Effects of methionine hydroxy analogue supplementation on the expression of antioxidant-related genes of acute heat stress-exposed broilers

We evaluated the effects of heat stress (HS) and methionine supplementation on biological markers of stress and expression of the genes for superoxide dismutase (SOD), thioredoxin (TRx), thioredoxin reductase 1 (TRxR1) and methionine sulfoxide reductase A (MsrA) in broilers aged 1 to 21 or 22 to 42 days. The broilers were divided into two treatments, one with the recommended level of methionine supplementation (MS, supplementation of dl-2-hydroxy-4-methylthiobutanoic acid (dl-HMTBA)) and one without methionine supplementation (MD). The animals were maintained at a temperature of thermal comfort or one of HS (38°C for 24 h). Mortality was only observed in 42-day-old broilers exposed to HS and fed the MD diet, and the rate was 5%. Starter period: we observed an interaction effect between diet and temperature on the gene expression of TRxR1 and MsrA, and expression of these genes was higher in the HS animals that received the MS diet than that in birds with the MD diet. Grower period: the expression of SOD, TRxR1 and MsrA genes, activities of aspartate aminotransferase (AST) and creatine kinase (CK) and content of creatinine were influenced by both study variables. In the HS animals, the expression of these genes, AST activity and creatinine content increased and CK activity decreased. In the animals on the MD diet, the expression of these genes and AST and creatinine values were higher and the CK activity was lower than those for the birds on the MS diet. Our results indicated that under HS conditions, the supplementation with dl-HMTBA could mitigate major damage caused by stress through the action on some genes related to TRx complex activity.     

Effects of Selenium Source and Level on Growth Performance, Tissue Selenium Concentrations, Antioxidation, and Immune Functions of Heat-Stressed Broilers

An experiment is conducted to investigate the effects of selenium (Se) source and level on growth performance, tissue Se concentrations, antioxidation, and immune functions of heat-stressed broilers from 22 to 42?days of age. A total of 210 22-day-old Arbor Acres commercial male chicks were assigned by body weight to one of seven treatments with six replicates of five birds each in a completely randomized design involving a 3?×?2 factorial arrangement plus one Se-unsupplemented basal diet control (containing 0.027?mg of Se/kg). The three Se sources were sodium selenite (Na₂SeO₃), Se yeast, and AMMS Se (Se protein), and the two supplemental Se levels were 0.15 or 0.30?mg Se/kg. All birds were reared under heat-stressed condition (33?±?1?°C during 0900?C1700?hours and 27?±?1?°C during 1900?C0700?hours with a relative humidity of 60?C80?%). The results showed that heat-stressed chicks fed Se-supplemented diets had higher (P?<?0.10) average daily feed intake, Se concentrations in liver and breast muscle, liver glutathione peroxidase (GSH-Px) activity, serum antibody titers against H5N1(Re-4 strain), H5N1(Re-5 strain) and lower (P?<?0.01) mortality compared with the control. Chicks fed the diets supplemented with 0.30?mg/kg of Se had higher (P?<?0.05) Se concentrations in liver and breast muscle, liver GSH-Px activity, and serum antibody titer against H5N1 (Re-4 strain) than those fed the diets supplemented with 0.15?mg/kg of Se. Broilers fed the diets supplemented with Se yeast had higher (P?<?0.001) Se concentrations in liver and breast muscle than those fed the diets supplemented with Na₂SeO₃ or AMMS Se. However, broilers fed the diets supplemented with AMMS Se had higher (P?<?0.05) serum antibody titers against H5N1 (Re-4 strain) and H5N1 (Re-5 strain) than those fed the diets supplemented with Na₂SeO₃. These results indicated that Se yeast was more effective than Na₂SeO₃ or AMMS Se in increasing tissue Se retention; however, AMMS Se was more effective than Na₂SeO₃ or Se yeast in improving immune functions of heat-stressed broilers.     

