Evaluation of mango saponin in broilers: effects on growth performance, carcass characteristics, meat quality and plasma biochemical indices.

OBJECTIVE: The objective of the present study was to determine whether mango saponin (MS) could be used as a feed additive in broiler chicks by evaluating growth performance, carcass characteristics, meat quality, and plasma biochemical indices. METHODS: A total of 216 1-d-old Arbor Acres male broiler chicks were randomly assigned into three dietary treatments supplemented with 0 (control), 0.14% (MS 0.14%), or 0.28% (MS 0.28%) MS. Each treatment had six replicates (cages) with 12 chicks each. The feeding trial lasted for six weeks. RESULTS: Compared with the control, dietary supplemented with 0.14% or 0.28% MS increased average daily weight gain of chicks in the grower (22 to 42 d) and the whole (1 to 42 d) phases, and the final body weight of chicks on d 42 was higher in MS supplemented groups (p<0.05). Lower L45 min* (lightness) and L24 h* values, lower b24 h* (yellowness) value, and higher a45 min* (redness) and a24 h* values of the breast muscle were observed in chicks fed with 0.28% MS on d 42 (p<0.05). The total antioxidant capacity in plasma increased in MS 0.14% group on d 21 (p<0.001). Lower contents of plasma total cholesterol and triglyceride were observed in chicks fed with 0.28% MS on d 21 and d 42, whereas the group supplemented with 0.14% MS only decreased plasma triglyceride content on d 21 (p<0.05). The glucose content in plasma decreased in MS 0.28% group on d 42 (p<0.001). CONCLUSION: Overall, MS could be used as a feed additive in broiler chicks, and the supplemental level of 0.28% MS in diet could improve growth performance, meat quality, and plasma lipid metabolism in broiler chicks.

Effects of Dietary Octacosanol on Growth Performance, Carcass Characteristics and Meat Quality of Broiler Chicks.

Octacosanol, which has prominent physiological activities and functions, has been recognized as a potential growth promoter in animals. A total of 392 1-d-old male Arbor Acres broiler chicks with similar body weight were randomly distributed into four dietary groups of seven replicates with 14 birds each supplemented with 0, 12, 24, or 36 mg octacosanol (extracted from rice bran, purity >92%)/kg feed. The feeding trial lasted for six weeks and was divided into the starter (day 1 to 21) and the grower (day 22 to 42) phases. The results showed that the feed conversion ratio (FCR) was significantly improved in broilers fed a diet containing 24 mg/kg octacosanol compared with those fed the control diet in the overall phase (day 1 to 42, p = 0.042). The average daily gain and FCR both showed linear effects in response to dietary supplementation of octacosanol during the overall phase (p = 0.031 and 0.018, respectively). Broilers fed with 24 or 36 mg/kg octacosanol diet showed a higher eviscerated yield, which increased by 5.88% and 4.26% respectively, than those fed the control diet (p = 0.030). The breast muscle yield of broilers fed with 24 mg/kg octacosanol diet increased significantly by 12.15% compared with those fed the control diet (p = 0.047). Eviscerated and breast muscle yield increased linearly with the increase in dietary octacosanol supplementation (p = 0.013 and 0.021, respectively). Broilers fed with 24 or 36 mg/kg octacosanol diet had a greater (p = 0.021) pH45min value in the breast muscle, which was maintained linearly in response to dietary octacosanol supplementation (p = 0.003). There was a significant decrease (p = 0.007) in drip loss value between the octacosanol-added and the control groups. The drip loss showed linear (p = 0.004) and quadratic (p = 0.041) responses with dietary supplementation of octacosanol. These studies indicate that octacosanol is a potentially effective and safe feed additive which may improve feed efficiency and meat quality, and increase eviscerated and breast muscle yield, in broiler chicks. Dietary supplementation of octacosanol at 24 mg/kg diet is regarded as the recommended dosage in the broilers' diet.

Application of low-gossypol cottonseed meal in laying hens' diet.

