Effects of dietary corticosterone and trilostane on growth and skeletal muscle protein turnover in broiler cockerels

Comparative Analysis of the Temporal Impacts of Corticosterone and Simulated Production Stressors on the Metabolome of Broiler Chickens

The impact of physiological stress on the metabolome of breast muscle, liver, kidney, and hippocampus was investigated in Ross 308 broiler chicks. Simulated on-farm stressors were compared to a corticosterone model of physiological stress. The three different stressors investigated were: (i) corticosterone at a dose of 15 mg/kg of feed; (ii) heat treatment of 36 °C and 40% RH for 8 h per day; and (iii) isolation for 1 h per day. Liver, kidney, breast muscle, and hippocampus samples were taken after 2, 4, 6, and 8 days of stress treatment, and subjected to untargeted ¹H-nuclear magnetic resonance (NMR) spectroscopy-based metabolomic analysis to provide insights on how stress can modulate metabolite profiles and biomarker discovery. Many of the metabolites that were significantly altered in tissues were amino acids, with glycine and alanine showing promise as candidate biomarkers of stress. Corticosterone was shown to significantly alter alanine, aspartate, and glutamate metabolism in the liver, breast, and hippocampus, while isolation altered the same pathways, but only in the kidneys and hippocampus. Isolation also significantly altered the glycine, serine, and threonine metabolism pathway in the liver and breast, while the same pathway was significantly altered by heat in the liver, kidneys, and hippocampus. The study's findings support corticosterone as a model of stress. Moreover, a number of potential metabolite biomarkers were identified in chicken tissues, which may allow producers to effectively monitor stress and to objectively develop and evaluate on-farm mitigations, including practices that reduce stress and enhance bird health.

Effects of genetic selection on activity of corticotropic and thyrotropic axes in modern broiler chickens

Commercial selection for meat-type (broiler) chickens has produced economically valuable birds with fast growth rates, enhanced muscle mass, and highly efficient feed utilization. The physiological changes that account for this improvement and unintended consequences associated with them remain largely unexplored, despite their potential to guide further advancements in broiler production efficiency. To identify effects of genetic selection on hormonal signaling in the adrenocorticotropic and thyrotropic axes, gene expression in muscle and liver and post-hatch circulating hormone concentrations were measured in legacy [Athens Canadian Random Bred (ACRB)] and modern (Ross 308) male broilers between embryonic days (e) 10 and e18 and post-hatch days (d) 10 and d40. No interactive effects or main effects of line were observed for adrenocorticotropic gene expression during either developmental period, although age effects appeared for corticosteroid-binding globulin in liver during embryogenesis and post-hatch and glucocorticoid receptor in both tissues post-hatch. There was a main line effect for circulating corticosterone, with levels in ACRB greater than those in Ross. Several thyrotropic genes exhibited line-by-age interactions during embryonic or post-hatch development. In liver, embryonic expression of thyroid hormone receptor beta was greater in ACRB on e12, and deiodinase 3 (DIO3) levels were greater in Ross on e14 and e16. In juvenile liver, deiodinase 2 (DIO2) expression was greater in ACRB on d10 but greater in Ross on d20, while DIO3 was higher in ACRB on d30 and d40. Levels of thyroid hormone receptor alpha mRNA exhibited a main line effect, with levels greater in ACRB juvenile breast muscle. Several thyrotropic genes exhibited main age effects, including DIO2 and DIO3 in embryonic breast muscle, thyroid hormone receptor alpha and thyroid hormone receptor beta in post-hatch liver, and DIO2 in post-hatch breast muscle. Circulating triiodothyronine displayed a main line effect, with levels in Ross significantly reduced as compared to ACRB. These findings suggest that in modern broilers, a decrease in levels of hormones that control basal metabolism triiodothyronine and the stress response circulating corticosterone, as well as altered expression of genes regulating thyroid hormone activity, could contribute to lower heat production, reduced stress response, and altered nutrient partitioning, leading to more efficient feed utilization and faster, more productive growth.

