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PubMed1997

Epidemiology and control of egg-associated Salmonella enteritidis in the United States of America.

The isolation rate for Salmonella enterica serotype Enteritidis (SE) in humans in the United States of America (USA) increased from 1,207 sporadic isolates identified in 1976 (0.6 isolates/100,000 population) to 10,201 identified in 1995 (4.0/100,000 population). The proportion of reported Salmonella isolates which were SE increased from 5% to 25% during the same time period. In 1990, 1994, and 1995, SE was the most commonly reported reported Salmonella serotype in the USA. Much of this increase has been associated with the consumption of contaminated shell eggs. An examination of the results of a United States Department of Agriculture (USDA) survey of spent hens at slaughter and unpasteurised liquid egg at breaker plants (liquid egg processors) in 1991 and 1995 reveals an increase in the prevalence of SE isolates overall and in most regions of the USA. SE phage type 4 (pt 4), the predominant SE phage type in other parts of the world, has emerged in the egg industry in the western USA concurrent with a sharp increase in the number of sporadic human SE pt 4 isolates in California and Utah. Research on the molecular structure and virulence of SE pt 4 isolates from the USA as compared with isolates from other parts of the world (human and poultry) should be a priority. A comparison of DNA from pt 4 isolates from the USA and Europe may provide information about the potential threat to public health and poultry in the USA from this phage type. Some regional success in the reduction of human illness as a result of SE control efforts is apparent. The Pennsylvania Egg Quality Assurance Program has shown progress in reducing SE infection in participating flocks. At a national level, however, neither the incidence of human illness due to SE nor the prevalence of SE in flocks and unpasteurised liquid eggs have decreased significantly, despite the implementation of the USDA 'trace back' regulation from 1990 to 1995, and intensified efforts to educate food handlers and to enforce safe food handling practices. More effort is needed to control SE at every stage of the egg continuum, from production through to consumption. A risk-reduction approach, with barriers to the introduction and multiplication of the pathogen throughout the farm-to-table continuum, is the most practical method for reducing human illness from SE in shell eggs at present. An effective long-term solution will require interdisciplinary efforts involving government, industry, consumers, and academics. Interventions should be developed and evaluated in compliance with the potential for reducing the risk to human health and cost-effectiveness.

Animal Husbandry↗
PubMed1999

Effect of induced molting in laying hens on production and immune parameters.

A total of 600 commercial strain (DeKalb) Single Comb White Leghorn hens, 80 wk of age, were used in this study to determine the effects of different induced molting programs on production and immune parameters. The hens were randomly divided into four treatment groups (three experimental and one control) of 150 hens each. The hens in the first treatment group were fed a layer ration containing 20,000 ppm of zinc for 5 d, and received a reduced photoperiod of 8 h/d for 5 d (Zn group). In the second group, feed was withdrawn for 10 d, the photoperiod was reduced to 8 h/d and oyster shell and water were provided for ad libitum consumption. At Day 11, hens consumed corn and oyster shell ad libitum until Day 30 and at Day 31, hens were returned to a full feed layer ration and received 16 h of light/d [California treatment (CAL group)]. In the third treatment, light was reduced to 8 h/d, and oyster shell was provided for ad libitum consumption until Day 60. Feed and water were removed for the first 2 d and on Days 4, 6, and 8. On Days 3, 5, 7, and 9, hens were fed 45 g of feed per hen. On Day 10 until Day 60, hens were fed 90 g/hen and at Day 61, hens were returned to the layer ration ad libitum and received 16 h of light/d [on-again, off-again program (ON-OFF group)]. The last group served as controls (CONT). Body weight, egg production, egg size, internal egg quality, shell weight, and mortality were determined. Total circulating leukocytes, differential leukocyte counts, and antibody production were also measured. The results demonstrated that induced molting significantly increased egg production from 64% to 77 to 83%, Haugh units from 80.4 to 85.9 to 87.3, and shell weight from 5.3 g to 6.3 to 6.4 g when compared to CONT. The body weight of the molted hens decreased significantly to 84.8, 74.5, and 88% of the initial body weight for Zn, CAL, and ON-OFF groups, respectively. The total circulating leukocytes was significantly lower in molted hens than in CONT hens. Differential leukocyte counts were affected by all induced molting programs and the heterophil to lymphocyte ratio was significantly increased, reaching 0.61, whereas that of CONT was only 0.20. Antibody production was largely unaffected by any of the induced molting programs.

