Effect of thyroid hormone on concentrations of plasma calcitonin in broiler chicks

The purpose of these studies was to determine the effect of thyroidectomy (Tx), and thyroid hormone (T₃/T₄) treatment on concentrations of plasma CT in chicks. In addition, the turnover of CT in Tx- and T₃/T₄-treated chicks was estimated using a novel nonradioactive salmon CT preparation. One-week-old broiler chicks (Gallus domesticus) (n=75) were divided into three groups. Group I was sham-injected daily (i.m. saline), Group II was injected with 50 μg/day of T₃/T₄ while Group III was injected with the goitrogen, methimazole, (150 mg/kg BW per day) for 8 weeks. Chicks (8–9 weeks old) were implanted with catheters in the brachial wing vein and administered ruthenium-labeled salmon CT. Blood samples were collected at 30 s, 1, 2, 4, 8, 20 min, and 3 h after injection. Results showed that concentrations of plasma CT were decreased in T₃/T₄-injected birds. There was no significant effect of methimazole on circulating concentrations of plasma CT. The half-life of CT was significantly increased (P<0.05) in both T₃/T₄-injected (n=6; 1.34±0.16 min) and goitrogen-treated birds (n=2; 5.81±2.83 min) compared to controls (n=7; 54±3 s) The results demonstrate that changes in concentrations of plasma thyroid hormones can significantly affect concentrations of plasma CT.     

Effect of protamine zinc insulin on feed intake and weight gain in broiler chicks.

Ten-day old Robro broiler chicks were used to test the effect of daily subcutaneous injections of two insulin levels (5- and 10-IU . kg-1 BW) administered for two different periods (5 and 21 days). Birds which received either 5- or 19-IU insulin significantly increased their feed intake over those of the controls (P less than 0.05). However, the lower insulin dose was found to be more effective in increasing both the feed consumption and weight gain of the birds, especially if administered for a long period. Between the injection periods, the high insulin dose seemed to have a greater carry-over effect. On the other hand, the administration of 5- or 10-IU insulin for either 5 or 21 days had no effect on efficiency.     

Effects of energy and/or protein restriction on hepatic microsomal mixed function oxidase in male broiler chicks

1. Effect of energy and/or protein intake on a mixed function oxidase system (MFO) in hepatic microsomes was studied in male broiler chicks. 2. Contents of cytochrome P-450 and b5 in 72 hr starvation were larger than those in 12 and 36 hr starvations. 3. Reduction of energy and protein intake did not change the MFO, except cytochrome P-450. 4. Reduction of energy intake under the same protein intake increased the cytochrome P-450 content and aminopyrine N-demethylase activity. An increase in protein intake under the same energy intake also increased the cytochrome P-450 content.     

Effect of feed restriction on Hershberger and pubertal male assay endpoints

BACKGROUND: The Hershberger and male pubertal onset assays have been identified as possible Tier I screening tests to detect endocrine‐active compounds (EACs). Both tests rely on changes in reproductive and/or accessory sex gland (ASG) weights in young animals. Because chemical treatment may affect growth rate, the relationship between body weight and reproductive/ASG weights was examined using feed restriction (FR) to produce a targeted 10% decrease in body weight. METHODS: In the male pubertal onset assay, 23‐day‐old rats (12/group) were given ad lib feed or FR until euthanized at 45, 49, 52, 56, or 59 days of age. Despite a 10% body weight differential, pubertal onset was not significantly delayed and testes weights were conserved. Absolute prostate, ventral prostate, seminal vesicle, epididymides, and liver weights were decreased by FR. Relative weights for the prostate, ventral prostate, and seminal vesicles were similar to controls, but relative epididymides and liver weights still exhibited FR‐mediated changes. In the Hershberger assay, male rats (12/group) castrated at 36 days of age were given ad lib feed or FR in the presence or absence of testosterone propionate (T) from 46–55, 50–59, or 56–65 days of age. At 56, 60, and 66 days of age, rats were euthanized. In untreated animals, FR did not alter absolute ventral prostate, seminal vesicles, or Cowper's gland weights; however, absolute and relative weights of the levator ani‐bulbocavernosus muscles (LABC) were affected. In T‐treated animals, absolute organ weights (the ventral prostate, seminal vesicles, LABC, and glans penis) were relatively insensitive to FR. The weight of the Cowper's gland was affected only at 66 days of age. RESULTS: These data show that reproductive and ASG organ weight endpoints in the Hershberger and male pubertal onset assays can be influenced by FR levels that produce a 10% change in terminal body weight. CONCLUSIONS: The establishment of objective criteria for a positive or negative result is problematic due to the confounding effects of body weight on some endpoints. Furthermore, a 10% decrease in body weight seems to be excessive as a requirement for high‐dose toxicity in these assays due to possible indictment of agents that are not EACs, as well as potential masking of EAC effects coincident with body weight changes. Minimally, caution must be used in interpreting assay results in the presence of a 10% body weight change, recognizing the possible confounding effects of this degree of growth suppression. Birth Defects Res B 68:363–374, 2003. © 2003 Wiley‐Liss, Inc.     

