Effect of dietary histidine on contents of carnosine and anserine in muscles of broilers

Carnosine (β‐alanyl‐L‐histidine) and anserine (β‐alanyl‐1‐methyl‐L‐histidine) are dipeptides mainly found in skeletal muscle and brain of many vertebrates, and particularly high concentrations are observed in chicken pectoral muscles. It was reported that these peptides have many functions, such as antioxidant activity. In this study, we examined the effect of different levels of dietary histidine on carnosine and anserine contents in broiler muscles. The 14‐days‐old female Chunky strain broilers were given feeds containing three different levels of histidine; 67% (Low‐His), 100% (Control) and 200% (High‐His) of histidine requirement according to the NRC (1994). Chicks were fed experimental diets for 10 days. Both dipeptides in muscle were significantly decreased. In particular, carnosine was not detected at all in the Low‐His group and was significantly increased in the High‐His group. Both dipeptides were not detected in plasma. These results indicated the possibility to produce chicken meat with enhanced amount of these dipeptides by high histidine feeding.     

Dietary β-alanine enhances brain, but not muscle, carnosine and anserine concentrations in broilers

Carnosine (β‐alanyl‐L‐histidine) and its derivative anserine (β‐alanyl‐1‐methyl‐L‐histidine) are present in high concentrations in the muscle and brain of chickens. They are known as antioxidants and putative neurotransmitters in the brain. If administration of β‐alanine (β‐Ala), one of the constituents of carnosine, could increase the concentrations of these dipeptides in the brain and muscles, it could improve brain function and increase the commercial value of the meat in chickens. As an early step in investigating this hypothesis, in the present study, the effect of dietary β‐Ala on these dipeptide concentrations in the brain, Musculus pectoralis superficialis, Musculus pectoralis profundus and Musculus biceps femoris was investigated in broilers. Four‐week‐old broilers were given a commercial diet or diet containing 0.5, 1 or 2%β‐Ala for 4 weeks. At the end of the experiment, concentrations of both dipeptides were increased in the brain, while taurine concentration was decreased. In the muscles, concentrations of these dipeptides were unchanged. These results indicate that dietary β‐Ala might influence brain function, but is ineffective in increasing the concentrations of carnosine and anserine in the muscles of broilers.     

Effects of dietary supplementation with carnosine on meat quality and antioxidant capacity in broiler chickens

1. This study aimed to investigate the effects of carnosine supplementation on meat quality, antioxidant capacity and lipid peroxidation status in broiler chickens.

2. A total of 256 1-d-old male Arbor Acres broilers were randomly assigned to 4 treatments consisting of 8 replicates of 8 chickens each. The birds were supplied with 4 different diets: a basal diet or a basal diet supplemented with 100, 200 or 400 mg/kg carnosine, respectively. The whole experiment lasted 42 d.

3. The results showed that dietary supplementation with carnosine linearly increased the values of pH_45 min and redness and reduced drip loss of breast meat. Dietary carnosine increased the activity of antioxidant enzymes in liver, serum and breast meat and decreased the contents of lipid peroxides at 21 and 42 d of age.

4. These findings indicated that dietary supplementation with carnosine was beneficial to enhance meat quality, antioxidant capacity and decrease lipid peroxidation status of breast meat.     

Accurate analysis of taurine,anserine, carnosine and free amino acids in a cattle muscle biopsy sample

We have established an analysis method for some free amino acids (FAAs), as well as taurine (Tau), anserine (Ans) and carnosine (Car), in a fresh biopsy sample from cattle muscle. A series of model biopsy samples, corresponding to the mixtures of lean meat, fat and connective tissue, was prepared and showed high correlation coefficients between the compound concentration and the 3‐methylhistidine (3‐MeHis) content derived from hydrolysis of the biopsy sample (r = 0.74–0.95, P < 0.01). Interference from blood contamination could not be neglected, because the concentration of some FAAs in blood was comparable to that in muscle. However, it was possible to control the contamination of Tau, Ans, Car, glutamic acid, glutamine, asparatic acid and alanine to less than 5.0% when the blood contamination was controlled to less than 23%.These results suggest the necessity of measuring 3‐MeHis as an index of lean meat and hemoglobin as an index of blood contamination when compounds in muscle biopsy samples are evaluated. We have carried out a series of these analyses using one biopsy sample and reveal differences in Tau, Ans, Car and some FAAs in beef muscle after different feeding regimes.     

