers of laying ducks. 3. Spearman correlation coefficients between the egg production (226–329 per day) and the serum parameters were all weak, being less than 0.3. This analysis was done on 22 serum parameters, with total protein (TP), total triglycerides (TG), calcium (Ca) and phosphorous (P) having the highest correlation coefficients (r = 0.56–0.88). The coefficients for blood markers, such as total cholesterol (CHOL), total bilirubin (TBIL), low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C) varied from 0.70–0.94. 4. Based on single-marker single-trait genome-wide analyses by a mixed linear model program of EMMAX, nine candidate genes were associated with enzyme traits (AST/ALT aspartate transaminase/glutamic-pyruvic transaminase, creatine kinase) and 19 candidate genes were associated with metabolism and protein-related serum parameters (glucose, total bile acid, uric acid (UA), albumin (ALB). 5. The mvLMM (multivariate linear mixed model) of GEMMA software was used to carry out multiple trait integrated GWAS. Two candidate genes were found in the TP-TG-CA-P analysis and seven candidate genes in the CHOL_LDL-C_HDL-C_TBIL study. There was a high genetic correlation between the two groups. [ABSTRACT FROM AUTHOR]

Abstract The avian eggshell is formed in the uterus. Changes in uterine function may have a significant effect on eggshell quality. To identify the vital genes impacting uterine functional maintenance in the chicken, uteri in three different periods (22W, 31W, 51W) were selected for RNA sequencing and bioinformatics analysis. In our study, 520, 706 and 736 differentially expressed genes (DEGs) were respectively detected in the W31 vs W22 group, W51 vs W31 group and W51 vs W22 group. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated DEGs were enriched in the extracellular matrix, extracellular region part, extracellular region, extracellular matrix structural constituent, ECM receptor interaction, collagen-containing extracellular matrix and collagen trimer in the uterus (P

The avian eggshell is formed in the uterus. Changes in uterine function may have a significant effect on eggshell quality. To identify the vital genes impacting uterine functional maintenance in the chicken, uteri in three different periods (22W, 31W, 51W) were selected for RNA sequencing and bioinformatics analysis. In our study, 520, 706 and 736 differentially expressed genes (DEGs) were respectively detected in the W31 vs W22 group, W51 vs W31 group and W51 vs W22 group. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated DEGs were enriched in the extracellular matrix, extracellular region part, extracellular region, extracellular matrix structural constituent, ECM receptor interaction, collagen-containing extracellular matrix and collagen trimer in the uterus (P < 0.05). Protein–protein interaction analysis revealed that FN1, LOX, THBS2, COL1A1, COL1A2, COL5A1, COL5A2, POSTN, MMP13, VANGL2, RAD54B, SPP1, SDC1, BTC, ANGPTL3 might be key candidate genes for uterine functional maintenance in chicken. This study discovered dominant genes and pathways which enhanced our knowledge of chicken uterine functional maintenance. [ABSTRACT FROM AUTHOR]

Abstract Background The development of the ovaries is an important factor that affects egg production performance in geese. Ovarian development is regulated by genes that are expressed dynamically and stage-specifically. The transcriptome profile analysis on ovarian tissues of goose at different egg laying stages could provide an important basis for screening and identifying key genes regulating ovarian development. Results In this study, 4 ovary tissues at each breeding period of pre-laying (PP), laying (LP), and ceased-laying period (CP), respectively, with significant morphology difference, were used for RNA extraction and mRNAs, lncRNAs, and miRNAs comparison in Yili geese. CeRNA regulatory network was constructed for key genes screening. A total of 337, 1136, and 525 differentially expressed DE mRNAs, 466, 925, and 742 DE lncRNAs and 258, 1131 and 909 DE miRNAs were identified between PP and LP, between CP and LP, and between CP and PP groups, respectively. Functional enrichment analysis showed that the differentially expressed mRNAs and non-coding RNA target genes were mainly involved in the cell process, cytokine-cytokine receptor interaction, phagosome, calcium signaling pathway, steroid biosynthesis and ECM-receptor interaction. Differential genes and non-coding RNAs, PDGFRB, ERBB4, LHCGR, MSTRG.129094.34, MSTRG.3524.1 and gga-miR-145–5p, related to reproduction and ovarian development were highly enriched. Furthermore, lncRNA-miRNA-mRNA regulatory networks related to ovary development were constructed. Conclusions Our study found dramatic transcriptomic differences in ovaries of Yili geese at different egg-laying stages, and a differential lncRNA-miRNA-mRNA regulatory network related to cell proliferation, differentiation and apoptosis and involved in stromal follicle development were established and preliminarily validated, which could be regarded as a key regulatory pathway of ovarian development in Yili geese.

Background: The development of the ovaries is an important factor that affects egg production performance in geese. Ovarian development is regulated by genes that are expressed dynamically and stage-specifically. The transcriptome profile analysis on ovarian tissues of goose at different egg laying stages could provide an important basis for screening and identifying key genes regulating ovarian development. Results: In this study, 4 ovary tissues at each breeding period of pre-laying (PP), laying (LP), and ceased-laying period (CP), respectively, with significant morphology difference, were used for RNA extraction and mRNAs, lncRNAs, and miRNAs comparison in Yili geese. CeRNA regulatory network was constructed for key genes screening. A total of 337, 1136, and 525 differentially expressed DE mRNAs, 466, 925, and 742 DE lncRNAs and 258, 1131 and 909 DE miRNAs were identified between PP and LP, between CP and LP, and between CP and PP groups, respectively. Functional enrichment analysis showed that the differentially expressed mRNAs and non-coding RNA target genes were mainly involved in the cell process, cytokine-cytokine receptor interaction, phagosome, calcium signaling pathway, steroid biosynthesis and ECM-receptor interaction. Differential genes and non-coding RNAs, PDGFRB, ERBB4, LHCGR, MSTRG.129094.34, MSTRG.3524.1 and gga-miR-145–5p, related to reproduction and ovarian development were highly enriched. Furthermore, lncRNA-miRNA-mRNA regulatory networks related to ovary development were constructed. Conclusions: Our study found dramatic transcriptomic differences in ovaries of Yili geese at different egg-laying stages, and a differential lncRNA-miRNA-mRNA regulatory network related to cell proliferation, differentiation and apoptosis and involved in stromal follicle development were established and preliminarily validated, which could be regarded as a key regulatory pathway of ovarian development in Yili geese. [ABSTRACT FROM AUTHOR]

