Effect of selenium and vitamin E content of the maternal diet on the antioxidant system of the yolk and the developing chick

1. The effects of selenium and vitamin E supplementation of the maternal diet on their transfer to the egg yolk and tissues of the newly hatched chick and on the development of the antioxidant system in the chick liver in early postnatal life were investigated. 2. One hundred Cobb broiler breeder hens were divided into 10 equal groups and housed in pens at 25 weeks of age. Each hen received 1 of the treatment diets which included 0.2 or 0.4 mg/kg selenium, 40, 100, 200 mg/kg vitamin E or their combination. After 6 weeks, the hens were artificially inseminated once per week. From week 8, eggs were collected and placed in an incubator. After hatching, chicks from each group were reared (under standard commercial conditions) to 10 d of age. The chicks were fed on a standard starter commercial broiler diet. At the time of hatching, and at 5 and 10 days old, 4 chicks from each group were sacrificed and blood, liver and brain were collected for the subsequent biochemical analyses. 3. The inclusion of organic selenium or vitamin E in the commercial diet significantly increased their concentration in the egg and in the liver of 1-d-old chicks obtained from the eggs enriched with these substances. A positive effect of such dietary supplementation was seen at d 5 and d 10 of postnatal development. 4. There was a positive effect of selenium supplementation of the maternal diet on glutathione concentration in the liver of 1-d-old and 5-d-old chicks. A combination of a dietary selenium supplementation with high vitamin E doses further increased glutathione concentration in the liver. Dietary selenium supplementation significantly increased selenium-dependent glutathione peroxidase (Se-GSH-Px) activity in the liver of the 1-d-old and 5-d-old chicks and decreased liver susceptibility to peroxidation. 6. It is concluded that the nutritional status of the laying hen determines the efficiency of the antioxidant system throughout embryonic and early postnatal development of the offspring.     

Tomato powder in laying hen diets: effects on concentrations of yolk carotenoids and lipid peroxidation

1. The effects of tomato powder supplementation on performance, egg quality, serum and egg yolk carotenoids, vitamins and malondialdehyde (MDA) concentrations in were investigated in laying hens in mid-lay.

2. A total of 90 laying hens, 49 weeks old, were divided into 3 groups consisting of 6 replicate cages, 5 birds per cage. Birds were randomly fed on one of three diets: basal diet and basal diet added with 5 or 10?g tomato powder per kg diet.

3. As tomato powder concentration increased, there were linear increases in feed intake, egg production, egg weight and yolk colour and a linear decrease in feed conversion. Shell weight, shell thickness and Haugh unit remained unchanged in response to dietary treatments.

4. Concentrations of serum and egg yolk lycopene, β-carotene, lutein and vitamin A increased for both diets including tomato powder, whereas MDA decreased linearly with increasing supplemental tomato powder concentration.

5. Tomato powder supplementation increased egg production persistency and increased carotenoids and vitamin A contents in egg yolk, accompanied by reduced yolk lipid peroxidation.     

Relationship between vitamin E content and susceptibility to lipid peroxidation in tissues of the newly hatched chick.

1. The effect of supplementing the diet of the parent hen with vitamin E on the vitamin E content of the yolk and of embryonic and neonatal tissues was evaluated and the effects of elevated tissue concentrations of vitamin E on peroxidation susceptibility was examined. 2. Laying hens (Ross 1 broiler-breeder strain) were maintained on diets containing either 147 (control diet) or 365 (high vitamin E diet) microg vitamin E/g feed. 3. In the day-16 embryo, the concentrations of of vitamin E in the yolk sac membrane, liver, brain and lung were respectively 5.0, 4.3, 1.7 and 5.6 times greater for those derived from the hens on the high vitamin E diet compared with those from the control group. 4. In the day-old chick, the concentrations of vitamin E in the yolk sac membrane, liver, brain and lung were respectively 14.8, 2.8, 3.0 and 5.1 times greater for those derived from hens on the high vitamin E diet compared with those from the control group. 5. Homogenates of tissues from the day-old chick were incubated in the absence and presence of Fe2+ in order to determine the extent of spontaneous and iron-stimulated peroxidation as measured by the generation of thiobarbituric acid reacting substances. For the chicks derived from hens on the control diet, the brain was markedly more susceptible to both spontaneous and iron-stimulated peroxidation than were the other tissues. Tissues from the chicks derived from the hens on the high vitamin E diet exhibited significantly reduced susceptibilities to peroxidation. In particular, the susceptibility of the brain was reduced to the same level as that of the other tissues. 6. It is concluded that the high peroxidative susceptibility of the chick's brain can be normalised by supplementation of the parent hen with vitamin E.     

