Reduction of radiocaesium transfer to broiler chicken meat by a clinoptilolite modified with hexacyanoferrate

The effect of RADEKONT (a natural clinoptilolite modified by hexacyanoferrate) on ¹³⁷Cs uptake into meat was tested in experiments with broiler chickens. Three experiments determined the influence of RADEKONT on radiocaesium transfer after single or repeated applications of artificially contaminated feed mixture and one experiment investigated the effect of RADEKONT when feeding a mixture containing wheat contaminated by the Chernobyl fallout. Independent of the effect of RADEKONT, the uptake of radiocaesium was faster in leg meat than in breast meat. Reduction factors (¹³⁷Cs transfer without the RADEKONT additive compared with those observed after supplementation of the additive into the feed mixture) of 1.1–1.3 and 1.2–2.3, respectively, were achieved after single and repeated administrations of artificially contaminated feed. No significant differences in reduction between breast and leg meat were observed. RADEKONT was more effective when the chickens were fed with Chernobyl-contaminated wheat (reduction factors of up to 3.7) than an artificial ¹³⁷Cs source. RADEKONT as a supplement during the decontamination period decreased the biological half-life of ¹³⁷Cs to less than 1 day. The timing of the application of RADEKONT might be important in determining its effectiveness, especially in young, rapidly growing chickens. Received: 9 January 1998 / Accepted in revised form: 10 January 1999     

Reduction of radiocaesium transfer to broiler chicken meat by the hexacyanoferrate-cellulose binder “Bifezh”

The influence of Bifezh (a hexacyanoferrate compound as veterinary feed additive) on the transfer of ¹³⁷Cs to meat was investigated in broiler chickens after application of an artificially contaminated feed mixture. The reduction factors reached 2.23 and 8.46 for single and multiple ¹³⁷Cs administration, respectively. The elimination rate of ¹³⁷Cs in the decontamination period was only slightly increased by Bifezh. The reduction effect of Bifezh was considerably and positively limited by various amounts of the additive during both radiocaesium accumulation and decontamination. No significant differences in the reduction effect between breast and thigh meat were observed. In conclusion, the hexacyanoferrate-cellulose binder Bifezh can be recommended as an alternative chemical measure for reducing ¹³⁷Cs contamination of broiler chicken meat, although administration rates may need to be enhanced over those currently recommended.     

Comparative study of 137Cs distribution in broilers and pheasants and possibilities for protection

The aim of the present study was to investigate distribution of (137)Cs in leg and breast meat of broilers and pheasants following single alimentary contamination and administration of two protectors (AFCF and clinoptilolite). The birds were administered a single dose of (137)CsCl, with an activity of 750?Bq. Protectors were given via gastric tube or mixed in the forage pellets. AFCF given via gastric tube decreased the (137)Cs concentration by a factor of 7.8 in broilers leg meat and 7.4 in broilers breast meat. When AFCF was mixed in pellets, the (137)Cs concentration was 19.5 times lower in broilers leg meat and 22.1 times lower in broilers breast meat, than in the control group. In pheasants, AFCF administered via gastric tube decreased the (137)Cs concentration by a factor of 12.4 in leg meat and by a factor of 13.7 in breast meat, respectively. In group 4, where pheasants were administered AFCF mixed in pellets, the (137)Cs concentration was 3.7 times lower in leg and breast meat, than in the control group. For comparison, clinoptilolite administered via gastric tube decreased the (137)Cs concentration 1.8 times in broilers leg meat and 2.0 times in breast meat, compared to the control group. In pheasants, (137)Cs concentration was 2.9 times lower in leg meat and 2.6 times lower in breast meat. Clinoptilolite mixed in the feed had relatively low efficiency of protection in broilers ((137)Cs concentration was 1.4 times lower in leg meat and 1.6 lower in breast meat). A similar trend was observed in pheasants ((137)Cs concentration was 1.6 lower in leg and breast meat).     