The disparity in fatty acids (FA) composition exhibits a significant impact on meat quality, however, the molecular regulatory mechanisms underlying this trait in chicken are far from clear. In this study, a total of 45 female Beijing-You chicken (BYC) hens, fed on the same diet, were collected at the slaughter age of 150, 300, or 450 days (D150, D300, and D450) from sexual maturation stage to culling stage (15 birds per age). Gas chromatography-mass spectrometry (GC-MS) and tandem mass tag labeling technology based on liquid chromatography mass spectrometry (TMT-LC-MS/MS) analysis strategies were applied to profile FA compositions and to compare differential expressed proteins (DEPs) between these different slaughter ages, respectively. The FA profiling showed that increasing hen ages resulted in increased contents of both saturated and unsaturated fatty acids. Proteomic analyses showed a total of 4,935 proteins in chicken breast muscle with the false discovery rate (FDR) < 1% and 664 of them were differentially expressed (fold change > 1.50 or < 0.67 and P < 0.01). There were 410 up- and 116 down-regulated proteins in D150 vs. D300 group, 32 up- and 20 down-regulated in D150 vs. D450 group, and 72 up- and 241 down-regulated in D300 vs. D450 group. A total of 57 DEPs related to FA/lipid-related metabolisms were obtained according to the enrichment analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). These DEPs were involved in 21 significantly enriched (P < 0.05) pathways, including well-known pathways for FA synthesis (metabolism, desaturation, and elongation) and the signaling pathways for lipid metabolism (PPAR, adipocytokine, calcium, VEGF, MAPK, and Wnt). In addition, there existed several representative DEPs (FABP, FABP3, apoA-I, apoA-IV, apoC-III, apoB, VTG1, and VTG2) involved in the regulation of FA/lipid transportation. The construction of the interaction networks indicated that HADH, ACAA2, HADHA, ACSL1, CD36, CPT1A, PPP3R1, and SPHK1 were the key core nodes. Finally, eight DEPs were quantified using parallel reaction monitoring (PRM) to validate the results from TMT analysis. These results expanded our understanding of how the laying age affects the FA compositions and metabolism in hen breast meat.

In order to explore the change rules of ovarian follicles in Rugao yellow chickens at different laying periods, by selecting the Rugao yellow chickens at the prelaying period (16 wk of age), the early laying period (20 wk of age), peak egg-laying period (27 wk of age), and the telophase of laying (64 wk of age), the statistics of the weight of oviduct, the ovarian weight, and the number of pre-hierarchical follicles were carried out. At. the same time, the original, primary and secondary follicles were observed and measured after the tissue section and HE staining of ovary, and the number changes of follicles at different stages were compared and analyzed. The results showed that the weight of ovary and fallopian tube showed an increasing trend with the development of laying period, and the number of four kinds of pre-hierarchical follicles reached the highest value at the peak egg-laying period. The number of the secondary follicles was the highest in the prelaying period, and the number of the secondary follicles with different diameters varied in the course of laying period. In addition, the average diameter of the primary follicle was also di任erent at different laying periods. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effect of dietary supplemental of glycine (Gly) on modulating physiological and reproduction performance of Mandarah (M) local chickens. A total of 135 hens and 18 cocks, from 28 to 40 weeks of age were randomly assigned to 3 treatments, and each treatment (T) include 45 hens and 6 cocks divided in 3 replicates of 15 hens and 2 cocks each. The 1st group (T1) was fed the basal diet and served as a control group (without supplementation). The 2nd group and 3rd group were fed the basal diet supplemented with 0.1 and 0.2 %, Gly (1 and 2 gm/ kg diet), respectively.). The study showed that the cocks Gly treatments (0.1 and 0.2 %) were significantly (P<0.05) increased in the ejaculate volume, total sperm output, semen quality factor, total motile sperm, thyroxine (T4) and folliclestimulating hormones (FSH) compared with control treatment. Chickens that received diet supplemented with 0.1 % Gly had significant higher sperm concentration, total antioxidant capacity (TAC), triiodothyronine (T3) than those of control T1. No significant differences among T2, T3 and control (T1) in sperm motility %, live sperm %, dead sperm %, abnormal sperm %, fertility, hatchability, catalase, glutathione enzyme and luteinizing hormone (LH). Conclusively, it could be recommended to supply layer diets with Gly for better physiologically performance during the laying period. [ABSTRACT FROM AUTHOR]

The experiment was to screen the special premix for Taihang chickens during the laying period, the effect of the premix on the production performance, egg quality, serum antioxidant capacity and economic benefits of Taihang chickens during the laying period were studied. 432 healthy 280-day-old Taihang chickens were selected and randomly divided into six groups, with six replicates in each group and 12 chickens in each replicate. Chickens in group A (control group) were fed with premix for commercial laying hens, and chickens in group D (100% premix) were fed with premix prepared according to chicken breeding standards and the physiological characteristics of Taihang chickens. Taihang chickens in group B, group C, group E and group F were fed with vitamin and trace element levels reduced by 50% and 25% and increased by 25% and 50% on the basis of group D. The results showed that compared with the control group, the egg production rate of group B and group C significantly decreased (P<0.05), and the feed-to-egg ratio significantly increased (P<0.05). The eggshell strength of group F was significantly higher than that of group B and group C (P<0.05). Compared with the control group, serum glutathione peroxidase (GSH-Px) activity in group B and group C was significantly reduced (P<0.05). The total antioxidant capacity (T-AOC) of group B was significantly reduced (P<0.05). The economic benefits of group D, group E and group F were 6.00%, 3.65% and 0.01% higher than those of control group, respectively. The economic benefits of group B and group C were lower than the control group by 16.39% and 16.61%. The experiment indicates that the premix D~F can guarantee the normal production performance, egg quality and serum antioxidant capacity of Taihang chickens during the peak laying period. Group D has the highest economic benefit and can be used as a special premix for Taihang chickens during the peak laying period. [ABSTRACT FROM AUTHOR]

