Effects of selenium-enriched yeast dietary supplementation on egg quality, gut morphology and caecal microflora of laying hens

Selenium (Se) is an essential micronutrient for humans and animals and is a powerful antioxidant that can promote reproductive and immune functions. The purpose of this study was to evaluate the effects of supplemental dietary selenium-enriched yeast (SeY) on egg quality, gut morphology and microflora in laying hens. In total, 100 HY-Line Brown laying hens (45-week old) were randomly allocated to two groups with 10 replicates and fed either a basal diet (without Se supplementation) or a basal diet containing 0.2 mg/kg Se in the form of SeY for 8 weeks. The Se supplementation did not have a significant effect on egg quality and intestinal morphology of laying hens. Based on the 16S rRNA sequencing, SeY dietary supplementation effectively modulated the cecal microbiota structure. An alpha diversity analysis demonstrated that birds fed 100 mg/kg SeY had a higher cecal bacterial diversity. SeY dietary addition elevated Erysipelotrichia (class), Lachnospiraceae (family), Erysipelotrichaceae (family) and Ruminococcus_torques_group (genus; p < .05). Analysis of microbial community-level phenotypes revealed that SeY supplementation decreased the microorganism abundance of facultatively anaerobic and potentially pathogenic phenotypes. Overall, SeY supplementation cannot significantly improve intestinal morphology; however, it modulated the composition of cecal microbiota toward a healthier gut.

The effects of chelated micro-elements feeding in broiler breeder hens and their progeny: A review

Micro-elements are essential for the optimal feeding of broiler hens. Since the chelated micro-elements negatively affect the content of micro- and macro-minerals, there has been a tendency to apply them as an alternative to common mineral forms of micro-elements in poultry diets. This paper reviews the effects of chelates of micro-elements (iron, copper, zinc, manganese, and selenium) on broiler breeder hens' internal and external egg quality and their egg products. The use of chelated micro-elements compared to the mineral forms does not have a significant effect on the performance of broiler breeder flocks, but they have significantly positive effects on the internal and external egg quality of broiler breeder flocks. The chelated micro-elements were also better than mineral resources of micro-elements in improving fertility (0.59%), hatchability (0.81%), and reducing mortality of progeny (2.25%). Chelated micro-elements have no negative impact on blood biochemistry or the immune system of broiler breeder hens and decrease cholesterol (0.84 mmol/l) and triglycerides (0.04 mmol/l) in most cases in comparison with the other mineral forms. Therefore, chelated forms of micro-elements instead of the inorganic mineral forms in diets of broiler breeder hens provide better protection for birds and the environment and also improve egg quality.

Performance of broiler breeders supplemented with organic and inorganic minerals

The present study aimed to evaluate the use of organic and inorganic minerals in Cobb500 broiler breeder diet and its effects on the performance. The birds were housed in an experimental house at Poultry Laboratory of the Federal University of Santa Maria with 20 floor pens of 4.61m2 each. The experiment was conducted between 51st and 65th weeks of age of birds. The design was completely randomized with four treatments and five pen replicates with 22 hens and 2 roosters each. The treatments evaluated were: PI=100% mineral inorganic premix; PO= 100% mineral organic premix: PI+PO= 70% mineral inorganic premix + 30% mineral organic premix and PI+Zn= 100% mineral inorganic premix, except zinc mineral, that was 70% inorganic form and 30% organic form. The following parameters of performance and egg quality were evaluated: laying rate, body weight, egg, albumen and yolk weight, yolk color and specific gravity of eggs. These parameters were performed one day per week throughout the experimental period to evaluated egg quality. Under the conditions and time that the experiment was conducted, the use of organic minerals had no significant effect on the performance and egg quality parameters evaluated in the broiler breeders.