Genotypic effects in phytoavailability of radiocaesium are pronounced at low K intensities in soil

The differences in radiocaesium uptake between species were analysed in a series of solution culture and pot trials. Since radiocaesium uptake is very sensitive to the solution potassium (K) concentration, it was hypothesised that species depleting K in the rhizosphere to a larger extent, will have a higher radiocaesium uptake. Five species (bean, lettuce, winter barley, ryegrass and bentgrass) were grown for 18–21 days in nutrient solution spiked with ¹³⁷Cs and at 4 K concentrations between 0.025 and 1.0 mM. Shoot ¹³⁷Cs activities all decreased between 17- and 81-fold with increasing K supply. Shoot ¹³⁷Cs activities were 4-fold different between species at the lowest K supply and 3.4-fold different at high K supply. The same five species were grown in two ¹³⁴Cs spiked soils with contrasting exchangeable K but similar clay content. Shoot ¹³⁴Cs activities were up to 19-fold higher in the soil with lowest exchangeable K. Differences in shoot activity concentrations between the species were only 4.5-fold in the high K soil, but were 15-fold in the low K soil. Bulk soil solution ¹³⁴Cs and K concentration data were combined with radiocaesium uptake characteristics measured in solution culture to predict radiocaesium uptake from soil. Predictions were within 1.6-fold of observations in the high K soil but largely underestimated ¹³⁴Cs uptake in lettuce, ryegrass and barley in the low K soil. A solute transport model was used to estimate K and radiocaesium concentrations in the rhizosphere. These calculations confirmed the assumption that higher radiocaesium uptake is found for species that deplete K in the rhizosphere to a larger extent.     

Monte-Carlo prediction of changes in areas of west Cumbria requiring restrictions on sheep following the Chernobyl accident

Following the 1986 Chernobyl accident radiocaesium levels in sheep meat in some upland areas of the United Kingdom were above the national intervention limit. West Cumbria was one of these areas and restrictions are currently still in place. In addition to deposition from the Chernobyl accident, Cumbria has been subject to radiocaesium deposition from atmospheric nuclear weapons tests, the 1957 Windscale accident and routine releases from the Sellafield nuclear reprocessing plant. A Monte-Carlo approach has been used to try to predict areas in west Cumbria where radiocaesium activity concentrations in lamb meat would require the imposition of restrictions at different times after the Chernobyl accident. The approach models the transfer of radiocaesium from soil to vegetation, based upon soil organic matter, and from vegetation to lamb meat. Spatial inputs are soil organic matter and total post-Chernobyl (137)Cs and (134)Cs deposition; a ratio of Chernobyl (137)Cs to (134)Cs deposition has been used to differentiate Chernobyl and pre-Chernobyl (137)Cs deposition. Comparisons of predicted radiocaesium transfer from soil-vegetation and the spatial variation in lamb (137)Cs activity concentrations are good and predicted restricted areas with time after Chernobyl compare well to the restricted areas set by UK government. We predict that restrictions may be required until 2024 and that in some areas the contribution of pre-Chernobyl (137)Cs to predicted lamb radiocaesium activity concentrations is significant, such that restrictions may only have been required until 1994 as a consequence of Chernobyl radiocaesium deposition alone. This work represents a novel implementation of a spatial radioecological model using a Monte-Carlo approach.     

The use of an optimised concentration of quercetin limits peroxidation of lipids in the meat of broiler chickens fed a diet containing flaxseed oil rich in omega-3

Ross 308 chickens were used to investigate fatty acid (FA) composition and oxidative stability of broiler chicken meat following the controlled inhibition of peroxidation in feed containing a concentrated source of omega-3 fatty acids (flaxseed oil, FLO), approximately 50% omega-3. Ninety-six one-day-old chicks were randomly allocated to four dietary treatments (n = 24/group) that included rapeseed oil (RO), flaxseed oil (FLO), RO with optimised quercetin (Q) – RO_Q, or FLO with optimised Q (FLO_Q). On day 35, breast and thigh muscles were collected in order to analyse their FA profile and malondialdehyde (MDA) levels. Dietary treatments had no effect on weight gain or feed conversion ratio in chickens. However, dietary FLO increased the deposition of α-linolenic acid in both pectoral and thigh meat (P < 0.05), and tended to decrease the ratio of omega-6/omega-3 FA in pectoral muscles (P < 0.07). Addition of an optimised concentration of Q proved to be an efficient way of limiting lipoperoxidation in breast and thigh muscles subjected to refrigeration at 2–3 °C for either 1 or 7 days. Results were consistent with the observed inhibition of peroxidation in feed mixtures and significantly correlated with MDA levels found in feed mixtures. These results provide evidence that it is possible to produce poultry meat with an improved proportion of omega-3 FA without significantly altering the performance of broiler chickens or the oxidative stability of their meat.     

