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PubMed2002

Microbial contamination in inoculated shell eggs: I. Effects of layer strain and hen age.

Three Ottawa control strains and a current commercial laying stock were reared and housed under identical environmental and management conditions. Eggs were collected from each strain when hens were 32, 45, 58, 71, and 84 wk of age. The eggs were inoculated with Salmonella enteritidis (SE), Pseudomonasfluorescens (PF), or a combination of the two. After storage at 26 C, bacterial counts were obtained from the exterior shell surfaces (rinse), air cell, egg contents, and shell structure. SE and PF survived at different rates on the shell surface with as much as a 1 log difference during a given collection period. Egg content counts tended to be higher than eggshell counts in PF, whereas the opposite was true for SE. These data suggest that PF is a primary invader of eggs that is more capable of contaminating egg contents through the shell membranes than SE. The PF and SE data suggest that bacterial contamination of air cells, shells, and egg contents is more easily achieved in eggs from older hens than from younger hens. There were also differences between the strains. Control Strain 10 consistently maintained a lower level of contamination for both organisms in each sampling location. The overall results of this study suggest that genetic selection has altered the ability of eggs to resist microbial contamination and that screening for microbial integrity should be considered in the selection process among the laying egg breeders.

Age Factors↗
PubMed2002

The effect of twenty-eight-hour ahemeral day lengths on carcass and reproductive characteristics of broiler breeder hens late in lay.

The effect of increasing the day length from 24 to 28 h on the reproductive and carcass characteristics of old broiler breeder hens was examined. A total of 128 birds aged 47 wk of age from three different strains; Classic, Experimental (EXP), and Feather Sexable Yield (FSY) were used. Selection was based on target BW and egg production rates; birds were housed in light-tight environment chamber facilities. Birds were feed restricted, and feed was allocated according to actual weekly BW relative to target BW. At 55 wk of age 125 broiler breeders were killed and dissected, and carcass and reproductive traits were examined. Overall, ahemeral day length negatively affected carcass and reproductive parameters. No significant differences were found for BW, yolk, albumen and shell weights, normal and atretic ovarian follicles, and breast, fat pad, and liver weights. Significantly lower production rates, higher amounts of defective eggs, lower oviduct and ovary weights, lower F1 follicle weight, poorer eggshell quality, and higher egg weights were found. Subsequently, broiler breeder hens increased egg weight at the expense of egg production when subjected to an ahemeral day length. It is not recommended that day length be increased this late in production because it results in reduced egg productivity.

Animal Husbandry↗
PubMed2002

Collagen X expression in oviduct tissue during the different stages of the egg laying cycle.

The purpose of this investigation was to study the expression of type X collagen in the hen's oviduct. Type X collagen is a short-chain collagen that is present in the fibers of eggshell membranes, and there is evidence to suggest that it contributes to structural integrity. In situ hybridization and Northern blot analysis were used to study the expression of this important matrix constituent. The results demonstrated that gene expression was predominantly in the tubular gland cells of the isthmus segment of the oviduct. In contrast to observations with other matrix proteins, such as parathyroid hormone-related peptide and osteopontin, gene expression did not fluctuate with the position of the egg in the oviduct.

Animals↗
PubMed2002

Mapping of quantitative trait loci affecting quality and production traits in egg layers.

A mapping population segregating for egg quality traits was created by a line cross between two egg layer lines and screened by a genome scan. The F2 generation consisted of 307 hens, which were scored for egg quality and production traits. The mapping population was genotyped for 99 microsatellite loci, spanning nine macrochromosomes and five small linkage groups. The linkage maps were used in mapping QTL affecting 14 traits, by using multiple markers and a least-squares approach. We detected 14 genomewide significant and six suggestive QTL that were located on chromosomes 2, 3, 4, 5, and, 8 and sex chromosome Z. A significant QTL affecting egg white thinning was found on chromosome 2. For eggshell strength, a significant QTL was found on chromosome Z. For production traits, the most interesting area was on chromosome 4, where highly significant QTL effects were detected for BW, egg weight, and feed intake in the same area. The most significant QTL explains 25.8% of the phenotypic variance in F2 of body weight. An area affecting the age at first egg, egg weight, and the number of eggs was located on chromosome Z.