The mixed application of organic and inorganic selenium shows better effects on incubation and progeny parameters

This experiment aims to study the effects of dietary selenium (Se) sources on the production performance, reproductive performance, and maternal effect of breeder laying hens. A total of 2,112 Hyline brown breeder laying hens of 42 wk of age were selected and randomly divided into 3 groups, with 8 repeats in each group and 88 chickens per repeat. The sources of dietary Se were sodium selenite (SS, added at 0.3 mg/kg), L-selenomethionine (L-SM, added at 0.2 mg/kg), and combination of SS and L-SM (SS 0.15 mg/kg + L-SM 0.15 mg/kg). The pretest period was 7 d, and the breeding period was 49 d. Compared with 0.3 mg/kg SS, the addition of 0.2 mg/kg L-SM in the diet significantly increased the hatchability (P < 0.05) and the Se content (P < 0.05) in egg yolk and chicken embryo tissues and improved the activity of yolk glutathione peroxidase (GSH-px) effectively (P < 0.05). Treatment with 0.2 mg/kg L-SM also reduced the content of yolk malondialdehyde (P < 0.05) and significantly improved the antioxidant performance of 1-day-old chicks, as manifested by increased activity of antioxidant enzymes (GSH-px, total antioxidant capacity and the ability to inhibit hydroxyl radicals) in serum, pectoral, heart, and liver (P < 0.05). This treatment decreased the malondialdehyde content (P < 0.05) and increased the expression of liver glutathione peroxidase 4 and deiodinase 1 mRNA (P < 0.05). Adding L-SM to the diets of chickens increased the hatchability of breeder eggs as well as the amount of Se deposited and antioxidant enzyme activity in breeder eggs and embryos. Compared with SS, L-SM was more effectively transferred from the mother to the embryo and offspring, showing efficient maternal nutrition. For breeder diets, the combination of organic and inorganic Se (0.15 mg/kg SS + 0.15 mg/kg L-SM) is an effective nutrient supplementation technology program for effectively improving the breeding performance of breeders and the antioxidant performance and health level of offspring chicks.

Assessment of Dietary Selenium and Vitamin E on Laying Performance and Quality Parameters of Fresh and Stored Eggs in Japanese Quails

The effect of dietary supplementation with VE and Se on the laying productive performance, immunity, and the quality parameters of fresh and stored eggs was assessed. For this study, five treatments, namely control (basal diet), control plus 30 mg of VE and 0.4 mg kg-1 sodium selenite (VE30SS), control plus 30 mg of VE and 0.4 mg kg-1 of Sel-Plex® (VE30SP), control plus 120 mg VE and 0.4 mg kg-1 Sodium selenite (VE120SS), and control plus 120 mg VE and 0.4 mg kg-1 Sel-Plex (VE120SP), were examined. There was no huge impact of VE and Se on feed consumption, FCR and egg yield rate. Quality parameters of fresh egg including egg surface area, eggshell thickness, yolk selenium concentration, albumen height, and Haugh unit were significantly increased following VE and Se supplementation (p < 0.05). For stored eggs, VE and Se significantly increased egg yolk color intensity (p < 0.05). Regardless of storage temperature, eggs from birds fed with VE and Se had less weight loss during 30 days of storage. Albumen height was significantly higher in VE and Se fed birds in eggs stored at 5 °C for 15 and 30 days. The combination of Sel-Plex with either levels of VE had significantly higher blood total antioxidant capacity. Dietary VE and Selenium, notably Sel-Plex, improved the antioxidant potential of blood and egg quality of laying quails.

Effect of Selenium Source and Level on Performance, Egg Quality, Egg Selenium Content, and Serum Biochemical Parameters in Laying Hens

The objective of this study was to compare the effect of sodium selenite (SS) and selenium yeast (SY) on performance, egg quality, and selenium concentration in eggs and serum biochemical indices in laying hens. Seven hundred twenty healthy Roman laying hens (21 weeks old, 18 weeks in lay) with a similar laying rate (90.27% ± 1.05%) were randomly divided into 5 groups with 6 replicates of 24 hens each. Five diets were prepared as a 1+2×2 factorial arrangement with control and two sources of Se at two levels. Control diet (control) was prepared without adding exogenous selenium (analyzed basal Se content of 0.178 mg/kg). The other four diets were prepared with the control diet supplemented with SY or SS at 0.3 mg/kg (low; L) or 0.5 mg/kg (high; H) to give 5 diets designated as control, SY-L, SY-H, SS-L, and SS-H. The analyzed selenium content in the SY-L, SY-H, SS-L, and SS-H diets were 0.362, 0.572, 0.323, and 0.533 mg/kg respectively. The pre-trial period lasted 7 d, and the experimental period lasted 56 d (30 weeks old), during which the egg production, egg quality, and hen serum parameters were measured. Results showed that selenium source and level had no effect (P > 0.05) on average daily egg weight and feed conversion ratio (FCR). However, the laying rate was different at the L and H levels of supplementation, regardless of source, such that hens that were supplemented had a higher performance than that of the control, and the H level of supplementation lead to a higher laying rate than that of the L level (P < 0.05). There was a difference in average daily feed intake (ADFI) with an interaction in selenium source and level (P < 0.05), such that SS-L was higher than other selenium supplemented treatment or control. There were no significant differences in egg quality (P > 0.05); at the high level, SY had higher egg yolk selenium compared with SS. However, within SY, adding 0.5 mg/kg selenium led to higher egg yolk selenium than 0.3 mg/kg selenium (P < 0.05). Moreover, adding 0.3 mg/kg SY, 0.3 mg/kg, or 0.5 mg/kg SS to the basal diet had no significant effect on the selenium content in the egg (P > 0.05). There were no significant differences in serum biochemical indices among the five groups (P > 0.05). In conclusion, adding a high level of selenium in the diet of laying hens significantly increased egg production, and addition of a high level of selenium in the form of SY led to a higher deposition of selenium in the yolk than that of SS. These results indicate that adding 0.5 mg/kg of SY in the diet of laying hens would result in Se-enriched eggs.