Influence of early qualitative feed restriction and environmental temperature on long bone development of broiler chickens

This investigation was carried out to study the influence of early qualitative feed restriction and environmental rearing temperature on long bone development in broiler. Energy and protein restriction reduced femur width and humerus weight, but did not affect tibia parameters. Broilers kept at cold environmental temperature showed reduced femur, tibia and humerus length and tibia weight, but the calculated density was not affected by rearing temperature. These findings suggest that qualitative feed restriction and environmental temperature influenced the normal long bone growth; however, bone weight/bone length index (calculated density) was not affected by rearing temperature.     

Effect of early feed restriction on physiological responses,performance and ascites incidence in broiler chickens raised in normal or cold environment

Intensive selection of broilers for faster growth and better feed efficiency resulted in greater susceptibility to metabolic disorders such as ascites syndrome, which is one of the major causes of mortality and economic loss in broiler industry. Whereas cool temperature is one of the primary triggers for ascites, early feed restriction (FDR) significantly alleviates its incidence and mortality. However, little is known about effects of FDR, cold environmental temperature and their interaction on physiological responses in broiler chickens. For this purpose, 320 one-day-old male broilers were divided into two treatment groups of Ad libitum (Ad) and feed restricted (FR) with eight pen replicates each. Chickens in FR group underwent feed access limitation from days 7 to 14 of age. On day 21 half of the birds (four pens) in each group exposed to the cold temperature (CT) and the other half (four pens) continued at normal temperature (NT). Average daily feed intake, average daily weight gain and feed conversion ratio (FCR) were measured at days 7, 14, 21, 28 and 42. At 39 and 46 days of age two chicks with a BW around the pen average were selected from each pen and slaughtered after collecting blood samples. Then, relative weight of internal organs and right ventricle weight per total ventricle weight (RV : TV) ratio were calculated. Compared with NT group, CT birds had higher daily feed intake and FCR (P<0.05) from day 28 to 42. Cumulative ascites mortality in CT chickens was higher (P<0.001) than NT chicks. Within the CT group, ascites mortality in FR chickens was reduced (P<0.001) to 1.25% compared with 8.75% in Ad chicks. Birds in CT group had significantly (P<0.05) thicker right ventricle and greater relative weight of heart, hematocrit and triiodothyronine concentration. However, none of these parameters were affected by FDR. Under cold stress conditions, FDR reduced activity of alanine aminotransferase and aspartate aminotransferase (P<0.05). Serum triglyceride, cholesterol, high-density lipoprotein and total protein were not influenced by either temperature or feeding regimen. In conclusion, these findings suggest that FDR reduces ascites incidence mainly by allowing better development of internal organs, which helps them to cope with the high metabolic pressure and suffer less damage.     

Early changes in plasma hormones and metabolites during fasting in king penguin chicks

Summary Chicks of the king penguin (Aptenodytes patagonica) can tolerate a fast of 4–6 months during the subantarctic winter. The aim of this work was to study their initial response to food deprivation. Nine chicks were starved for 18 days. Two phases of starvation were defined according to changes in the specific daily loss in body mass: it decreased by 92% in phase I (6.6±0.3 days) and remained steady and low in phase II. Phase I was marked by a large decline in protein utilization, indicated by decreases in plasma levels of alanine (58%), uric acid (89%) and urea (76%) together with a decrease in circulating corticosterone (60%) and thyroxine (75%). In phase I, plasma insulin concentration decreased (61%) in some birds, but did not change in others; plasma pancreatic glucagon was stable whereas gut-glucagon decreased by 75%. Free fatty acids and -hydroxybutyrate concentrations gradually rode during the fast to 5 to 6 times pre-fast levels. Glycemia remained unchanged. Phase II was characterized by no change in plasma concentrations of protein-derived metabolites and by no or little change in circulating hormone levels. From comparison with previous data, we conclude that there are similar early adjustments to food deprivation in king penguin chick, rat and man: (1) a decrease in resting metabolic rate, (2) a decrease in protein utilization, and (3) mobilization of fat stores. The key, adaptations to long-term fasting in these species are therefore effectiveness in protein sparing and ability to prolong this situation.Abbreviations GLI glucagon-like immunoreactivity - PG pancreatic glucagon - -OHB -hydroxybutyrate - FFA free fatty acids - T ₃ triiodothyronine - T ₄ thyroxine     