Corticosterone-Mediated Physiological Stress Alters Liver, Kidney, and Breast Muscle Metabolomic Profiles in Chickens

The impact of physiological stress on the metabolomes of liver, kidney, and breast muscle was investigated in chickens. To incite a stress response, birds were continuously administered corticosterone (CORT) in their drinking water at three doses (0, 10, and 30 mg L-1), and they were sampled 1, 5, and 12 days after the start of the CORT administration. To solubilize CORT, it was first dissolved in ethanol and then added to water. The administration of ethanol alone significantly altered branched chain amino acid metabolism in both the liver and the kidney, and amino acid and nitrogen metabolism in breast muscle. CORT significantly altered sugar and amino acid metabolism in all three tissues, but to a much greater degree than ethanol alone. In this regard, CORT administration significantly altered 11, 46, and 14 unique metabolites in liver, kidney, and breast muscle, respectively. Many of the metabolites that were affected by CORT administration, such as mannose and glucose, were previously linked to increases in glycosylation and gluconeogenesis in chickens under conditions of production stress. Moreover, several of these metabolites, such as dimethylglycine, galactose, and carnosine were also previously linked to reduced quality meat. In summary, the administration of CORT in chickens significantly modulated host metabolism. Moreover, results indicated that energy potentials are diverted from muscle anabolism to muscle catabolism and gluconeogenesis during periods of stress.

Effect of aromatase inhibitors on sex differentiation and embryonic development in chicks

Background

Sexual differentiation can occur after exposure to aromatase into the left gonad at 6.5 days of incubation. Aromatase inhibitors work by inhibiting the action of the aromatase, which converts androgens into estrogens by a process called aromatization.

Objectives

The aim of this study was to investigate the effect of in ovo exposure to the aromatase inhibitor from tomato and garlic extract on sexual differentiation and embryonic development in chicken embryos.

Methods

Three hundred eggs divided into five groups: Control 1 (CO; no injection); control 2 distilled water, DW; 0.1 ml/egg); garlic extract (GAR; 0.1 mg/egg); tomato extract (TOM; 0.1 mg/egg); and garlic and tomato extract mixed (ATM, 0.1 ml/egg). The solution was prepared and injected into the albumin from the thin end of the eggs on day five by using a 1 ml syringe with a 23‐gauge needle. The embryonic test (embryo/egg weight) conducted at 7, 14 and 17 days of incubation. After hatching, feather sexing conducted to determine the initial male. Chicks sex was later confirmed on day 42 by an optical microscope lens.

Results

The results revealed that there was a significant increase (p < 0.01) in embryonic growth traits in all experimental treatments as compared to control treatments. There was a significant increase (p < 0.01) in the percentage of hatchability for all experimental treatments compared to control treatments and a significant increase (p < 0.01) in chick quality including one‐day‐old chick length and body weight. All experimental treatments showed a significant increase (p < 0.01) in the male‐to‐female ratio compared to control treatments.

Conclusions

The effect of in ovo exposure to aromatase inhibitors stimulated female‐to‐male sex reversal and improved embryonic development.

The effects of the mixture of betaine, vitamin C, St John's wort (Hypericum perforatum L.), lavender, and Melissa officinalis on performance and some physiological parameters in broiler chickens exposed to heat stress

The unprecedented rate of global warming requires more immaculate strategies to fight the heat stress and its detrimental effects on poultry sector. Nutritional strategies, particularly herbal extracts, play a crucial importance in this scenario. Therefore, this study was conducted to evaluate the effects of a novel selected mixture (hereafter refers to as Stress-Bio-Max, SBM) comprising St John's wort, lavender, Melissa officinalis extracts, betaine, and Vit C on heat-stressed broilers. A total of 300 male broiler chicks were allocated to 4 treatments: T1, Control (no SBM in drinking water); T2, 0.25 mL/L of SBM in drinking water; T3, 0.5 and T4, 1 mL/L of SBM, which applied since d 32. The birds underwent heat stress (40 ± 1) daily from d 35 to 42 of the experiment (2 pm–8 pm). The results show the superior weight gain of T2 and T3 from d 7 to 42 compared to other groups, 72.5 and 72.7 g/d, respectively (P < 0.05). Corticosterone level was higher on d 35 in T1 (4.674 ng/mL, P < 0.05) and lower in T2 and T3 (2.64 and 2.952 ng/mL, respectively, P < 0.05); T2 and T3 also caused the lowest concentrations of corticosterone on d 40 (5.198 and 6.458 ng/mL, respectively, P < 0.05). The superior triiodothyronine levels belonged to T2 (0.935 ng/mL, P < 0.05) on d 35 and T2 and T3 on d 40 (0.699 and 0.582 ng/mL, respectively, P < 0.05). T2, T3, and T4 caused a rise in glutathione peroxidase (GPX) and superoxide dismutase (SOD) activities (P < 0.05). A significant higher amount of total antioxidant capacity (TAC) belonged to the groups treating with SBM (P < 0.05). The SBM in T2 and T3 resulted in the lowest levels of malondialdehyde (MDA), aspartate transaminase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP). Results from this study indicate that SBM may alleviate the negative impacts associated with heat stress in broiler chickens.