Interactions Between Different Selenium Compounds and Essential Trace Elements Involved in the Antioxidant System of Laying Hens

The purpose of this study was to investigate the interactions between different selenium (Se) compounds including sodium selenite (SS), selenium-enriched yeast (SY), and nano-selenium (NS) and various essential trace elements involved in the antioxidant systems, and to evaluate the effects on laying performance and egg quality. A total of 288 21-week-old Hyline Sophie hens were allotted to four dietary treatments: (1) basal diet without Se supplementation; (2) basal diet supplemented with 0.3 mg/kg Se of SS; (3) basal diet supplemented with 0.3 mg/kg Se of SY; (4) basal diet supplemented with 0.3 mg/kg Se of NS. Each treatment had eight replicates with nine hens per replicate. The trial lasted for 35 days. Results demonstrated that NS supplementation decreased the egg production (EP) and increased the feed conversion rate (FCR) and eggshell thickness and that SY changed the egg shape index (p < 0.05). Supplementation with three Se compounds significantly increased serum Se concentration and glutathione peroxidase (GSH-Px) activity in all treatment groups, as well as total superoxide dismutase (T-SOD) activity in the SY and NS groups. Yolk iron (Fe) and copper (Cu) concentrations in the NS group were also increased with Se supplementation. While the serum zinc (Zn) concentration decreased in the NS and SY groups, as well as the yolk manganese (Mn) concentration in the SY group. And the total antioxidant capability (T-AOC) of yolk with 3 days of storage in the SY and NS groups, malondialdehyde (MDA) value in the NS group, and the T-SOD activity and MDA value of yolk with 10 days of storage in the SY group also decreased. Thus, the source of Se compounds may influence the balance between Se and other trace elements including Zn, Mn, Fe, and Cu, which is important for proper antioxidant defense in blood and egg yolk of laying hens.

Impact of colibacillosis on production in laying hens associated with interference of the phosphotransfer network and oxidative stress

The objective of this study was to evaluate the productive impact of colibacillosis on laying hens and to investigate whether energetic metabolism and oxidative stress were involved in the pathogenesis of the disease. An experimental shed containing 270 laying hens of the Hy-Line lineage (32 weeks old) presented approximately 40% daily laying, and many birds presented with diarrhea and apathy followed by death. Necropsy revealed macroscopic lesions compatible with colibacillosis and infectious agent Escherichia coli was isolated from fecal samples of all birds in the infected group, as well as from tissue (ovary, liver and peritoneum). Sixteen chickens were selected for this study, divided into two groups: Control (animals without clinical alterations) and infected (with diarrhea and apathetic). E. coli isolates were subjected to the antimicrobial susceptibility testing according to the methodology approved by CLSI, 2018. This testing showed sensitivity to gentamicin, amoxicillin, norfloxacin and colistin. It was then determined that laying hens would be treated with norfloxacin (15 mg/kg) diluted in water offered at will to the birds for three days. Blood collections were performed via brachial vein after the diagnosis of E. coli (before starting treatment) and seven days after treatment. Three debilitated chickens died on the second day after initiating therapy. Before treatment, birds with clinical signs had higher levels of lipoperoxidation (LPO) and activities of antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GPx) than in the control group (asymptomatic animals). After treatment, LPO levels remained higher in birds that had clinical disease (infected group), whereas the activity of SOD and GPx enzymes did not differ between groups. Activity levels of creatine kinase (CK) and pyruvate kinase (PK) were higher in the group of chickens with clinical disease before treatment. Post-treatment, no differences were observed between groups in terms of CK; however, PK activity remained high in these animals. In the hens that died, there were lesions characteristic of avian colibacillosis, with ovary involvement, explaining the low laying activity of the birds at their peak of production. For 10 days after starting treatment, the percentage of laying increased to 90%. Therefore, we conclude that colibacillosis interferes with the phosphotransfer network by stimulating ATP production, in addition to causing oxidative stress of the birds during laying, that negatively affects health and productive efficiency.

