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At least 19 recordsLinked to original sources
PubMed1977

The effect of dietary copper sulphate on laying performance, nutrient intake and tissue copper and iron levels of the mature, laying, domestic fowl.

1. A cereal-based diet containing 16 mg copper/kg was fed ad lib. to a group of laying hens for 35 d. Five other groups were given this control diet to which was added 120, 240, 480, and 1920 mg Cu/kg (as copper sulphate). 2. Records were kept of daily food intake, water intake and egg production. 3. After 35 d the hens were slaughtered and blood haemoglobin, packed cell volume, Cu and aspartate aminotransferase (EC 2.6.1.1) levels assayed. Liver, oviduct, kidney and breast muscle Cu and iron concentrations were measured. 4. Food and water intakes were depressed by the two highest levels of dietary Cu and water intake was increased by the diet with 240 mg added Cu/kg. Both food and water intake showed a quadratic relationship with the level of added dietary Cu. 5. Body-weight loss was increased by the addition of Cu and showed a significant linear relationship with the concentration of added Cu in the diet. Liver and oviduct weights were depressed at the two highest levels of Cu addition. 6. Liver and oviduct Cu and Fe concentrations were significantly increased by high dietary Cu and mean total liver and kidney Cu and Fe showed an increase although for the liver this was not statistically significant.

Animal Nutritional Physiological Phenomena↗
PubMed2026

Dietary L-Tyrosine Sustains Egg Production and Quality by Modulating Promoter CpG Methylation, Gene Expression, and Hormone Profiles in Reproductive Signalling Pathways of Aged Laying Hens.

Managing prolactin (PRL)-mediated reproductive suppression is critical for maintaining egg production in commercial laying hens. L-tyrosine (TYR), a precursor of dopamine (DA), may counteract age-related reproductive decline by suppressing PRL, thereby sustaining productivity and egg quality in late-phase laying hens. The present study evaluated the effects of dietary L-tyrosine supplementation on laying performance, egg quality, reproductive hormone profiles, gene expression, and promoter CpG methylation in aged laying hens. A total of 180 Atak-S laying hens (71 weeks old) were randomly assigned to three dietary treatments, each with six replicates of 10 hens, and were fed a basal diet without L-tyrosine (control) or the basal diet supplemented with 0.5&#x2009;g/kg (TYR0.5) or 1&#x2009;g/kg (TYR1) L-tyrosine for 12 weeks. Hens in the TYR1 group exhibited higher hen-day egg production, improved feed conversion ratio, and significantly greater eggshell weight, shell thickness, Haugh unit, yolk index, and albumen index than the control group (p&#x2009;<&#x2009;0.05). Dietary L-tyrosine increased plasma DA and serum estradiol while reducing serum PRL (p&#x2009;<&#x2009;0.05). L-tyrosine also upregulated the expression of key dopaminergic and reproductive signalling genes, with corresponding promoter hypomethylation (p&#x2009;<&#x2009;0.05), whereas PRL mRNA expression tended to decrease with concurrent promoter hypermethylation. A significant negative correlation was observed between target gene expression and promoter CpG methylation levels (p&#x2009;<&#x2009;0.05). These findings indicate that dietary L-tyrosine modulates reproductive hormone profiles and molecular responses within reproductive signalling pathways, resulting in improved laying performance and egg quality. Therefore, L-tyrosine may represent a promising nutritional intervention to sustain reproductive function and productivity in late-phase laying hens.

Animals↗
PubMed1976

Effect of calcium propionate on performance of laying hens.

Laying hens kept in individual cages were fed a practical diet supplemented with 0, 0.1, 0.2., 0.4, or 0.8% calcium propionate for a six-week period. Rate of egg production, average egg weight, feed consumption, and body weight change during the experiment were not significantly affected by and dietary treatments. Liver weight, moisture content and fat content were also no significantly affected by dietary treatments. The results show that the performance of normal hens is not changed by calcium propionate supplementation.

Animals↗
PubMed1976

Rapeseed meal glucosinolates: metabolism and effect on performance in laying hens.

Two experiments were conducted with Hyline Leghorn hens to study the metabolism and detrimental effects of rapeseed meal (RSM) glucosinolates. Raw Target RSM was force fed to 12 hens which were killed after varying time intervals (15 min., 30 min., 60 min.) and the contents of areas of the digestive tract (crop; proventriculus and gizzard; duodenum and ileum) were analyzed for the presence of hydrolysis products of progoitrin. Nitrile compounds were found to be present in all areas of the digestive tract in much larger relative amounts than was oxazolidinethione. When commercially prepared RSMs of varying glucosinolate content were fed to laying hens at a 50% level of dietary inclusion, high glucosinolate-content RSM depressed egg production (P less than 0.05) more than low glucosinolate-content RSM but did not cause a greater frequency of liver hemorrhage. Histological examination of liver tissues from hens suffering liver hemorrhage revealed a severe reticulolysis.