ABSTRACT: Xupu goose, a breed from Hunan province, produces high quality and quantity of meat and liver. However, its egg production rate is low, with poor reproductive traits but strong broody performance. These characteristics decrease the economic value of Xupu goose significantly. Here, RNA-seq was used to analyze the transcriptome changes of ovaries of Xupu goose at different stages to explore the molecular mechanism of reproduction from the pre-laying period to the broody period. A total of 258 genes were differentially expressed in the 3 stages. These genes are associated with inflammation, reproduction, mutual recognition and adhesion between cells, and cytoskeleton formation, and so on. In particular, we report, for the first time, the expression patterns of MRP126, serglycin, TXNIP, and FZD2 during the pre-laying, egg-laying, and broody periods of goose ovaries. Functional analysis by GO annotation revealed that GO terms were mainly involved in actin, cell signal transduction and regulation, and cellular components. Three pathways, including focal adhesion (gga04510), ECM-receptor interaction (gga04512), and N-Glycan biosynthesis (gga00510), were significantly enriched in the three groups. These findings provide a basis for further exploration of profiles of goose ovaries to improve egg production of Xupu goose.

Raman spectroscopy has been widely applied in the analysis of biological tissues. In this study, beak cuticle was studied to investigate its compositional and secondary structural changes during the laying period and aging of laying hens. The analysis revealed markedly increased contents of amide I and amino acids (phenylalanine and tyrosine) within the beak during the intense laying period from 17 to 20 weeks. In addition, α-helical protein was also gradually synthesized in this period. The relative area ratio of 1003/1448 cm−1 (assigned to the vibrations of phenylalanine and organic C-H respectively) was confirmed as an excellent indicator for estimating the start of the laying period. This ratio increased from 0.36 to 0.42 from 17 to 20 weeks. The Raman peak at 1156 cm−1 was assigned to carotenoids in the beak. The intensities of the 1156 cm−1 peak significantly decreased during aging. The area ratio of 1156/1448 cm−1 was successfully applied to estimate ages (still within the laying period) of laying hens. This study shows the potential of using Raman spectroscopy to quantify ages and laying period of birds.

ABSTRACT In any broiler breeder flock, there is always some mortality that is considered to be “normal” during the life of the flock. The aim of this study is to summarize the prevalence and patterns of mortality during the production period. To evaluate the mortality, each dead hen was systematically and completely examined via necropsy. In addition to post mortem evaluation, weights (whole body, liver, spleen and heart) were recorded to correlate the bird’s physical condition with the mortality category or lesion. In general, the variation in mortality was not associated with the specific weight of the organs. However, for specific diseases like fatty liver, septicemia and ascites, there was a correlation with the organ weight of the liver, spleen and heart respectively. Ovaritis was observed to be the most prevalent lesion found in dead hens during the production period followed by ovarian regression (atrophy), peritonitis, internal lay and vent pecking. The two periods with the higher total percentage of morality were onset of lay (25-30 weeks) and end-stage of the production period (56-61 weeks). During the laying period, we mainly observed metabolic disorders followed by infectious lesions. Infectious lesions, including ovaritis and septicemia, were the predominant cause for mortality at the onset production. Vent and feather pecking were also primarily concentrated during the first weeks of the production period. Metabolic diseases were observed in higher prevalence during the latter half of the production period.

The high laying performance of today’s laying hens places enormous demands on their mineral metabolism. While up-to-date data are rare, the present study aimed to describe blood parameters associated with egg laying and bone metabolism during the pre-laying period, in the course of the laying period and the daily egg laying cycle. Ten to 15 laying hens of two high-performing, phylogenetically divergent lines (BLA: brown-egg layer; WLA: white-egg layer), kept in single cages were blood sampled at 17, 25, 29, 49, and 69 weeks of age. Sampling was made at 6 a.m., 10 a.m., 2 p.m. and, with the exception of week 17, 6 p.m. Blood samples were analyzed for concentrations of total and ionized calcium, inorganic phosphate (PO4), markers of bone formation (osteocalcin) and resorption [carboxyterminal crosslinked telopeptide of type I collagen (CTX-I)], 25-hydroxycholecalciferol (25(OH)D3) and estradiol-17β. In the pre-laying period (17 week), the estradiol-17β level calculated for WLA was more than twice as high as the level calculated for BLA, while no significant difference could be observed in the laying period (25 to 69 weeks). BLA hens had significantly higher total calcium concentrations at 49 weeks of age as well as up to twice as high levels of osteocalcin and 25(OH)D3 than WLA at any time of the day from 25 to 69 weeks of age. While osteocalcin, CTX-I and 25(OH)D3 concentrations were significantly higher before the onset of lay, total calcium and estradiol-17β levels significantly increased from 17 to 69 weeks of age. In contrast, PO4 values varied only slightly during the experimental period and ionized calcium was highest at 17 and 49 weeks of age and lowest around peak production (29 week). In the course of the daily egg laying cycle blood concentrations clearly reflected the stage of egg formation. Our results provide up-to-date data of bone- and egg laying-associated blood parameters of two contemporary purebred layer lines over the course of the pre- and egg-laying period and the daily egg laying cycle. Differences between brown- and white-egg layers raise questions, whether phylogenetic background determines their efficiency to cope with high calcium demands relating to egg production.