Long-Term Supplementation of Laying Hen Diets with Various Selenium Sources as a Method for the Fortification of Eggs with Selenium

The following study focuses on a comparison of the effectiveness of egg content enrichment with selenium (Se) via application of sodium selenite (Na-selenite), selenium-enriched yeast (Se-Yeast), or selenomethionine (Se-Met) in laying hen diets. Two hundred sixteen laying hens were divided into four treatments, each comprising eighteen replications, and each with three hens per cage. Animals were fed a basal diet without Se supplementation (control: selenium content 0.058 mg/kg), with the addition of Na-selenite, Se-Yeast, or Se-Met in amounts equivalent to 0.3 mg/kg of added selenium. The egg quality, the selenium content in eggs after the third and the fifth months of using Se supplementation, and the selenium level in the liver were determined. Enrichment of egg content with selenium was the most effective (382 μg/kg) via application of dietary Se-Met. Application of Na-selenite and Se-Yeast led to a similar effect on Se-accretion in egg content (255.9 and 258.9 μg/kg, respectively). Additionally, the calculated average Se concentration in one fresh egg was also higher in eggs from hens that received selenium additives in their diet and was far higher, almost three times higher for Se-Met addition, than the concentrations in controls. Se-accretion in the liver wet tissue was greater following application of Se-Yeast in the diet than following other treatments. These results indicate that the use of selenomethionine in the laying hen diet is the best method of enriching eggs with this micronutrient. In turn, the eggs obtained in this way can be an excellent source of highly bioavailable selenium in the human diet.

Effect of Selenium from Selenium-Enriched Kale Sprout Versus Other Selenium Sources on Productivity and Selenium Concentrations in Egg and Tissue of Laying Hens

A 6-week trial was conducted to compare the effect of selenium (Se) from hydroponically produced Se-enriched kale sprout (HPSeKS), sodium selenite (SS), and Se-enriched yeast (SeY) in laying hens. A total of 144 40-week-old hens were randomly divided into four groups, according to a completely randomized design. Each group consisted of four replicates with nine hens per replicate. The dietary treatments were T1 (basal diet) and T2, T3, and T4 (basal diets supplemented with 0.30 mg Se/kg from SS, SeY, and HPSeKS, respectively). Results showed that Se supplement did not affect (p > 0.05) productivity and egg quality. Hens fed Se from HPSeKS and SeY exhibited higher (p < 0.05) Se bioavailability than hens fed Se from SS. Whole egg Se concentration of hens fed Se from HPSeKS was similar (p > 0.05) to that of hens fed Se from SeY, but higher (p < 0.05) than that of hens fed Se from SS. However, the breast muscle and heart tissue Se concentrations of hens fed Se from SS, SeY, and HPSeKS were not different (p > 0.05). The results of this trial demonstrated that Se from HPSeKS and SeY was more efficient than Se from SS on Se bioavailability and whole egg Se concentration in laying hens.

Safety Assessment and Comparison of Sodium Selenite and Bioselenium Obtained from Yeast in Mice

Detailed safety assessment of sodium selenite and bioselenium (bio-Se) was conducted and the results were compared and discussed for the purpose of assessing safety of bio-Se for use in food applications. In this work, acute toxicity studies, micronucleus test, and sperm aberration study in mice, 30-day feeding test of mice, were conducted to evaluate the toxicity of bio-Se obtained from yeast with different fermentation time (transformative time: one month, three months, and six months), and the results were compared with that of inorganic Se (sodium selenite). LD₅₀ of sodium selenite was calculated to be 21.17 mg/kg. LD₅₀ of bio-Se obtained from yeast with different fermentation time was calculated to be 740.2 mg/kg, 915.3 mg/kg, and 1179.0 mg/kg, respectively. In the genotoxicity test, bio-Se did not show cytotoxicity and genotoxicity of mice while sodium selenite at all dose groups was significantly different from the negative group. In the 30-day subchronic oral toxicity study, sodium selenite may slow down the growth of the mice and lead to organic damage to some extent. Bio-Se had facilitated effect towards the body weight of the mice and had no significant effect on the shape and function of the important organs of the mice.