Animals↗
PubMed2000

Application of the agar gel precipitin test to detect antibodies to Salmonella enterica serovar enteritidis in serum and egg yolks from infected hens.

Serological surveillance can be an important component for egg quality assurance programs geared toward controlling problems with Salmonella enterica serovar Enteritidis (S. enteritidis) within a flock. Serum is the primary sample source for the procedures, although egg yolk antibody assays have become popularity in recent years. However, these assays tend to be labor intensive, requiring procedures for extracting antibodies from the yolk followed by assaying the samples. We describe an adaptation of the agar gel precipitin (AGP) test for use in detecting antibodies to S. enteritidis deposited in egg yolks of infected hens. Yolk or sera from infected birds were administered to wells cut into seven-well clusters in an agar gel plate, and detection antigen was added to the center well. The agar gels were incubated for 24 h and then examined for the presence of precipitin lines formed by the interaction of antibody with antigen. Three different antigens were tested: S. enteritidis flagella, SEF14 (a 14-kDa fimbrial protein produced ostensibly by S. enteritidis), and a sodium deoxycholate extract of whole S. enteritidis organism. Flagella and the organism extract detected antibodies to S. enteritidis in the yolk and sera, whereas SEF14 was not reactive. Positive reactions were observed in serum 1 wk postchallenge, whereas in yolks, this was further delayed by 1 wk. The sensitivity of the test was slightly less than the standard microagglutination assay, although specificity was slightly higher, as indicated by results from sera and yolks from birds infected with Salmonella enterica serovar Typhimurium. Simplicity and low labor requirements of the assay would allow for the potential testing of several hundred egg samples within a day, which would make up for test shortcomings due to sensitivity. The AGP test could be an important tool for individuals using serological testing to monitor the S. enteritidis situation within their flocks or as a rapid screen for vaccine responses. The assay could also be used in tandem with other AGP tests to screen for the presence of multiple avian pathogens.

Animals↗
PubMed2005

From egg to embryo: a peripatetic journey.

The recent surge of interest in oocyte development has been spurred in large part by the increasing implementation of assisted reproductive technologies (ART) to treat human infertility. What is becoming apparent is that 'egg quality' is a primary factor in the success of ART (Sauer 1998), and yet we know virtually nothing about the molecular signature of a 'high quality' oocyte, i.e., an oocyte that is capable of maturing, being fertilized and supporting development to term. We are gaining marked insights, however, into how sperm activate eggs and the changes in gene expression that accompany preimplantation development. Nevertheless, embryo culture is known to effect gene expression (Rinaudo & Schultz 2004), the long-term consequences of which are only recently being unmasked. This review will briefly highlight these topics that were presented during the Biennial Joint Meeting of the UK Fertility Societies at Warwick University in April 2005.

Animals↗
PubMed1990

Effect of environmental stress on the ascorbic acid requirement of laying hens.

An experiment with a factorial arrangement of treatment (3 by 2 by 2 by 2) was conducted to determine the effect of ascorbic-acid supplementation (0, 100, and 200 ppm) on the performance of two commercial layer strains housed at a density of either 3 or 4 birds per cage and relative humidities (RH) of 40% or 60%. The hens were subjected to a continuous heat stress of 31.1 degrees C for the 3-mo experimental period. As a comparison with an unstressed control group, an additional group of hens was housed at 23.9 degrees C and 40% RH and was fed the diet without ascorbic-acid supplementation. Mortality was reduced by ascorbic-acid supplementation. Shell weight per unit surface area showed a small increase with the added ascorbic acid. Values (in Haugh units) were increased by ascorbic-acid supplementation at the 200 ppm level and by the lower relative humidity. The higher RH reduced egg production by 4.16% and changed feed efficiency from 2.29 to 2.45 g of feed intake per gram of egg mass. There were differences in blood pH, blood CO2, blood HCO3-, and blood and adrenal ascorbic-acid levels due to the housing temperature. The higher RH produced blood-chemistry changes that were typical of respiratory alkalosis, which has been shown to occur in layers at high temperatures. Higher cage density, on the other hand, showed no change in the HCO3 level; but blood pCO2 was increased while blood pH was decreased. These results demonstrate that ascorbic-acid supplementation can be effective in reducing laying-hen mortality due to environmental stress and has small influences on egg quality.