The high laying performance of today's laying hens places enormous demands on their mineral metabolism. While up-to-date data are rare, the present study aimed to describe blood parameters associated with egg laying and bone metabolism during the pre-laying period, in the course of the laying period and the daily egg laying cycle. Ten to 15 laying hens of two high-performing, phylogenetically divergent lines (BLA: brown-egg layer; WLA: white-egg layer), kept in single cages were blood sampled at 17, 25, 29, 49, and 69 weeks of age. Sampling was made at 6 a.m., 10 a.m., 2 p.m. and, with the exception of week 17, 6 p.m. Blood samples were analyzed for concentrations of total and ionized calcium, inorganic phosphate (PO4), markers of bone formation (osteocalcin) and resorption [carboxyterminal crosslinked telopeptide of type I collagen (CTX-I)], 25-hydroxycholecalciferol (25(OH)D3) and estradiol-17β. In the pre-laying period (17 week), the estradiol-17β level calculated for WLA was more than twice as high as the level calculated for BLA, while no significant difference could be observed in the laying period (25 to 69 weeks). BLA hens had significantly higher total calcium concentrations at 49 weeks of age as well as up to twice as high levels of osteocalcin and 25(OH)D3 than WLA at any time of the day from 25 to 69 weeks of age. While osteocalcin, CTX-I and 25(OH)D3 concentrations were significantly higher before the onset of lay, total calcium and estradiol-17β levels significantly increased from 17 to 69 weeks of age. In contrast, PO4 values varied only slightly during the experimental period and ionized calcium was highest at 17 and 49 weeks of age and lowest around peak production (29 week). In the course of the daily egg laying cycle blood concentrations clearly reflected the stage of egg formation. Our results provide up-to-date data of bone- and egg laying-associated blood parameters of two contemporary purebred layer lines over the course of the pre- and egg-laying period and the daily egg laying cycle. Differences between brown- and white-egg layers raise questions, whether phylogenetic background determines their efficiency to cope with high calcium demands relating to egg production. [ABSTRACT FROM AUTHOR]

The aim of the study was to investigate selected factors that affect the course of embryogenesis and the quality of golden pheasant chicks during artificial incubation. All hatching eggs (n = 76) laid in one breeding season (April-June) by a single flock of golden pheasants (1 male and 3 unrelated females) from one breeding pen were analysed for the effect of egg origin and egg-laying period on hatchability, egg weight, egg shape index, and egg weight loss. The average weight of a golden pheasant egg was 26.7 ± 1.84 g and was strongly dependent on the individual, but not on the egg-laying period. In 19 days of incubation, the weight loss was 13.2% on average, with an error/variation range of 2.17%, which was inversely correlated (r = -0.51) with initial egg weight. The highest hatchability was at the beginning of the egg-laying period: 77% in the first set and 80% in the second. Moreover, the hatchability decreased gradually from 86% to 38% for eggs stored for 1-3 days and 4-10 days respectively. The weight of one-day-old chicks (ca. 17 g) was strongly correlated with egg weight before setting (r = 0.82). In conclusion, the embryo development of the golden pheasant is affected by similar factors as known from other Galliformes species. [ABSTRACT FROM AUTHOR]

1. Prolactin hormone (governed by the PRL gene) is secreted by the anterior pituitary of animals, which combines with its receptor (prolactin receptor, PRLR) to act on target cells. Both PRL and PRLR are mainly associated with reproductive performance. The genetic mechanism of nesting in poultry is not yet clear, and so the aim of the current study was to determine expression patterns of PRL and PRLR at different times across the breeding stages of black Muscovy ducks. 2. In this study, the CDS regions of PRL and PRLR were determined by RACE sequencing. The expression levels of PRL and PRLR in the pituitary, ovary and uterus from the black Muscovy duck were compared and analysed during the pre-laying, laying and nesting periods. 3. The results showed that PRL and PRLR are highly homologous in a variety of poultry species. The expression of the PRL gene in the pituitary was the highest, which was significantly higher than seen in the ovary and uterus. This trend ran through the entire prenatal period, i.e. the laying period and the nesting period. The expression level of the PRLR gene in the pituitary and ovary was generally low, and expression in the uterus was the highest. There was no significant difference in expression of the PRLR gene between pituitary and ovary during different periods, but the expression level of the PRLR gene in the uterus reached its highest level during the nesting stage, which was significantly higher than seen in the early laying period. [ABSTRACT FROM AUTHOR]

Laying hens suffer from osteoporosis during their laying period, which causes bone fragility and susceptibility to fracture. This study evaluated the changes of mechanical properties of their bones during the laying period (from 18 to 77 wk) by using nano-indentation, atomic force microscope, X-Ray diffraction, and Raman spectroscopy. Results indicated that the crystallite sizes of bioapatite in femur decreased significantly from 34.45 to 29.26 nm during aging from 18 to 49 wk. Then, the value increased to 37.79 nm at 77 wk. Despite the abundance in bone (usually >50 wt.%), bioapatite mineral content showed no continuous enhancement during aging. The fibrils demonstrated more regular and organized structure during the laying period. Meanwhile the elastic moduli (E) and hardness (H) of femur increased from 10.84 to 18.39 GPa and 43.79 to 97.21 Vickers respectively during this period. The changes in mechanical properties are hence tightly related to the structure of bone (composed of both collagen and mineral), rather than directly related to the mineralogical properties of bone bioapatite. This study addressed the importance of the interaction between collagen and bioapatite mineral during the laying period of hens by microscopic, physicochemical, and mechanical analysis. [ABSTRACT FROM AUTHOR]