Effects of Methionine Supplementation on the Expression of Protein Deposition-Related Genes in Acute Heat Stress-Exposed Broilers

The objective of this study was to evaluate the effect of heat stress and methionine supplementation on the gene expression of insulin-like growth factor I (IGF-I), growth hormone receptor (GHR), phosphatidylinositol 3-kinase, and regulatory 1 (PI3KR1) in the liver, as well as the expression of the atrogin 1 and cathepsin L2 (CTSL2) genes in the breast muscle of broilers. Broilers from 1–21 and 22–42 days of age were divided into three treatments related to methionine supplementation as follows: without methionine supplementation (MD), recommended level of methionine (DL1), and excess supplementation of methionine (DL2). The animals were either maintained at a thermal comfort temperature or exposed to heat stress (HS) (38°C for 24 hours, starting on day 20 or day 41 for experiments 1 and 2, respectively). The heat stress increased the body temperature at both ages. Starter period: The HS animals presented increased plasma creatinine content (P<0.0001) and the highest CTSL2 gene expression (P<0.0001). The methionine supplementation increased the IGF-I (P = 0.0144) and GHR (P = 0.0011) gene expression and decreased the CTSL2 (P = 0.0004) and atrogin 1 (P = 0.0012) gene expression. Grower period: Significant effects for the interaction between supplementation and environment were observed for GHR (P = 0.0252) and CTSL2 (P = 0.0011) gene expression. The highest GHR expression was observed in animals that remained in thermal comfort on the DL2 diet, and the lowest expression occurred in the HS animals fed the MD diet. For CTSL2, the HS animals fed the MD diet presented the highest CTSL2 gene expression, and the lowest expression was observed in the animals maintained at thermal comfort on DL1 and DL2 diets. Only methionine supplementation had effect on atrogin-1 gene expression (P<0.0001), with higher methionine content in the diet lower atrogin-1 gene expression was observed. Our results suggest that heat stress induces greater protein degradation and that methionine supplementation could induce protein deposition because methionine increased the expression of genes related to protein synthesis and decreased the expression of genes related to protein breakdown.     

Probiotic bacteria maintain normal growth mechanisms of heat stressed broiler chickens

Probiotics have growth promoting effects even under periods of heat stress challenge. More information is needed to understand the mechanisms by which probiotics maintain the growth performance. The aim of this study was to evaluate the effect of a probiotic based on Bacillus subtilis bacteria on growth related mechanisms of broilers under heat stress conditions. Specifically, growth performance, skeletal bone characteristics, skeletal muscles size, intestinal villus-crypt structure, intestinal bacteria, growth hormone (GH), insulin-like growth factor-1 (IGF-1), cholesterol, and glucose. A total of 1200 one day old Ross 308 male broilers were randomly distributed into 4 treatments, with 12 replicates per treatment and 25 birds per replicate. A 2 × 2 factorial arrangement was used; the main factors were environmental temperature (thermoneutral or heat stress) and diet (control or control + B. subtilis; 3 × 10⁷ cfu/kg of feed). From d 22 to 35 of age, birds were either exposed to thermoneutral conditions (21 °C) or chronic heat stress (30 °C). During the same period, each group was divided into 2 subgroups and fed either the control diet or the B. subtilis supplemented diet. The results demonstrated that B. subtilis had positive effects (P < 0.05) on the body weight gain, feed conversion ratio, villus height, crypt depth, villus surface area, absorptive epithelial cell area and viable counts of intestinal beneficial bacteria. B. subtilis increased (P < 0.05) serum GH, IGF-1 and maintain normal levels of cholesterol and glucose under heat stress conditions. In addition, broilers fed B. subtilis under heat stress conditions exhibited higher (P < 0.05) skeletal muscles size and improved (P < 0.05) tibia traits and lower (P < 0.05) abdominal fat pads deposition compared with the controls. B. subtilis had no effect on rectal temperature under thermoneutral or heat stress conditions. It is concluded that B. subtilis can be used as growth promoters in broilers, particularly during the periods of heat stress conditions.     