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↗
PubMed1979

[Utilization of 15N-labelled urea by laying hens. 1. Survey of the literature, 15N-excretion in feces and urine].

Three colostomated leghorn hybrids with an average laying performance of 75% received a ration with 17.7% crude protein and an energy content of 519 energetic feed units for hens per kg mixed feed over a period of 8 days. In the first six days of the experiment the 1%-supplement of urea to the ration was labelled. Its atom-% 15N excess (15N') amounted to 96.06%. During the last two days the urea supplement was not labelled. The total N, trichloracetic acid (TCA)-soluble N and the ammonia N were determined in the feces samples collected daily. In the urine samples collected daily the total N, urea N and ammonia N per hen were determined as well. In all samples the atom-% 15N excess (15N') was measured. The percentage of 14N in feces of the 14N dose was, on an average of the three hens, 21.3% and the analogous quota of 15N' 4.6%. The quota of ammonia 14N of the total 14N in feces had an average of 2.5%, the corresponding 15N' quota was 10.1%. The atom-% 15N' of the urea N in urine was considerably above that of the total urine N and had a maximum of more than 50%. The quota of urine 14N of the 14N taken in had an average of 44.4%, and the corresponding 15N' quota was 56.9%. On an average of the three hens, 61.6% of the 15N' were excreted in feces and urine during the 8-day test period.

Ammonia↗
PubMed1976

Lysine requirement of White Leghorn pullets from 8 to 21 weeks of age.

White Leghorn pullets were fed rations in which the protein supplementary to that provided by the grain portion of the ration was derived from soybean meal, meat and bone meal, anchovy fish meal or cottonseed meal from 8 to 21 weeks of age. Protein levels were varied so that each protein supplement was tested in a feeding program in which pullets received 16% protein diets from 8 to 14 weeks and 14% protein from 14 to 21 weeks and in another feeding program in which 14% protein was fed from 8 to 14 weeks and 12% protein from 14 to 21 weeks. Each of the developing rations contained sufficient nutrient to enable pullets to develop and attain high rate of laying performance. The 14% and 12% protein cottonseed meal diets contained only 0.50% and 0.45% lysine respectively. Thus the lysine requirement of White Leghorn pullets from 8 to 14 weeks and from 14 to 21 weeks is not over 0.50% and 0.45% respectively.

Age Factors↗
PubMed1976

Effects of different cereal grains in diets for laying hens on production parameters and liver fat content.

Two experiments were conducted with White Leghorn laying hens to study the effects of different cereal grains on production criteria and liver fat content. The results of Experiment 1, in which pullets 21 weeks of age were used for a period of 22 weeks indicated that Gaines wheat or triticale (Trailblazer) were equal to corn in supporting egg production, egg weight and body weight, with comparable feed consumption. Henry wheat(a hard red winter class) was slightly, yet significantly (P less than 0.05) inferior to corn for the above criteria. No significant differences were observed among four treatments in wet liver weight and liver fat content. Hens fed the corn diet had significantly (P less than 0.05) lower carcass fat followed by the hens fed triticale in comparison with those fed Gaines or Henyry wheat. Mortality was very low and not related to dietary treatments. Neither dietary fat nor energy content was related to fat content of liver and carcass of the hens. Body weight and liver fat content were not closely related to each other. Wet liver weight was the only significantly (P less than 0.05) related factor to liver fat content. In the second experiment, in which hens 33 weeks of age were used for an experimental period of 20 weeks, opaque-2 corn was slightly superior to normal corn and triticale was comparable to normal corn in supporting egg production and egg weight. Supplementation of the diets containing the two corns and triticale with lysine failed to improve egg production and egg weight. Hens fed the diets containing either normal corn or opaque-2 corn as the only grain in the diet had significantly (P less than 0.05) higher liver fat content in comparison with hens fed the diet containing triticale as the only grain. Mortality, however, was much higher among hens fed triticale-containing diets in comparison with groups fed corn-containing diets in spite of the fact that they had significantly lower liver fat content. Regardless of dietary treatments or grains used, the hens that died were diagnosed to have fatty liver hemorrhagic syndrome. Dietary fat content was postively and significantly (P less than 0.05) related to liver fat content. Dietary energy or body weight was not closely related to liver content. Liver fat content and mortality were negatively related to each other. The higher for content did not adversely affect laying performance.

Animal Feed↗
PubMed1977

Effects of T-2 toxin on reproductive performance and health of laying hens.