Embryo development and chick quality are influenced by parental genotype, age, nutrition, environment, and flock management. The aim of study was to determine if genotype, age of goose or eggs laid near the onset of egg production vs. eggs laid near the end of reproduction influence the stage of embryo at oviposition. Three experiments were undertaken. To compare genotypes (Experiment 1) 150 eggs were collected from 3-year-old commercial line White Koluda (WK) geese and from two breeds involved in a genetic resources conservation program, Zatorska (Za) and Bilgoraj (Bi). Age comparison (Experiment 2) was conducted with 200 eggs collected from 1-, 2-, 3-, and 4-year-old WK geese. To compare laying periods (Experiment 3), 150 WK eggs were collected at the first week of March and 100 at the second half of June. Eggs were stored for 72 h at 16°C, staged using Eyal-Giladi and Kochav (EGK, Roman numerals) and Hamburger and Hamilton (HH, Arabic numerals) procedures. Experiment 1: Individual breed differences were evident with Stage X EGK embryos comprising 42.4, 33.3, and 38.7% in the eggs examined from the WK, Bi, and Za, respectively. For all breeds combined, 38.8% of the embryos were in Stage X, but in the next order in WK there was stage XI (18.2%), while in geese from the genetic reserve it was stage XIII (Bi – 33.3; Za – 29.0%). Experiment 2: In eggs of 1-, 2-, and 3-year-old WK geese, the majority of embryos (38.7, 32.4 and 42.2%, respectively) were in Stage X. In contrast, in 4-year-old geese the embryos were in Stage XI (36.1%). Experiment 3: In eggs collected in March and in June most of embryos were in Stage X (33.7% and 43.6%, respectively). In addition, more developmentally advanced stages (XI-XIII) were similar in both periods. However, embryos in Stage 2 HH were only observed in eggs collected at the end of laying season. Interestingly, earlier stages (VI-IX) were observed exclusively in the eggs collected in March. [ABSTRACT FROM AUTHOR]

The study was conducted to determine the effect of laying period on egg quality traits as well as the chemical composition of Lindovskaya geese. The egg quality traits were examined by randomly taking a total of 90 eggs on the 45th ± 5, 60th ± 5, and 75th ± 5 days of the laying period from 3-year-old female Lindovskaya geese. It was determined that the effect of the laying period on external quality traits of eggs was statistically nonsignificant (P > 0.05). The effect of laying period on internal quality traits including height, diameter, and index of the yolk and albumen was statistically significant (P < 0.05). The eggs collected on the 45th ± 5 day had higher values compared to eggs obtained on the other days in terms of yolk height, diameter, and index, as well as albumen length and albumen width. The effect of laying period on dry matter, protein, and ash ratio of the egg yolk and albumen was statistically significant (P < 0.05). Dry matter and protein ratios of the yolk and albumen reached their peaks on the 75th ± 5 day of the laying period. These results are the first data for identification of egg quality traits in Turkish-reared Lindovskaya geese. It was concluded that the quality of eggs obtained on the 45th ± 5 day of the laying period was higher than those obtained on the other two control days in terms of internal traits. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyze the biological components of eggs as well as lysozyme activity in relation to the age of hens. The research material consisted of eggs from parent stock of Ross 308 meat chickens. The eggs were evaluated at peak laying, i.e. eggs from 30-week-old hens, and after peak laying, i.e. from hens aged 60 weeks. Ninety eggs were evaluated in each period (180 eggs in total). Egg quality traits were divided into destructive and nondestructive traits. In addition, lysozyme activity in the albumen of the eggs was assessed. The quantitative characteristics of the eggs were found to increase with the age of the hens, with a smaller proportion of albumen and a larger of yolk. Egg weight, egg shape index, albumen and yolk weight, and air cell depth were increased with the hen's age. The eggshell qualitative traits were changed with the hen's age. Analyses showed that the shell weight and color of shells increased with the decrease of the density and strength of this element. In eggs from older hens marbled shells and pimples were found significantly more frequently. The lysozyme activity in the egg albumen also changed with the age of the hens. The activity of this enzyme was higher in the eggs of older hens. [ABSTRACT FROM AUTHOR]

• We simulated the response of broiler breeder hens in the function of lighting programmes during the growth period. • We used the stochastic model to simulate the population from 24 to 60 weeks of age. • Were estimated body compositions, age at from first egg and egg production in function of age. • Were observed differences in requirements between the lighting programmes until all the broiler breeders begin laying eggs. The aim of this study was to model the changes in the egg production and requirements of broiler breeder hens flock, in response to different lighting programmes during the rearing period. The growth of each individual in a population up to the time when its first egg is laid was simulated and then averaged to obtain the mean response of the population to different lighting programmes. The information about the age, body weight and body composition over the growth period are required in order to determine the amino acid requirements of broiler breeder hens until sexual maturity (egg-laying period), the age at first egg (AFE) and egg production. Were used equations to estimate body, feather, ovary, oviduct and compositions of these parts, as a function of age. Also was estimated AFE and EP according to the lighting programmes: Constant daylengths during rearing: 8, 10, 12, 14, 16, 18 h and Single increment from 8 to 16 h at 8, 10, 12, 14, 16, 18 and 20 weeks of age. It is important to point out the greater differences in the requirements until all the broiler breeders begin laying the egg. For 24 weeks of age, the requirements may vary 329–602 mg/bird/day of Lys, 258–550 mg/bird/day of Met + Cys and 180–392 mg/bird/day Thr. For 28 weeks of age, the requirements range 362–922 for Lys; 303–830 for Met + Cys and 213–599 for Thr. For 32 weeks of age, the requirements range 824–982; 711–888; 514–644 mg/bird/day for Lys, Met + Cys and Thr, respectively. Knowing the requirements helps to establish the best nutritional program, and optimize feeding without excesses and deficiencies. These results support the view that a modelling approach has the potential to help nutritionists to make decisions about feeding broiler breeder flocks more efficiently. [ABSTRACT FROM AUTHOR]

Data were collected from Little Bittern, Water Rail and Little Crake nests located in North-Western Romania, between April and July of 2002 - 2006 and 2010 - 2012. The repeatability was calculated as intra-class correlation of length, breadth and egg volume coefficients. The total number of active nests considered for the present study was as follows: 43 for Little Bittern, 25 for Water Rail and 9 for Little Crake. The clutch size in Little Bittern ranged from 4 to 7 eggs, in Water Rail from 4 to 10 and in Little Crake from 4 to 8 eggs. The repeatability values of egg parameters varied between 0.844 to 0.860 in Little Bittern, 0.262 - 0.374 in Water Rail and 0.310 - 0.574 in Little Crake. Short-term environmental impact was strong in case of Water Rail and Little Cracke, while the genetic component had little influence. For these two species, the low repeatability could be explained by larger numbers of eggs in a clutch, reflecting in turn a longer laying period. [ABSTRACT FROM AUTHOR]