An experiment was conducted to evaluate the application of dietary low-gossypol cottonseed meal (LCSM) in layers' diets. A total of 432 40-week-old Hy-line W36 laying hens were allocated to one of the six dietary treatments with 6 replicates of 12 birds each. The control group was fed a corn-soybean meal basal diet, and the 4 experimental diets consisted of a basal diet with 50, 98.3, 144.2, or 189 g/kg LCSM, respectively (correspondingly 25%, 50%, 75%, 100% dietary protein provided by soybean meal were replaced by LCSM). The sixth group was fed a basal diet supplemented with free gossypol (FG group). The feeding trial lasted for 12 weeks. The results showed that no significant difference was observed on egg production or feed conversion ratio (FCR, feed/egg, g/g) among all groups, but feed intake and egg weight were significantly decreased in the 189 g/kg LCSM group in weeks 46 to 51 (P < 0.05). A significant decrease was not observed in shell strength, shell thickness, and yolk color in all periods, but Haugh unit, albumen height, and egg white protein content were reduced in 189 g/kg LCSM group in weeks 46 to 51 (P < 0.05). No significant differences were found between the control and FG group. There was no obvious difference on plasma levels of total protein, blood urea nitrogen, uric acid, and activities of albumen, alanine aminotransferase, aspartate aminotransferase and the histopathology of liver, kidney, and oviduct in all groups. In conclusion, decreasing feed intake, egg weight, and egg quality were observed in the 189 g/kg LCSM group. However, the adverse effect was not relevant to the presence of FG in LCSM. Dietary LCSM supplementation of 98.3 g/kg was recommended with optimum FCR and without adverse effect on egg production, quality, and health of layers.

Effects of dietary pyrroloquinoline quinone disodium on growth, carcass characteristics, redox status, and mitochondria metabolism in broilers.

The potential benefits of supplementing pyrroloquinoline quinone disodium (PQQ·Na2) in the diet of broiler chicks were explored. We first examined the effect of different levels of dietary PQQ·Na2 on growth performance, carcass characteristics, and plasma biochemical parameters (trial 1). A total of 490 1-day-old male Arbor Acres (AA) broiler chicks were randomly divided into 5 dietary groups supplemented with 0, 0.05, 0.1, 0.2, or 0.4 mg PQQ·Na2/kg feed. As the 0.2 mg/kg PQQ·Na2 supplement gave the best performance, we then investigated whether this level of PQQ·Na2 influenced the redox status of plasma samples and mitochondrial-related metabolism (trial 2). A total of 120 1-day-old male AA chicks were randomly divided into 2 groups supplemented with 0 or 0.2 mg PQQ·Na2/kg diet. In trial 1, birds fed a diet containing 0.2 mg PQQ·Na2/kg showed lower feed conversion ratio compared with those fed the control diet in the overall study (d 1 to 42, P=0.039). Breast muscle yield (d 42) increased quadratically in response to dietary PQQ·Na2 supplementation (P=0.021). Analysis of plasma biochemical parameters revealed that feeding broiler chicks with ≤0.4 mg/kg PQQ·Na2 did not cause adverse health effects. In trial 2, birds fed 0.2 mg/kg PQQ·Na2 again showed improved feed efficiency than the control birds in the grower and overall phases (P=0.038 and 0.016, respectively). In addition, dietary PQQ·Na2 supplementation resulted in a higher anti-oxidative capacity (P=0.001), lower redox potential (P=0.008), and higher hepatic citrate synthase activity (P=0.002). In contrast, no difference in hepatic mitochondrial DNA copy number was observed between the 2 experimental groups (P>0.1). These results indicate that PQQ·Na2 is a potentially effective feed additive for improving feed efficiency, stimulating breast muscle development, and maintaining redox status in broiler chicks. Enhancement of mitochondria efficiency, rather than modulating mitochondria numbers, may underlie the growth-promoting effect of PQQ·Na2.

Bioefficacy comparison of organic manganese with inorganic manganese for eggshell quality in Hy-Line Brown laying hens.

This study was aimed at investigating the bioefficacy of organic compared with inorganic manganese (Mn) for eggshell quality. An amino acid-Mn complex or Mn sulfate monohydrate was used as the organic or inorganic Mn source. A total of six hundred forty-eight 50-wk-old layers (Hy-Line Brown) were divided into 9 groups; each group consisted of 6 replicates with 12 layers each. The feeding trial lasted 12 wk. During the first 4 wk of the feeding trial, the groups were fed a basal diet, which met the nutrient requirements of the layers, except for Mn. During the following 8 wk, 9 levels of Mn (inorganic Mn: 0, 25, 50, 100, and 200 mg/kg; organic Mn: 25, 50, 100, and 200 mg/kg) were used to supplement, respectively, in the basal diet on an equimolar basis. An exponential regression model was applied to calculate the bioefficacy of organic Mn compared with the inorganic Mn. Dietary supplementation with either organic or inorganic Mn did not influence egg production and feed efficiency of (P > 0.05), and eggshell quality did not exhibit a significant response to dietary supplementation with Mn sources at 56 and 58 wk (P > 0.05). Dietary supplementation with either organic Mn or inorganic Mn significantly enhanced the thickness, breaking strength, and elastic modulus of the eggshells compared with the control group at the end of 62 wk (P < 0.05). At the end of 62 wk, the bioefficacy of organic Mn was 357% (shell thickness), 406% (breaking strength), 458% (elastic modulus), and 470% (eggshell Mn), as efficacious as inorganic Mn at equimolar levels. This study suggests that organic Mn enhances eggshell quality in aged laying hens compared with inorganic Mn.