Animals↗
PubMed2003

The physiology of induced molting.

The initiation of seasonal feather molting in wild avian species frequently coincides with incubation of eggs and brooding of offspring. A period of natural inappetence or anorexia usually accompanies this molt. This is particularly true of the jungle fowl, the wild ancestor of the domestic chicken. Brooding of eggs by the jungle fowl is accompanied by spontaneous anorexia, with little food or water consumed throughout the period of egg incubation. During this time, the reproductive tract regresses, and feather molting is initiated. Selective breeding for a high rate of egg production has blunted the response of the commercial laying hen to exogenous environmental cues and reduced or eliminated the endogenous biological cues that coordinate initiation of seasonal molting. However, commercial layers retain in their physiological repertoire the ability to tolerate prolonged fasting and to undergo a spontaneous regression of the reproductive tract and feather molting. Induction of a coordinated molt, by manipulation of environmental and nutritional cues, or endocrine manipulation, can be used in domestic hens to regress and regenerate the reproductive tract. This improves subsequent egg production and eggshell quality. This process also induces temporary recrudescence of lymphoid tissues and may alter immune function in hens. The process of molting, and the subsequent recovery from the molt, may be viewed as a complex physiological constellation, induced by environmental and nutritional cues, involving endocrine systems, reproductive tissue structure and function, lymphoid structure, and immune function.

Agriculture↗
PubMed2003

Effect of embryonic photostimulation on the posthatch growth of turkey poults.

Artificial illumination, including light quality, is important in modern meat-type poultry management. In the present study, the effect of in ovo monochromatic green light photostimulation on posthatch growth of turkey poults was investigated. In experiment 1, 182 turkey eggs were divided into two light treatment groups (n = 91). The first group was intermittently photostimulated (3 min on and 3 min off) with green light provided by five light-emitting diodes (LED) per egg at 0.1 W/m2 at the upper eggshell surface. The second group was incubated in the dark and served as the control. Posthatch BW were recorded at 0, 2, 6, 13, 20, 28, 35, and 59 d of age. A heavier BW, occurring at 28 d of age and persisting until the end of the experiment (59 d of age), was observed in the in ovo green light stimulated females as compared to their corresponding controls. In experiment 2, 273 turkey eggs were divided into three light treatment groups (n = 91). The first group was intermittently photostimulated (15 min on and 15 min off) with green light provided by seven LED per egg at 0.14 W/m2. The second group was photostimulated with white light provided by one mini-incandescent lamp per egg at light intensity and schedule similar to the first group. Eggs of the third group were incubated in the dark and served as controls. Posthatch BW were recorded at 0, 7, 14, 28, 42, 56, and 79 d of age. No differences were found among the BW of males incubated under different light conditions. As in experiment 1, female turkeys with stimulated green light in ovo had greater BW compared to their corresponding control and white light groups from 28 d of age until termination of the experiment at 79 d of age. Breast muscle weight was greater in female turkeys incubated under green light when compared to white and dark incubation treatment groups. We suggest that in ovo green light photostimulation enhances the posthatch BW of female turkey poults.

Aging↗
PubMed2004

Effects of feeding blends of grains naturally contaminated with Fusarium mycotoxins on performance and metabolism of laying hens.

An experiment was conducted to evaluate the effects of feeding laying hens grains naturally contaminated with a combination of Fusarium mycotoxins. Parameters measured included performance, organ weights, and plasma chemistry. One hundred and forty-four, 45-wk-old laying hens were fed diets including: (1) control, (2) contaminated grains, and (3) contaminated grains + 0.2% polymeric glucomannan mycotoxin adsorbent (GMA) for a 12-wk period. The feeding of contaminated grains decreased feed consumption compared with controls in the first 4 wk. Feed consumption increased, however, from 4 to 8 wk and from 8 to 12 wk. The efficiency of feed utilization (feed consumption/egg mass) decreased compared with controls in the periods from 4 to 8 and from 8 to 12 wk when birds were fed contaminated grains. Supplementation with GMA decreased feed consumption and increased the efficiency of feed utilization in the period from 8 to 12 wk. Egg production and egg mass decreased in wk 4 and 8 compared with controls when contaminated grains were fed, whereas egg and eggshell weights decreased in the fourth wk. Plasma uric acid concentrations increased throughout the experiment and relative kidney weights increased at the end of the experiment compared with controls when birds were fed contaminated grains. The feeding of GMA prevented the elevation in uric acid concentrations and relative kidney weights. It was concluded that layer performance and metabolism were adversely affected by chronic feeding of a combination of Fusarium mycotoxins, and that GMA prevented many of these effects.