Comparative evaluation of the effect of two maternal diets on fatty acids, vitamin E and carotenoids in the chick embryo.

1. The fatty acid profile of egg yolk and vitamin E and carotenoid accumulation in the egg yolk and embryonic tissues were investigated in relation to the maternal diet. 2. Two hundred fertile eggs (Ross 308 Broiler Breeder), obtained from hens fed on a maize-based (M-diet) or a wheat-based diet (W-diet), were incubated using standard conditions. 3. The egg yolk and embryo tissues (residual yolk, yolk sac membrane, liver, kidney, lung, muscles, adipose tissue and plasma) were collected on d 18 of incubation and on d 21 (newly-hatched chicks) and analysed for fatty acids, vitamin E and carotenoids. 4. The diets did not differ in terms of fatty acid or alpha-tocopherol concentrations. The concentration of carotenoids in the M-diet was 11.8 mg/kg and in the W-diet was 5.6 mg/kg with lutein and zeaxanthin being major carotenoids. 5. Eggs from the M-group contained higher (P<0.01) concentrations of beta+gamma-tocopherols, total carotenoids, lutein and zeaxanthin. Chickens hatched from those eggs were characterised by the increased concentrations of total carotenoids and zeaxanthin in all the tissues studied. The concentration of beta+gamma-tocopherol was enhanced only in the liver and yolk sac membrane. 6. It is concluded that the maternal diet plays an important role in antioxidant systems formation during chick embryonic development; the M-diet can increase the antioxidant potential of the egg yolk and embryonic tissues compared to the antioxidant potential provided by parent birds fed the W-diet.     

Effect of vitamin A on the antioxidant system of the chick during early postnatal development

1. The effect of increasing vitamin A doses on the concentrations of vitamins A, E, ascorbic acid and carotenoids in the liver and blood plasma of the neonatal chick were investigated. 2. In the 1st experiment 75 d-old chickens were divided into 3 equal groups and in the 2nd experiment 100 d-old chickens were divided into 5 groups. Retinyl acetate in corn oil (1.72; 4.30; 8.60 or 17.2 mg) was intubated directly into the crop daily during the first 5 d after hatch. 3. The intubation of vitamin A increased its accumulation in the liver, with a plateau at about 6,000 microg/g, and was associated with inhibition of vitamin E and carotenoid utilisation from the liver during postnatal development. 4. Moderate amounts of vitamin A intubation increased ascorbic acid concentration in the liver, kidney, brain and plasma. A further increase in vitamin A intubation had an adverse effect on ascorbic acid concentrations in the plasma and brain. 5. The 2 highest inputs of vitamin A decreased glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities in the chicken liver and brain. 6. It is concluded that the effect of vitamin A on development of the antioxidant system in the neonatal chick is dose-dependent and an excess of vitamin A can compromise the antioxidant defence system.     

Influence of high vitamin E dosages on retinol and carotinoid concentration in body tissues and eggs of laying hens.

The aim of the study was to contribute to the discussion of overdosing vitamin E in laying hens. A total of 45 laying hens, divided into 5 groups were fed diets supplemented with either 0; 100; 1000; 10,000 or 20,000 mg dl-alpha-tocopheryl acetate/kg diet over a period of 10 weeks. Concentrations of vitamins A and E were measured in plasma, various tissues and egg yolk. Furthermore egg yolk colour and some carotinoids were measured in egg yolks. None of the vitamin E doses significantly influenced performance of the hens. As expected, vitamin E concentration in plasma, all tissue samples and egg yolk was significantly increased with increasing tocopherol content in the diet. The egg yolk showed the highest vitamin E concentration, followed by liver and muscles. Feeding 1000 mg alpha-tocopheryl acetate per kg diet resulted in an increase of vitamin A concentration in the liver. Very high doses (10,000 and 20,000 mg/kg diet) significantly decreased retinol concentration in the liver and egg yolk, as well as carotinoid concentration in the egg yolk. The lower carotinoid concentration in egg yolk resulted in a decreased intensity of egg yolk colour. A prooxidative and/or competitive effect of very high doses of vitamin E with other fat soluble substances has been discussed.     