Effects of l-leucine in ovo feeding on thermotolerance,growth and amino acid metabolism under heat stress in broilers

Recently, we found that in ovo feeding of l-leucine (l-Leu) afforded thermotolerance, stimulated lipid metabolism and modified amino acid metabolism in male broiler chicks. However, the effects of in ovo feeding of l-Leu on thermoregulation and growth performance until marketing age of broilers are still unknown. In this study, we investigated the effects of in ovo feeding of l-Leu on body weight (BW) gain under control thermoneutral temperature or chronic heat stress. We measured changes of body temperature and food intake, organ weight, as well as amino acid metabolism and plasma metabolites under acute and chronic heat stress in broilers. A total of 168 fertilized Chunky broiler eggs were randomly divided into 2 treatment groups in experiments. The eggs were in ovo fed with l-Leu (34.5 µmol/500 µl per egg) or sterile water (500 µl/egg) during incubation. After hatching, male broilers were selected and assigned seven to nine replicates (one bird/replicate) in each group for heat challenge experiments. Broilers (29- or 30-day-old) were exposed to acute heat stress (30 ± 1°C) for 120 min or a chronic heat cyclic and continued heat stress (over 30 ± 1°C; ages, 15 to 44 days). In ovo feeding of l-Leu caused a significant suppression of enhanced body temperature without affecting food intake, plasma triacylglycerol, non-esterified fatty acids, ketone bodies, glucose, lactic acid or thyroid hormones under acute heat stress. Daily body temperature was significantly increased by l-Leu in ovo feeding under chronic heat stress. Interestingly, in ovo feeding of l-Leu caused a significantly higher daily BW gain compared with that of the control group under chronic heat stress. Moreover, some essential amino acids, including Leu and isoleucine, were significantly increased in the liver and decreased in the plasma by l-Leu in ovo feeding under acute heat stress. These results suggested that l-Leu in ovo feeding afforded thermotolerance to broilers under acute heat stress mainly through changing amino acid metabolism until marketing age.     

Effects of feed form and energy levels on growth performance,carcass yield and nutrient digestibility in broilers

Feed form is well recognized to improve broiler performance, specially by increasing feed intake (FI). However, when different diet energy levels are used, the results differ in the literature. Therefore, this experiment was conducted to evaluate the influence of feed form and dietary metabolizable energy (ME) levels on broiler performance, carcass yield and on the digestibility of DM, CP, starch and gross energy. In total, 1152 male Cobb 500 broilers were evaluated between 35 and 47 days. The birds were distributed according to a completely randomized design in a 2 × 4 factorial arrangement, consisting of two feed forms (mash or pellet) and four ME levels (12.73, 13.06, 13.40 or 13.73 MJ/kg), totaling eight treatments with eight replicates of 18 birds. Broilers fed the lowest ME level presented the lowest weight gain (WG) and worst feed per unit gain (P < 0.01). Metabolizable energy intake increased (P < 0.01) with progressive increments of ME, which, however, did not affect caloric conversion (CC, P > 0.05). Pelleted diets promoted higher FI, WG, ME intake (P < 0.01) and better feed per unit gain and CC (P < 0.05) compared with mash. In mash diets, increasing dietary ME levels promoted a linear increase in WG (P < 0.01) and reduced feed per unit gain (P ≤ 0.05), but did not affect FI (P > 0.05). In pelleted diets, on the other hand, increasing ME levels linearly reduced FI (P < 0.05) and feed per unit gain (P < 0.01). Broilers fed pelleted diets presented higher abdominal fat deposition than those fed mash (P < 0.05). Increasing ME levels reduced the coefficients of ileal apparent digestibility of DM (P < 0.01) and total starch (P < 0.05) but did not affect the digestibility of other evaluated nutrients. The digestibility of all nutrients was lower when pelleted diets were fed compared with mash. Increasing inert material inclusion in the diets at the expense of soybean oil to reduce dietary ME levels promoted higher pellet durability index values (P < 0.05) and the percentage of fines (P < 0.01). Overall, the results suggest that pelleted diets promote better broiler performance because they increase FI, since the digestibility of dietary fractions is reduced. Chickens consuming low-energy pelleted diets may increase FI to compensate for energy deficit. In contrast, broilers fed mash diets may have reached their maximum intake capacity and did not regulate FI by changing feed energy density. When feeding pelleted diets, dietary energy reduction should be considered to reduce feed costs and to improve the carcass quality of broilers.     