Adsorption↗
PubMed2004

Efficacy of electrolyzed oxidizing water for the microbial safety and quality of eggs.

During commercial processing, eggs are washed in an alkaline detergent and then rinsed with chlorine to reduce dirt, debris, and microorganism levels. The alkaline and acidic fractions of electrolyzed oxidizing (EO) water have the ability to fit into the 2-step commercial egg washing process easily if proven to be effective. Therefore, the efficacy of EO water to decontaminate Salmonella Enteritidis and Escherichia coli K12 on artificially inoculated shell eggs was investigated. For the in vitro study, eggs were soaked in alkaline EO water followed by soaking in acidic EO water at various temperatures and times. Treated eggs showed a reduction in population between > or = 0.6 to > or =2.6 log10 cfu/g of shell for S. Enteritidis and > or =0.9 and > or =2.6 log10 for E. coli K12. Log10 reductions of 1.7 and 2.0 for S. Enteritidis and E. coli K12, respectively, were observed for typical commercial detergent-sanitizer treatments, whereas log10 reductions of > or =2.1 and > or =2.3 for S. Enteritidis and E. coli K12, respectively, were achieved using the EO water treatment. For the pilot-scale study, both fractions of EO water were compared with the detergent-sanitizer treatment using E. coli K12. Log10 reductions of > or = 2.98 and > or = 2.91 were found using the EO water treatment and the detergent-sanitizer treatment, respectively. The effects of 2 treatments on egg quality were investigated. EO water and the detergent-sanitizer treatments did not significantly affect albumen height or eggshell strength; however, there were significant affects on cuticle presence. These results indicate that EO water has the potential to be used as a sanitizing agent for the egg washing process.

Animals↗
PubMed2004

Overview of bone biology in the egg-laying hen.

In young pullets, long bones elongate by endochondral growth. Growth plate chondrocytes proliferate, then hypertrophy, and are replaced by osteoblasts that form a network of trabecular bone. This bone is gradually resorbed by osteoclasts as the bone lengthens. Long bones widen, and flat bones are formed, by intramembranous ossification in which cortical bone formation by osteoblasts in the periosteal layer is accompanied by osteoclastic resorption at the inner endosteal surface. Growth of structural trabecular and cortical bone types continues up to the onset of sexual maturity in pullets. At this point, the large surge in estrogen changes the function of osteoblasts to forming medullary bone rather than structural bone. Medullary bone is a woven bone that acts as a labile source of calcium for eggshell formation. It lines structural bone and also occurs as spicules within the marrow cavity. It has little inherent strength but can contribute to fracture resistance. Osteoclasts resorb both medullary and structural bone so that during the period the hen remains in reproductive condition there is a progressive loss of structural bone throughout the skeleton, which is characteristic of osteoporosis. The increasing fragility of the bones makes them more susceptible to fractures. The dynamics of bone loss can be affected by a number of nutritional, environmental, and genetic factors. If the hen goes out of reproductive condition, estrogen levels fall, osteoblasts resume structural bone formation, and skeletal regeneration can take place.

Animal Feed↗
PubMed2004

Assessing bone mineral density in vivo: dual energy X-ray absorptiometry.