Tryptophan in poultry nutrition: Impacts and mechanisms of action

Many studies have shown that productivity, immune system, antioxidant status, and meat and egg quality can be optimized by dietary supplementation with amino acids that are not usually added to poultry diets. Understanding the effects of these amino acids may encourage feed manufacturers and poultry producers to include them as additives. One of these amino acids is tryptophan (Trp). The importance of Trp is directly related to its role in protein anabolism and indirectly related to its metabolites such as serotonin and melatonin. Thus, Trp could affect the secretion of hormones, development of immune organs, meat and egg production, and meat and egg quality in poultry raised under controlled or stressed conditions. Therefore, this review discusses the main roles of Trp in poultry production and its mode (s) of action in order to help poultry producers decide whether they need to add Trp to poultry diets. Further areas of research are also identified to address information gaps.

Effects of steroid growth promoter on morphological and biochemical adaptations in liver of broiler

Aim

The study was conducted to observe the effects of dexamethasone (DEX) on the gross study and histomorphometry of liver and on the alterations of biochemical parameters of broilers.

Materials and Methods

Ninety day-old chicks were collected and assigned to one of three groups: The control, Group A, and Group B. The control, Group A, and Group B were fed for 28 days with a homemade ration, a commercial broiler type ration, and a homemade ration with DEX (7 mg/kg feed), respectively. Liver samples were collected from the individual birds after sacrificing on days 7, 14, 21, and 28 of the experiment. Morphometric characteristics (length, weight, color, and texture) of the liver were examined. Histomorphological alterations of the liver were assessed with routine hematoxylin and eosin staining. To measure the biochemical parameters, blood samples were collected on days 7, 14, 21, and 28 of the experiment. Liver function test was performed spectrophotometrically by analyzing serum biochemical markers, that is, alanine aminotransferase (ALT), aspartate aminotransferase, and alkaline phosphatase (ALP). Thin-layer chromatography (TLC) was performed for the detection of hepatic steroids.

Results

Hemorrhagic and congested livers were found in broilers of Group B. There were no significant changes found in weight and length of the livers; only numerical decrease in weight and length was observed in birds of Group B. Liver width was increased in Group B on day 21. Histological observation of livers showed accumulation of lipid droplets, congestion of the sinusoids, and central veins in broilers of Group B. Biochemical analyses showed increased levels of ALT in Group B as compared to Group A on day 14 of the experiment. TLC evaluation revealed a positive result in Group B on 28 days of the experiment.

Conclusion

The present study results show that DEX may alter the liver morphology and the concentration of ALT in the circulation of broilers.

Organic Selenium, Probiotics, and Prebiotics Effects on Growth, Blood Biochemistry, and Carcass Traits of Growing Rabbits During Summer and Winter Seasons

The effect of organic selenium, prebiotics, or probiotics on productive performances, blood biochemistry, and carcass characteristics of growing rabbits was studied throughout summer and winter seasons. In an 8-week feeding trial, a total of 100 New Zealand White rabbits were randomly distributed to 10 groups. Two seasons (winter and summer) and five diets fortified with 0 (control), 0.03 mg selenium, 3 g Bio-Mos®, 1 g Bactocell® (1 × 10¹⁰ CFU) or 3 g yeast/kg diet were used in 2 × 5 factorial design. Results indicated that growth performance, feed intake (FI), and blood components (red blood cells [RBCs], serum total protein [TP], globulin [GLOB], albumin [ALB]) decreased significantly in rabbits reared during summer than in those during winter. In contrast, white blood cells, urea-N, creatinine, alanine transaminase [ALT], and aspartate transaminase [AST] increased significantly in summer. However, growth performance indices, FI, blood hemoglobin, RBCs, TP, ALB, and GLOB increased significantly in rabbits when fed the tested feed additives. The respiration rate, rectal temperature, and heart rate of the animals were significantly decreased with all feed additives. Adjusted weight of carcass, liver, kidney fat, and carcass cuts were not affected by feed additives. Final margin and margin efficiency increased in rabbit fed diets supplemented with feed additives than those fed the basal diet without any supplementation. Results of the current study concluded that a supplementation of rabbit diets with organic selenium, probiotics, and prebiotics can promote rabbit performance during mild weather and also alleviate the adverse impact of heat stress during summer season.