Effect of canthaxanthin content of the maternal diet on the antioxidant system of the developing chick

1. Effects of canthaxanthin supplementation of the maternal diet on the antioxidant system of the developing chick were investigated. 2. Three hundred and twenty female broiler breeder birds were housed in one of 4 controlled environment rooms with 3 replicates for all treatments, with the exception of the control treatment of which there were 4 replicates. All birds received one of 5 diets: control low xanthophyll diet, or the same diet supplemented with 3, 6, 12 or 24 mg/kg canthaxanthin in the form of Carophyll Red. At 30 weeks of age 60 eggs from each of the 5 groups were incubated. At d 16 of the embryo development, at d 1 and d 7 posthatch tissue samples were collected and analysed by HPLC-based methods. 3. Canthaxanthin accumulation in the egg yolk was proportional to dietary content. Furthermore, at 12 to 24 mg/kg canthaxanthin was associated with an increase in gamma-tocopherol concentration in the egg yolk. Canthaxanthin was transferred from the egg yolk to the developing embryo and, as a result, its concentration in the liver of the embryo at 16 and in 1-d-old chicks was increased. Even at d 7 posthatch canthaxanthin concentration in the chicken liver was elevated. 4. Canthaxanthin supplementation of the maternal diet at 12 mg/kg was associated with an increased alpha-tocopherol concentration in the liver of 1-d-old chicks and resulted in decreased tissue susceptibility to lipid peroxidation. 5. Canthaxanthin supplementation at 6 to 24 mg/kg was also associated with a delay in alpha-tocopherol depletion from the liver for 7-d posthatch. As a result of the increased canthaxanthin and vitamin E concentrations in the liver of 7-d-old chicks, tissue susceptibility to lipid peroxidation decreased. 6. The results support an idea that dietary carotenoids can modulate antioxidant systems of the developing chicken.     

Dietary selenium increases vitamin E contents of egg yolk and chicken meat

1. The influence of different forms of dietary selenium (Se) on vitamin E (alpha-tocopherol) and Se contents of egg yolk and chicken meat was investigated. 2. Eggs were collected from laying hens subjected to 4 different dietary treatments after 24 weeks of age. Treatments compared the effects of inorganic Se supplementation (selenite) to those of organic (Se-enriched yeast, Se-enriched alga Chlorella) supplements. In a second experiment the effect of the above organic dietary Se supplementation on the alpha-tocopherol contents of meat from broiler chickens was evaluated. 3. Dietary Se supplementation increased the alpha-tocopherol content of egg yolks from 297 mg/kg dry matter in treatment without supplementation to 311 mg/kg when selenium was supplemented as selenite, and to 370-375 mg/kg when organic supplements were used. The Se and alpha-tocopherol contents of breast and thigh meat in broilers were significantly increased by organic dietary Se supplementation. 4. The inclusion of organic dietary Se sources in the diets of laying hens and broilers would enhance the nutritional value (vitamin E and Se contents) of products (eggs and meat) for human consumption.     

Chromatographic analysis of lypophilic compounds in eggs from organically fed hens

Egg yolks represent a common foodstuff in the human diet and are an important source of nutrients including lipids and carotenoids. The aim of this study was to compare the carotenoid, fatty acid and vitamin E contents of the yolk of eggs from nine hen breeds (Barred Plymouth Rock, Speckled Italian, Black Italian, Red Italian, Rhode Island, Silver Laced Wyandotte, Gold Araucana, Partridge Brahma and Yellow Cochin) raised in barns in an enclosed house. Gas chromatography-mass spectrometry (GC-MS) was used for the fatty acid analyses, and reversed phase-high performance liquid chromatography-photodiode array detection (RP-HPLC-PDA) for carotenoids and vitamin E quantification. The major carotenoids identified were lutein and zeaxanthin, which together represented more than 93% of the total carotenoids, followed by β-cryptoxanthin and β-carotene.The results indicated that the total carotenoid content of the eggs ranged from 16.84–87.31 μg/g egg yolk (average value 49 μg/g egg yolk). The most representative fatty acids found were palmitic acid, stearic acid, oleic acid and linoleic acid. Significant differences in the proportions of α-linolenic acid were observed among the samples. The α-tocopherol content was directly correlated with the total carotenoid content. The results show that the chemical composition of egg yolk varies greatly among hen breeds.     