Effect of hatching time on time to first feed intake,organ development,enzymatic activity and growth in broiler chicks hatched on-farm

The conventional commercial hatcheries used today do not allow the newly hatched chicks to consume feed or water. Combined with natural variation in hatching time, this can lead to early hatched chicks being feed-deprived for up to 72 h before being unloaded at the rearing site. This study investigated the effects of hatching time on time to first feed intake and development of organs, digestive enzymes and productivity in terms of growth and feed conversion ratio in chicks hatched on-farm. Chicks were divided into three hatching groups (early, mid-term and late), and assessed over a full production cycle of 34 days. The results revealed that chicks remain inactive for a considerable amount of time before engaging in eating-related activities. Eating activity of 5% (i.e. when 5% of birds in each hatching group were eating or standing close to the feeder) was recorded at an average biological age (BA) of 25.4 h and a proportion of 50% birds with full crop was reached at an average BA of 30.6 h. Considering that the hatching window was 35 h in this study, the average chick probably did not benefit from access to feed and water immediately post-hatch in this case. At hatch, mid-term hatchlings had a heavier small intestine (30.1 g/kg bw) than both early (26.4 g/kg bw) and late (26.0 g/kg bw) hatchlings. Relative length of the small intestine was shorter in late hatchlings (735 cm/kg bw) than in mid-term (849 cm/kg bw) and early (831 cm/kg bw) hatchlings. However, the relative weight of the bursa fabricii was greater in mid-term (1.30 g/kg bw) than in early hatchlings (1.01 g/kg bw). At hatch, late hatchlings were heavier than early and mid-term hatchlings (P < 0.05), but by 3 days of age early hatchlings were heavier than mid-term and late hatchlings (P < 0.01). The only effect persisting throughout the study was a difference in the relative weight of the small intestine, where late hatchlings had heavier intestines than early hatchlings (P < 0.05). Thus, while there were differences between hatching groups, this study showed that the hatchlings seemed capable of compensating for these as they grew.     

Effect of chronic heat stress on gastrointestinal histology and expression of feed intake-regulatory hormones in broiler chickens

Heat stress (HS) dramatically impairs the growth performance of broiler chickens, mainly as a consequence of reduced feed intake due to the loss of appetite. This study was aimed at evaluating the alterations induced by chronic HS conditions on the morphological and morphometric features of the gastrointestinal (GI) tract and on the expression of some enteroendocrine cells (EECs) involved in the regulation of feed intake in chickens. Three hundred male chickens (Ross 308) were divided into two experimental groups and raised either in thermoneutral environment for the whole fattening period (0–41 days) (TNT group) or subjected to chronic HS conditions (30 °C for 24 h/day) from 35 to 41 days (HS group). Samples of proventriculus, duodenum, jejunum and cecum were collected from 24 broilers (12/group). Haematoxylin-eosin was used for the morphometric evaluations, while immunohistochemistry was applied for the evaluation of EECs expressing ghrelin (GHR), cholecystokinin (CCK), neuropeptide Y (NPY), glucagon-like peptide-1 (GLP-1), and serotonin (5-HT). In the proventriculus, HS reduced total wall thickness and mucous layer height (P ≤ 0.01) as well as mean diameter, circumference, and area of the compound tubular glands (P ≤ 0.001) with respect to TNT. The small intestine of HS birds was characterised by decreased villous height and total thickness (duodenum, P ≤ 0.01; jejunum, P ≤ 0.001), whereas crypt depth and width were reduced only in the jejunum (P ≤ 0.01). HS had negligible effects on the morphological aspects of the cecum. In the proventriculus, an increase in GHR and NPY EECs was observed in response to HS (P ≤ 0.001). Similarly, the small intestine villi of the HS group showed greater GLP-1 (P ≤ 0.05), 5-HT (P ≤ 0.001) and CCK (P ≤ 0.01) EECs. Moreover, the expression of 5-HT EECs was higher in the duodenal (P ≤ 0.01) and jejunal (P ≤ 0.01) crypts of HS birds, whereas GLP-1 and CCK EECs increased only in jejunal crypts (P ≤ 0.05). Finally, 5-HT EEC expression was increased in the cecum of HS group (P ≤ 0.01). In conclusion, these outcomes demonstrate that chronic HS induces morphometric alterations not only in the small intestine but also in a key organ such as the proventriculus. Furthermore, HS conditions affect the presence and distribution of EECs, suggesting that some GI peptides and biogenic amine may be implicated in the regulation of appetite and voluntary feed intake in heat-stressed broiler chickens.     