Carcass and meat quality traits of chickens fed diets concurrently supplemented with vitamins C and E under constant heat stress

The objective of this study was to determine if a diet supplemented simultaneously with vitamins C and E would alleviate the negative effects of heat stress, applied between 28 and 42 days of age, on performance, carcass and meat quality traits of broiler chickens. A total of 384 male broiler chickens were assigned to a completely randomized design, with a 2×3 factorial arrangement (diet with or without vitamin supplementation and two ambient temperatures plus a pair-feeding group) and 16 replicates. Chickens were kept in thermoneutral conditions up to 28 days of age. They were then housed in groups of four per cage, in three environmentally controlled chambers: two thermoneutral (22.5 and 22.6°C) and one for heat stress (32°C). Half the chickens were fed a diet supplemented with vitamins C (257 to 288 mg/kg) and E (93 to 109 mg/kg). In the thermoneutral chambers, half of the chickens were pair-fed to heat stressed chickens, receiving each day the average feed intake recorded in the heat stress chamber in the previous day. Meat physical quality analyses were performed on the pectoralis major muscle. No ambient temperature×diet supplementation interaction effects were detected on performance, carcass, or meat quality traits. The supplemented diet resulted in lower growth performance, attributed either to a carry-over effect of the lower initial BW, or to a possible catabolic effect of vitamins C and E when supplemented simultaneously at high levels. Heat stress reduced slaughter and carcass weights, average daily gain and feed intake, and increased feed conversion. Growth performance of pair-fed chickens was similar to that of heat stressed chickens. Exposure to heat stress increased carcass and abdominal fat percentages, but reduced breast, liver and heart percentages. Pair-fed chickens showed the lowest fat percentage and their breast percentage was similar to controls. Heat stress increased meat pH and negatively affected meat color and cooking loss. In pair-fed chickens, meat color was similar to the heat stressed group. Shear force was not influenced by heat stress, but pair-fed chickens showed the tenderest meat. In conclusion, reduction in growth performance and negative changes in meat color in heat stressed chickens were attributed to depression in feed intake, whereas negative changes in body composition, higher meat pH and cooking loss were credited to high ambient temperature per se. Diet supplementation with vitamins C and E as antioxidants did not mitigate any of these negative effects.     

Radiocesium activity reduction in boar meat by brining

Meat of wild boar with an intial ¹³⁷Cs activity concentration of 103 Bq kg⁻¹ of fresh mass was treated by brining. Dry-salting reduced the ¹³⁷Cs activity only by about 12–18%. Subsequent brining was done by using both pure sodium chloride and a mixture of sodium chloride and potassium nitrate. After double-brine exchange, the ¹³⁷Cs activity concentration was reduced by at least 72%. The double-brine exchanges were done for two time intervals (the first each 24 h and the second each 7 days). There were no differences in the ¹³⁷Cs activity reduction for these two time intervals. From the technological point of view, the repeated exchange of the brine solution represents a relative easy method of ¹³⁷Cs activity reduction in contaminated pork meat.     

Some biochemical indices in chicken skin tissue during ontogenesis and under the effect of ionizing radiation

The research shows some biochemical indices in ontogenesis in broiler hen skin tissues and also its reaction to inner introduction of different doses of radioactive 137Cs. Namely, the irradiation ionizing irradiation influences actively to the indices of nuclein changes with 1 day and 1 week aged chickens. The quantity of phosphorus of nuclein acids is less with the chickens of the third group (500 Bk pr day) than with the second group (3000 Bk/day). The quantity of soluble protein, activity of the estimated fragments, the quantity of inorganic phosphorus, the concentration of ions of magnesium with chickens of the controlled group is larger than in the studied ones. It proves the influence of radionucleid 137Cs on indices which characterize the protein-nuclein change.     