Effect of dietary Rhodobacter capsulatus on lipid fractions and egg-yolk fatty acid composition in laying hens

The present study was conducted to investigate the effect of dietary Rhodobacter capsulatus on lipid fractions and egg‐yolk fatty acid composition in laying hens. Thirty‐six laying hens (30 weeks old) were randomly assigned into two dietary groups fed diets with (0.04%) or without (control) R. capsulatus for a 60‐day feeding trial. Dietary R. capsulatus decreased (p < 0.05) serum and hepatic cholesterol and increased (p < 0.05) the excreta cholesterol, and resultant lower (p < 0.05) cholesterol contents in egg yolk. The concentration of polyunsaturated fatty acids (PUFA) and ratio to saturated fatty acids in egg yolk was improved (p < 0.05) by dietary R. capsulatus. The concentration of hepatic bile acid was increased (p < 0.05) and excreta bile acid was decreased (p < 0.01) in the laying hens fed R. capsulatus diet. The incorporation of 1‐¹⁴C‐palmitic acid into hepatic lipids and lipid fractions was increased (p < 0.05) in laying hens fed R. capsulatus diet. Moreover, dietary R. capsulatus did not appear to cause any adverse effects on laying hen performances. Therefore, dietary supplementation of R. capsulatus in layer diets may be a feasible means of producing eggs with lower cholesterol and higher PUFA contents for health conscious consumers.     

Vitamin E requirements of laying hens

In 5 experiments with 1,296 laying hybrids at the age of 22-73 weeks producing eggs for consumption a varied supplementation of between 0 and 20 mg vitamin E per kg of a semisynthetic ration was tested. The vitamin E content of the basal ration was less than 1 mg per kg feed. The quotas of selenium and unsaturated fatty acids in the feed were taken into consideration. Vitamin E and Se supplements did not influence, feed intake, laying, performance, feed efficiency/100 g egg development of body weight and mortality. The supplementation of 14% vitamin-E-free sunflower oil caused a significant decrease of the laying performance by 15%. There was no relation between the humoral immune reaction and vitamin E supply. The peroxide value of the abdominal fat and the activities of the creatine phosphokinase, the aspartate and alanine amino transferase in the blood serum were not directionally changed by the vitamin E, Se and oil supplements. There were no significant relations between the vitamin E content of the feed and that of the yolk and the yolk sac of the chicken. A vitamin E requirement of less than 1 mg and a requirement norm, including a safety margin, of 5 mg per kg feed was derived from the results for laying hens for egg production. A supplement of synthetic vitamin E to laying hen feed is thus not necessary.     

Relation between vitamin E supply and the fertility of laying hens

In 4 experiments with a total of 1296 laying hens it was ascertained that a laying hen requires 1 mg vitamin E/kg feed for egg production if the ration contains sufficient selenium and is not rich in multiply unsaturated fatty acids. For the fertilization of the eggs little more of this vitamin is required. There were close relations, however, between the amount of vitamin E supplement to the feed and the number of hatched chickens in % of the fertilized eggs. With the help of the experiments carried out so far the exact requirement could not yet be ascertained. Based on the results of our experiments we recommend 20 mg vitamin E/kg feed for breeding hens of the laying variant. There is a close relation between the vitamin E content of the feed and that of the yolk. A supplement of 7 or 14% resp. of vitamin-free sunflower oil decreases -in dependence on the vitamin E supplement-hatching in particular without diminishing the vitamin E content of the yolk. The vitamin E content of the yolk sac, however, was drastically reduced. The influence of polyene fatty acids in hatching is smaller when sunflower oil rich in vitamin E is supplemented. Vitamin-free sunflower oil has an influence on the vitamin content of the yolk, but it diminishes drastically the vitamin content of the yolk sac and, provided that vitamin E supply is low, prevents hatching.     

维生素E对蛋鸡产蛋后期产蛋性能和蛋品质的影响

文章旨在研究日粮中不同梯度维生素E添加水平对蛋鸡产蛋后期产蛋性能和蛋品质的影响.试验选择60周龄罗曼白壳商品蛋鸡300羽,试验随机分为5组,添加水平分别为0(对照组),30、60、120、240 mg/kg,每组6个重复,每个重复10羽鸡,预试期1周,正试期8周.结果表明:与对照组相比,蛋鸡产蛋后期日粮中添加120 m...     