Growth performance and antioxidant status of growing rabbits fed on diets supplemented with Eucommia ulmoides leaves

<p>The present study evaluated the effect of dietary <em>Eucommia ulmoides leaves</em> (EUL) on growth performance and antioxidant status of growing rabbits under heat stress condition. Four hundred and fifty weaned New Zealand male rabbits (6 wk old) were randomly divided into 3 equal groups (150 rabbits/group) and fed with a basal diet (control, digestible energy (DE): 15.92 MJ/kg and crude protein (CP): 19.24%) or the basal diet supplemented with 1 or 5 g of EUL/kg of diet (EUL1 and EUL5), in which the same quantity of barley meal was replaced. During the 21 d of experiment (43 to 63 d of age), the temperature and relative humidity of the rabbit house ranged from 27.5 to 32.5°C and from 65 to 73%, respectively. We analysed feed intake, growth performance and antioxidant status of growing rabbits. Compared with the control group, at the end of the experimental period, EUL supplementation significantly reduced the average daily feed intake (92.0, 92.8 and 100.7 g/d for EUL1, EUL5 and control, respectively; P&lt;0.05), improved the feed conversion ratio (3.80, 3.81 and 4.59 for EUL1, EUL5 and control, respectively; P&lt;0.05), increased the activities of glutathione peroxidase (+35.5 and +35.0% in plasma and liver of rabbits in EUL5 vs. control group, respectively; P&lt;0.05) and reduced those of malondialdehyde (–12.0 and –46.0% in plasma and liver of rabbits in EUL5 vs. control group, respectively; P&lt;0.05). These results suggest that inclusion of EUL in the diet of growing rabbits improved the growth performance and antioxidant status in growing rabbits.</p>

Palliative effects of extra virgin olive oil, gallic acid, and lemongrass oil dietary supplementation on growth performance, digestibility, carcass traits, and antioxidant status of heat-stressed growing New Zealand White rabbits

This study explored the effects of supplemental dietary extra virgin olive oil (EVOO), gallic acid (GA), or lemongrass essential oil (LGEO) on growth performance, nutrient digestibility, carcass traits, lipid peroxidation, hematological, and antioxidative status in growing rabbits under heat stress conditions. A total of 48 male growing New Zealand White rabbits were randomly divided into four equal groups, which received a basal diet without any supplementation or supplemented with 15 g EVOO, 500 mg GA, or 400 mg LGEO/kg of diet, for eight consecutive weeks. Results revealed that the overall mean of temperature humidity index was 84.67 ± 0.35, reflecting a state of severe heat stress. Moreover, dietary supplementation with EVOO, GA, or LGEO significantly increased live body weight and daily body weight gain but decreased both feed conversion ratio and daily water consumption. Additionally, a significant increase in both organic matter and crude protein digestibility besides a remarkable elevation in the nutritive values of digestible crude protein, total digestible nutrients, and digestible energy, as well as an increase in the numbers of WBCs, lymphocytes, and heterophils was significant in EVOO-supplemented rabbits. Supplementation with EVOO, GA, or LGEO in the heat-stressed growing rabbit's diet enhanced catalase activity and reduced glutathione content, whereas EVOO-treated rabbits had the highest values. Also, malondialdehyde activity was reduced in response to all tested additives. In conclusion, these findings suggested that addition of EVOO, GA, or LGEO in growing rabbit's diet could be used effectively to alleviate negative impacts of heat stress load on performance, nutrient digestibility, oxidative status, and hemato-biochemical features. Furthermore, among these additives, EVOO achieved the best effects.