The high cost of egg production in organic farming justifies a detailed study of egg quality, considering both the age of the hens and environmental factors. The aim of the study was to determine the effect of the production cycle and season on the qualitative traits of eggs from local Greenleg Partridge (ZS-11) hens kept under organic conditions. The physical quality of eggs (N=140) and fatty acid profile of the yolk (N=40) in the first and second production period (one- and two-year-old hens) were evaluated. Moreover, the season (winter and summer) was included as an experimental trial factor. The following egg parameters were recorded: shell colour, density, strength and thickness, albumen height, Haugh units and yolk colour (Egg Quality Measurements). For hens in the second production cycle, an increase in egg weight and lower shell parameters were noted. Nonetheless, shell quality was on a level acceptable for commercial production. No influence of production cycle on the fatty acid profile of yolk lipids was detected. Eggs laid in summer had higher yolk colour intensity and PUFA acids content, while shell quality parameters were higher for winter eggs. The ratio of PUFA n-6/n-3 in the yolk of eggs laid in winter was lower--more beneficial from the standpoint of consumer health. Research results confirm the validity of rearing hens in an organic system for a period of two years. The quality of organic eggs differs in relation to the production cycle of hens (one- vs two-yearsold), but the interaction with the environmental conditions must be considered as well. The small differences in the fatty acid profile in yolk lipids that were observed between the first vs second production period and winter vs summer conditions are unlikely to have a significant metabolic effect on the consumer. [ABSTRACT FROM AUTHOR]

Poultry farms are a complex environment for close contact between humans and animals. Accumulating evidence has indicated that pathogens and drug resistance genes in chicken houses may pose a serious threat to public health and economic concerns. However, insufficient knowledge of the indoor aerosol microbiome and resistome profiles of layer hen houses hampers the understanding of their health effects. Environmental surveillance of antibiotic resistance may contribute to a better understanding and management of the human exposure risk of bioaerosols under the environmental conditions of chicken houses. In addition, the chicken house has a long operation cycle, and the bacterial diversity and antibiotic resistance genes of aerosols in different periods may be different. In this study, air samples were collected from 18 chicken houses on three farms, including the early laying period (EL), peak laying period (PL), and late laying period (LL). 16S rRNA gene sequencing and metagenomics were used to study the composition of the bacteria and resistome in aerosols of layer hen houses and the results showed that they varied with laying period. The highest alpha diversity of bacteria was observed in PL bioaerosols. The dominant bacterial phyla included Firmicutes, Bacteroidetes and Proteobacteria. Three potential pathogenic bacterial genera (Bacteroides , Corynebacterium and Fusobacterium) were found. The most abundant ARG type was aminoglycosides in all laying periods. In total, 22 possible ARG host genera were detected. ARG subtypes and abundance were both higher in LL. Network analysis also showed higher co-occurrence patterns between the bacteria and resistome in bioaerosols. The laying period plays an important role in the bacterial community and resistome in layer house aerosols. [ABSTRACT FROM AUTHOR]

Kluai Hin banana peel meal (KHBPM) contained 92.70% dry matter, 5.61% crude protein, 6.66% crude fat, 9.32% crude fiber, 10.90% ash, 60.21% NFE, 0.37% Ca, 0.22% P and 1.25% tannin on dry basis and 4,362 Kcal GE/kg. It was incorporated into 8 Japanese quail diets at 0, 5, 10, 15, 20, 25, 30 and 35%. Three hundred and thirty head of 5-weeks-old birds were randomly allotted to 8 treatments each with 4 replicates (10 quails/ replicate), fed with the above mentioned diets until 20 weeks of age. The results showed no significant (p> 0.05) difference among treatments in terms of their ages at first laying, egg production, egg weight, feed efficiency and feed consumption and feed cost when KHBPM was included up to 25% of the diet. However, treatment at the higher levels (>25% KHBPM), gave significantly (p

The effects of diet supplemented with sodium bicarbonate (NaHCO3) upon blood pH, blood gases and eggshell quality during the laying cycle in geese were investigated. Fourteen geese aged 2 yr old were divided into two groups as; control (Group C, n = 7) and 0.5% NaHCO3 -supplemented group (Group T, n = 7). After 15 days of adaptation period, blood samples were collected every 6 h during a single laying cycle (over 42 h) and the data obtained were analysed for the pH, base excess (BE-B), HCO3- concentration, partial CO2 pressure (pCO2) and total CO2 concentration (tCO2). The parameters of eggshell quality (i.e. thickness and weight) were also measured following the laying. No correlation was found between the groups for the same blood parameters measured. But, there was a significant correlation (min. r = 0.946 and P < 0.05) between all the parameters except for the pH in the groups. Following NaHCO3 supplementation of diet however, there was no significant improvement in eggshell thickness and weight. These findings indicate that the NaHCO3 supplementation of diet may support the maintenance of venous blood pH, BE-B, HCO3-, pCO2 and tCO2 levels at the physiological ranges which are required for normal health and production status of goose during the laying cycle.