Dietary Protein Sources Affect Internal Quality of Raw and Cooked Shell Eggs under Refrigerated Conditions.

This study was conducted to evaluate the effects of various protein sources (soybean meal, SBM; cottonseed protein, CSP; double-zero rapeseed meal, DRM) on the internal quality of refrigerated eggs. A total of 360 laying hens (32 wk of age) were randomly allotted to six treatment groups (five replicates per treatment) and fed diets containing SBM, CSP, or DRM individually or in combination with equal crude protein content (SBM-CSP, SBM-DRM, and CSP-DRM) as the protein ingredient(s). A 6×3 factorial arrangement was employed with dietary types and storage time (0 d, 2 wk, and 4 wk) as the main effects. After 12 wk of diet feeding, a total of 270 eggs were collected for egg quality determination. The egg Haugh unit (HU) in the CSP, SBM-DRM, and DRM groups were significantly lower than those in the SBM and SBM-CSP groups. The hardness and springiness of the cooked yolk in the CSP group were significantly higher than those in the other treatment groups. A lower HU, lower yolk index and higher albumen pH were observed in the DRM group compared to the SBM and SBM-CSP groups when the eggs were stored to 4 wk, and the HU was improved in the CSP-DRM group compared to the DRM group (p<0.05). Higher yolk hardness was observed in the CSP group compared to the other groups during storage (p<0.05), but the hardness of the cooked yolk in the SBM-CSP and CSP-DRM groups showed no difference in comparison to the SBM group. In conclusion, CSP may ameliorate the negative effects of DRM on the HU of refrigerated eggs, and SBM or DRM may alleviate the adverse effects of CSP on yolk hardness.

Manganese supplementation enhances the synthesis of glycosaminoglycan in eggshell membrane: a strategy to improve eggshell quality in laying hens.

This study investigated the effect of dietary Mn supplementation on eggshell quality, ultrastructure, glycosaminoglycan (GAG), and uronic acid content, and mRNA and protein expression of Galß1,3-glucuronosyltransferase (GlcAT-I). A total of 216 layers (Hy-Line Grey) at age of 50 wk were divided into 3 groups. In the first 8 wk of the 12-wk feeding trial, all groups were fed a basal diet that met all layer nutrient requirements except for Mn. In the last 4 wk, each group was fed 1 of 3 diets supplemented with Mn levels at 0, 25, or 100 mg Mn/kg. Dietary Mn deficiency did not affect the egg performance of layers. Dietary Mn supplementation significantly improved the breaking strength, thickness, and fracture toughness of eggshells (P < 0.05). In photographs of eggshell ultrastructure, the size of mammillary cones and cracks in the outer surface were decreased by dietary Mn supplementation. The contents of GAG and uronic acids in eggshell membrane were significantly increased by dietary Mn addition (P < 0.05). This result was further confirmed by increased mRNA expression and protein expression of GlcAT-I when Mn was added to the diet. This study suggests that dietary Mn supplementation can improve eggshell quality by enhancing the GAG and uronic acid synthesis in the eggshell glands, which can affect the ultrastructure of eggshells.

Trimethylamine deposition in the egg yolk from laying hens with different FMO3 genotypes.

The A/T polymorphism at position nt 1,034 of the chicken FMO3 cDNA sequence is associated with elevated levels of trimethylamine (TMA) in the egg yolk, which is responsible for the fishy egg flavor. This study was aimed to investigate yolk TMA deposition in eggs from different FMO3 genotype (AA, AT, TT) laying hens fed a high level of choline, and the relationship between egg yolk TMA contents and yolk acceptability. A total of 132 genotyped laying hens, 38 wk of age, were assigned to 1 of the 4 dietary treatments: 1) a control group of AA hens fed 370 mg of choline/kg of diet (practical choline level, provided by 500 mg of choline chloride/kg of diet); 2) AA hens were fed 2,960 mg of choline/kg of diet (higher dietary choline level, provided by 4,000 mg of choline chloride/kg of diet); 3) AT hens were fed 2,960 mg of choline/kg of diet; and 4) TT hens were fed 2,960 mg of choline/kg of diet. All layers were fed a 370 mg of choline/kg added diet for a period of 1-wk adaptation followed by a 6-wk trial period. A remarkable increase in yolk TMA concentration of TT hens (P < 0.001) caused by dietary choline addition at 2,960 mg/kg was observed. The relationship between TMA concentration in the egg yolk (µg/g, y) and deposition time (1~42 d, x) for TT hens is y = 0.0005x(3) - 0.0419x(2) + 1.0924x + 0.4323 (R(2) = 0.9259). The fish-flavor scores of egg yolks rose steadily (R(2) = 0.9324) as the TMA concentration increased, and there was also a corresponding decrease in the acceptance score (R(2) = 0.8276). The eggs were acceptable when the yolk TMA concentrations were less than 4.516 µg/g of yolk.