Comparative proteomic analysis of the breast muscle response to chronic corticosterone administration in broiler chickens showing long or short tonic immobility

Broilers of the same genetic origin were classified as short or long tonic immobility duration (STI and LTI, respectively) phenotypes and treated chronically with vehicle (control) or corticosterone (CORT) dissolved in drinking water between 27 and 42 d of age. Differential expression of proteins and mRNA was examined using 2-dimensional gel electrophoresis and real-time PCR to elucidate the mechanism behind the severe retardation of broiler breast muscle growth caused by LTI and CORT. The majority of the 13 proteins found to be differentially expressed in breast muscle of STI and LTI broilers are involved in either glycolysis (5 proteins) or myofilament formation (5 proteins). Of the 16 proteins differentially expressed in breast muscle following CORT treatment, 6 are structural proteins, 5 are categorized as cellular defense and stress proteins, and 3 (pyruvate kinase, l-lactate dehydrogenase, and creatine kinase) are involved in responses to stress and muscle damage. Real-time PCR results indicated that expression of these proteins is transcriptionally and posttranscriptionally regulated. Protein synthesis capacity, estimated by the RNA-to-protein ratio, was significantly lower in the breast muscle of CORT-treated broilers than in untreated control broilers. The level of Leu, Gly, and Ser in serum was significantly higher in CORT-treated broilers than in the control birds. Therefore, we conclude that CORT treatment retards the growth of skeletal muscle by suppressing protein synthesis and augmenting protein catabolism, paralleling the response to severe stress and muscle damage, and the negative effect of LTI on muscle growth is likely mediated through glucose metabolism. No interaction was observed between CORT and tonic immobility affecting growth performance or any parameter examined in the current study.

Dietary mannanase-hydrolyzed copra meal improves growth and increases muscle weights in growing broiler chickens

The utilization of copra meal as a feed ingredient is limited because it contains a high level of mannan. However, recent findings indicate that the effect of copra meal on growth performance in broiler chickens can be improved by the supplementation of mannanase in the diet. In the present study, we examined the effect of mannanase-hydrolyzed copra meal (MCM) on growth performance and muscle protein metabolism in growing broiler chickens (Gallus gallus domesticus). Forty 8-day-old male broiler chicks were assigned to two groups (four birds in each pen, five replicates) and fed either a commercial diet (as a control diet) or a diet containing MCM at 0.2% until 22 days of age. Dietary MCM significantly increased the weights of body, breast muscle, and thighs in chickens, whereas the weights of abdominal adipose tissue and liver were not affected. Cumulative feed intake was significantly increased by MCM. Dietary MCM significantly decreased plasma 3-methylhistidine level. The messenger RNA and protein levels of muscle protein metabolism-related factors were not altered by MCM. These findings suggest that the growth-promoting effect of MCM is related to the suppression of muscle proteolysis in growing broiler chickens.

Dietary sodium butyrate alleviates the oxidative stress induced by corticosterone exposure and improves meat quality in broiler chickens

The present study was to investigate the effects of dietary microencapsulated sodium butyrate (SB) and acute pre-slaughter stress, mimicked by subcutaneous corticosterone (CORT) administration, on BW, carcass characteristics, muscle antioxidant status, and meat quality of broiler chickens. A total of 120 1-d-old broiler chickens were fed a control diet (without SB) or a 0.4-g microencapsulated SB/kg diet. On 42 d, half of the birds from each treatment were given 1 single subcutaneous injection of CORT (4 mg/kg of BW in corn oil) to mimic acute stress, whereas the other half were injected with the same amount of corn oil (sham control). Three hours later, BW loss was determined and breast meat samples were collected. The results showed that the BW of the CORT-challenged groups lost much more than the sham control group (P < 0.001), whereas it was alleviated by the dietary microencapsulated SB (P < 0.05). Meanwhile, the catalase activity was decreased and malondialdehyde level was increased by the stress (P < 0.05), and the microencapsulated-SB diet significantly inhibited this effect (P < 0.05). Lower pH values and higher yellowness values were also observed in CORT-challenged chickens (P < 0.05), and the microencapsulated-SB diet treatment partially exerted a preventive effect. Microencapsulated SB significantly decreased the contents of saturated fatty acids and C18:0 (P < 0.01 and P < 0.001), and increased C20:0 and C20:4 contents. However, the effect of the stress treatment on fatty acid composition was insignificant (P > 0.05). In addition, diet and stress did not significantly influence carcass characteristics and the chemical composition of breast meat (P > 0.05). These results suggest that microencapsulated SB was favorable for chickens in the presence of stress, which may be partially ascribed to the ability of SB to decrease catabolism and oxidative injury of tissues.

