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PubMed1981

[Peas (Pisum sativum L.) as a mixed feed component for laying hens].

Percentages of 0, 10, 20 and 30% peas (Pisum sativum) of the variety "Nadia" in the mixed feed with methionine supplementation were tested with 2,100 laying hybrids of the species White Leghorn in the age period between the 22nd and 73rd week of their lives which were kept in 3-storeyed cages. The feeding of peas had no influence on feed intake, laying performance, the weight of the individual egg, the stability of the egg shell, body weight, mortality, the hemoglobin content and the hematocrit value of the blood. With the increasing percentage of peas the consumption per animal and day and the expenditure of energy and methionine/cystine per 100 g egg decreased and that of lysine increased (p less than 0.05). On the basis of the investigations the conclusion is drawn that in laying hen feed supplemented with methionine a quota of up to 30% peas is possible without a decrease in performance.

Amino Acids↗
PubMed1997

The stress of not being able to perform dustbathing in laying hens.

The stress of not being able to perform dustbathing was studied in small groups of laying hens. The birds were reared and kept for 2.5 years in cages with either sand ("sand birds") or wire floors ("wire birds"), and subsequently deprived of sand (sand birds) or given access to sand (wire birds). Before this change, wire birds had a higher incidence of unilateral wing/leg stretching and stereotypic pecking compared to sand birds; however, there was no difference in corticosterone concentrations. Deprivation of sand in the sand birds resulted in a total absence of dustbathing and in a significant increase in corticosterone concentrations. Although the wire birds dustbathed on the wire before the change of floors, there was a significant increase in the incidence of dustbathing after sand was provided, but no changes in the concentrations of corticosterone. Threats and allopecks decreased in the wire birds after access to sand, whereas no changes were found in the sand birds. Stereotypic pecks on feathers were absent in the sand birds, but were frequent in most of the wire birds both before and after they were given sand. Also, in the wire birds, all feather pecking (stereotypic and nonstereotypic) was positively correlated with the concentration of corticosterone, and this kind of pecking may, thus, be an expression of stress in laying hens. We conclude that the nonperformance of dustbathing behavior is associated with the experience of stress.

Animals↗
PubMed1998

Plasma alkaline phosphatase and production traits in laying hens as influenced by dietary protein, strain and age.

1. Plasma alkaline phosphatase (ALP) activity was determined in 4 laying strains (White Leghorn, New Hampshire, Native Brown and Native Barred) at 48 and 54 weeks of age. Birds were fed 1 of 2 isoenergetic diets with calculated crude protein contents of 152 and 181 g/kg. 2. No significant differences in plasma ALP activity were noted between the strains, although significant differences in laying performance between strains were evident. 3. There was no response in plasma ALP activity to the high dietary protein level in any strain. Depressed plasma ALP activity was associated with increasing age of birds. 4. The results failed to confirm the suggestion that ALP activity is related to egg production of the laying hen.

Aging↗
PubMedDate not supplied

Timing of the calcium intake and effect of calcium deficiency on behaviour and egg laying in captive great tits, Parus major.

The calcium demand of egg-laying birds is much higher than in other vertebrates during reproduction. We showed elsewhere that a low level of calcium availability can greatly affect the eggshell quality and reproduction of free-living passerines. However, there are few data on calcium demand and calcium intake in relation to egg laying and behaviour and egg-laying performance under conditions of calcium shortage in nondomesticated birds. We examined these aspects in an experiment with captive great tits, Parus major, on a diet deficient in calcium, with or without snail shells as an additional calcium source. More than 90% of the calcium intake for egg production took place during the egg-laying period. Females ingested about 1.7 times as much calcium as they deposited in eggshells. Removing the snail shells after the first egg resulted in eggshell defects and interruptions of laying after 1-3 d. Females without snail shells doubled their searching effort and started to burrow in the soil and to eat sand, small stones, and their own eggs. Most calcium was consumed in the evening, probably to supplement the calcium available from the medullary bone with an additional calcium source in the gut during eggshell formation. The results demonstrated that eggshell formation requires accurate timing of the calcium intake and that obtaining sufficient calcium is time-consuming, even in calcium-rich environments. These factors pertaining to calcium intake greatly affect the ability of birds to collect sufficient calcium for eggshell formation in calcium-poor areas.