Dual-energy X-ray absorptiometry can be used as a noninvasive tool to monitor the skeletal integrity of live birds. A pDexa X-ray bone densitometer was used to determine bone mineral densities (BMD) of the left tibia together with the fibula and the humerus of live, unanesthetized birds. Densitometry effectively detected changes in bone integrity of live birds fed varying levels of dietary calcium. Hens consuming 1.8, 3.6, or 5.4% dietary calcium had BMD of 0.147, 0.157, and 0.176 g/cm2 (SEM = 0.005), respectively (linear effect, P < 0.001). Likewise, bone ash weight, breaking force, stress, modulus of elasticity, and eggshell traits also increased linearly in response to increased calcium in the diet (P < 0.05). Densitometric live scans for BMD were positively correlated (P < 0.001) with bone breaking force (r = 0.65) and bone ash (r = 0.77). We also monitored BMD in live Leghorn and broiler females during their life cycle. The tibial BMD of White Leghorns and broilers increased from 15 to 65 wk of age with the BMD of the broiler tibia increasing at a greater rate than that of the Leghorn tibia (line x age interaction, P < 0.0001). A precipitous drop in BMD occurred during an induced molt of Leghorns subjected to 10 d of feed withdrawal. Our long-term goal is to improve skeletal integrity in egg-type chickens by genetic selection for improved BMD. By crossing a broiler with an egg-laying line, an F2 resource population of birds has been developed to identify quantitative trait loci influencing BMD in chickens.

Absorptiometry, Photon↗
PubMed2004

End-of-cycle bone quality in white- and brown-egg laying hens.

Broken and weak bones of laying hens are major welfare concerns in the table egg industry. Bone quality at the end of lay of brown- (Shaver 579) and white-(Shaver 2000) egg strains were compared. Prior to the start of the experiment, the hens had been housed in laying hen cages (2/cage). At 423 d of age (60 wk + 3 d), 24 hens of each strain were selected and individually caged, and egg production records were kept until 462 d of age (the end of 65 wk) for a total of 39 d. Egg quality analysis was undertaken during wk 65 of age. Hens were killed at 66 wk of age (463 d), and carcass and reproductive morphology traits were measured. Femur and humerus mineral density were measured using quantitative computed tomography, and breaking strength was measured by an Instron Materials Tester. The white-egg strain produced 3.7% more marketable eggs during the experiment due to a 0.3 d shorter mean pause length in egg production. Eggs from the brown strain were 3.4% heavier, had 4.0% more eggshell, and had a higher specific gravity than the white strain eggs (1.077 and 1.072, respectively). Final BW was 330 g greater in the brown-egg strain. Total bone density of the femur was not different between the 2 strains but was greater in the humerus of the brown-egg layers. Total femur and humerus bone areas were greater in the brown strain than the white-egg strain. Bone breaking strengths of the brown-egg strain were greater by 22% (femur) and 18% (humerus) than in the white-egg strain hens. These results indicate that this brown-egg strain may be more resistant to weak and broken bones at the end of production than the white-egg strain.

Aging↗
PubMed2004

Biological and economic optimum level of calcium in White Leghorn laying hens.

Calcium is important in eggshell formation; inadequate levels in the diet of laying hens may affect shell quality and egg production. An experiment with 250 Leghorn Hy-Line W-98 hens was conducted to evaluate 5 dietary Ca levels (2.96, 3.22, 3.83, 4.31, and 4.82%) in 3 laying periods. The evaluated variables were egg production (EP), egg mass (EM), average daily feed intake (ADFI), feed conversion (FC), and specific gravity (SG). The biological optimum level (BOL) of Ca for maximum egg production and specific gravity, and the economic optimum level (EOL) to maximize profits were calculated. There was no interaction between Ca level and laying period. The results show that the Ca level of the diet (P < 0.05) affected the intake of this nutrient (3.34, 3.68, 4.26, 4.89, and 5.39 g bird/day), ADFI (113, 114, 111, 113, and 111 g bird/day), and SG (1.080, 1.081, 1.082, 1.083, and 1.083). As the hens aged, EP and SG diminished (P < 0.05). BOL for maximum EP and SG were 4.34 and 4.62%, and EOL was 4.38%.

Aging↗
PubMed2004

Genetic and phenotypic correlations between feather pecking behavior, stress response, immune response, and egg quality traits in laying hens.