Effects of breeder hen age and dietary L-carnitine on progeny embryogenesis

1. Ross 308 broiler breeder hens were given diets containing 0 or 25 mg L-carnitine/kg (8 replications per treatment) from 21 weeks of age. 2. Hens were inseminated with semen from Ross broiler breeder males. In a common facility, subsequent progeny hatchability and embryonic mortality at 25, 30, 32, and 38 weeks of breeder age were evaluated. 3. Subsequent egg component weights, incubational egg water loss, progeny embryo growth, and embryo, yolk sac and liver composition through 18 d of incubation at 27, 32, and 38 weeks of breeder age were evaluated. 4. Calculated additions of L-carnitine were in agreement with analysed contents of 3.5 and 31.1 mg free L-carnitine/kg of diet, respectively, and total L-carnitine concentrations increased by 48.6, 21.7, and 10.0% in 0-d yolk, 18-d yolk sac, and 18-d liver samples, respectively, due to the addition of dietary L-carnitine. 5. Supplemental L-carnitine resulted in increased (0.6%) relative 0-d egg yolk weight across weeks 27, 32, and 38, and reduced (0.38%) 18-d yolk sac palmitoleic acid concentration at week 27 without altering embryogenesis. 6. In conclusion, dietary L-carnitine (25 mg/kg of the diet) was deposited in the yolks of broiler breeder hens and was subsequently transferred to the embryonic liver via yolk sac absorption through 18 d of incubation. Furthermore, dietary L-carnitine supplementation increased ovarian follicle yolk deposition in 27-, 32-, and 38-week-old breeder hens, and influenced yolk sac fatty acid beta-oxidation in embryos from 27-week-old breeder hens causing yolk sac palmitoleic acid concentrations to be reduced by 18 d of incubation.     

Effects of saturated and unsaturated fats with vitamin E supplementation on the antioxidant status of broiler chicken tissues

The influence of fish oil (highly unsaturated) and beef tallow (highly saturated) with vitamin E (100 IU/kg) supplementation on the antioxidant status of broiler chicken cockerels was investigated. Chicks were fed a control diet with no added fat, 40 g/kg each of fish oil and beef tallow diets, respectively, from 11 to 42 days of age. Tocopherol concentration and the rate of lipid peroxidation, thiobarbituric acid reactive substance (TBARS) in liver, fatty acid composition of the liver lipids, blood serum total antioxidant status (TAS), and reduced glutathione (GSH) content were determined. Vitamin E supplementation of the diet increased liver alpha-tocopherol content in chicks regardless of the type of dietary fat. Fish oil diet resulted in higher liver TBARS value while beef tallow diet showed lower values compared to the control diet. Vitamin E supplementation reduced liver TBARS as well as serum GSH, and raised serum TAS for all diets. Serum GSH was the same for vitamin E supplemented diets regardless of the fat supplement. Fish oil diets resulted in a significant increase in hepatic lipid n-3 PUFA content. A significant positive correlation was found between liver TBARS and n-3 PUFA content. No relationships were established, however, between liver TBARS and n-6 PUFA or saturated fatty acids. The results suggest that feeding oils rich in n-3 PUFA increases tissue concentration of these fatty acids, consequently increasing tissue lipid peroxidation and reducing the antioxidative status of broiler chickens. Supplementing high levels of vitamin E with such oils may increase tissue oxidative stability. Serum TAS or GSH may be used as a measure of antioxidative status in chickens.     

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.     

Comparative Pigmentation Efficiency of High Dietary Levels of Apo-Ester and Marigold Extract on Quality Traits of Whole Liquid Egg of Two Strains of Laying Hens

This trial was carried out to compare the effect of the dietary supplementation of high doses of either synthetic pigment ethyl ester of β-apo-8′-carotenoic acid (apo-ester) or natural pigments, mainly lutein and zeaxanthin, extracted from Tagetes erecta, on egg quality of hens laying brown shell eggs (ISA Brown) and white shell eggs (Hy-Line White W-36). The hens of each strain were divided into 6 groups and fed a corn-soybean basal diet supplemented either with 40, 60, and 80 ppm of apo-ester (APO) or with 120, 180, and 240 ppm of marigold extract (MAR). Egg pigmentation rose linearly and significantly (P < 0.01) as the dietary levels of apo-ester increased, but this did not occur when MAR supplementation was used. The amount of β-carotene equivalents in whole liquid egg of MAR treatments was almost constant with varying pigment dietary dose and was significantly lower (P < 0.01) than in APO treatments. In both hen strains, whole liquid egg redness (a*) and yellowness (b*) were higher with APO supplementation. The egg component weights were highly affected (P < 0.01) by the hen strain, with yolk:egg ratio higher in the Hy-Line. The trial confirms that in spite of the higher level of MAR supplementation, APO has a better efficiency in whole liquid egg pigmentation. The ISA Brown hens showed a better ability to absorb dietary carotenoids than did the Hy-Line White.     