Animals↗
PubMed2004

Cognitive functioning in young people with first episode psychosis: relationship to diagnosis and clinical characteristics.

OBJECTIVE: To examine the extent and nature of neuropsychological deficits in adolescents and young people with first episode psychosis (FEP), and to determine whether the pattern and extent of neuropsychological deficits varied according to diagnosis. METHOD: A total of 83 FEP subjects aged 13-25 years, and 31 healthy controls completed a comprehensive battery of neuropsychological tests, grouped into 10 cognitive domains. First episode psychosis subjects were stratified into three diagnostic groups (schizophrenia, affective disorders, substance-induced psychosis) and differences in cognitive profiles were examined. The contribution of demographic and clinical characteristics to cognitive performance was also explored. RESULTS: The schizophrenia group demonstrated significantly worse performance on tasks of verbal learning and memory than the affective disorders group. Compared to healthy controls, the schizophrenia group also demonstrated global impairment across the majority of cognitive domains. The substance-induced group's performance lay between that of the schizophrenia and affective disorders groups. Analyses of differential deficits revealed that verbal learning, verbal memory and current intellectual functioning were selectively impaired in the schizophrenia group, whereas the affective disorders group demonstrated a selective deficit in speeded processing. Premorbid intellectual functioning, negative symptomatology and medication levels were the strongest predictors of cognitive performance in FEP subjects. CONCLUSIONS: Verbal memory deficits differentiate individuals with schizophrenia from those with psychotic affective disorders. Although significant cognitive deficits are evident across all diagnostic FEP groups, individuals with schizophrenia appear to have more generalized impairment across a broad array of cognitive functions than other psychotic diagnoses. Lower premorbid intellectual functioning does not appear to contribute to greater cognitive deterioration following onset of psychosis, but severity of illness may be a more important factor than levels of mood disturbance.

Adolescent↗
PubMed1985

[Choline requirement of the laying hen. 2. Effect of methionine and fat content of rations on choline requirement].

165 laying hens per group received 3.0, 3.5, or 4.0 g methionine, 29 or 59 g fat and supplements of 0, 108, 217, 434 or 868 mg choline per kg feed resp. (3 X 2 X 5) over a period of 336 days. The average laying performance was 70% and was not influenced values by the content of the feed. The methionine supplements significantly increased the weight of the eggs by 0.6 and 1.1 g resp. The higher fat content increased the weight of the eggs by 0.6 g. Feed expenditure was not influenced by the subject of the experiment. The results of the experiment show that laying hens do not require choline as feed supplement and that therefore no interactions between choline and the fat and methionine content of the ration are to be expected.

Animal Feed↗
PubMed1985

[Evaluation of laying-hen feed with varied vitamin E and antioxidant supplementation].

In two experiments with 1,250 laying hybrids the influence of the elimination of vitamin E and antioxidant supplements to the laying hen feed was tested. With mixed feed according to official quality requirements but without vitamin E and antioxidant supplements laying hens achieved the same laying performance and individual weight as the control group. There was no influence on feed consumption, feed expenditure per 100 g egg, mortality, development of body weight, the tensile strength of the eggs and the fat quality of the body either. Vitamin E content in the yolk increases with the growing vitamin E content in the feed. The vitamin E requirement norm of laying hens for consumer egg production is achieved at a native vitamin E content of 7 mg/kg laying hen feed. The supplement of synthetic antioxidant is unnecessary.

Animal Feed↗
PubMed1998

Physiological responses of hens divergently selected on the number of chicks obtained from a single insemination.