The Influence of Naringin or Hesperidin Dietary Supplementation on Broiler Meat Quality and Oxidative Stability

An experiment was conducted to examine the effects of supplementing broiler feed with hesperidin or naringin, on growth performance, carcass characteristics, breast meat quality and the oxidative stability of breast and thigh meat. Two hundred and forty 1-day-old Ross 308 broiler chickens were randomly assigned to 6 groups. One of the groups served as a control (C) and was given commercial basal diets, whereas the other five groups were given the same diets further supplemented with naringin at 0.75 g/kg (N1), naringin at 1.5 g/kg (N2), hesperidin at 0.75 g/kg (E1), hesperidin at 1.5 g/kg (E2) and a-tocopheryl acetate at 0.2 g/kg (E). At 42 days of age, 10 chickens per treatment group were slaughtered for meat quality and oxidative stability assessment. No significant differences were observed among groups in final body weight, carcass weight and internal organs weights (P>0.05) apart from liver that decreased linearly with increased levels of naringin (P-linear<0.05). Regarding the breast meat quality parameters, only redness (a*) value was higher in E1 and N1 group compared to VE group (P<0.05), while all the others i.e. shear values (N/mm²), pH₂₄, cooking loss (%) and L* and b* color parameters were not significantly different among groups (P>0.05). Measurement of lipid oxidation values showed that after hesperidin and naringin dietary supplementation, malondialdehyde values decreased in tissue samples in a dose depended manner (P-linear<0.05). In conclusion, hesperidin and naringin, positively influence meat antioxidative properties without negative implications on growth performance and meat quality characteristics in poultry, thus appearing as important additives for both the consumer and the industry.     

Breast muscle and plasma metabolomics profile of broiler chickens exposed to chronic heat stress conditions

Understanding the variations of muscle and plasma metabolites in response to high environmental temperature can provide important information on the molecular mechanisms related to body energy homeostasis in heat-stressed broiler chickens. In this study, we investigated the effect of chronic heat stress conditions on the breast muscle (Pectoralis major) and plasma metabolomics profile of broiler chickens by means of an innovative, high-throughput analytical approach such as the proton nuclear magnetic resonance (¹H NMR) spectrometry. A total of 300 Ross 308 male chicks were split into two experimental groups and raised in either thermoneutral conditions for the entire rearing cycle (0–41 days) (TNT group; six replicates of 25 birds/each) or exposed to chronic heat stress conditions (30 °C for 24 h/day) from 35 to 41 days (CHS group; six replicates of 25 birds/each). At processing (41 days), plasma and breast muscle samples were obtained from 12 birds/experimental group and then subjected to ¹H NMR analysis. The reduction of BW and feed intake as well as the increase in rectal temperature and heterophil: lymphocyte ratio confirmed that our experimental model was able to stimulate a thermal stress response without significantly affecting mortality. The ¹H NMR analysis revealed that a total of 26 and 19 molecules, mostly related to energy and protein metabolism as well as antioxidant response, showed significantly different concentrations respectively in the breast muscle and plasma in response to the thermal challenge. In conclusion, the results obtained in this study indicated that chronic heat stress significantly modulates the breast muscle and plasma metabolome in fast-growing broiler chickens, allowing to delineate potential metabolic changes that can have important implications in terms of body energy homeostasis, growth performance and product quality.     