早期和后期限饲对肉鸡腓肠肌肌纤维类型和生长轴相关基因表达的影响

1日龄三黄雏鸡随机分为自由采食对照组(C)、1-14日龄隔日饲喂的早期限饲组(ER)和50-63日龄隔日饲喂的后期限饲组(LR)。63日龄采腓肠肌外侧头,ATPase染色法及相对定量RT-PCR法检测不同类型肌纤维含量及生长轴相关基因(GHR、IGF-I、IGF-IR)表达。结果表明:E组慢肌纤维含量降低,快肌纤维含量增加,L组无变化。E组慢肌肌球蛋白重链基因表达低于对照组(P<0·05),并伴随生长激素受体(GHR)和胰岛素样生长因子Ⅰ(IGF-ⅠR)mRNA表达的上调(P<0·05),L组无显著变化。提示:早期限饲可对肉鸡生长和肌纤维类型产生长期而且显著的影响,并且涉及肌肉中生长相关基因表达的改变,而后期限饲对肉鸡影响较小,说明早期和后期限饲通过截然不同的机制影响肉鸡肌肉生长。     

Dietary selenium status and plasma thyroid hormones in chicks

Experiments were conducted to study the effect of marginal levels of selenium and vitamin E on plasma thyroid hormones of meattype chicks. Plasma thyroxine (T₄) was significantly increased when a semipurified diet was supplemented with either selenium or vitamin E. Triiodothyronine (T₃) was also significantly increased by vitamin E and in one experiment with selenium supplementation. No significant increase in these hormones was observed in birds fed a corn-soybean-meal diet supplemented with these nutrients. Plasma corticosterone level was reduced and weight of the bursa of Fabricius increased by selenium or vitamin E supplementation. These nutrients may be necessary for providing the optimum thyroid conditions for activity of thyroid peroxidase.     

Effect of Escherichia coli infection on growth and protein metabolism in broiler chicks (Gallus domesticus)

1. A controlled experimental Escherichia coli infection was developed in broiler chicks. 2. Infection with E. coli significantly reduced feed intake, altered growth of the whole body, eviscerated carcass, skeletal muscles, heart and liver. Organ weight and/or the proportions of organs within the body were affected. 3. Protein accumulation in the eviscerated carcass, extensor digitorum communis and sartorius muscles was severely inhibited by infection, and to a greater extent than body weight. 4. Failure of muscle tissue to accumulate protein was associated with a significant decline in protein synthesis, when measured in vitro (-48%; P less than 0.05) and in vivo (-42%; P less than 0.001). Protein degradation also declined (-28.7%), but to a smaller extent than protein synthesis. 5. Although the infected chicks showed no viable bacteria at day 12 after infection, chicks did not reach the same body weight as controls by day 30 after infection.     

Dexamethasone facilitates lipid accumulation and mild feed restriction improves fatty acids oxidation in skeletal muscle of broiler chicks (Gallus gallus domesticus)

Effects of dexamethasone (DEX) and mild feed restriction on the uptake and utilization of fatty acids in skeletal muscle of broiler chicks (Gallus gallus domesticus) were investigated. Male Arbor Acres chicks (7-days old, n = 30) were injected with DEX or saline for 3 days, and a feed restriction group was included. DEX enhanced circulating very low density lipoprotein (VLDL) level and the lipid accumulation in both adipose and skeletal muscle tissues. Compared with the control, liver-carnitine palmitoyltransferase 1 (L-CPT1) and AMP-activated protein kinase (AMPK) α2 mRNA level of M. biceps femoris (BF) were down-regulated significantly by DEX, while mRNA expression of lipoprotein lipase (LPL), fatty acid transport protein 1 (FATP1), heart-fatty acid binding protein (H-FABP), long-chain acyl-CoA dehydrogenase (LCAD), activities of LPL and AMPK in both skeletal muscles were not obviously affected. Feed restriction increased the mRNA expression of LPL, L-CPT1 and LCAD of M. pectoralis major (PM), and FATP1, H-FABP, L-CPT1 and LCAD of BF. In conclusion, DEX retards the growth of body mass but facilitates lipid accumulation in both adipose and skeletal muscle tissues. In contrast to the favorable effect of mild feed restriction, DEX did not alter the uptake of fatty acids in the skeletal muscle. The result suggests that DEX may promote intramyocellular lipid accumulation by suppressed fatty acid oxidation while mild feed restriction improved fatty acid oxidation in skeletal muscle, especially in red muscle. Glucocorticoids (GCs) regulated muscle fatty acid metabolism in a different way from energy deficit caused by mild feed restriction.     