A series of experiments was conducted in domestic fowl to investigate the consequences of five generations of divergent selection for increased (L+) or decreased (L-) numbers of hatched chicks. After artificial insemination with pooled ejaculates within the same line (L+ males x L+ hens or L- males x L- hens), significant differences were observed between L+ and L- hens for mean fertility rates (L+ 94.8%, L- 70.2%, P < 0.0001) and for effective and maximum duration of fertility (P < 0.00001). A comparison of the overall laying performance and shell quality between the two selected lines showed that L- hens laid fewer eggs than L+ hens (P < 0.00001) and L- eggs had poorer shell quality (shell breaking strength) than L+ eggs (P < 0.00001). These observations were associated with significantly higher percentages of early embryo death in eggs from L- hens compared with L+ hens. Another series of experiments revealed the presence of larger initial populations of spermatozoa in the sperm storage tubules as well as in the perivitelline layer of eggs from L+ hens. The populations of spermatozoa in the sperm storage tubules of commercial laying hens inseminated with pooled semen samples from L+ males was compared with those in hens inseminated with samples from L- males to determine whether the variations in oviductal sperm storage between the two lines were male dependent. No significant differences between the populations of spermatozoa present in the sperm storage tubules of either group of hens could be detected at any of the intervals examined after insemination (days 1, 3 and 10). Finally, an experiment conducted on hens originating from the two selected lines indicated that the utero-vaginal junction of L+ hens contained significantly more sperm storage tubules compared with L- hens (P < 0.01). It is concluded that selection based on overall reproductive performance modifies the number of eggs capable of developing viable embryos and also influences the efficacy of initial sperm storage by increasing or altering the population of sperm storage tubules located in the utero-vaginal junction. Such changes have major consequences on the duration of the fertile period, which in avian species is directly dependent on both the actual population of spermatozoa stored in the oviduct and on their rate of release from the storage sites.

Animals↗
PubMed2001

Nutritive and economic values of high oil corn in layer diet.

Two layer feeding trials were conducted to demonstrate the nutritive and economic values of recently developed high oil corn (HOC) in Korea. A corn-soybean meal-based commercial layer diet was chosen as the control diet. The yellow dent corn in the control diet was replaced with HOC to give an isocaloric diet, or replaced with HOC on a 1:1 basis to give a high energy diet. In Trial 1, 510 23-wk-old ISA Brown layers were allotted to three dietary treatments with five replicates per treatment. In Trial 2, 600 38-wk-old Hy-Line Brown layers were allotted to three dietary treatments, again with five replicates per treatment. Both trials were conducted for 15 wk. To measure the ME values of typical corn and HOC, two metabolism trials were performed with layers and adult roosters. The HOC used in this trial contained approximately 94% higher crude fat (6.60% as-fed basis) compared with typical corns. The gross energy, AMEn, and TME values of HOC, are 5.7 to 7.7% higher than those of typical corns, indicating that the energy use of each corn were similar. Oil from the HOC contains 6.5 to 8.3% more oleic acid and 6 to 7% less linoleic acid than oil from typical corns. HOC feeding, on an isocaloric basis or on 1:1 replacement with typical corn, did not exert any effect on various laying performances, including the physical quality of egg. This result reflects the quality of the commercial diet chosen as the control diet, which was already fairly good, such that the performance was already maximal. The polyunsaturated fatty acid content in yolk from hens fed HOC was higher than that from hens fed typical corns, reflecting higher linoleic acid content in the HOC. HOC feeding decreased the saturated fatty acid content in the yolk, due primarily to decreased palmitic acid. If used alone replacing typical corn completely in a layer diet, the acceptance price of HOC was estimated to be 154 won/kg when the price of typical corn was 131 won/kg (118:100). When both corns were allowed to be used, the acceptance price of HOC increased to 184 won/kg (140:100), indicating that a lot cheaper layer diet can be formulated when both HOC and typical corn are used in laying hen diet formulation.

Animal Feed↗
PubMed1995

[Effects of L-carnitine in poultry].

Because of the well established function of carnitine possible effects of carnitine were studied in poultry. In trial I it was investigated if carnitine and its precursors (lysine, methionine) reduce the formation of abdominal fat in broilers. Chickens (10 groups of 10 chickens each) were fed different diets (control, lysine and methionine in excess and deficient, respectively, with or without 5% fat supplement, L-carnitine and DL-carnitine supplement, respectively). Performance (body weight gain, feed conversion), amount of abdominal fat and carnitine concentration in blood, muscles (M. sartorius, M. pectoralis superficialis, cardiac), liver and kidney were determined. Performance and abdominal fat were influenced by dietary fat, lysine and methionine as expected and were not altered by carnitine. Excess and deficiency of lysine and methionine did not influence, fat supplement reduced and carnitine supplementation significantly increased tissue concentration of carnitine. In trial II it was studied if supplementation of a commercial layers' ration with either 500 mg L-carnitine or 500 mg nicotinic acid or both per kg reduces the cholesterol concentration in yolk. Influence on body weight, feed intake, laying performance, serum and yolk cholesterol concentration could not be observed, but yolk concentration of carnitine was significantly increased in supplemented groups. Trial III should clarify if the L-carnitine content in broiler parent stock ration influences hatchability. Four groups of 1350 hens each were fed a commercial all-mash supplemented with 0, 20, 50 and 100 mg L-carnitine, respectively. Hatching rate was increased from 83% to 87% and from 82.4% to 85.3% in groups supplemented with 50 and 100 mg L-carnitine, respectively, and in randomly sampled eggs of these groups carnitine concentration in yolk was higher.