Age-related oxidative stress and antioxidant capacity in heat-stressed broilers

We aimed to evaluate the effects of acute heat stress (HS) and age on the redox state in broilers aged 21 and 42 days. We evaluated the expression of genes related to antioxidant capacity, the production of hydrogen peroxide (H₂O₂), and the activity of antioxidant enzymes in the liver, as well as oxidative stress markers in the liver and plasma. The experiment had a completely randomized factorial design with two thermal environments (thermoneutral and HS, 38°C for 24 h) and two ages (21 and 42 days). Twenty-one-day-old animals exposed to HS showed the highest thioredoxin reductase 1 (TrxR1) (P<0.0001) and glutathione synthetase (GSS) (P<0.0001) gene expression levels. Age influenced the expression of the thioredoxin (Trx) (P=0.0090), superoxide dismutase (SOD) (P=0.0194), glutathione reductase (GSR) (P<0.0001) and glutathione peroxidase 7 (GPx7) (P<0.0001) genes; we observed greater expression in birds at 21 days than at 42 days. Forty-two-day-old HS birds showed the highest H₂O₂ production (222.31 pmol dichlorofluorescein produced/min×mg mitochondrial protein). We also verified the effects of age and environment on the liver content of Glutathione (GSH) (P<0.0001 and P=0.0039, respectively) and catalase (CAT) enzyme activity (P=0.0007 and P=0.0004, respectively). Higher GSH content and lower CAT activity were observed in animals from the thermoneutral environment compared with the HS environment and in animals at 21 days compared with 42 days. Broilers at 42 days of age had higher plasma creatinine content (0.05 v. 0.01 mg/dl) and higher aspartate aminotransferase activity (546.50 v. 230.67 U/l) than chickens at 21 days of age. Our results suggest that under HS conditions, in which there is higher H₂O₂ production, 21-day-old broilers have greater antioxidant capacity than 42-day-old animals.     

Adaptation to oxidative stress and impact of chronic oxidative stress on immunity in heat-stressed broilers

1. Glutathione peroxidase activity and serum malondialdehyde of heat-stressed broilers were increased in the early period of heat exposure, and then these parameters decreased.

2. The lesion scores of bursa of Fabricius in heat-stressed broilers were increased and decreased in accordance with the activity of glutathione peroxidase and serum malondialdehyde.

3. High environmental temperature had not affected relative bursa of Fabricius weight and NDV-HI titer of heat-stressed broilers.

4. We concluded that heat-stressed broilers could adapt to oxidative stress, and environmental temperature set at 38±2 °C had not affected humoral immunity.

Periodic usage of low-protein methionine-fortified diets in broiler chickens under high ambient temperature conditions: effects on performance,slaughter traits,leukocyte profiles and antibody response