Adrenal Glands↗
PubMed1998

Semen quality: is there a paternal effect on pregnancy outcome in in-vitro fertilization/intracytoplasmic sperm injection?

The objective of this study was to investigate the role of the spermatozoon (paternal effects) on implantation and pregnancy outcome in in-vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI). Male individuals of three types were analysed: infertile men with oligoasthenoteratozoospermia (OAT), infertile men with normozoospermia and fertile men (donors). Female counterparts were judged to have comparable egg quality within two groups studied, i.e. infertile women with pure mechanical (tubal) infertility and recipients of donor eggs. There were significantly higher differences in implantation and pregnancy rates in groups using donor spermatozoa and donor egg recipients. Analyses of key set groups revealed a trend toward a poorer implantation and pregnancy outcome when comparing OAT versus normozoospermic patients within IVF, but not within ICSI treatments, in couples with tubal infertility. In couples who were recipients of donor eggs, no differences were observed between OAT patients treated by ICSI and normozoospermic patients treated with IVF. No significant differences were observed in miscarriage rates within any groups studied. In conclusion, the poorer results observed in OAT patients undergoing IVF may be secondary to spermatozoal effects due to a high insemination concentration. Overall, there does not seem to be a significant effect of severe male infertility (OAT) on implantation and pregnancy outcome. However, this does not preclude that specific sperm aberrations may exert a negative effect on embryogenesis and therefore on implantation potential following assisted or in-vivo reproduction.

Adult↗
PubMed1980

Performance of laying hens fed on practical diets containing different levels of supplemental biotin during the rearing and laying stages.

1. The effect of biotin supplementation of low-biotin practical diets during rearing and laying stages on performance was studied in White Leghorn-type laying hens. 2. Biotin supplementation during rearing did not have any apparent effect on the condition of the bird at point-of-lay or on subsequent laying performance. 3. Biotin supplementation during lay did not have any beneficial effect upon egg number, egg size or food intake or food conversion efficiency. 4. Internal egg quality, as reflected by albumen height, was slightly improved by biotin supplementation of layer's diet. 5. Input-output relationships were calculated for the incorporation of biotin in egg yolk. 6. Metabolic measurements suggested that biotin concentration in egg yolk was the best criterion of biotin status in the hen. 7. It is concluded that practical diets contain sufficient biotin to support optimum egg-laying performance in hens.

Animals↗
PubMed2006

In ovo exposure quail assay for risk assessment of endocrine disrupting chemicals.

Although there are in vivo assays using various organisms for the risk assessment of chemicals with endocrine disrupting properties, effective experimental methods for avian species are still under debate. We have developed an in ovo exposure assay using Japanese quail eggs, aimed at assessing disrupting effects on avian reproductive development and function. Hybrid eggs from Brazilian Brown male and White Egg female quails, which can be genetically sexed by their plumage color after hatching, were prepared, and test materials dissolved in olive oil were injected into the air-chamber on day 10 of incubation. After sexual maturation of hatched chicks, we observed egg production by females and the egg quality and male-typical reproductive behavior, and then examined reproductive system morphology and serum steroid concentrations in both sexes. Treatment with a synthetic estrogen, diethylstilbestrol (DES, 0.5-50 ng/g egg), dose-dependently reduced the eggshell thickness and strength of eggs. A few females treated with 5 ng/g DES per egg produced soft-shelled/ unmarked eggs, and all laying females treated with 50 ng/g egg produced eggs completely lacking shells. DES also induced shortening of the left oviduct and abnormal development of the right oviduct in a dose-dependent manner, while testis weight was reduced symmetrically. In addition, 2,2',4',6'-tetrachlorobiphenyl-4-ol (10-1,000 ng/g egg), which previously showed relatively high estrogenic activity in vitro, caused dose-dependent shortening of the left oviduct and reduction in testis weight. The methods for evaluating endocrine disrupting effects and preparing experimental birds proposed in the present study are expected to facilitate assays for avian reproductive toxicology.