Effect of ß-hydroxy-ß-methylbutyrate calcium on growth, blood parameters, and carcass qualities of broiler chickens.

Beta-hydroxy-ß-methylbutyrate (HMB), the metabolite of leucine, plays an important role in muscle protein metabolism. To investigate the effect of dietary HMB calcium (HMB-Ca) on growth performance, breast muscle development, and serum parameters in broiler chickens, a total of two hundred seventy 1-d-old Arbor Acres male broiler chicks were randomly allotted into 3 dietary treatments supplemented with 0, 0.05%, or 0.1% HMB-Ca during the starter (1 to 21 d) and grower (22 to 42 d) period. The results showed that broilers fed 0.1% HMB-Ca diet had higher ADG during the starter or the whole period, and gain 148 g more BW than the chicks fed the control diet at 42 d of age (P < 0.05). At 21 d of age, birds receiving 0.1% HMB-Ca had more breast muscle yield, less abdominal fat than the control, and more dressing percentage than birds fed the control or 0.05% HMB-Ca diet (P < 0.05). At 42 d of age, 0.1% HMB-Ca increased breast muscle yield than the control and decreased abdominal fat compared with the control or 0.05% HMB-Ca group (P < 0.05). In comparison with the control, feeding 0.1% HMB-Ca increased the triiodothyronine, thyroxine, triiodothyronine/thyroxine ratio and decreased the serum uric acid level at d 21 (P < 0.05). At 42 d of age, serum thyroxine level was elevated in the 0.05% HMB-Ca treatment, and the uric acid concentration was significantly decreased by the 0.1% HMB-Ca-supplemented diet (P < 0.05). Dietary HMB-Ca did not affect the growth hormone or insulin content. This study suggested that dietary supplementation of HMB-Ca improved growth performance, stimulated the breast muscle development, and decreased the abdominal fat deposition in broiler chickens, and the favorable effects were more pronounced in the starter phase. The growth promotion effect of HMB-Ca may be partly related to the increased serum thyroid hormones in broiler chickens.

Effect of dietary choline supplementation under different flavin-containing monooxygenase 3 genotypes on trimethylamine metabolism in laying hens.

To evaluate the effect of flavin-containing monooxygenase 3 (FMO3) genotype and dietary choline supplementation on trimethylamine (TMA) metabolism in HyLine Brown laying hens, a 3 × 2 two-factorial arrangement was employed with FMO3 genotypes (AA, AT, and TT) and dietary choline supplemental levels (370 and 2,960 mg/kg of diet) as main effects. At 46 wk of age, 108 hens of AT genotype and 108 hens of TT genotype were randomly allotted to one of the 2 dietary treatments, and each dietary treatment consisted of 6 replicates with 9 birds each. A total of 24 hens with AA genotype was allotted to one of the 2 dietary treatments that consisted of 6 replicates with 2 hens. Hens were fed the diet with 370 mg/kg of choline supplementation for 1 wk of adaptation followed by a 6-wk trial period. Yolk TMA concentration was increased by dietary supplemental choline at 2,960 mg/kg (P < 0.05), and TT hens showed a higher TMA content in egg yolks than that in AA and AT hens (P < 0.05). Dietary supplementation of choline at 2,960 mg/kg increased the TMA concentration of cecal chyme (P < 0.05) and serum (P < 0.05). Hepatic FMO3 mRNA levels in hens were reduced by higher choline added to the diet (P < 0.05). The TMA and methimazole oxidation rate in AA hens was higher than those in AT and TT hens (P < 0.05). A higher choline diet decreased hepatic FMO3 activity by 33.99% (P < 0.05) and 61.39% (P < 0.05) toward TMA and methimazole, respectively. These results suggest that lower hepatic FMO3 activity caused by the mutation may be responsible for the genotype difference in the TMA metabolism. Exposure to a high dosage of dietary choline increased TMA synthesis in the cecum, suppressed activity of FMO3 in liver, and consequently aggravated the burden of TMA metabolism, especially in TT hens.

Effect of monochromatic light stimuli during embryogenesis on muscular growth, chemical composition, and meat quality of breast muscle in male broilers.