Animal Feed↗
PubMed1993

[The use of native triticale in poultry. 3. Use in laying hens].

In three trials with a total of 3240 white laying hybrids, 10 to 72% Triticale of the variety "Grado" was used as a substitute for maize and wheat. The feeding of Triticale had no influence on feed consumption, laying performance, feed efficiency, mortality or weight gain. In two of three trials the egg weight was lowered with an increasing amount of Triticale in the diet. After supplementation of 1 or 1.5% sunflower oil to the diets with 50 resp. 72% Triticale the egg weight increased again to the level of the control group. With the exception of one group, there was no correlation between breaking strength and deformation of the eggs. The colour intensity of the egg yolk was decreased with increasing amounts of Triticale in the diet. It can be concluded, that laying hen feed supplemented with oil may contain up to 50% Triticale, but in non-supplemented diets the highest amount of Triticale should be only 20% because of the risk of linoleic acid shortage.

Animal Feed↗
PubMed1999

Effects of fenfluramine on body weight, feed intake, and reproductive activities of broiler breeder hens.

Inherited overfeeding and fattiness reduce laying performance in broiler breeder pullets. Although feed restriction is used to compensate for overeating and weight gain, this management practice leads to increases in BW variation, labor cost, and bird stress. Dietary supplementation of anorectic agents, such as fenfluramine, may be an alternative. Anak female prebreeder hens (19 wk of age; n = 10 per group) were treated as follows: daily oral administration of 5, 10, 20, or 40 mg DL-fenfluramine/kg BW or saline with food provided for ad libitum intake or administration of saline and feed restriction. Daily feed intake (FI), laying rate, egg composition, and BW were measured. At 40 wk of age, adipose tissue and ovary weights were measured. Fenfluramine depressed (P < 0.05) BW and FI in a dose-dependent manner, but was less effective in reducing BW than feed restriction. Suppression of FI occurred in two phases: a dynamic phase, coinciding with the rapid growth phase, during which FI declined progressively and a static phase during which FI reached a plateau at a significantly low level until the end of the experimental period. Egg production peaked first in saline-treated hens fed for ad libitum intake, but soon after started to decline. In all fenfluramine-treated and feed-restricted hens, egg production peaked 3 to 4 wk later and remained high until the end of the experiment. There were no differences in egg and egg component weights among the experimental groups. Abdominal adipose tissue weight was reduced by fenfluramine in a dose-related manner, and its weight in the group treated with the highest dose was similar to that of feed-restricted hens. In these two groups, ovarian weight was significantly higher than in the saline-treated hens fed for ad libitum intake, and a small, nonsignificant increase in ovary size was observed in groups treated with the two median doses of fenfluramine. The effect of fenfluramine on egg production was similar to that of feed restriction, but it was not dose-dependent and, thus, not directly related to its leaning effect. In broiler breeder hens, oral fenfluramine may be used for chemical feed restriction and diminution of fattiness without reducing egg production relative to manually feed-restricted hens.

Adipose Tissue↗
PubMed1996

Evaluation of early feed restriction on egg size and hen performance.

Feed restriction was implemented in a factorial design (2x4) when pullets were at either 5 or 10% egg production. Periods of feed restriction were for 0, 3, 4, or 5 d. Two trials each using 672 Hy-line W-77 White Leghorn Hens 19 wk of age were identified and randomly assigned to 16, 2x3 m pens at a density of 7 birds per square meter. Data recorded were days at sexual maturity, egg production, mortality, feed consumption, feed conversion, egg weight, body weight gain, and body weight uniformity. Hens placed on feed restriction reached sexual maturity 3 to 5 d later (P < 0.05) than the unrestricted birds. No significant main effects or interactions were found for egg production, feed consumption, feed conversion, mortality, egg weight, body weight gain, or body weight uniformity for the initial 15 wk or the entire egg production period. These results suggest that early egg size was not increased with the practice of early feed restriction nor did short- or long-term laying performance improve.