Animals↗
PubMed2002

Effect of vitamin E and A supplementation on egg yolk alpha-tocopherol concentration.

The objective of this study was to asses the effect of dietary dl-alpha-tocopheryl acetate (alpha-TAC) and vitamin A supplementation on egg yolk alpha-tocopherol (alpha-T) concentration. A total of 96 ISA brown hens (a brown-egg laying hen), 32 wk of age, was used. Eight concentrations of alpha-TAC (0, 20, 40, 80, 160, 320, 640, and 1,280 IU/kg diet) were included in a corn-soybean meal-based diet containing 4,000 IU of vitamin A/kg diet. Production parameters were not affected by dietary treatment. Interhen variation in yolk alpha-T concentration increased at higher dietary intakes. Logarithmic transformation stabilized variance and showed the existence of a linear relationship between dietary alpha-TAC supplementation level and alpha-T egg yolk concentration (P < 0.001). As the dietary concentration of alpha-TAC rose, efficiency of uptake of alpha-T from feed to yolk decreased linearly (P < 0.001). A parallel experiment was carried out in which four additional groups of hens were fed diets containing four levels of dietary alpha-TAC (0, 40, 160, and 640 IU/kg) and 40,000 IU vitamin A/kg diet. A significantly lower egg yolk alpha-T concentration was found in hens fed diets including the highest level of vitamin A supplementation (P < 0.001). No interaction of dietary alpha-TAC and vitamin A concentrations was observed on egg yolk alpha-T concentration. No effect of dietary treatment was observed on yolk oxidation and other egg quality characteristics.

Animals↗
PubMed2006

Effects of commercial enzyme preparations on egg and eggshell quality in laying hens.

1. Four different commercial enzyme products were added to standard commercial layer diets, based on barley, wheat or triticale. 2. Diets were fed to 4 different strains of commercial laying hen: ISA Brown, Hy-Line CB, Tegel SB2 and Tegel HiSex. 3. Diets were given for 5 weeks prior to measurements of egg and eggshell quality. 4. The inclusion of commercial enzyme products in the diets had no effect on egg weight. 5. Positive effects of the enzymes were: improved eggshell breaking strength, shell weight, percentage shell and shell thickness for the barley-based diet and increased eggshell breaking strength for two of the enzymes with the wheat-based diets. 6. Negative effects of the enzyme products were slightly lighter coloured eggshells and reduced albumen quality for the barley-based diet and for two enzymes with the wheat-based diet. 7. The addition of commercial enzyme preparations had no main effect on egg and eggshell quality for the triticale-based diet, except for effects on yolk colour. 8. Yolk colour was lower than control for enzyme 3 in all diets and for enzyme 4 with the barley- and wheat-based diets. 9. Further investigation is required to elucidate the specific enzyme components that influence egg quality.

Animal Feed↗
PubMed1986

Effects of cage and floor pen management on behavior, production, and physiological stress responses of laying hens.

Behavior, physiology, health, egg production, and egg quality characteristics of laying hens housed either 1/1394-cm2 cage (S), 2/1394-cm2 cage (HD), 2/2788-cm2 cage (LD), or in floor pens (P), each containing 25 hens, were monitored in order to assess hen welfare in different management systems. Egg production was highest in P and S hens. There were no differences among treatment groups in feed efficiency, egg weight, or egg taste, although egg shell breaking strengths were lower in HD hens despite their relatively low egg production. Blood spots were most common in eggs from caged hens. With respect to behavior, penned hens locomoted more, spent less time in stationary exploration than caged birds, and utilized nest boxes for activities in addition to egg laying. The HD hens fed less frequently than did the LD, and HD cage pairs engaged less frequently in simultaneous feeding, drinking, and resting behavior than LD pairs. Plasma corticosterone levels were initially found to be higher in pens than cages; this difference disappeared when the use of trap-nesting to capture P birds for sampling was discontinued. Nighttime corticosterone levels were higher in HD hens. In contrast, primary and secondary hemagglutination titers to sheep erythrocyte (SRBC) antigen, heterophil to lymphocyte ratios, hepatic zinc metallothionein, serum zinc, and body weights did not differ among treatments. Mortality, however, was lower in pens. It was concluded that, although there were striking dissimilarities in behavior between the pen and cage environments, physiological and production data did not provide evidence of stress associated with cage housing per se. High density caging, however, may be a stressor; this is discussed with reference to other research.