Purified T-2 toxin was fed to S.C.W.L. hens at levels of 0 (control), 0.5, 1.0, 2.0, 4.0 and 8.0 p.p.m. of an otherwise balanced diet. Feed consumption, egg production and shell thickness were significantly (P less than 0.05) decreased in hens fed 8 p.p.m. as compared with control hens. The fertility and progeny performance were not depressed by feeding T-2 toxin, but the hatchability of fertile eggs of hens fed 2 and 8 p.p.m. was significantly (P less than 0.05) lower than that of hens fed the control diet. The weights of liver, heart, gizzard and spleen were not influenced by T-2 toxin. Serum levels of alkaline phosphatase, LDH and uric acid of hens fed high concentrations of T-2 toxin were greater than those of control hens. SGPT in hens fed 8.0 p.p.m. was lower when compared with control hens. No outward changes in hematocrit, hemoglobin, erythrocyte, leukocyte and differential leukocyte counts were noted with feeding T-2 toxin. Most hens fed T-2 toxin developed oral lesions: circumscribed proliferative yellow caseous plaques at the margin of the beak, mucosa of the hard palate and angle of the mouth, and tongue. The incidence and severity of lesions were proportional to the dietary level of T-2 toxin. The only other lesion observed in necropsy examination at the end of the experiment was the small mucosal ulcer in the anterior portion of the gizzard in hens fed high levels of T-2 toxin. Microscostrointestinal tract, etc.) revealed no significant pathological change except the necrotic lesions in the gizzard and crop.

Alanine Transaminase↗
PubMed1976

Influence of Fusarium-infected corn and F-2 on laying hens.

Diets containing either Fusarium-infected corn supplying 25 and 100 p.p.m. of F-2 (zearalenone) or purified F-2 at these levels did not adversely influence the reproductive performance of laying hens. In trial 1, no deleterious effects were observed for 20- and 36-week body weights, age at first egg, egg weight, albumen height, shell deformation, fertility or hatchability when Fusarium-infected corn was fed to 20-week-old pullets for 28 days. Percent hen-day egg production of birds fed Fusarium-infected corn supplying 25 and 100 p.p.m. of F-2 was superior (P less than or equal to 0.5) to egg production of nontreated controls. In trial 2, three replications of ten adult Leghorn hens were evaluated under five dietary treatments: (1) 16.7% protein basal; (2) basal plus Fusarium-infected corn (25 p.p.m. of F-2); (3) basal plus 25 p.p.m. of (purified) F-2; (4) basal plus Fusarium-infected corn (100 p.p.m. of F-2); (5) basal plus 100 p.p.m. of (purified) F-2. Difference between dietary treatments for 14-day pre-treatment, treatment and post-treatment periods were nonsignificant for 42- and 44-week body weights, egg production, egg weights, fertility and hatchability. Body weights of chicks from hens fed F-2 diets were not significantly different from those of chicks from hens fed the basal diet.

Animals↗
PubMed1977

The effect of Marek's disease vaccination and day-old debeaking on the performance of growing pullets and laying hens.

In a 2 X 2 completely randomized factorial design, four hundred day-old Single Comb White Leghorn pullets were randomly assigned to four treatment combinations of vaccinated, non-vaccinated, debeaked and non-debeaked groups. Vaccination and debeaking were performed at day-old by administering 2,000 P.F.U. of HVT vaccine/chick and by removing approximately 2/3 of the upper beak, respectively. All the data were analyzed at 5% level of probability. Vaccination reduced feed consumption significantly only during the early growing period of the first 12 weeks, whereas debeaking caused a significant reduction in feed consumption throughout the experimental period of 80 weeks. Mortality during the 20-week growing period was not affected by either vaccination or debeaking. During the laying period (20-80 weeks of age), vaccination reduced the mortality numerically, while debeaking reduced the mortality significantly. Final body weight, hen-day egg production, egg weight, albumen height and egg shell thickness were not influenced by either vaccination, debeaking or a combination of the two. Debeaking had no effect on the incidence of blood-spotting in the eggs. Vaccination, however, significantly reduced percent blood spots in the eggs. Day-old debeaking effectively prevented the occurrence of cannibalism.

Animals↗
PubMed1976

[Substitution of protein animal feed through lysine-supplemented high-protein wheat during the breeding and laying periods of hens. 5. Influence of graded lysine supplements fed during the laying period on the production characteristics of hens].