During a broiler breeder trial with 3200 Cobb 500 hens, the effects of lighting treatment after 20 weeks' feed allocation and of feed form on the length of time taken to consume the daily allocation of feed were measured. Pullets were reared on 8-hour photoperiods to 20 weeks, then transferred to one of four lighting treatments: permanently to 11 h or 16 hours, transferred temporarily to 11 hours, then given 2-hours increments at 40, 44 and 48 weeks to reach 17 hours or a commercially recommended step-up lighting programme (11 hours at 20 weeks, incrementing by 30 min per week to reach 16 h by 30 weeks). Feed was made available in mash or pelleted form, and hens received 160 g or 180 g by 30 weeks. This allocation was increased linearly from 100 g at 20 weeks. After 40 weeks, the daily feed allocation was reduced by 5 g/bird for each 5% reduction in rate of lay to a minimum of 150 or 160 g/bird. On five occasions, when the hens were 39, 40, 41, 45 and 54 weeks old, the time taken by the hens to consume all their feed was measured and scaled to min/100 g consumed. Hens learned to consume the feed more rapidly as the laying period progressed. The mean clean-up time over all treatments was 67.7, 62.1, 63.4, 47.1 and 40.2 min/100 g at the five ages. Over all treatments and ages, the time taken to consume all their feed was 40.0 min/100 g for birds fed 160 g, versus 72.2 min for those given 180 g of food daily, but this difference was greater at 39 weeks (43.5 versus 91.8) than at 54 weeks (34.0 versus 46.4 min/100 g, respectively). This effect was also evident with feed form, the difference in time taken to consume mash and pellets being greater at 39 weeks (69.2 versus 66.1) than at 54 weeks (54.7 versus 25.7 min/100 g, respectively). The lighting programmes also had an effect on the feed clean-up time. The main effects were 53.5, 56.3, 52.1 and 62.5 min/100 g for the 11-hour constant, 11 to 16 hours, 16-hour constant and step-up programmes, respectively. Significant interactions occurred between treatments. The main reason was the much longer time taken initially by birds receiving the step-up lighting programme and 180 g of pelleted feed to consume all their feed. The effects of these treatments on bird welfare are discussed. [ABSTRACT FROM AUTHOR]

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Laying records on 1,534 F2 hens, derived from a reciprocal cross between White Leghorns and Dongxiang blue-shelled chickens, were used to estimate genetic parameters for residual feed intake (RFI), feed conversion ratio (FCR), daily feed intake (FI), metabolic BW (MBW), BW gain (BWG), and daily egg mass (EM) at 37 to 40 (T1) and 57 to 60 wk age (T2), respectively. Genetic analysis was subsequently conducted with the AI-REML method using an animal model. Estimates for heritability of RFI, FCR, and FI were 0.21, 0.19, and 0.20 in T1, and 0.29, 0.13, and 0.26 in T2, respectively. In T1 and T2, RFI showed high and positive genetic correlations with FCR (0.51, 0.43) and FI (0.72, 0.84), whereas the genetic correlation between FI and FCR was very low (--0.09, 0.11). Genetically, negative correlations were found between RFI and its component traits (--0.01 to --0.47). In addition, high genetic correlations, from 0.76 to 0.94, were observed between T1 and T2 for RFI, FCR, and FI, suggesting that feed efficiency traits in the 2 stages had a similar genetic background. The results indicate that selection for low RFI could reduce FI without significant changes in EM, while selection on FCR will increase EM. The present study lays the foundation for genetic improvement of feed efficiency during the laying period of chickens. [ABSTRACT FROM AUTHOR]

O presente trabalho teve por objetivo determinar o efeito de diferentes níveis de proteína e energia metabolizável na fase de postura de fêmeas da raça Plymouth Rock Barrada (PRB) provenientes do Setor de Avicultura do Departamento de Zootecnia da Universidade Federal de Santa Maria. Selecionou-se 384 fêmeas as 21ª semanas, ao final da fase de recria, as quais foram alojadas em um galpão de postura. Estas aves foram submetidas a 4 dietas experimentais em cada período analisado, resultando assim num fatorial 2x2 (dois níveis protéicos e dois níveis energéticos) em cada fase de postura, com 12 repetições de 8 aves. Na Fase I (23ª a 42ª semana) foram utilizados níveis de 15,5 e 17% de PB e 2700 e 2800kcal de EM/kg de ração. Na Fase II os níveis protéicos sofreram uma redução de uma unidade de percentagem e os níveis energéticos permaneceram os mesmos. O desempenho produtivo foi avaliado através do peso corporal, consumo de ração, produção de ovos, taxas de postura, peso dos ovos, massa de ovos, conversão alimentar (kg/dz), gravidade específica dos ovos e pico de produção. Análises de variância foram conduzidas a cada período de 28 dias e no final da fase de postura, para os parâmetros avaliados. Sempre que diferenças significativas foram encontradas a nível de 5%, empregou-se o teste de Tuckey. O nível de 2800kcal de EM/kg de ração propiciou aumentos significativos na taxa de postura (períodos II, IV e V), na massa de ovo (períodos IV, V e VIII) e na conversão alimentar (períodos V e VI) das fêmeas. Os parâmetros peso corporal, consumo de ração e gravidade específica dos ovos não foram afetados por qualquer nível de proteína bruta ou energia metabolizável e/ou suas interaçôes utilizados nas diferentes fases. Novos estudos nutricionais devem ser conduzidos para melhor avaliar esta raça.This work was conducted to determine the effects of different levels of crude protein (CP) and energy (EM) in laying phase of Plymouth Rock Barred (PRB) hens. The birds were obtained at the Poultry Section of the Departament of Animal Science, at the Federal University of Santa Maria. At the 21st week (end of the growing phase), 384 females were selected and allocated in a laying house. These birds were submitted to four experimental diets, in each analised period, resulting in a factorial analysis (two levels of protein X two levels of energy) with 12 replications of eight birds. In the phase I (23th to 42th week) and the phase II (43th to 54th wek) levels of 15.5 and 17.0% of CP, 2700 and 2800kcal of ME/kg were used. In the second phase the protein levels decreased one percent unit, and the energy levels were the same. The productive performance was estimated through body weight, feed intake, egg production, egg weight, egg mass, feed conversion (kg/dz), egg specific gravify and the peak of egg to each breed. During the laying period it was used a factorial analysis (two levels of protein x two levels of energy) with 12 replications of eight birds, per breed. The analysis of variance were conducted for each period of 28 days and at the end of the experimental period. The Tuckey test was used when at least 5% of significance was obtained. Females PRB feddiet with 2800kcal of ME/kg of the diet showed significant increased in the laying rate (periods II, IV and V), in the egg mass (periods IV, V and VIII) and in the feed conversion (periods V and VI). For females RIR the higherst energy level gave a better feed conversion in the period I (P