This study was conducted to evaluate the effect of monochromatic light stimuli during embryogenesis on breast muscle growth, chemical composition, and meat quality of male broilers. Fertile broiler eggs (Arbor Acres; n = 1,320) were preweighed and randomly assigned to 1 of 3 treatment groups in 3 modified incubators: 1) control group (in dark condition), 2) monochromatic green light group (560 nm), and 3) monochromatic blue light group (480 nm). The monochromatic lighting systems sourced from light-emitting diode lamps and were equalized at the intensity of 15 lx at eggshell level. After hatch, 120 male chicks from each group were placed in 6 replicates with 20 birds each. All of the birds were housed under white light (30 lx at bird-head level) with a light schedule of 23L:1D. At 21, 35, and 42 d of age, BW and breast muscle weight in the green light group were significantly increased compared with birds in the blue or dark groups (P < 0.05). The breast muscle weight and breast muscle percentages in birds incubated under green light were significantly elevated by 50.39 g (0.76%) and 54.07 g (1.20%) than those in the dark condition or blue group at 42 d of market age (P < 0.05), respectively. In the green light group, feed intake during 0~42 d was higher than that in the other 2 treatment groups (P < 0.05); feed conversion ratio during 0~35 and 0~42 d were lower than that in the dark condition (P < 0.05). No significant differences in the contents of breast moisture, CP, crude fat, and crude ash among all groups were observed (P > 0.05). Green light stimuli tended to increase cooking loss (P = 0.08) and L* value of 24-h meat color (P = 0.09). These results suggest that green light stimuli during embryogenesis enhanced the posthatch BW of male broilers, increased breast muscle growth, and improved the feed conversion ratio, but it did not cause any noticeable changes in breast chemical composition or overall meat quality characteristics.

Comparison of lipid oxidation, messenger ribonucleic acid levels of avian uncoupling protein, avian adenine nucleotide translocator, and avian peroxisome proliferator-activated receptor-γ coactivator-1α in skeletal muscles from electrical- and gas-stunned broilers.

The aim of this study was to compare the effects of stunning methods [electrical stunning (ES) vs. gas stunning (GS)] on lipid oxidation in broiler meat and to investigate possible mechanisms of lipid oxidation by measuring plasma variables, muscle reactive oxygen species (ROS), and TBA reactive substance (TBARS) concentrations, muscle fiber ratios, and mRNA levels of avian uncoupling protein (avUCP), avian adenine nucleotide translocator, and avian peroxisome proliferator-activated receptor-γ coactivator-1α (avPGC-1α). Arbor Acres broilers (n = 36) were not stunned (control) or were exposed to the following stunning treatments: 40% CO(2) + 21% O(2) + N(2); 60% CO(2) + 21% O(2) + N(2); 35 V, 47 mA, 400 Hz; 50 V, 67 mA, 160 Hz; and 65 V, 86 mA, 1,000 Hz. The ROS level in tibialis anterior (TA; P < 0.05) and the TBARS concentration in pectoralis major (PM; P < 0.01) were decreased in the GS groups compared with the ES groups at 45 min postmortem. However, the TBARS concentrations at 24 h postmortem in the PM and TA groups were not affected by stunning method (ES or GS). Compared with ES, GS caused greater expression of avUCP mRNA (1.47-fold in PM, and 2.41-fold in TA) and avPGC-1α mRNA (1.42-fold in PM, and 2.08-fold in TA). In conclusion, the upregulation of avUCP and avPGC-1α reduced ROS accumulation and lipid oxidation at 45 min postmortem in the skeletal muscles of broilers stunned with hypercapnic moderate oxygenation GS. However, these changes were not sufficient to cause a difference in meat lipid oxidation at 24 h postmortem between broilers stunned with hypercapnic moderate oxygenation GS and those stunned with low-current, high-frequency ES.

Effects of dietary oxidized oil on laying performance, lipid metabolism, and apolipoprotein gene expression in laying hens.

We studied the effects of dietary oxidized oils on serum lipid metabolic indices, estradiol level, and the gene expression of apolipoprotein B-100 and apolipoprotein VLDL-II in laying hens. Hy-Line Grey hens (280 ± 10 d old; average egg production, 90.0 ± 2.5%) were allotted to 1 of 4 dietary treatments, which were supplemented with 0 (control group), 1% (low oxidized group), 2% (moderately oxidized group), or 4% (highly oxidized group) thermally oxidized soybean oil. Each treatment contained 6 replicates, with 12 birds each. The feeding trial lasted for 30 d. Laying performance data were recorded weekly. Other indices were measured on d 0, 2, 6, 14, and 30 of the feeding trial. Hens in the moderately and highly oxidized groups had significantly lowered feed conversion ratios (P < 0.05). Those in the highly oxidized group also had decreased concentrations of serum very low density lipoprotein cholesterol on d 30 (P < 0.05) compared with the very low density lipoprotein cholesterol of hens in the moderately oxidized group. Hens in the moderately oxidized group had significantly increased expression of apolipoprotein B-100 (P < 0.05) from d 6 to 30. Consequently, hepatic triglyceride increased in this group on d 30 (P < 0.05). Serum triglyceride decreased in the moderately oxidized group on d 30 (P < 0.05), which may have been caused by the activation of peroxisome proliferator-activating receptor α. Serum estradiol levels were not significantly affected by oxidized oils at any time of measurement, but were significantly different between d 0 and 30 within the moderately oxidized group. This fact indicated that the effect of oxidized oils on apolipoprotein B-100 might partially be a cumulative result of the increasing secretion of estradiol. The results suggested that oxidized oil may affect the performance of laying hens through the regulation of apolipoproteins and estradiol.