The objective of the current study was to estimate genetic and phenotypic correlations among feather pecking (FP) behavior and stress response, immune response, and egg quality parameters. These traits have been measured in an F2 cross, coming from a cross between a high and a low FP line of laying hens. Heritabilities (h2) of stress response (32 wk), primary immune response to keyhole limpet hemocyanin (KLH) (36 wk) and Mycobacterium butyricum (39 wk), and egg quality parameters (35, 44, and 50 wk of age) were calculated. The h2 was 0.05 +/- 0.05 (SE) for stress response, 0.15 +/- 0.07 for antibody response to KLH, and 0.08 +/- 0.06 for antibody response to M. butyricum. The h2 for egg quality traits were in the range of 0.12 to 0.30. Significant phenotypic correlations were found between gentle FP in adult hens and stress response, egg weight at 44 and 50 wk, and egg deformation at 50 wk. Significant additive genetic correlations were found between severe FP in adult hens and antibody response to KLH (0.79 +/- 0.35), and between ground pecking in adult hens and egg deformation at 50 wk (0.63 +/- 0.26), and between ground pecking and eggshell strength at 35, 44, and 50 wk of age (-0.86 +/- 0.29, -0.81 +/- 0.20, -0.76 +/- 0.24, respectively).

Aging↗
PubMed2004

Monochromatic light stimuli during embryogenesis enhance embryo development and posthatch growth.

Photostimulation with green light accelerated BW and muscle development of broilers. In experiment 1, temperature sensors were inserted into 50 broiler eggs. The eggs were placed under 5 green light-emitting diode (LED) lamps at an intensity of 0.1 W/m2 at eggshell level for 5, 10, 15, 20, and 25 min (n = 10). Egg temperatures were recorded continuously. A high correlation was found between lighting period and egg temperature elevation, and an intermittent light regimen of 15 min on and 15 min off was found to eliminate light-induced egg overheating. In experiment 2, the effect of in ovo green light photostimulation on embryonic development was studied. Five hundred fertile eggs were divided into 2 groups: the first was photostimulated with green light from 5 d of incubation until hatch (0.1 W/m2 intensity) and the second was incubated in the dark. In ovo green light photostimulation caused a significant elevation in BW and breast muscle weight during embryo development and posthatch until 6 d of age. In experiment 3, 240 fertile broiler eggs were divided into 2 groups as described in experiment 2. At hatch, chicks from each in ovo light treatment were divided into 2 subgroups: the first was reared under green light and the second under white light. In ovo photostimulation with green light enhanced BW and breast muscle weight. However, rearing under green light did not have any synergistic effect on BW. Collectively, the results suggest that stimulation with green light enhances development and growth in chicks and that the best effect is achieved when this stimulus is provided during incubation.

Animals↗
PubMed2004

Ornithine decarboxylase: haplotype structure and trait associations in White Leghorn chickens.

Sequence analysis of 4,230 bp of the 3' end of the ornithine decarboxylase gene of 20 chickens from a noninbred White Leghorn strain revealed a total of 62 polymorphisms. Of these 61% were transitions, 24% were transversions, and 16% were deletions or insertions. Despite the high number of polymorphisms, only 3 haplotypes were present among the 40 alleles analyzed. Based on the genetic distances between haplotypes they segregated early during domestication of the chicken. Ornithine decarboxylase is a pivotal enzyme in regulating the synthesis of polyamines, cations that are important regulators of cell division, differentiation, and apoptosis. Variants of ornithine decarboxylase are, therefore, expected to affect many different traits. Association analyses between genotypes and the major egg production traits in female chickens of the same strain revealed significant effects on the onset of sexual maturity, BW at sexual maturity, eggshell thickness (a measure of calcium deposition), and residual feed consumption (a measure of the metabolic rate). Further, comparisons of the genotypes indicated that the 3 haplotypes differ in their phenotypic properties. Our results show that variations in a gene that is ubiquitously expressed in all cells of an organism may nevertheless contribute to distinct phenotypic properties of the organism as a whole.

Animals↗
PubMed2005

Recovery of Salmonella from commercial shell eggs by shell rinse and shell crush methodologies.