The study was conducted to determine the extent to which broiler breeder hens could make use of excess body lipid reserves as a means of maintaining laying performance. The experiment was divided into two phases. In the first phase, the birds aged 37 weeks were allocated one of four daily allowances: 160, 175, 190 or 205 g of a commercial broiler breeder feed for a period of four weeks in order to achieve four levels of fatness in the hens. During the second phase, also lasting four weeks, the birds were given a high protein, low energy feed at three rates of allocation (120, 100 or 80 g/hen d). Performance was higher over the final two weeks of Phase 2 when birds were fed 120 g/d in this period, with production tending to decrease as allocations increased in Phase 1, although this was not significant. The same pattern of response was seen in birds given 100 g/d in the second phase of the trial, i.e. excessive lipid reserves tended to be detrimental to performance in these two treatments. However, where 80 g was allocated daily in Phase 2 this was clearly insufficient to sustain performance, but in this case egg production was considerably higher in birds that had been given larger amounts of food in Phase 1, and which could therefore draw on body lipid reserves as a source of energy. Rate of lay increased by 3.5% and egg output by 4.0 g/d for every additional 10 g of food given in Phase 1, as a result of lipid reserves having been utilised when daily food intake was severely depressed. Egg weight was not affected by any of the feed allocations until the last two weeks of the trial when birds fed 80 g/d started laying smaller eggs. Broiler breeders are capable of maintaining their egg production for short periods at an energy intake that is much lower than is recommended and this has implications when modelling the effect of food composition on performance of broiler breeder hens. [ABSTRACT FROM AUTHOR]

Ross 308 broiler breeder females, maintained in litter-floor pens, were reared from 2 d of age on 8-h photoperiods and transferred abruptly to an 11-, 12-, 13-, or 14-h photoperiod at 20 wk of age and at a mean BW of 2.09 kg. Four qualitative dietary treatments were superimposed upon each photoperiodic treatment, but, in the absence of any significant interactions of photoperiod with diet, only photoperiodic means are reported. Age at 50% egg production (ASM) was progressively advanced as photoperiod increased from 11 to 13 h but was similar for 13-h and 14-h birds. Egg production was significantly related to ASM, with peak egg numbers being stimulated by a transfer to 13-h photoperiods. Rate of lay after 48 wk of age declined more rapidly in the 14-h birds than in any of the other groups, suggestive of an earlier onset of adult photorefractoriness. More eggs were laid outside the nest box and more cracked and dirty eggs were produced by birds on 11and 12-h photoperiods than on 13or 14-h photoperiods. Mean egg weight was positively correlated with ASM but negatively related to photoperiod; the number of eggs thought to be doubleyolked was not significantly affected by photoperiod. Total egg mass output was not significantly affected by photoperiod. Birds exposed to 11-h and 12-h photopenods were heavier at 60 wk than birds transferred to 13or 14-h photoperiods. These findings show that a transfer from 8 to 13 h at 20 wk optimizes egg-laying performance in broiler breeder females, especially when they are kept beyond 60 wk of age. [ABSTRACT FROM AUTHOR]

We investigated the correlations between different eggshell and membrane strength parameters and their changes over time. Eggshell and membrane characteristics were measured for 2 different lines of laying hens, Hisex Brown and Bovans Brown, from wk 33 up to wk 78. Several parameters were investigated: 2 parameters concerning total eggshell strength (static and dynamic stiffness), 1 structural parameter (i.e., eggshell thickness), 2 parameters describing the material characteristics of the shell [dynamic Young's modulus (EM) and nitrogen content], and 3 parameters to measure the membrane characteristics (attachment force breaking strength and nitrogen content). This study shows that the correlations among parameters change during the laying period and among lines. The EM of the eggshell increased during the laying period for the Hisex line. No difference was observed in case of the Bovans line. In general, a negative correlation was obtained between eggshell thickness and the EM. The correlation between static and dynamic stiffness increased during lay. Finally, the attachment force and breaking strength of the membranes declined during the laying period. [ABSTRACT FROM AUTHOR]

Nests of radiotransmittered wild turkeys (Meleagris gallopavo) that are destroyed or abandoned prior to incubation are particularly difficult to locate. As a result researchers often report only incubated nests or estimate numbers of nests attempted by localization of movement or other behavioral changes without quantification. We used radiotelemetry to obtain movement data on female wild turkeys during the nesting season (1 Apr-30 Jun) in South Dakota. We collected prelaying (1 April until 14 days before the female initiated incubation) and laying (<14 days before incubation) movement distances from 160 adult female wild turkeys [75 eastern (M. g. silvestris), 19 Rio Grande (M. g. intermedia), and 66 Merriam's (M. g. merriam,) wild turkeysi. Our objectives were to quantify the relationship between movement behavior and nesting attempts to allow more accurate determination of initiation of nesting for calculation of nest rates, nesting success, and renesting rates. Daily movements of females decreased abruptly when they transitioned from prelaying to laying behaviors. Movements of females that were less than 364.9 m for eastern turkeys, 115.0 m for Rio Grande turkeys, and 331 .0 m for Merriam's turkeys were indicative of nest initiation. Changes in movements of females can identify nesting wild turkeys and can be used post hoc to identify nests that were abandoned or destroyed prior to incubation if sufficient locations are collected. Following our analysis, we estimated that females had an additional 46 nests (eastern=15, Rio Grande=7, and Merriam's=24), which we used in estimating reproduction parameters. Quantitative comparisons of movements between prelaying and laying confirmed a behavioral change of localized movements concurrent with nest initiation in wild turkey females. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented which discusses the process of replacement clutches among birds of prey smaller species.