Radiocaesium in lynx in relation to ground deposition and diet

The european lynx (Lynx lynx) might be expected to have a high intake of radiocaesium in the parts of Sweden where the main prey of the lynx, namely reindeer and roe deer have high activity concentrations of radiocaesium because of high ground deposition. We have measured ¹³⁷Cs in muscle samples from 733 lynx during 1996–2003. The aim was to quantify the extent to which radiocaesium is transferred from fallout deposition to lynx, to test whether the transfer was higher in areas where there are reindeer present, to see if there was any decline in radiocaesium over time, and to calculate the radiation dose to lynx. Most samples were collected in central and northern Sweden during January–April. Activity concentrations in lynx varied from 13 Bq kg^–1 to about 15 kBq kg^–1 fresh weight, with the highest value corresponding to a radiation dose at 18 mGy/year. Aggregated transfer coefficients (Tag), calculated by dividing the ¹³⁷Cs activity concentration in lynx muscle by the average ground deposition (total from Chernobyl and nuclear weapon tests) within a 50 km radius around the location of the lynx, varied from 0.004 to 1.3 m² kg^–1 and were significantly higher within the reindeer herding area than outside. The concentration ratio (CR) for lynx/reindeer was 2.6 on average, whilst the average for lynx/roe deer outside the reindeer herding area was lower at 1.3. Based on these results, a CR of around 2 could be considered representative for the general ratio between predator and prey. A long-term decline of radiocaesium in prey species was reflected in lynx, with an effective half-life of 7 years from 1996 to 2003. The study shows that the accumulation of radiocaesium in predators, especially predators of reindeer, makes them more vulnerable to high radiocaesium deposition than most other wild species.     

Distribution of radiocaesium activities in the waters of a Bavarian chain of lakes

The procedure to extract caesium from seawater developed by Mann and Casso (1984) has been slightly modified and applied to the determination of radiocaesium originating from the Chernobyl accident in the waters of a Bavarian chain of lakes. Activity concentrations and estimated water inventories are given for 15 lakes 5 years after the accident, and depth profiles of the¹³⁷Cs activity concentration in the water column of three selected lakes are presented. The activity concentrations in water of the different lakes show a high variability from 1.2 to 93 mBq 1^–1. The calculated inventory of dissolved radiocaesium has decreased over the 5 years to 0.03% and 2% of the deposited activity, respectively.     

Effects of Simple and Microencapsulated <Emphasis Type="Italic">Lactobacillus acidophilus</Emphasis> With or Without Inulin on the Broiler Meat Quality Infected by Avian Influenza Virus (H<Subscript>9</Subscript>N<Subscript>2</Subscript>)

The aims of the present study were to investigate the effects of simple and microencapsulated Lactobacillus acidophilus as probiotic with or without inulin as prebiotic on meat quality of broiler infected by avian influenza virus (H₉N₂). Two hundred-day-old chicks were randomly allocated into 14 groups based on simple, microencapsulated probiotic and prebiotic and based on vaccination and challenge with H₉N₂ virus. Groups 1–7 contained 20 chicks, and groups 8–12 and 14 contained 10 chicks. Group 13 was derived from group 1 with 10 chicks at challenge day with avian influenza virus (AIV). Half of the groups were vaccinated by H₉N₂ vaccine on day 5. All groups except the negative control and positive vaccine control were challenged with 10^6.5 EID₅₀ of low-virulence H₉N₂ AIV at day 21. Each bird was received 10⁹ CFU of simple or microencapsulated probiotic on days 0 and 17 by gavage. Prebiotic as dose as 0.1 % of feed weight was used daily. Increase in water-holding capacity, dry matter, ash and protein content, and decrease in dripping loss plus beneficial changes in lightness and redness of breast meat were detected in response to probiotic especially microencapsulated synbiotic. In conclusion, probiotic alone or with prebiotic was able to improve the physicochemical properties of chicken breast muscle in both healthy and AIV-infected chickens.     