Evaluation of the toxicity of selenium from hydroponically produced selenium-enriched kale sprout in laying hens

Hydroponically produced Se-enriched kale sprouts (HPSeKS) are studied for their use as an alternative dietary Se supplement for poultry. The study experimented with different levels and sources of Se to determine toxicity and how the toxicity may affect productive performance, Se concentration in egg and tissues, and physiological responses of laying hens. One-hundred and twenty hens, 59 weeks of age, were divided into 5 groups. Each group consisted of 4 replicates and each replicate had 6 birds according to a 2 × 2 + 1 Augmented Factorial Experiment in a Completely Randomized Design. The experiment was conducted over a 4 week period, and 5 dietary treatments (T) were used: T1 basal diet, T2 and T3 basal diet plus 5 and 10mg Se/kg from sodium selenite (SS), T4 and T5 basal diet plus 5 and 10mg Se/kg from HPSeKS, respectively. The results make clear that Se from HPSeKS, at 5-10mg/kg, did not affect (P>0.05) feed intake and egg production; however, Se bioavailability decreased (P<0.05). Egg, tissue and plasma Se concentrations, and GSH-Px activity in red blood cells increased (P<0.05) compared to those in T1. Final body weight, feed intake, Se bioavailability, concentration of Se in breast muscle and plasma of hens fed Se from SS were lower (P<0.05) than those of hens fed Se from HPSeKS. The findings demonstrate that dietary Se from HPSeKS at 5-10mg/kg is not considered a toxic level for laying hens. The toxicity of Se from HPSeKS was less than the toxicity of Se from SS.

Comparative study of DL-selenomethionine vs sodium selenite and seleno-yeast on antioxidant activity and selenium status in laying hens

The aim of this study was to compare the effect of DL-selenomethionine (SM) with 2 routinely used Se sources, sodium selenite (SS) and seleno-yeast (SY), on relative bioavailability based on antioxidant activity and tissue Se content. Six hundred thirty 131-day-old brown laying hens were randomly assigned to 7 treatments for 168 d (24 wks) with 6 replicates of 15 hens per replicate. The SS and SY animals were supplemented a cornmeal and soybean diet that supplied a total Se 0.3 mg/kg whereas SM was added at 4 different levels to the total Se at 0.1, 0.3, 0.5 and 0.7 mg/kg. All hens fed the Se-supplemented diet showed higher glutathione peroxidase (GSH-Px) activity (P < 0.01), higher superoxide dismutase (SOD) activity (P < 0.05), lower malondialdehyde (MDA) content (P < 0.05) in plasma, and greater Se contents in egg yolks, albumen, leg muscle, breast muscle, liver, and plasma compared with those fed the control diet (P < 0.01). The organic sources (SY and SM) exhibited a greater ability to increase the GSH-Px activity (P < 0.01) and Se content in albumen (P < 0.01), leg, and breast muscles (P = 0.0099 and P = 0.0014, respectively) than the SS that was added at 0.3 mg Se/kg. The higher SM added levels increased the GSH-Px activity until the dose of 0.5mg Se/kg (P < 0.01).The greater Se concentrations in albumen, muscle and liver appeared in the higher SM-added level, as well as above the dose of 0.1 mg Se/kg (P < 0.01). In addition, hens fed the diet with SM accumulated more Se in albumen, leg, and breast muscle than those fed diets with SY (P < 0.05). These results confirmed the higher ability of organic Se sources to increase the antioxidant activity and Se deposition in egg albumen, leg, and breast muscles compared with SS, and demonstrated a significantly better efficiency of SM compared with SY for albumen and muscle Se enrichment.