Effect of electrical stunning current and frequency on meat quality, plasma parameters, and glycolytic potential in broilers.

This study was designed to determine the effect of electrical stunning variables (low currents and high frequencies) on meat quality, glycolytic potential, and blood parameters in broilers. A total of 54 broilers were stunned with 9 electrical stunning methods for 18 s using sinusoidal alternating currents combining 3 current levels (35 V, 47 mA; 50 V, 67 mA; and 65 V, 86 mA) with 3 frequencies (160, 400, and 1,000 Hz). Samples for meat quality were obtained from the pectoralis major (PM) and musculus iliofibularis (MI), and samples for glycogen metabolism were taken from the PM and tibialis anterior muscle at 45 min postmortem. The use of high frequency reduced the shear value in PM (400 and 1,000 Hz vs. 160 Hz; P < 0.01) and cooking loss in MI (1,000 Hz vs. 160 and 400 Hz; P < 0.01). The shear value of PM decreased at high frequency (400 and 1,000 Hz) when current was high (50 V, 67 mA and 65 V, 86 mA; P < 0.01) but increased at high frequency (1,000 Hz) when current was low (35 V, 47 mA). Stunning with 1,000 Hz (vs. 160 Hz) caused low glycogen and glycolytic potential in PM (P < 0.05). Plasma corticosterone decreased (P < 0.05) at high currents (≥50 V, 67 mA) but was not affected by changes in frequency. Electrical current interacted with frequency in plasma glucose, redness 24 h postmortem, shear value (PM), pH 24 h postmortem (MI), and glycolytic potential (tibialis anterior; P < 0.05). This study indicated that high stunning frequencies (400 and 1,000 Hz) may improve meat quality without aggregating stress when the current was not too low (>50 V, 67 mA).

Plasma variables, meat quality, and glycolytic potential in broilers stunned with different carbon dioxide concentrations.

This study aimed to investigate the effects of different CO(2) concentrations on blood variables, glycolytic potential (GP), and meat quality of hot-boned muscles in broilers. Thirty broilers were exposed to one of the following 5 gas mixtures for 90 s: 40% CO(2) + 30% O(2) + N(2) (control), 30% CO(2) + 21% O(2) + N(2) (G30%), 40% CO(2) + 21% O(2) + N(2) (G40%), 50% CO(2) + 21% O(2) + N(2) (G50%), and 60% CO(2) + 21% O(2) + N(2) (G60%). Samples were taken from the pectoralis major (PM), musculus iliofibularis (MI), and tibialis anterior muscles 45 min postmortem. The ultimate pH in both the PM (vs. G30% and G40%) and MI (vs. G40%) was decreased with G60% (P < 0.05), whereas drip loss in the PM (vs. G30%, P = 0.01) was increased with G60%. Drip loss in the MI (vs. control and G30%, P < 0.01) was increased with G50%. Lightness after 24 h in PM (vs. G30% and G40%, P < 0.01) was increased with G50%. In MI, lightness after 24 h was slightly decreased with G40% compared with the control (P < 0.10). The GP value in the PM was lower in the G30% and G40% than in G60% (P < 0.05), and the GP value in the tibialis anterior was the lowest in G30% (P < 0.01). Plasma corticosterone, plasma glucose, and meat quality (pH, lightness, redness, yellowness) 45 min postmortem were not affected by CO(2) levels (P > 0.05). In conclusion, stunning broilers with low CO(2) levels (30 and 40%) improved meat quality but had no advantage in animal welfare compared with high CO(2) levels (50 and 60%).

Comparison of blood variables, fiber intensity, and muscle metabolites in hot-boned muscles from electrical- and gas-stunned broilers.