Effect of protein or energy restriction during late gestation on hormonal and metabolic status in pregnant goats and postnatal male offspring

The objective of this study was to investigate the effects of maternal protein or energy restriction on hormonal and metabolic status of pregnant goats during late gestation and their postnatal male kids. Forty-five pregnant goats were fed a control (CON), 40% protein-restricted (PR) or 40% energy-restricted (ER) diet from 90 days of gestation until parturition. Plasma of mothers (90, 125 and 145 days of gestation) and kids (6 weeks of age) were sampled to determine metabolites and hormones. Glucose concentration for pregnant goats subjected to PR or ER was less (P<0.001) than that of CON goats at 125 and 145 days of gestation. However, plasma nonesterified fatty acids concentration was greater (P<0.01) at 125 and 145 days for PR and ER than CON. Protein restriction increased (P<0.01) maternal cortisol concentration by 145 days of gestation, and ER decreased (P<0.01) maternal insulin concentration at 125 days of gestation. Moreover, maternal amino acid (AA) concentrations were affected by nutritional restriction, with greater (P<0.05) total AA (TAA) and nonessential AA (NEAA) for PR goats but less (P<0.05) TAA and NEAA for ER goats at 125 days of gestation. After 6 weeks of nutritional recovery, plasma concentrations of most metabolic and hormonal parameters in restricted kids were similar to CON kids, except for reduced (P<0.05) insulin concentration in ER, and reduced (P<0.05) Asp concentration in PR and ER kids. These results provide information on potential metabolic mechanisms responsible for fetal programming.     

Therapeutic supplementation of caprylic acid in feed reduces Campylobacter jejuni colonization in broiler chicks

Poultry colonized with Campylobacter species are a significant source of human food-borne illness. The therapeutic use of the medium chain fatty acid caprylic acid consistently reduced enteric C. jejuni colonization in chicks by 3 to 4 logs in three separate trials. These results support caprylic acid's potential to reduce Campylobacter carriage in poultry.     

Effects of dietary grape proanthocyanidins on the growth performance,jejunum morphology and plasma biochemical indices of broiler chicks

Grape proanthocyanidins (GPCs) are a family of naturally derived polyphenols that have aroused interest in the poultry industry due to their versatile role in animal health. This study was conducted to investigate the potential benefits and appropriate dosages of GPCs on growth performance, jejunum morphology, plasma antioxidant capacity and the biochemical indices of broiler chicks. A total of 280 newly hatched male Cobb 500 broiler chicks were randomly allocated into four treatments of seven replicates each, and were fed a wheat–soybean meal-type diet with or without (control group), 7.5, 15 or 30 mg/kg of GPCs. Results show that dietary GPCs decrease the feed conversion ratio and average daily gain from day 21 to day 42, increase breast muscle yield by day 42 and improve jejunum morphology between day 21 and day 42. Chicks fed 7.5 and 15 mg/kg of GPCs show increased breast muscle yield and exhibit improved jejunum morphologies than birds in the control group. Dietary GPCs fed at a level of 15 mg/kg markedly increased total superoxide dismutase (T-SOD) activity between day 21 and day 42, whereas a supplement of GPCs at 7.5 mg/kg significantly increased T-SOD activity and decreased lipid peroxidation malondialdehyde content by day 42. A supplement of 30 mg/kg of GPCs has no effect on antioxidant status but adversely affects the blood biochemical indices, as evidenced by increased creatinine content, increased alkaline phosphatase by day 21 and increased alanine aminotransferase by day 42 in plasma. GPC levels caused quadratic effect on growth, jejunum morphology and plasma antioxidant capacity. The predicted optimal GPC levels for best plasma antioxidant capacity at 42 days was 13 to 15 mg/kg, for best feed efficiency during grower phase was 16 mg/kg, for best jejunum morphology at 42 days was 17 mg/kg. In conclusion, GPCs (fed at a level of 13 to 17 mg/kg) have the potential to be a promising feed additive for broiler chicks.     