Animals↗
PubMed2000

Producing and marketing a specialty egg.

Eggland's Best, Inc. markets premium quality shell eggs under the Eggland's Best (EB) brand name. The company, started in 1988, is comprised of a franchise network of established egg producers and covers most of the United States. Eggland's Best provides its franchisees with marketing and technical support. The franchisees produce, process, and distribute EB eggs according to the strict program established and monitored by EB. Production follows the all-natural vegetarian feed program in accordance with the company's US patent entitled "Eggs Compatible with a Cholesterol Reducing Diet and Method of Producing the Same." The EB program excludes animal fat and other animal byproducts. Eggland's Best eggs have seven times the generic level of vitamin E, nearly three times more omega-3 fatty acids and iodine, and 25% less saturated fat than regular generic eggs. Eggland's Best has one of the finest shell egg quality assurance programs anywhere. Eggland's Best franchisees submit weekly egg samples that are analyzed for shell quality, interior quality, vitamin E, iodine, cholesterol and fatty acids. Samples of feed and the EB-patented feed supplement are also analyzed. Approximately 28,000 total laboratory tests are conducted annually. Nationwide product and display retail evaluations are contracted through an outside audit company (40 to 50 cities evaluated four times per year). All EB eggs are USDA graded according to EB's strict quality standards. Producers must follow a food safety quality assurance program (United Egg Producers Association 5-Star or equivalent state or company program). Each egg is stamped "EB" as assurance of meeting EB's highest standards of flavor, quality, and nutrition. Eggland's Best has enjoyed record sales growth for the past 3 yr.

Animals↗
PubMed1994

Production variables and nutrient retention in single comb White Leghorn laying pullets fed diets supplemented with direct-fed microbials.

Two experiments were carried out for six and seven 28-d periods, respectively, with DeKalb XL Single Comb White Leghorn laying pullets to ascertain the effect of feeding 1,100 mg Lactobacillus (Lacto)/kg diet (ppm) and 2,200 ppm Lacto diets, and the supplementation of these diets with 1 and 3% fat, on layer performance and nitrogen, calcium, and phosphorus retention. The dietary treatments were corn-soybean meal (C-S) control, C-S plus condensed cane molasses solubles (CCMS)-1,100 ppm Lacto (4.4 x 10(7) cfu/mg Lacto), and C-S plus CCMS-2,200 ppm Lacto (8.8 x 10(7) cfu/mg Lacto) without fat (Experiment 1) and without and with 1 and 3% supplemental fat to each Lacto level (Experiment 2). In both experiments, layers fed the 1,100 ppm Lacto diets had better (P < .05) hen-day production, daily feed consumption, egg mass, egg weight, egg size, and feed conversion than layers fed diets without Lacto. Egg mass, interior egg quality, and feed conversion (Experiment 1), mean body weight gains, and nitrogen, calcium, and phosphorus retention (Experiment 2) were further improved (P < .05) with feeding 2,200 ppm Lacto diets. Feeding Lacto diets with 1% fat provided (P < .05) larger eggs and better (P < .05) nitrogen and phosphorus retention, whereas 3% fat decreased (P < .05) feed consumption and nutrient retention and improved (P < .05) feed conversion and body weight gain. Positive correlations between Lacto diets and nitrogen and calcium retentions, daily feed consumption, and egg size were observed. Feeding 1,100 ppm Lacto diets to layers stimulated appetite and improved egg production, egg mass, egg weight, egg size, and feed conversion. Addition of fat to Lacto diets reduced daily feed consumption and provided better feed conversion, egg masses, egg sizes, body weight gains, and nutrient retentions.