Effects of corticosterone treatment in laying Japanese quail

1. The effects of exogenous corticosterone on plasma corticosterone concentrations, body weight, food intake, the percentage of birds that laid an egg each day and egg weight were measured in laying Japanese quail. Data were collected from birds in the week before corticosterone treatment began, during a 21-d treatment period, and in the 22 d after treatment ended. 2. Groups of quail were treated with corticosterone at three different concentrations in their drinking water. Corticosterone intakes were calculated for each bird and birds were then assigned to 4 intake groups. The groups were 0 (control group), 0.31-0.60, 0.61-0.90, 0.91-1.50 or >1.51 mg corticosterone/bird/d. 3. Plasma corticosterone concentrations in the 4 intake groups increased from around 1 ng/ml on the day before corticosterone treatment began to maximum mean concentrations of 13-18 ng/ml on day 14 of treatment. Mean corticosterone concentrations did not change between day 14 of treatment and the day after treatment ended, and had decreased in only one of 4 intake groups one week later. 4. Mean body weight in the highest intake group remained significantly lower than in controls 22 d after corticosterone treatment ended. Whilst there was no clear effect of corticosterone on food intake during treatment, mean food intake in the three highest corticosterone intake groups was significantly lower than in controls in the week after treatment ended. The percentage of birds that laid an egg each day and egg weight were both decreased by corticosterone, and the percentage of birds that laid an egg each day remained significantly lower in the highest corticosterone intake group compared with controls in the third week after treatment ended. 5. It is suggested that elevated plasma corticosterone concentrations in quail after treatment ended were maintained by a hyperactive hypothalamo-pituitary-adrenal axis for at least one week. Although none of the negative effects of corticosterone were evident in the group of quail with the lowest corticosterone intakes, the findings of the present study show that corticosterone treatment can affect birds for up to several weeks after corticosterone intake ends.

Perspectives on the endocrinology of poultry growth and metabolism

Birds have rapid pre- and post-hatching growth rates. The major hormones required to support normal growth are growth hormone (GH), triiodothyronine (T(3)) and insulin-like growth factor-I (IGF-I). Optimal growth requires a "set-point" concentration of both IGF-I and T(3) in the circulation. Pituitary GH plays a role in controlling the circulating concentrations of both IGF-I and T(3). Nutritional restriction (energy, protein) leads to reductions in circulating concentrations of both IGF-I and T(3) with increased GH secretion due removal of negative feedback. Similarly, there is un-coupling of the GH-IGF-I axis in stunting disease. A critical control point is at the level of the liver and GH receptor/signal transduction. The major hormones controlling metabolism include glucagon, insulin, adrenal glucocorticoid hormone, corticosterone and potentially somatostatin. Chickens and turkeys have higher circulating concentrations of glucose than those of livestock mammals. What are not known include the following: the biological basis for the high basal glucose concentrations; the quantitative fluxes of key metabolites in the fed and fasted state through growth and development; the relative contribution of different organs to gluconeogenesis; the relative importance of insulin and somatostatin in controlling lipolysis and the role of gastro-intestinal hormones in the control of metabolism.

Effects of a short period of elevated circulating corticosterone on postnatal growth in free-living Eurasian kestrels Falco tinnunculus

Environmental conditions affect growth and development and, through developmental plasticity, create phenotypic variation. In suboptimal conditions current survival is traded-off against development. Corticosterone, the main glucocorticoid in birds, may be involved in the reallocation of energy from growth to maintenance, but its effect on growth has rarely been investigated in altricial birds under natural conditions in the wild. In free-living Eurasian kestrel Falco tinnunculus nestlings, we artificially elevated corticosterone to stress-induced levels over 2-3 days in the middle of the nestling stage by implanting biodegradable implants, controlling the treatment with a placebo group. We measured the length of primary feather 8, hand length, tarsus length, body mass and subcutaneous fat stores from day 10 to 25. During corticosterone elevation, primary growth of cort-nestlings was significantly reduced to 71% of placebo-nestlings, hand and tarsus growth were significantly reduced to 14% and 26% of placebo-nestlings, respectively, and body mass increase stopped, while subcutaneous fat-store growth was not affected. Over the following 5 days, primary growth was still significantly suppressed to 84% of placebo-nestlings, while hand, tarsus and body mass growth were back to normal. During the subsequent 4 days, cort-nestlings partly compensated for the lag in body mass by significantly accelerating the body mass increase compared with placebo-nestlings. Before fledging, primary length was 10% shorter, hand and tarsus 5% and 4% shorter and body mass 8.5% lower in cort-nestlings than in placebo-nestlings, while fat score did not differ significantly between the two groups. Thus, we have shown that in free-living, altricial nestlings a few days of elevated plasma corticosterone levels alone, without food restriction, suppressed growth and this could only partly be compensated for afterwards. Feather, bone and body mass growth were reduced to different degrees, indicating that corticosterone had a differential effect on different structures. This demonstrates that corticosterone is probably involved in the control of developmental plasticity.