This study was performed to evaluate the effects of adding methionine supplements to low-protein diets and subsequent re-feeding with a normal diet on the productive performance, slaughter parameters, leukocyte profiles and antibody response in broiler chickens reared under heat stress conditions. During the whole experimental period (6–49 days), the birds were raised in battery cages located in high ambient temperature in an open-sided housing system. A total of 360 6-day-old male chickens were divided into six treatments in six replicates with ten chicks each. Six isoenergetic diets, with similar total sulfur amino acids levels, were formulated to provide 100 and 100 (control), 85 and 100 (85S), 70 and 100 (70S), 85 and 85 (85SG), 70 and 85 (70S85G), and 70 and 70 % (70SG) of National Research Council recommended levels for crude protein during the starter (6–21 day) and grower (22–42 day) periods, respectively. Subsequently, all groups received a diet containing the same nutrients during the finisher period (43–49 day). The results showed that, under heat stress conditions, average daily gain and feed conversion ratio and performance index from day 6 to 49, breast and thigh yields and antibody titer against Newcastle disease in the birds fed diets 85S, 70S and 85SG were similar to those of birds fed control diet, whereas feeding diets 70S85G and 70SG significantly decreased the values of above-mentioned parameters. Additionally, diets 85S, 70S and 85SG significantly decreased mortality rate and heterophil:lymphocyte ratio compared with the control diet. In conclusion, the results indicate that supplementation of methionine to diets 85S, 70S and 85SG, and then re-feeding with a conventional diet is an effective tool to maintain productive performance and to improve health indices and heat resistance in broilers under high ambient temperature conditions.     

Influence of micronization (fine grinding) of soya bean meal and full-fat soya bean on the ileal digestibility of amino acids for broilers

A trial was conducted to test the effect of fine grinding (micronization) of soya bean meal (SBM) and full-fat soya bean (FFSB) on coefficient of ileal apparent digestibility (CIAD) and coefficient of ileal true digestibility (CITD) of amino acids in 23-day-old broilers. A completely randomized block design with four treatments arranged factorially (SBM and FFSB; micronized and ground) and six replicates (eight broilers per treatment) was used. Mean particle size (MPS) was 47 and 41 μm for micronized SBM and FFSB and 881 and 778 μm for ground SBM and FFSB, respectively. The four diets were based on maize starch and sucrose with the soya product tested as the sole source of dietary crude protein (CP, 200 g/kg). In addition, a nitrogen-free diet was formulated to estimate the basal ileal endogenous losses of the amino acids. Broilers were fed a commercial pelleted maize-SBM diet from 1 to 19 days of age and, then, their respective experimental diets in mash form from 20 to 23 days of age. Broilers fed SBM had higher CIAD of organic matter, CP, arginine, leucine, methionine and valine (P<0.05) and tended to have higher CIAD of threonine (P<0.10) than broilers fed FFSB. In addition, broilers fed SBM had higher CITD of CP (P<0.05), leucine, methionine and valine (P<0.01) than broilers fed FFSB. Particle size did not affect the ileal digestibility of CP or of any of the essential amino acids. It is concluded that broilers fed soya bean meal had higher ileal digestibility of amino acids than broilers fed full-fat soya bean and that fine grinding of the soya products did not affect amino acid digestibility.     

Effect of epigallocatechin gallate on growth performance and antioxidant capacity in heat-stressed broilers

This study investigated the effects of epigallocatechin gallate (EGCG) on the growth performance and antioxidant capacity of 35-d-old broilers exposed to heat stress. Broilers, 14 d of age, were divided into four groups with six replicates per group (eight chickens/replicate). Thermoneutral group (Group TN) was fed the basal diet and maintained at 28°C for 24 h/d. The heat-stressed groups were housed at 35°C for 12 h/d and 28°C for 12 h/d and fed the basal diet supplemented with EGCG at 0, 300 and 600 mg/kg diet (Groups HS0, HS 300 and HS600, respectively). Compared with Group TN, heat-stressed groups showed significantly reduced gain, feed intake and serum total protein and glucose levels; inhibited serum alkaline phosphatase activities; and increased serum levels of uric acid, cholesterol and triglycerides and the activity of serum creatine kinase, lactate dehydrogenase and aspartate aminotransferase (p < 0.05). Compared with Group HS0, Group HS600 exhibited an increased gain and feed intake; and normalised blood parameters and enzyme activities. Compared with Group TN, the expression of antioxidant-related liver proteins was decreased in Group HS0 and increased in Groups HS300 and HS600 (p < 0.05). The results suggest that EGCG can improve the growth performance and alleviate the oxidant damage by modulating the antioxidant properties of broilers.     