Animals↗
PubMed2001

Nitrogen retention and performance of brown laying hens on diets with different protein content and constant concentration of amino acids and energy.

1. The aim of this study was to determine the nitrogen balance and the performance of laying hens fed on diets with a protein content lower than the diets currently used in commercial practice but with adequate concentrations of lysine, sulphur amino acids, tryptophan and threonine. 2. Ninety-six Hy-Line Brown hens, 24 weeks old, were divided into 3 groups of 8 replicates and received, for 16 weeks, diets formulated to have 3 different protein concentrations: 170 (control), 150 and 130 g/kg CP and the same energy content. For each protein concentration, the contents of lysine, methionine, methionine+cystine, tryptophan and threonine were maintained at minimum requirement concentrations by supplying synthetic amino acids. 3. In the first half of the trial, egg production and egg weight were similar in all groups. From the 9th week onwards group 150 CP laid heavier eggs and had a slightly lower egg deposition and total mass. Food conversion ratio was best in the control group. 4. Nitrogen intake was related to the protein concentration of the diet, the food intake being almost the same in the 3 experimental groups. Faecal nitrogen content significantly and linearly decreased with reduction in dietary protein content and was about 50% of the intake. Considering the nitrogen faecal/intake ratio, the 150 CP group showed better nitrogen utilisation at each sampling time.

Amino Acids↗
PubMed2005

Use of L-carnitine and humate in laying quail diets.

This experiment was carried out to determine the effects of using L-carnitine and humate alone or in combination in quail diets on laying performance, egg traits and blood parameters. A total of 280 Japanese quails aged 10 weeks, divided into one control group and three treatment groups, were used. The diets of the first, second and third treatment groups were supplemented with 100 mg L-carnitine/kg, 1.5 g humate (Farmagülatör Dry Plus)/kg and 100 mg L-camitine + 1.5 g humate/kg, respectively. The experimental period lasted 16 weeks. The addition of L-carnitine and sodium humate alone or in combination did not significantly affect body weight, feed consumption, egg production, feed conversion ratio, mortality, egg-shell thickness, egg yolk index and the percentages of egg-shell, albumen and yolk. Egg weight increased (P < 0.001) with L-carnitine supplementation. The values of egg albumen height (P < 0.05), egg albumen index (P < 0.01) and egg Haugh unit (P < 0.05) were increased with humate supplementation. Egg cholesterol content and blood serum parameters were not affected by the supplementation of L-carnitine with or without humate. The results in this study demonstrated that L-carnitine supplementation increased egg weight while humate addition increased egg albumen index and egg Haugh unit of laying quails. However, the combined administration of L-carnitine and humate did not have any significant effects on the parameters measured.

Animal Feed↗
PubMed2026

Research note: Genetic background influences the relationship between age at first egg and long-term egg production in layers.

Age at first egg (AFE) is a key selection criterion in layers breeding. With the laying cycle being extended to 100 weeks, the relationship between AFE and long-term productivity and egg quality should be evaluated to ensure that selection for AFE aligns with current breeding objectives. In this study, Beijing-You chickens and White Leghorns were used to generate purebreds and crossbreds. Egg-laying performance was recorded including AFE, egg number and cumulative egg number at different stages from onset till 100 weeks, and egg quality traits at 32, 54, 72, 86, and 100 weeks. Genetic correlations were estimated, both in the combined population of purebreds and crossbreds and within each genetic group. In the combined population, a positive genetic correlation was observed between AFE and cumulative egg number till 100 weeks. Age-dependent genetic correlations between egg number at different stages and AFE further revealed that extremely early-maturing hens showed initial production advantages, but these advantages diminished at later stages. Importantly, the genetic and phenotypic correlations between AFE and egg quality traits were weak, with correlation coefficients ranging from -0.18 to 0.35. Within each genetic group, the relationships between AFE and egg production also showed consistent age-dependent patterns. For the long-term production targets, optimal AFE seems to differ by genetic backgrounds. White Leghorns showed higher egg production with earlier maturity, whereas in Beijing-You chickens, maintaining AFE at approximately 140-189 days appeared to be more favorable. Overall, these findings demonstrated that earlier AFE does not ensure higher egg production at extended laying cycles and has negligible influence on egg quality, highlighting the importance of optimizing AFE according to genetic background.