Salmonella is the most important human pathogen associated with shell eggs. Salmonella Enteritidis is the serotype most often implicated in outbreaks, although other serotypes have been recovered from eggs and from the commercial shell egg washing environment. Many sample methods are used to recover microorganisms from eggshells and membranes. A shell rinse and modified shell-and-membrane crush method for recovery of Salmonella were compared. Eggs were collected from 3 commercial shell-washing facilities (X, Y, and Z) during 3 visits. Twelve eggs were collected from each of 10 to 12 locations along the egg processing chain. After being transported back to the laboratory, each egg was sampled first by a shell rinse method and then by a shell crush method. For each technique (rinse or crush), 2 pools of 5 eggs per location sampled were selectively enriched for the recovery of Salmonella. Presumptive samples positive for Salmonella were confirmed serologically. Overall, there were 10.1% (40/396) Salmonella-positive pooled samples. Salmonella were recovered by the shell rinse and shell crush techniques (4.8 vs. 5.3%, respectively). Plant X yielded 21.5% Salmonella positives, whereas less than 5% of samples from plants Y and Z were found to be contaminated with the organism (4.2 and 4.5%, respectively). Salmonella was recovered more often from unwashed eggs (15.8%) than from washed eggs (8.3%). For some eggs, Salmonella was only recovered by one of the methods. Use of both approaches in the same experiment increased sampling sensitivity, although in most cases, crushing provided more sensitive Salmonella recovery.

Animals↗
PubMed2005

Quantification of the heat exchange of chicken eggs.

In the incubation process of domestic avian eggs, the development of the embryo is mainly influenced by the physical microenvironment around the egg. Only small spatiotemporal deviations in the optimal incubator air temperature are allowed to optimize hatchability and hatchling quality. The temperature of the embryo depends on 3 factors: (1) the air temperature, (2) the exchange of heat between the egg and its microenvironment and (3) the time-variable heat production of the embryo. Theoretical estimates on the heat exchange between an egg and its physical microenvironment are approximated using equations that assume an approximate spherical shape for eggs. The objective of this research was to determine the heat transfer between the eggshell and its microenvironment and then compare this value to various theoretical estimates. By using experimental data, the overall and the convective heat transfer coefficients were determined as a function of heat production, air humidity, air speed, and air temperature. Heat transfer was not affected by air humidity but solely by air temperature, embryonic heat generation, and air speed and flow around eggs. Also, heat transfer in forced-air incubators occurs mainly by convective heat loss, which is dependent on the speed of airflow. A vertical airflow is more efficient than a horizontal airflow in transferring heat from the egg. We showed that describing an egg as a sphere underestimated convective heat transfer by 33% and was, therefore, too simplistic to accurately assess actual heat transfer from real eggs.

Air Movements↗
PubMed2005

Effect of dietary phosphorus and phytase levels on the reproductive performance of large white turkey breeder hens.

An experiment was conducted to determine the effect of dietary P levels and dietary phytase enzyme (E) inclusion on Large White turkey breeder hen reproductive performance from 31 to 62 wk of age. Hens were placed in a curtain-sided house with 48 pens (10 birds per pen; 8 pens per treatment) at 31 wk and were fed a breeder ration with treatments as follows: HP, dietary available P = 0.55%; HPE, HP + E; MP, dietary available P = 0.35%; MPE, MP + E; LP, dietary available P = 0.17%; and LPE, LP + E. Feed and water were available ad libitum for 28 wk of lay. Diets were fed in mash form, and all other nutrients were formulated to meet or exceed NRC requirements. All hens were photostimulated in January (31 wk) with 15.5 h of light daily. Production data were recorded on a pen basis. Individual bird BW and feed consumption, by pen, were determined at monthly intervals from 31 to 62 wk. Hens were observed for weekly reproductive performance for hen housed egg production, hen-day egg production, settable eggs, cumulative settable eggs, hens out of lay, and hen mortality and for biweekly performance for egg fertility, hatchability of all eggs, hatchability of fertile eggs, egg weight loss, conductance, conductance constant (k), and embryonic mortality. Egg weight, eggshell thickness, egg components, and albumen and yolk P were measured monthly. At 62 wk of age, hen tibia P, plasma P, total fecal P, and water-soluble fecal P were determined. Decreasing dietary P resulted in no decreases in reproductive performance for turkey breeder hens to 62 wk. Additionally, decreased dietary P resulted in decreased total fecal P and water-soluble fecal P. Feeding turkey breeder hens dietary phytase enzyme resulted in significantly fewer hens going out of lay; however, this was not reflected in hen housed egg production. It was concluded that phosphorus could be lowered in turkey breeder hen diets, compared with current surveyed industry levels, without impairing reproductive performance.

6-Phytase↗