The aim of this study was to compare the effects of gas stunning (GS) and electrical stunning (ES) on energy metabolism in Arbor Acres broilers. Thirty-six birds were slaughtered without stunning (control) or after stunning with the following treatments: 40% CO(2) + 21% O(2) + N(2) (G40%); 60% CO(2) + 21% O(2) + N(2) (G60%); 35 V, 47 mA, 400 Hz (E35V); 50 V, 67 mA, 160 Hz (E50V); and 65 V, 86 mA, 1,000 Hz (E65V). Muscle samples were obtained from the pectoralis major (breast) and tibialis anterior (leg) muscles in ambient temperature within 45 min postmortem and stored at -80°C. Blood pH decreased consistently with GS (G40% and G60%) compared with ES and the control (P < 0.01). No consistent differences were observed between GS and ES in the plasma variables, glycolytic potential, adenosine phosphates, or fiber intensities. Plasma lactate increased with G40% and E35V (P < 0.05), whereas plasma uric acid and urea nitrogen increased with E35V (P < 0.05) compared with the control. Compared with the control, the intensity of type IIB fibers decreased in broilers stunned with E35V and E50V (P < 0.05) and glycolytic potential increased (P < 0.01) with G60% in the breast muscle and decreased (P < 0.01) in the leg muscle with all the stunning treatments except for E50V. Energy decreased (lower adenosine triphosphate, higher adenosine monophosphate, and adenosine monophosphate:adenosine triphosphate ratio, P < 0.05) in breast muscle with G40% compared with ES at high currents (E50V and E65V). However, the adenosine phosphates with GS were not significantly different (P > 0.05) from ES at low current (E35V) in either breast or leg muscle. In conclusion, no essential difference in energy metabolism was found in broilers stunned with ES and GS when ES was based on low current and high frequency and GS was based on hypercapnic moderate oxygenation. This study indicated that G40% was potentially a superior stunning variable.

Dietary supplementation with sodium bicarbonate or sodium sulfate affects eggshell quality by altering ultrastructure and components in laying hens.

Dietary sodium (Na) levels were related to the content of the eggshell matrix. We therefore speculated that dietary Na supplementation as sodium bicarbonate (NaHCO3) or sodium sulfate (Na2SO4) may improve eggshell quality. Additionally, dietary NaHCO3 or Na2SO4 supplementation may further affect eggshell quality in different ways due to differences in anions. This study investigated and compared the effects of dietary Na supplementation in either NaHCO3 or Na2SO4 form on laying performance, eggshell quality, ultrastructure and components in laying hens. A total of 576 29-week-old Hy-Line Brown laying hens were randomly allocated to 8 dietary treatments that were fed a Na-deficient basal diet (0.07% Na, 0.15% Cl) supplemented with Na2SO4 or NaHCO3 at 0.08, 0.18, 0.23 or 0.33% Na for 12 weeks. No differences were observed in laying production performance with dietary Na supplementation. Dietary Na supplementation resulted in quadratic increases of eggshell breaking strength in both Na2SO4 and NaHCO3 added groups (P < 0.05), and Na2SO4-fed groups had a quadratic increase in the eggshell ratio at week 12 (P < 0.05). Compared with supplementing 0.08% Na, dietary supplementation of 0.23% Na increased the effective thickness (P < 0.05) in both Na2SO4 and NaHCO3 added groups, but decreased the thickness and knob width of the mammillary layer (P < 0.05). A linear increase on the calcium content of the shell was only observed with Na supplementation from NaHCO3 (P < 0.05). No differences were observed in Na contents of the shell with dietary Na supplemented by both sources. Dietary Na addition had a quadratic increase on uronic acid contents of shell membrane in NaHCO3-fed groups (P < 0.05). Moreover, the sulfated glycosaminoglycan (GAG) contents of shell membranes increased linearly with dietary Na supplementation (P < 0.05). Dietary supplementation of 0.23% Na from Na2SO4 increased the sulfated GAG contents of calcified eggshell (P < 0.05). Additionally, compared with NaHCO3-fed groups, Na2SO4-fed groups had higher eggshell breaking strength, thickness, eggshell weight ratio, effective thickness and the sulfated GAG contents of calcified eggshell at week 12. Overall, dietary supplementation of NaHCO3 or Na2SO4 could increase eggshell breaking strength, which may be related to increased sulfated GAG contents in eggshell membranes and improved ultrastructure. Higher eggshell breaking strength, thickness and eggshell ratio could be obtained when the diet was supplemented with 0.23% Na from Na2SO4.

Effects of transport stress on blood metabolism, glycolytic potential, and meat quality in meat-type yellow-feathered chickens.

To investigate the effects of transport stress on blood metabolism, glycolytic potential, and meat quality in male Chinese Lingnan meat-type yellow-feathered chickens, three hundred sixty 72-d-old birds were randomly assigned to 1 of 5 treatments: unstressed control, 45-min (short-term) transport with 45-min (short-term) recovery, 45-min transport with 3-h (long-term) recovery, 3-h (long-term) transport with 45-min recovery, and 3-h transport with 3-h recovery. Each treatment consisted of 6 replicates with 12 birds each. All birds (except control group) were transported according to a designed protocol. Long-term transport decreased the plasma glucose level (P < 0.001), glycogen concentration in both breast (P = 0.023) and thigh (P = 0.012) muscles, and affected the size of IIb fibers in the tibialis anterior by decreasing the area (P = 0.031) and increasing the density (P = 0.046), drip loss (P = 0.045), and the a* (redness; P = 0.040) value in breast muscle. Long-term recovery after transport also decreased the plasma glucose level (P = 0.018) and showed a trend toward decreased breast glycogen concentration (P = 0.064). These results suggested that transport did not cause any noticeable changes in overall meat quality characteristics, although breast meat drip loss and meat color were affected. A long-term recovery from a period of feed and water deprivation also caused hypoglycemia and did not improve meat quality in Lingnan meat-type yellow-feathered chickens.