A large-scale trial was performed with 1500 laying hens which were kept under conditions of industrial egg production. The trial was carried out to investigate whether supplements of L-lysine would increase the food value of high-protein wheat and in which way a proportional decrease of dietary protein by 50% would affect the egg production of the hens. Additionally, studies were made to investigate whether the egg production of the hens was influenced by changes in the plane of feeding of the young hens during their rearing period. Both the young hens and the laying hens received isonitrogenous and isocaloric rations containing 4 graded levels of lysine. All of the 16 groups of the hens received a different diet. This was achieved by suitable combinations within the feeding regime. The control animals received, at all periods of age, food prepared on the basis of government-controlled standard rations. No significant differences in the level of food consumption were observed between the experimental groups whereas the control birds consumed more food (124 g per bird/day) than the experimental hens (120 g per bird/day; alpha less than 0.05). The levels of production were in all groups associated with the lysine content of the ration. The lysine-deficient birds produced the smallest eggs, layed the smallest number of eggs and consumed the largest quantity of food per 100 g of egg weight. The egg production of the hens in groups 11 and 12 (receiving a fish meal ration during the rearing period and a fish meal or wheat ration + 0.15% L-lysine during the laying period) was 70% of that of the birds in the control groups. The results of the present trial suggest that lysine-supplemented high-protein wheat rations for laying hens could be used but care should be taken that the plane of feeding for the young hens will not be too much restricted.

Animal Feed↗
PubMed1977

Productive performance and liver lesions in two strains of laying hens receiving two rapeseed meals.

A comparative study was conducted to determine the effect of two varieties of rapeseed meal at 10 and 20% levels in the diet on the productive performance, organ weights and liver lesions of two commercial strains of laying hens. The double-low (Brassica napus 1788) rapeseed meal appeared to be superior to Span meal (Brassica campestris) at the 10% level in maintaining egg production, feed efficiency, thyroid weight and body weight gain. However at the 20% level the productive performance was decreased in all the hens except the thyroid weights in the double-low group. Mortality caused by haemorrhagic liver syndrome was significantly higher among birds fed rapeseed meals than in the controls and was higher in the Span-fed groups than in those receiving the double-low variety. The two strains of birds showed no difference in mortality due to haemorrhagic liver syndrome. It was suggested that the lower level of glucosinolates in the double-low variety was responsible for the superiority of this meal over the Span meal.

Animal Feed↗
PubMed1978

Absorption, tissue deposition and passage into eggs of N-nitrosodimethylamine in hens.

The experiments were performed on 262 laying hens divided into 8 groups: 5 groups of hens were given orally N-nitrosodimethylamine (NDMA) in single doses of 30, 10, 3, 1 and 0.1 mg/kg of body weight, two groups received tap water containing 2 and 5 mg NDMA/kg, provided ad libitum for 20 consecutive days, and one group of layers served as a control. Birds were selected at random and sacrificed at one or two day intervals and NDMA content was determined in blood, muscles, liver, brain and in collected eggs. The highest concentrations of NDMA were found 24-36 hours after dosing in all investigated tissues and eggs. A single oral dose of 0.1 mg NDMA/kg produced tissue levels up to 0.06 mg/kg and resulted in excretion of detectable amounts of the carcinogen in eggs for up to 6 days. After large doses, 10 mg and 30 mg NDMA/kg, concentrations in corresponding tissues reached 6.0 and 12.7 mg/kg, and the presence of NDMA in eggs could still be detected after 12 and 14 days. Birds receiving NDMA in drinking water showed increasing NDMA concentrations in all analysed tissue and eggs. After 12 days, the highest levels were found in eggs, blood and brain. Practical implications of the results must be evaluated from the point of view of human safety.

Animals↗
PubMed1978

Autogenous profundaplasty: The key to long-term patency in secondary repair of aortofemoral graft occlusion.

The records of 281 patients undergoing aortic grafting to 522 femoral arteries over a period of 18 years were reviewed. Fifty-four patients suffering graft limb occlusion to 71 femoral arteries requiring subsequent secondary repair were identified for detailed analysis. Occlusive disease of the profunda femoris artery was identified as the primary cause of thrombosis. Repair consisted of profunda femoris angioplasty, and transfemoral retrograde graft thrombectomy was possible in all but three instances which were managed by cross-over femoral-femoral bypass. In no instance was laparotomy and abdominal graft replacement necessary. The 30 day operative survival and graft patency were 100%. Analysis of factors that have influenced late graft patency demonstrated that the key factors were the method of profundaplasty and the association of diabetes mellitus. When autogenous profundaplasty (on-lay arterial patches, saphenous vein, or limited endarterectomy) was employed, the overall patency combining diabetics and non-diabetics was two and one-half times greater than when profundaplasty was performed with an on-lay Dacron((R)) patch. If diabetics were separated from nondiabetics in the autogenous angioplasty group, the 36 month patency for non-diabetics was 85%, and 0% for diabetics. We conclude that autogenous profundaplasty provides considerable advantage from the standpoint of long-term patency and that the diabetic patients are relatively poor candidates for secondary arterial repair of an occluded aortofemoral bypass graft.

Adult↗