Effect of polyphenols extracted from tamarind (Tamarindus indica L.) seed coat on pathophysiological changes and red blood cell glutathione peroxidase activity in heat-stressed broilers

The purpose of this study was to determine the effect of polyphenols extracted from the tamarind seed coat (PETSC) on glutathione peroxidase (GPx) activity, red blood cell parameters and bilirubin in heat-stressed broilers. One hundred forty-seven broilers, 18-days old were divided into two groups. In group 1, broilers were maintained at an environmental temperature of 26?±?2 °C throughout the experimental period. In group 2, the broilers were maintained at 38?±?2 °C (cyclic temperature: 26?±?2 °C; ?38?±?2 °C; and ?26?±?2 °C, and broilers were maintained at 38?±?2 °C for 6 h/ day) and received PETSC at a concentration of 0, 100, 200, 300, 400 or 500 mg/kg in their diet ad libitum. Parameters were investigated on days 1, 7, 14 and 21 of the experimental period. Results showed that GPx activity of heat-stressed broilers that received 100 mg/kg of PETSC in their diet was lower (P?<?0.05) than that in broilers fed the other concentrations. The mean total red blood cell count and hemoglobin concentration of heat-stressed broilers that received 100 mg/kg PETSC was higher (P?<?0.05) than those in broilers in group 1 and those fed the other concentrations. The mean bilirubin level in the excreta of heat-stressed broilers that received 100 mg/kg of PETSC was lower (P?<?0.05) than that in broilers that received 0, 300, 400 and 500 mg/kg of PETSC. This showed that PETSC could reduce GPx activity and bilirubin in feces, and increase red blood cell parameters in heat-stressed broilers.     

Effect of Dietary Supplementation with Copper Sulfate or Tribasic Copper Chloride on the Growth Performance, Liver Copper Concentrations of Broilers Fed in Floor Pens, and Stabilities of Vitamin E and Phytase in Feeds

An experiment was conducted using a total of 840, 1-day-old, Arbor Acres commercial male broilers to compare copper (Cu) sulfate and tribasic Cu chloride (TBCC, Cu₂(OH)₃Cl) as sources of supplemental Cu for broilers fed in floor pens. Chicks were randomly allotted to one of seven treatments for six replicate pens of 20 birds each, and were fed a basal corn–soybean meal diet (10.20 mg/kg Cu) supplemented with 0, 100, 150, or 200 mg/kg Cu from either Cu sulfate or TBCC for 21 days. Chicks fed 200 mg/kg Cu as TBCC had a higher (P?<?0.05) average daily gain (ADG) than those consuming other diets. Liver Cu contents of broilers fed diets supplemented with TBCC were numerically lower (P?>?0.05) than those of broilers fed diets supplemented with Cu sulfate. The vitamin E contents and the phytase activities in the feed fortified with TBCC were higher (P?<?0.01) and numerically higher (P?>?0.05) compared with those in the feeds fortified with Cu sulfate stored at room temperature, respectively. The vitamin E contents in liver and plasma of broilers fed diets supplemented with TBCC were higher (P?<?0.05) than those of birds fed diets supplemented with Cu sulfate. This result indicates that TBCC is more effective than Cu sulfate in improving the growth of broilers fed in floor pens, and it is chemically less active than Cu sulfate in promoting the undesirable oxidation of vitamin E in feeds.     

Soybean oligosaccharides attenuate odour compounds in excreta by modulating the caecal microbiota in broilers