Effect of dietary karaya saponin on serum and egg yolk cholesterol in laying hens

1. The objective of the study was to investigate the effect of dietary karaya saponin on cholesterol deposition in laying hens. 2. A total of 40 Boris Brown hens were randomly assigned at 20 weeks of age to 4 treatment groups and fed on diets supplemented with 0 (control), 25, 50 or 75 mg/kg karaya saponin for an 8-week experimental period. 3. After 8 weeks of dietary supplementation, karaya-saponin-treated groups had significantly lower serum cholesterol (23·0%) and triglycerides but increased high density lipoproteins cholesterol concentration than controls, irrespective of karaya saponin content in the diet. Egg yolk cholesterol and triglycerides were also significantly reduced by dietary karaya saponin. Hepatic cholesterol and triglycerides were significantly reduced by karaya saponin but bile acids concentration in the faeces and liver were significantly increased by karaya saponin. The concentrations of oleic, linoleic and linolenic acids in the yolk were greater in hens receiving karaya saponin than in controls. Karaya saponin significantly increased egg production, feed efficiency and yolk colour compared with controls. Karaya saponin tended to increase egg weight, feed consumption, Haugh units, albumen weight and yolk index. 4. In conclusion, karaya saponin is a potential agent for reducing yolk cholesterol concentration together with an overall increase of production performance and improvement in egg quality.     

Effects of continuous supplementations of ascorbic acid, aspirin, vitamin E and selenium on some haematological parameters and serum superoxide dismutase level in broiler chickens

1. This study was conducted using male broiler chickens to determine the effects of ascorbic acid, aspirin, ascorbic acid+aspirin, vitamin E+selenium and ascorbic acid+aspirin+vitamin E+selenium supplementations on haematological parameters and serum superoxide dismutase concentration. 2. One hundred and twenty day-old male Hubbunt broiler chicks were randomly divided into 6 experimental groups of 20 chicks each and placed in different pens. Groups 2, 3, 4, 5 and 6 were given a diet supplemented with ascorbic acid, aspirin (in water), ascorbic acid+aspirin, vitamin E+selenium and ascorbic acid+aspirin+vitamin E+selenium, respectively for 45 d while group 1 was given a commercial broiler diet. 3. There was no significant effect of ascorbic acid, aspirin, ascorbic acid+aspirin, vitamin E+selenium supplementations on any of the haematological parameters (red blood cell, haemoglobin, haematocrit, mean corpuscular volume, mean corpuscular haemoglobin concentration, mean corpuscular haemoglobin) in broilers but ascorbic acid+aspirin+vitamin E+selenium supplementation significantly decreased the white blood cell counts. 4. In addition to this, ascorbic acid, aspirin, ascorbic acid+aspirin and ascorbic acid+aspirin+vitamin E+selenium supplementations had no significant effect on the serum superoxide dismutase level, but vitamin E+selenium supplementation increased the serum superoxide dismutase level.     

The vitamin A supply of laying hens including during rearing. 2. Effect of varied vitamin A supplementation of mixed feed in rearing on production in the laying period

In six experiments with laying hybrids the influence of a varied nutritive beta-carotene and vitamin A supply during rearing on the performance in the laying period was tested. Basal rations poor in carotene without vitamin A supplementation in the rearing period diminished feed intake and laying performance in the laying period, retarded the beginning of intensive laying and increased feed expenditure per 100 g egg if the feed for laying hens contained less than 5000 IU vitamin A per kg. Relations between varied vitamin A supply and the performance parameters of the laying performance could not be proved if chick and young hen feed with maize even without vitamin A supplement or if rearing feed with approximately 2500 IU vitamin A or laying hen feed greater than 5000 IU vitamin A supply were used.