Epigallocatechin-3-gallate supplementation can improve antioxidant status in stressed quail

1. Heat stress causes oxidative stress, which decreases plasma antioxidants in poultry. Epigallocatechin gallate (EGCG), the most abundant polyphenol in green tea, is a powerful antioxidant against lipid peroxidation. This experiment was conducted to evaluate the effects of dietary EGCG supplementation on performance, carcase characteristics, concentrations of malondialdehyde, lipid peroxidation indicator, vitamins C, E, A, cholesterol, triglyceride, and glucose in Japanese quail (Coturnix coturnix japonica) exposed to a high ambient temperature of 34 degrees C. 2. One hundred and eighty Japanese quails (10 d old) were assigned at random to 6 treatment groups consisting of 10 replicates of three birds. Birds were kept in cages in a temperature-controlled room at either 22 degrees C (thermo-neutral) or 34 degrees C (heat stress) for 8 h/d. Birds were fed either a basal diet or the diet supplemented with 200 or 400 mg of EGCG/kg of diet. 3. EGCG supplementation linearly increased feed intake, live weight gain, feed efficiency, cold carcase weight and yield under heat stress conditions but did not show the same effect at thermoneutral conditions. Serum vitamin C, E, and A concentrations increased in birds reared at high temperature while non-significant changes occurred in thermo-neutral groups. Malondialdehyde concentrations in serum and liver decreased in all birds of both thermo-neutral and heat stressed groups as dietary EGCG supplementation increased. Heat stress-induced increase in serum cholesterol, triglycerides and glucose concentrations were linearly reversed by EGCG supplementation. 4. The results indicate that EGCG supplementation improved the live performance and antioxidant status of heat-stressed Japanese quail.

The effects of tomato powder supplementation on performance and lipid peroxidation in quail

Recent studies have suggested a protective role for lycopene, an antioxidant carotenoid, in the prevention of stress including environmental stress. Tomatoes and tomato products are the major dietary source of lycopene. The objective of the present study was to investigate the effect of dietary tomato powder supplementation on the performance and lipid peroxidation of meat in Japanese quail (Coturnix coturnix japonica) exposed to a high ambient temperature of 34 degrees C. A total of 180 ten-day-old male quails were randomly allocated into 6 groups consisting of 10 replicates of 3 birds. Birds were kept in wire cages in a temperature-controlled room at either 22 degrees C (thermoneutral) or 34 degrees C (heat stress) for 8 h/ d (0900 to 1700 h during the study). Birds were fed either a basal diet or the basal diet supplemented with 2.5 or 5.0% of tomato powder. Tomato powder supplementation linearly increased feed intake, live weight gain, and feed conversion (P = 0.01) under heat stress conditions but did not show the same effect at thermoneutral conditions (P > 0.05). Heat stress significantly increased malondialdehyde concentration and decreased vitamin concentrations in the serum, liver, and muscles of quail. Serum lycopene and vitamin C, E, and A (P = 0.01) concentrations increased linearly in birds at all groups. Malondialdehyde levels in serum, liver (P = 0.001), and muscles linearly decreased in all birds of both thermoneutral and heat stress groups as dietary tomato powder supplementation increased. The results of the study indicate that tomato powder modulates the oxidation-antioxidation system of the muscles in Japanese quail exposed to high ambient temperature.