Abatement of odour emissions in poultry production is important to ensure the quality and safety in the poultry industry as well as for the benefit of the environment. This study was conducted to compare the effects of supplementation with different amounts of dietary soybean oligosaccharides (SBO) and chlortetracycline (CHL) on the major odour-causing compounds in the excreta and on the caecal microbiota in broiler chickens. One-day-old broiler chickens were subjected to a 42-day experiment involving 6 treatments with 6 replicates per treatment (10 birds/cage). The treatments were as follows: negative control (NC; basal diet), positive control (PC; basal diet supplemented with CHL) and basal diet supplemented with 0.5, 2.0, 3.5 and 5.0 g/kg SBO (0.5SBO, 2.0SBO, 3.5SBO and 5.0SBO, respectively). Fresh excreta were sampled for the analysis of odour compounds by HPLC. Caecum content was collected for the caecal microbiota analysis through 16S rRNA sequencing. Results showed that on day 42, the excreta indole concentration in the broilers fed with 2.0SBO, 3.5SBO and 5.0SBO and PC was significantly decreased (P < 0.01) compared with that in the NC-fed broilers. The excreta skatole concentration (P < 0.001) and pH (P < 0.05) were also decreased by SBO and CHL, and they were lowest in birds fed with 3.5SBO. The formate concentrations in birds fed with 3.5SBO and 5.0SBO were higher than those in birds fed with the other diets (P < 0.001). Similarly, acetate concentration (P = 0.003) was increased in birds fed with 3.5SBO. Deep sequencing of 16S rRNA revealed that the composition of the caecal microbial digesta was slightly or significantly changed by the SBO or by the CHL supplementation, respectively. The SBO supplementation decreased the abundance of Bacteroides, Bilophila and Escherichia, which were associated with the skatole and indole concentrations in the excreta. By contrast, the CHL supplementation demonstrated a strong tendency to enrich Ruminococcus and to reduce the abundance of Rikenella. These results indicated that supplementation with dietary SBO is beneficial in attenuating the concentration of odour-causing compounds and that it modulates the composition of caecal microbiota in broiler chickens.     

Dietary Supplementation of Selenium-Enriched Probiotics Enhances Meat Quality of Broiler Chickens (<Emphasis Type="Italic">Gallus gallus domesticus</Emphasis>) Raised Under High Ambient Temperature

We investigated the effects of selenium-enriched probiotics (SP) on broiler meat quality under high ambient temperature and explore their underlying mechanisms. A total of 200 1-day-old male broiler chicks (Ross 308) were randomly allotted to four treatment groups, each with five replicates, in groups of ten birds. These birds were fed a corn-soybean basal diet (C), a basal diet plus probiotics supplementation (P), a basal diet plus Se supplementation in the form of sodium selenite (SS, 0.30 mg Se/kg), and a basal diet with the addition of selenium-enriched probiotics (SP, 0.30 mg Se/kg). The experiment lasted for 42 days. The birds were sacrificed by cervical dislocation, and the breast muscles were removed for further process. Our results showed that SP diet significantly increased (p < 0.05) the physical (pH, colors, water holding capacity, drip loss, shear force) and sensory characteristics of breast meat. All P, SS, and SP supplementation enhanced the antioxidant system by increasing (p < 0.05) the Se concentrations, glutathione (GSH) levels, activities of glutathione peroxidase (GSH-Px), and superoxide dismutase (SOD) whereas decreasing (p < 0.05) malondialdehyde (MDA) levels, with SP being higher than P and SS. Moreover, SP diet significantly upregulated (p < 0.05) the mRNA levels of glutathione peroxidase genes (GPx1, GPx4) while it downregulated heat stress biomarkers such as heat shock protein (HSP) 70 as compared to C, P, and SS diets. In conclusion, our findings suggest that SP may function as beneficial nutritive supplement that is capable of improving meat quality during the summer season.     

Effect of raw and fermented grape seed on growth performance,antioxidant capacity,and cecal microflora in broiler chickens