Tissue Distribution and Metabolism of Aflatoxin B1-14C in Broiler Chickens

The effects of administering low levels of aflatoxin B(1)-(14)C by crop intubation daily for 14 days to broiler chickens were determined. Studies on the distribution of (14)C in the blood, selected organs, tissues, and excreta were conducted. No toxic effects were observed in broiler chickens during the 14 days of the experiment. The broiler chickens excreted 90.64% of the (14)C administered. Of the (14)C retained, 11.04, 9.83, 4.30, 12.52, 31.66, and 30.63% were detected in the blood, liver, heart, gizzard, breast, and leg, respectively. Chemical assay of those samples demonstrating radioactivity revealed that 81.2% of the radioactivity in these substrates was not extractable by classical extraction procedures while approximately 10% was extractable. Treatment of aqueous extracts for conjugated steroids by treatments with beta-glucuronidase revealed that 31.5% of the (14)C detected in the aqueous extract was a liberated glucuronide conjugate of aflatoxin M(1)-(14)C.     

Evaluation of cefquinome's efficacy in controlling avian colibacillosis and detection of its residues using high performance liquid chromatography (HPLC)

This study aimed to evaluate the efficacy of cefquinome in treatment and controlling of Escherichia coli experimentally infected broiler chickens, in addition of detection of its residues using High performance liquid chromatography (HPLC). In this study, 150 one-day old Cobb broiler chicks were used. On the 14^th day chicks experimentally infected and divided into 3 equal groups (50 each); control group (G1) non-infected, non-treated, (G2) infected with E. coli O₇₈ non treated, (G3) infected with E. coli O₇₈, cefquinome treated. Cefquinome was administrated 5^th day post infection, intramuscularly by a dose of (2 mg/ kg b w.t) for 3 consecutive days. Experimental E. coli infection in broilers induced weakness, loss of appetite, depression, cough and watery diarrhea in addition to a recorded mortality (30%) with reduction in growth performance, erythrogram, total proteins, albumin, antioxidants and haemagglutination inhibition (HI) titers. In addition, a significant increase in feed conversion rate (FCR), leukocytic count, liver enzymes, kidney functions, total globulins, malondialdehyde, nitric oxide and lysozyme activity. Treatment with cefquinome led to decreased mortality rate, improvement in clinical signs, growth performance and modulated most of these altered parameters. Cefquinome's residues was not detected in breast muscles 3^rd day and liver and kidneys 7^th days post treatment. Therefore, it's recommended that cefquinome is a good choice for controlling of colibacillosis in broilers and its withdrawal time 3 days in breast muscles and 7 days in liver and kidney post treatment.     

Canonical discriminant analysis applied to broiler chicken performance

The mechanisms involved in the control of growth in chickens are too complex to be explained only under univariate analysis because all related traits are biologically correlated. Therefore, we evaluated broiler chicken performance under a multivariate approach, using the canonical discriminant analysis. A total of 1920 chicks from eight treatments, defined as the combination of four broiler chicken strains (Arbor Acres, AgRoss 308, Cobb 500 and RX) from both sexes, were housed in 48 pens. Average feed intake, average live weight, feed conversion and carcass, breast and leg weights were obtained for days 1 to 42. Canonical discriminant analysis was implemented by SAS^R CANDISC procedure and differences between treatments were obtained by the F-test (P < 0.05) over the squared Mahalanobis’ distances. Multivariate performance from all treatments could be easily visualised because one graph was obtained from two first canonical variables, which explained 96.49% of total variation, using a SAS^R CONELIP macro. A clear distinction between sexes was found, where males were better than females. Also between strains, Arbor Acres, AgRoss 308 and Cobb 500 (commercial) were better than RX (experimental). Evaluation of broiler chicken performance was facilitated by the fact that the six original traits were reduced to only two canonical variables. Average live weight and carcass weight (first canonical variable) were the most important traits to discriminate treatments. The contrast between average feed intake and average live weight plus feed conversion (second canonical variable) were used to classify them. We suggest analysing performance data sets using canonical discriminant analysis.     