Transport stress in broilers. II. Superoxide production, adenosine phosphate concentrations, and mRNA levels of avian uncoupling protein, avian adenine nucleotide translocator, and avian peroxisome proliferator-activated receptor-gamma coactivator-1alpha in skeletal muscles.

The effect of transport stress on superoxide production and adenosine phosphate concentration in addition to avian uncoupling protein (avUCP), avian adenine nucleotide translocator, and avian peroxisome proliferator-activated receptor-gamma coactivator-1alpha mRNA levels of skeletal muscles in broilers was investigated. Arbor Acres chicks (n = 360, 46 d old, males) were randomly allotted to 1 of 5 treatments: unstressed control, 45-min (short-term) transport with 45-min (short-term) recovery, 45-min transport with 3-h (long-term) recovery, 3-h (long-term) transport with 45-min recovery, and 3-h transport with 3-h recovery. Each treatment consisted of 6 replicates with 12 birds each. All birds (except control group) were transported according to a designed protocol. Transport time affected reactive oxygen species production in the thigh muscle (P < 0.05), adenosine triphosphate (ATP) content and energy charge (EC) in both breast and thigh muscles (P < 0.05 for all 4 comparisons), ATP:adenosine diphosphate (ADP) ratio in the breast muscle (P < 0.05), and avUCP mRNA levels in the thigh muscle (P < 0.05). Long-term transport increased (P < 0.05) reactive oxygen species production, ATP content, ATP:ADP ratio, and EC in the thigh muscle, but it decreased ATP content, ATP:ADP ratio, and EC in the breast muscle. Long-term transport increased avUCP mRNA in the thigh muscle (P < 0.05). Long-term recovery increased the ATP (P < 0.05) and ADP (P < 0.05) concentrations, avian adenine nucleotide translocator mRNA (P < 0.05), and avian peroxisome proliferator-activated receptor-gamma coactivator-1alpha mRNA (P < 0.05) in the thigh muscle, whereas EC decreased (P < 0.05) in the breast muscle. There were interactions between transport and recovery time on ATP (P < 0.05), EC (P < 0.05), and avUCP mRNA level (P < 0.05) in the thigh muscle. This study suggests that long-term transport accelerates muscle energy metabolism and lipid peroxidation. A long-term recovery may help alleviate cellular damage and maintain meat quality by reducing the rate of energy metabolism and scavenging of free radicals formed.

Transport stress in broilers: I. Blood metabolism, glycolytic potential, and meat quality.

The effect of transport stress on blood metabolism, glycolytic potential, and meat quality in broilers was investigated. Arbor Acres chicks (n = 360, 1 d old, males) were randomly allotted to 1 of 5 treatments: unstressed control, 45-min (short-term) transport with 45-min (short-term) recovery, 45-min transport with 3-h (long-term) recovery; 3 h (long-term) transport with 45-min recovery, and 3-h transport with 3-h recovery. Each treatment consisted of 6 replicates with 12 birds each. On d 46, all birds (except the control group) were transported according to a designed protocol. Transport time affected plasma glucose level (P<0.05) and glycogen level (P=0.06) in breast muscle as well as the area (P<0.01) and density (P<0.01) of IIa fibers. Glucose concentration increased slightly during the first 45 min of transport and then decreased dramatically in the long-term transported broilers (P<0.05). Long-term transport decreased the concentration of breast glycogen (P=0.06) and affected the size of IIa fibers in tibialis anterior by decreasing the area (P<0.01) with an increase in density (P<0.01). However, a long-term recovery after transport contributed to the homeostasis of blood corticosterone (CORT, P=0.05) and low levels of glycogen (P<0.05), lactate (P<0.01), and glycolytic potential (P<0.01) in thigh muscles. Interactions existed between transport and recovery time on area (P<0.05) and density (P<0.01) of IIa fibers. Furthermore, plasma nonesterified fatty acids increased significantly in the 3-h transport with 3-h recovery group (P<0.05) in comparison with the control. These results suggested that transport induced the release of plasma CORT and glycopenia, which affected the contractive status of muscle fibers by changing their area and density, and enhanced glycolysis and even lipolysis. A long-term recovery after transport was beneficial in lowering plasma CORT levels and reducing muscle glycolysis, which might improve broiler meat quality.