Animals↗
PubMed2005

Identification of QTL for production traits in chickens.

If the poultry industry hopes to continue to flourish, the identification of potential quantitative trait loci (QTL) for production-related traits must be pursued This remains true despite the sequencing of the chicken genome. In view of this need, a scan of the chicken genome using 72 microsatellite markers was carried out on a meat-type x egg-type resource population measured for production and egg quality traits. Using a Bayesian analysis, potential QTL for a number of traits were identified on several chromosomes. Evidence of eight QTL regions associated with a total of eight traits (specific gravity, albumin height, Haugh score, shell shape, total number of eggs, final body weight, gain, and feed efficiency) was found. Two of these regions, one spanning the area of 263/287 cM on GAA01 and the other spanning the area of 23/28 cM on GAA02, were associated with multiple QTL.

Animals↗
PubMed2005

Chick development in free-living great tits Parus major in relation to calcium availability and egg composition.

Evidence from a number of avian studies suggests that limitation of exogenous calcium (Ca) may reduce egg quality and retard nestling growth. However, it is poorly understood whether reduction in chick growth in Ca-poor areas is due to insufficient intake of dietary Ca or caused by maternal Ca limitation mediated through subtle changes in composition of eggs. In this study, we provide new evidence that Ca availability during egg formation may indeed affect egg composition and influence chick development of the great tit Parus major at early developmental stages. Ca-supplemented birds breeding in base-poor pine forests produced eggs with elevated yolk Ca concentration compared with controls, while no such effect of supplementation was detected in case of eggshell thickness. Nestling tarsus length in the first half of the nestling period was positively influenced by both yolk dry mass and yolk Ca concentration. The effect of supplementary Ca did not persist throughout the nestling period; initial effects of egg components disappeared as nestlings aged. We conclude that apparently normal eggs may harbor poor nutrient and mineral conditions for chick growth. Such subtle changes in composition of eggs can depress chick growth, especially in harsh years.

Analysis of Variance↗
PubMed1986

Effects of feeding hens a high level of vomitoxin-contaminated corn on performance and tissue residues.

A balance experiment was conducted with hens fed a high level of vomitoxin (V) to study the effect on live performance, egg quality, and tissue residues of V. Twenty Single Comb White Leghorn (SCWL) hens, approximately 26 weeks of age, were individually housed in metabolic cages and fed a control (C) or V (82.8 mg/kg) diet for 27 days. No significant differences were observed in feed consumption, body weight gain, egg production, egg weight, haugh units, shell deformation, or egg shell thickness between treatments. No gross pathological lesions were observed in the oral cavity, proventriculus, small or large intestine, liver, spleen, heart, or kidney. Small erosions were present in the gizzard mucosa of birds fed the V-diet. No significant V residues were found in the yolk, albumen, egg shell, liver, kidney, thigh, or breast muscle, but levels of approximately 20 ppb were found in the gizzard. About 4.2% of the total V consumed by hens were recovered in the feces.

Animals↗
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↗
PubMed2002

Relationship between microsatellite marker alleles on chromosomes 1-5 originating from the Rhode Island Red and Green-legged Partrigenous breeds and egg production and quality traits in F(2) mapping population.

The objective of this study was to determine the relationship between the origin of marker alleles from the Rhode Island Red (RIR) and Green-legged Partrigenous (GlP) breeds and chosen egg production and quality traits in F(2) generation consisting of 10 full-sib families. Polymorphism analysis of 23 microsatellite markers within the mapping population (519 F(2)) was made. In parental generation 17 alleles were identified as specific for the GlP and 23 for the RIR. The least squares method was used to evaluate the significance of effects of genotype (GlP/GlP, RIR/RIR, GlP/RIR) on the analysed quantitative traits. Thirty traits of egg production and quality were measured during the laying period. It was shown that the effects of the genotype (GlP/GlP, RIR/RIR, GlP/RIR) at the loci on analysed traits of F(2) animals were diversified. Significant effects were found for 16 traits. These results confirm that the analysed microsatellite loci may be linked to the genes affecting egg production and quality traits. The loci examined and the experimental population constitutes a valuable material for QTL mapping (linkage analysis).

Alleles↗