Grape seed (GS) is a by-product of the fruit juice and wine industry with the potential to be an alternative to synthetic antioxidants due to its antioxidant activity. Agro-industrial residues can be converted to more effective products by solid-state fermentation. The objective of the study was to investigate the effects of GS and fermented grape seed (FGS) on the growth performance, antioxidant capacity, and cecal microflora in broiler chickens. A total of 128 female broilers were randomly allocated into four treatment groups, each consisting of four replicates of eight birds. Throughout the 42-day feeding period, the birds were fed with soybean-corn based diet (CON), 0.15 g/kg synthetic antioxidant (butylated hydroxyanisole) supplemented diet (AO), 5 g/kg GS supplemented diet (GS), and 5 g/kg FGS supplemented diet (FGS). Dietary GS, FGS, and AO supplementation increased the BW (P < 0.05) and average daily weight gain (ADG, P < 0.05) compared with the CON group in the overall period of 42 days. Dietary FGS also increased the ADG (P < 0.05) in the period of 22–42 days compared with the control group. The pH of the breast meat of the chickens fed GS was higher (P < 0.01) than CON and FGS groups. Dietary FGS and AO decreased the b* value (P < 0.01) of breast meat compared with the CON group. Grape seed had the highest serum glutathione peroxidase (P < 0.05) and catalase (CAT, P < 0.01) levels among the treatment groups. The FGS also increased serum CAT level (P < 0.01) compared with the AO group. Moreover, dietary FGS supplementation increased Lactobacillus spp. (P < 0.05) in the cecum compared with the other treatment groups and decreased Staphylococcus aureus (P < 0.05) compared with the CON and AO groups. The present findings indicate that GS and FGS can be used in broiler diets as alternatives to synthetic antioxidants.     

Excessive dietary vitamin D supplementation as a risk factor for sudden death syndrome in fast growing commercial broilers

Broiler diets are frequently fortified with vitamin D (D₃) above the recommended levels in an attempt to prevent commonly occurring leg problems. Since the basal levels of dietary D₃ are rarely known, there is a risk of over-supplementation. Over-supplementation of D₃ has been shown to have detrimental effects on the heart. Sudden death syndrome (SDS) is a condition commonly observed in broiler flocks and is associated with acute heart failure. The present study examines the effects of excessive levels of vitamin D₃ on cardiac health in fast growing broiler chickens. Commercial male broilers (Gallus gallus) were exposed to either a commercial diet or a commercial diet supplemented with D₃. Throughout the trial all birds were monitored several times daily for overt signs of heart disease, and periodically electrocardiographic measurements were obtained. Morbidity and mortality data were collected daily. On day 32 a simulated stress challenge consisting of a single injection of epinephrine (100 μg/kg BW) was administered under continuous ECG monitoring. Broilers fed the high D₃ diet were 2.5 fold more likely to succumb to acute heart failure and die of SDS (p < 0.05). Electrocardiographic examination showed a higher rate of cardiac arrhythmia in birds fed the high D₃ diet (22.6%), in comparison to those fed the control diet (11.8%). The stress challenge test revealed that broilers exposed to high dietary D₃ were more susceptible to ventricular arrhythmia. Our findings indicate that over-supplementation of vitamin D increases the risk of SDS in broilers, and that the most likely mechanism is associated with increased susceptibility of the ventricular myocardium to arrhythmia.     

Effects of feeding crambe meal upon intake,gain, health and meat quality of broiler chicks

True metabolizable energy of crambe meal was determined with adult cecectomized turkeys to be 11.8 kJ(2.8 kcal)g⁻¹. Amino acid digestibilities were 90% or greater, indicating that protein quality of crambe meal was high. Growing broilers were fed diets containing 0, 50, 100 or 150 (g crambe meal) kg⁻¹ diet (control, 50C, 100C and 150C, respectively) for 56 days. Feed intake for the 150C birds was lower than the other treatments initially; at the end of the experiment, intake of the 150C birds compensated and was similar to the control birds. Weight gain patterns were similar to intake responses. Birds on the 150C treatment had reduced tibial ash content and locomotor difficulties in the first half of the experiment; these effects were absent in the second half of the experiment. Meat quality and serum chemistries were unaffected by feeding crambe meal. Broilers fed the 150C diet had increased liver and kidney weights. Broilers can be fed diets containing up to 50 (g crambe meal) kg⁻¹ diet with no adverse effects on gain and health and up to 100 g kg⁻¹ diet with minimal adverse effects on gain and health.