Effects of corticosterone treatment on growth, development, and the corticosterone response to handling in young Japanese quail (Coturnix coturnix japonica)

Corticosterone, a glucocorticoid secreted during stress responses, has a range of actions that help birds respond to stressors. Although effects of corticosterone treatment have been described in several avian species, the impacts of defined increases in plasma corticosterone on early development and on corticosterone stress responses are little known. These issues were addressed by providing quail with different doses of corticosterone in drinking water from days 8 to 38 post-hatch. The corticosterone dose consumed by each bird during treatment days 15-30 was calculated by measuring water intake. The corticosterone dose was inversely, but weakly, correlated with weights of the bursa, thymus, spleen, liver, testes, oviduct, muscle, and body, and positively correlated with peritoneal fat deposition. When birds were divided into groups based on their corticosterone intake, weights of the spleen, thymus, bursa, muscle, testes, and oviduct were significantly reduced in birds receiving the highest doses; with the exception of muscle, similar reductions were also observed in birds receiving medium doses, and thymic growth was inhibited in birds receiving low doses. The acute corticosterone stress response was measured by handling birds for 15 min. Plasma corticosterone was transiently increased at 15 min in control birds in response to the handling stressor. Some birds consuming low doses of corticosterone had corticosterone responses similar to control birds. Initial corticosterone concentrations were elevated in birds consuming higher doses of corticosterone. Plasma corticosterone in these birds decreased from 0 to 15 min, then increased from 15 to 30 min. The initial decrease could be due to corticosterone clearance, whilst the increase could indicate that the birds had a greater response than control birds to isolation as a stressor. Corticosterone treatment may have reduced the strength of corticosterone negative feedback within the hypothalamo-pituitary-adrenal axis. The results indicate that individuals and organs differ in their sensitivity to corticosterone. Moreover, elevated plasma corticosterone may disrupt the acute corticosterone stress response, and may thus reduce the ability of birds to cope with stressors.

Ascorbic acid and melatonin reduce heat-induced performance inhibition and oxidative stress in Japanese quails

1. The effects of ascorbic acid (L-ascorbic acid) and melatonin supplementation on performance, carcase characteristics, malondialdehyde (MDA) as lipid peroxidation indicator, ascorbic acid, retinol, tocopherol and mineral status in the Japanese quail (Coturnix coturnix japonica) exposed to high ambient temperature were evaluated. 2. Two hundred and forty Japanese quails (10 d old) were randomly assigned to 8 treatment groups consisting of 10 replicates of three birds each. The birds were kept in a temperature-controlled room at 22 degrees C (Thermoneutral, TN groups) or 34 degrees C (for 8 h/d; 09:00 to 17:00 h; Heat stress, HS groups). Birds in both TN and HS were fed either a basal (control) diet or the basal diet supplemented with 250 mg of L-ascorbic acid/kg of diet (Ascorbic acid group), 40 mg of melatonin/kg of diet (Melatonin group) or both (Ascorbic acid + Melatonin group). 3. Supplementing heat-stressed quails with ascorbic acid and melatonin improved performance compared with the control group. Effects generally were greatest in quails supplemented with both ascorbic acid and melatonin. 4. Although supplementation did not consistently restore the concentrations of serum ascorbic acid, retinol and tocopherol to those of TN groups, these concentrations increased significantly with supplementation. Furthermore, serum and liver MDA and serum cholesterol and glucose concentrations were lower in the supplemented groups than in the heat-stressed controls. 5. Within each environment, excretion of Ca, P, Mg, Zn, Fe and Cr were lowest in the combination group and, in all cases, highest in the HS group. Interactions between diet and temperature were detected for live weight gain, cold carcase weight, MDA, ascorbic acid, tocopherol concentrations and excretion of zinc. 6. The results of the study indicate that ascorbic acid and melatonin supplementation attenuate the decline in performance and antioxidant and mineral status caused by heat stress and such supplementation may offer protection against heat-stress-related depression in performance of Japanese quails.

Chick skeletal muscle proteolysis in vitro increased by corticosterone

Six-day-old chick skeletal muscle (extensor digitorum longus) was incubated in the presence of corticosterone (CTC; 0, 3, 30, and 300 ng/ml) for 2 h at 37 degrees C. Tyrosine and N (tau)-methylhistidine releases, as indices of total muscle and myofibrillar proteolysis, were increased by CTC but with different dose responses, indicating an independent regulation of myofibrillar and non-myofibrillar protein degradation.