Age at first egg↗
PubMed2026

The current and future perspective of ChickenGTEx project and its applications in precision breeding.

The Chicken Genotype-Tissue Expression (ChickenGTEx) project was established to systematically characterize the regulatory landscape of the chicken genome and to accelerate the translation of functional genomics into precision breeding. By integrating whole-genome sequencing with multi-tissue transcriptomic profiling, ChickenGTEx provides a comprehensive atlas of gene expression regulation across diverse tissues and physiological systems. Current findings demonstrate that complex production traits are governed by coordinated regulatory networks rather than isolated loci, with substantial contributions from tissue-specific gene expression, structural variation, and genotype-by-sex interactions. Sex-dependent regulatory effects further refine the genetic architecture of metabolic, immune, and reproductive traits, highlighting the importance of incorporating sex as a biological variable in genomic analyses. Application of integrative omics frameworks within elite layer populations has revealed multilayer regulatory mechanisms underlying extended laying performance, feed efficiency, metabolic health, and eggshell quality. By partitioning phenotypic variance into genetic, regulatory, and host-microbiome components, these approaches move beyond association-based mapping toward causal inference and biological interpretation. Importantly, validated regulatory loci identified through ChickenGTEx and related analyses provide actionable markers for genomic selection and rational targets for precision genome modification. Looking forward, continued expansion of regulatory atlases, incorporation of single-cell and longitudinal data in diverse environmental conditions, and integration of functional annotation into breeding pipelines will further enhance prediction accuracy and sustainable genetic improvement. The ChickenGTEx project thus represents a foundational platform bridging functional genomics and practical poultry breeding.

Animals↗
PubMed2026

Ovarian H3K27ac remodeling is associated with impaired follicular development in laying hens with fatty liver hemorrhagic syndrome.

Fatty liver hemorrhagic syndrome (FLHS) is a metabolic disease of laying hens that reduces egg production and is accompanied by reproductive impairment, but the ovarian regulatory mechanisms that connect nutritional stress to follicular dysfunction remain unclear. This study examined whether active chromatin remodeling in the ovary is associated with FLHS induced by a high-energy, low-protein (HELP) diet. Hy-Line Brown hens were assigned to a basal diet or HELP diet, and ovarian tissue was collected for histone H3 lysine 27 acetylation (H3K27ac) chromatin immunoprecipitation sequencing and RNA sequencing. The HELP diet reduced laying performance and the numbers of small yellow and hierarchical follicles, indicating compromised follicular development. Genome-wide H3K27ac profiling identified 2,111 regions with lower acetylation and 1,707 regions with higher acetylation in FLHS ovaries. Genes linked to differential H3K27ac regions were enriched in pathways related to oocyte meiosis, cell cycle control, FoxO signaling, gonadotropin-releasing hormone signaling, and steroid hormone biosynthesis. RNA sequencing identified 341 differentially expressed genes, with a predominance of downregulated genes. Integration of chromatin and transcriptome data highlighted folliculogenesis-related genes, including FGF1, FGF9, and MMP10, that showed reduced H3K27ac enrichment together with decreased expression. Super-enhancer analysis further identified 131 regions with reduced H3K27ac signal in FLHS ovaries, including regions located near PCNA and RAP1A, two genes involved in cellular proliferation and survival signaling. Motif enrichment of differential H3K27ac regions implicated Fos, SF-1/NR5A1, and GATA-4 as candidate transcriptional regulators. These findings indicate that HELP diet-induced FLHS is associated with broad attenuation of active ovarian regulatory elements and reduced expression of genes required for follicle growth, tissue remodeling, and steroidogenic function. The study provides an ovarian epigenomic framework for understanding reproductive decline in FLHS-affected laying hens.

Fatty liver hemorrhagic syndrome↗