Comparative study of the effects of organic selenium on hen performance and productivity of broiler breeders

1. A 10-week experiment was conducted with Ross 308 broiler breeder chickens in cages to evaluate the influence of organic and inorganic sources of selenium (Se) supplementation. A total of 600 birds at 29 weeks of age were divided at random into 4 groups and fed on a maize-soya basal diet supplemented with different forms of Se. 2. The first (control) group was given the basal diet without Se supplementation, whereas the second, third and fourth groups were given, respectively, the basal diet with 0.3 mg/kg of inorganic Se in the form of sodium selenite or 0.3 and 0.5 mg/kg of organic Se in the form of Se enriched yeast (Se-yeast). 3. The experiment was carried out for 10 weeks to compare and evaluate the influence of Se supplementation on breeder performance, egg production, hatchability and the quality of eggs. Samples were collected for analysis at weeks 0, 5 and 10 of the experimental period. 4. At the end of the experiment (39 weeks), there was a reduction in mortality in breeders given diets supplemented with 0.5 mg/kg of Se-yeast. Supplementation of feed with 0.5 mg/kg organic Se increased egg production, percentage of settable eggs and hatchability. 5. Selenium supplementation increased egg weight and specific gravity compared to the control diet. However, no significant variation was found in albumen or yolk protein content at the end of week 10. 6. Selenium accumulation and glutathione peroxidase (GSHPx) activity were lower in the egg albumen and yolk of control compared with Se-supplemented treatments. Se accumulation and GSHPx activity were higher in the group given 0.3 mg/kg organic compared to 0.3 mg/kg of inorganic Se. 7. The results favour the use of Se-yeast at the dose of 0.5 mg/kg in broiler breeder diets for better productivity of eggs, settable eggs, hatchability and higher Se accumulation and antioxidant status in eggs.

Effects of high selenium and fat supplementation on growth performance and thyroid hormones concentration of broilers

A total of 400, as hatched, broilers were used to investigate the effect of increase of selenium and energy intake on thyroid hormone metabolism, growth and liver fatty acid profile. There were 5 replicates of 4 dietary treatments namely, TA (0.289mg Se per kg diet and adequate energy content), TB (0.583mg Se per kg diet and adequate energy content), TC (0.267mg Se per kg diet and 9% increase of energy content) and TD (0.576mg Se per kg diet and 9% increase of energy content). Diets were isonitrogenous. Zinc L-selenomethionine complex was used to increase Se content and corn oil was used to increase the energy content. The experiment lasted 42 days. Broiler growth performance was not significantly affected by dietary treatments. Liver glutathione peroxidase (GPx) activity increased (P<0.05) in broilers fed high Se and energy diets compared to other ones. Whole blood GPx activity was higher in Se supplemented groups however, it was reduced by age. Thyroid hormone concentrations were unaffected by dietary treatments. A significant increase of linoleic and arachidonic acid concentration (P<0.001) was observed in the liver of broilers fed diets with moderately increased energy content and supplemented with Se compared to those fed diets with moderately increased energy content alone. In conclusion, zinc L-selenomethionine complex and moderate increase of energy content did not affect growth rate or thyroid hormone metabolism but led to increased liver fatty acid content and hepatic GPx activity.

Comparative study of a new organic selenium source v. seleno-yeast and mineral selenium sources on muscle selenium enrichment and selenium digestibility in broiler chickens

Two experiments were conducted on broiler chickens to compare the effect of a new organic Se source, 2-hydroxy-4-methylselenobutanoic acid (HMSeBA; SO), with two practical Se additives, sodium selenite (SS) and Se yeast (SY). The relative bioavailability of the different Se sources was compared on muscle (pectoralis major) total Se, selenomethionine (SeMet) and selenocysteine (SeCys) concentrations and apparent digestibility of total Se (ADSe). In the first experiment, from day (d) 0 to d21, Se sources were tested at different supplied levels and compared with an unsupplemented diet (NC). No significant effects were observed on growth performance during the experimental period. However, the different Se sources and levels improved muscle Se concentration compared with the NC, with a significant source effect in the following order: SS < SY < SO (P<0·05). Seleno-amino acids speciation results for NC, SY and SO at 0·3 mg Se/kg feed indicated that muscle Se was only present as SeMet or SeCys, showing a full conversion of Se by the bird. The second experiment (d0-d24) compared SS, SY or SO at 0·3 mg Se/kg feed. The ADSe measurements carried out between d20 and d23 were 24, 46 and 49% for SS, SY and SO, respectively, with significant differences between the organic and mineral Se sources (P<0·05). These results confirmed the higher bioavailability of organic Se sources compared with the mineral source and demonstrated a significantly better efficiency of HMSeBA compared with SY for muscle Se enrichment.