Effect of caponisation on physicochemical and sensory characteristics of chickens

The meat fats content associated to nutritional and sensory characteristics are the most important concerns of consumers. To study the effect of caponisation on the meat quality of two different breed chickens, slaughtered at 18 weeks of age, raised under the same conditions, the physicochemical and sensory characteristics of capons (castrated males at 8 weeks of age) and roosters’ meat of native Amarela Portuguesa and native Pedrês Portuguesa breeds were evaluated. Forty Amarela (20 roosters and 20 capons), 40 Pedrês (20 roosters and 20 capons) chickens, and also, six free-range chicken and six broilers were evaluated. The pH, water-holding capacity, Warner-Bratzler shear force, moisture content, ash, myoglobin, collagen, CP, total fat and fatty acids profile were evaluated in breast and leg meat, according to standard procedures. Leg meat capon showed greater intramuscular fat content (P⩽0.05), monounsaturated fatty acids (MUFA) and CP (P⩽0.001) than leg roosters. Caponisation increased the content of myoglobin and MUFA (P⩽0.05) and reduced the moisture content in the leg (P⩽0.05). The main fatty acids found were oleic acid (C18:1), palmitic acid (C16:0) and linoleic acid (C18:2). The greatest value of C18:1 was observed in capon’s breast (P⩽0.01). Sensory analysis was made to compare the Amarela and Pedrês meat with a free-range chicken and a broiler. The sensory taste panel classified the capon’s meat (Amarela and Pedrês) as juicier, less fibrous and tougher than rooster’s meat. The broiler was in general juicier, tenderer and less fibrous than the other birds. The results of sensory analysis complement those obtained in physicochemical analysis, suggesting that caponisation promotes an overall improvement in meat quality.     

Eucalyptus leaves powder,antibiotic and probiotic addition to broiler diets: effect on growth performance,immune response,blood components and carcass traits

The study was conducted to investigate the effects of different levels of eucalyptus powder (EP), virginiamycin and probiotic on performance, immunity, blood components and carcass traits of broiler chickens. A total of 250, 1-day-old male broiler chickens (Ross 308) were randomly allocated to five treatments with five replicates and 10 chicks each, as a completely randomized design. The dietary treatments consisted of: basal diet (BD), BD+0.25% EP, BD+0.5% EP, BD+0.01% of diet probiotic (Protexin), BD+0.02% of diet antibiotic (virginiamycin). Dietary supplementation did not affect feed intake, BW gain (BWG) and feed conversion ratio (FCR) during starter and grower phases, but BWG and FCR were affected during the finisher and whole periods (P<0.05).The highest BWG and lowest FCR were obtained in birds fed with virginiamycin and 0.5% EP. Dietary supplementation significantly increased the relative weight of carcass and breast (P<0.05). Treatments had no effect on relative weights of internal organs and small intestine except for bursa that increased by treatments. Relative length of jejunum also increased by treatments (P<0.05). Antibody production against sheep red blood cells did not changed in primary titer (day 35), but it significantly increased in secondary titer (day 42) by 0.5% EP. White blood cell counts were increased and cholesterol decreased by dietary supplementation (P<0.05). In conclusion, the results of this study showed that 0.5% EP served as a useful replacement for antibiotic and would improve performance and immune response of broiler chickens.     

Regulation of myostatin expression is associated with growth and muscle development in commercial broiler and DMC muscle

Myostatin is a negative regulator of skeletal muscle growth. Muscle tissue is the largest tissue in the body and influences body growth. Commercial Avian broiler chickens are selected for high growth rate and muscularity. Daweishan mini chickens are a slow growing small-sized chicken breed. We investigated the relations between muscle (breast and leg) myostatin mRNA expression and body and muscle growth. Twenty chickens per breed were slaughtered at 0, 30, 60, 90, 120, and 150 days of age. Body and muscle weights were higher at all times in Avian chickens. Breast muscle myostatin expression was higher in Avian chickens than in Daweishan mini chickens at day 30. Myostatin expression peaked at day 60 in Daweishan mini chickens and expression remained higher in breast muscle. Daweishan mini chickens myostatin expression correlated positively with carcass weight, breast and leg muscle weight from day 0 to 60, and correlated negatively with body weight from day 90 to 150, while myostatin expression in Avian chickens was negatively correlated with carcass and muscle weight from day 90 to 150. The results suggest that myostatin expression is related to regulation of body growth and muscle development, with two different regulatory mechanisms that switch between days 30 and 60.