Influence of continuous challenge via the feed on competitive exclusion of salmonellas from broiler chicks

A survey has been made of the bacterial and fungal populations carried at three different sites on the feet of 60 individuals. The bacteria found at the three sites were quantitatively similar and Micrococcaceae and aerobic coryneform bacteria predominated. The carriage of other bacterial groups was generally low. There was a quantitative variation between sites—mean total counts were 1.04 ± 10⁷ cfu/cm² skin in the fourth toe cleft, 4.08 ± 10⁵ cfu/cm² skin on the sole and 1.21 ± 10³ cfu/cm² skin on the dorsal surface. Staphylococci were most often dominant on the sole and dorsal surface whereas aerobic coryneforms predominated in the majority of fourth toe clefts. The higher the total count at a given site the more likely it was that aerobic coryneform bacteria predominated. The skin surface pH was significantly higher on the sole (mean value 6.25) than on the dorsal surface (mean value 5.23). Factors controlling the microbial ecology of the foot are discussed.     

Manipulation of plasma uric acid in broiler chicks and its effect on leukocyte oxidative activity

Birds have high metabolic rates, body temperatures, and plasma glucose concentrations yet physiologically age at a rate slower than comparably sized mammals. These studies were designed to test the hypothesis that the antioxidant uric acid protects birds against oxidative stress. Mixed sex broiler chicks (3 wk old) were fed diets supplemented or not with purines (0.6 mol hypoxanthine or inosine). Study 1 consisted of 18 female Cobb x Cobb broilers that were fed purines for 7 days, whereas study 2 consisted of 12 males in a 21-day trial. Study 3 involved 30 mixed sex broilers that were fed 40 or 50 mg allopurinol/kg body mass (BM) for 21 days, a drug that lowers plasma uric acid (PUA). PUA and leukocyte oxidative activity (LOA) were determined weekly for all studies. For study 2, pectoralis major shear force, relative kidney and liver sizes (RKS and RLS), and plasma glucose concentrations were also determined. In study 1, PUA concentration was increased three- and twofold (P < 0.001) in birds fed inosine or hypoxanthine, respectively, compared with control birds. LOA of birds supplemented with inosine was lower (P < 0.05) than that of control or hypoxanthine birds. In study 2, PUA concentrations were increased fivefold (P < 0.001) in birds fed inosine and twofold (P < 0.001) in birds fed hypoxanthine compared with control birds at day 21. RKS (g/kg BM) was greater (P < 0.001) for chicks fed purine diets compared with control chicks. Muscle shear value was lower (P < 0.05) in chicks fed purine diets. PUA concentration was decreased (P < 0.001) in birds consuming allopurinol diets, whereas LOA was increased (P < 0.01) in study 3. These studies show that PUA concentrations can be related to oxidative stress in birds, which can be linked to tissue aging.     

Effects of dietary grape seed extract on growth performance,amino acid digestibility and plasma lipids and mineral content in broiler chicks

Polyphenols are chemically and biologically active compounds. Grape seed extracts (GSEs) have been widely used as a human food supplement for health promotion and disease prevention. However, there is little information regarding its application in animal feeds. An experiment was conducted to investigate the effect of inclusion of GSE at 0.025, 0.25, 2.5 and 5.0 g/kg in a wheat soya bean control diet on growth performance, protein and amino acid (AA) digestibility and plasma lipid and mineral concentrations in broiler chickens at 21 days of age. Performance was not affected by dietary treatment except in the case of birds fed the diet with the highest GSE concentration, which showed a worsening of weight gain and feed conversion. Apparent ileal digestibility (AID) of protein was significantly reduced in the birds fed the highest concentration of GSE, which also had a reduction on the AID of arginine, histidine, phenylalanine, cystine, glutamic acid and proline compared with those fed control diet. The inclusion of graded concentration of GSE in the chicken diets caused a significant linear decrease in the concentrations of plasma copper, iron and zinc. Plasma cholesterol, triglycerides and lipoproteins (high-density lipoprotein, low-density lipoprotein and very-low-density lipoprotein) concentrations were not affected by dietary GSE. In conclusion, this study demonstrated that incorporation of GSE in chicken diets up to 2.5 g/kg had no adverse effect on growth performance or protein and AA digestibility. Feed conversion was reduced and growth rate was retarded, when chickens were fed 5 g/kg of GSE. This study also indicated that grape polyphenols reduce the free plasma minerals.