Dietary supplementation with carnosine improves antioxidant capacity and meat quality of finishing pigs

This study was conducted to determine the effect of dietary carnosine (β‐alanyl‐l ‐histidine) supplementation on antioxidant capacity and meat quality of pigs. 72 pigs approximately 60 kg were fed a corn‐ and soybean meal‐based diet supplemented with 0, 25, 50 or 100 mg carnosine per kg diet for 8 weeks. Carnosine supplementation did not affect growth performance and carcass traits of pigs. However, the addition of 100 mg carnosine per kg diet increased pH value of muscle at 45 min, 24 h and 48 h postmortem. It also decreased drip loss at 48 h postmortem and increased redness value of muscle at 45 min postmortem (p < 0.05). The addition of 100 mg carnosine per kg diet enhanced glycogen concentration and Ca‐ATPase activity at 24 and 48 h postmortem, and reduced malondialdehyde and carbonyl protein complexes concentrations in muscle at 24 h postmortem (p < 0.05). The addition of 100 mg carnosine per kg diet increased glutathione peroxidase (GSH‐Px), superoxide dismutase (SOD) and catalase (CAT) activities in plasma, liver or muscle, as well as SOD and GSH‐Px genes expression in muscle (p < 0.05). Taken together, these findings indicate that carnosine supplementation improves antioxidant capacity and meat quality of pigs.     

脱氢表雄酮对AA肉种鸡生产性能和肌纤维发育的影响

为探讨母源性添加DHEA对子生理机能影响的母体效应机制,本试验选用100羽16周龄AA种母鸡随机分成对照组、低剂量试验组、中剂量试验组和高剂量试验组,每组25只。于34周龄开始在饲料中添加DHEA,剂量分别为0、25、50和100 mg.kg-1,连续饲喂7周,期间记录每天的产蛋数并称重。在试验的第49天禁饲12 h,宰杀各组鸡。采集血液、腹脂、左侧胸肌和腿肌,计算产蛋率、平均蛋重、腹脂率、相对胸肌重和相对腿肌重。测定血清中尿酸(UA)和肌酐(Cr)含量。取腿肌和胸肌制作冰冻组织切片,测定肌纤维直径和密度。结果表明,与对照组相比,低剂量组母鸡产蛋率极显著升高(P0.01),中剂量组和高剂量组则极显著降低(P0.01);试验组平均蛋重差异不显著(P0.05);高剂量组母鸡的相对腿肌重显著升高(P0.05),而低剂量组和中剂量组差异不显著(P0.05);试验组腹脂率和相对胸肌重量差异不显著(P0.05);低剂量组血清UA含量极显著升高(P0.01),中剂量组有升高趋势,高剂量组显著升高(P0.05);中剂量组和高剂量组血清Cr含量没有显著变化(P0.05),低剂量组极显著升高(P0.01);3个剂量组AA肉种鸡胸肌肌纤维直径和密度均没有显著变化(P0.05);低剂量组腿肌肌纤维直径没有显著变化(P0.05),中剂量组显著减小(P0.05),高剂量组极显著减小(P0.01);低剂量组腿肌肌纤维密度没有显著变化(P0.05),中剂量组显著增大(P0.05),高剂量组极显著增大(P0.01)。     

The effects of pelleting and glucanase supplementation in hulled barley based diets on feed manufacture,broiler performance,and digesta viscosity

Feeding broilers barley-based diets requires special consideration primarily due to effects on increased digesta viscosity and decreased nutrient digestion. Pelleting and glucanase supplementation are commonly performed prior to feeding broilers barley-based diets; however, the interaction of these practices is complex. The objective of this study was to establish a comprehensive evaluation of glucanase efficacy including: degree of processing, activity postpelleting, broiler performance, and digesta viscosity. Treatments were arranged in a 5 (diet formulation) × 2 (processing) factorial in a randomized complete block design with 8 replications/treatment. The 5 diet formulations consisted of positive control (PC), negative control (NC), glucanase A (GA) 125 or 1,000 β-Glu-U/kg feed, and glucanase B (GB) 1,000 β-Glu-U/kg feed. The PC and NC diets differed in metabolizable energy by 150 kcal/kg and enzymes were added to NC formulations. Diets were either fed as unprocessed mash or ground pellets. Diet formulation × processing did not interact for feed intake (FI), FCR, or total tract viscosity (P > 0.05); however, a trend was observed for ending bird weight, demonstrating that for ground pellets, GA 1,000 β-Glu-U/kg feed was improved relative to NC and similar to PC (P = 0.0903). Benefits associated with GB were not of similar magnitude, perhaps in part due to a 50% decrease in activity postpelleting. In addition, GA benefits were not suggested for unprocessed mash. The main effect processing was significant (P < 0.0001) demonstrating that broilers fed ground pellets resulted in greater pen ending bird weight, FI, and bird live weight gain (LWG) compared to birds fed unprocessed mash diets. Evaluations of glucanase should go beyond in vitro activity and include live bird performance using feed that has undergone pelleting.     

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

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

氟西汀和5-羟色胺对肉鸡肺动脉平滑肌细胞增殖与凋亡的影响

为探讨5-羟色胺转载体(5-HTT)在肉鸡肺动脉高压综合征发病中的机制,采用MTT比色法、流式细胞术及Hoechst33258荧光染色法研究5-羟色胺(5-HT)和5-HTT抑制剂氟西汀对体外培养的肉鸡肺动脉平滑肌细胞(PASMC)增殖与凋亡的影响,发现氟西汀能够抑制5-HT促PASMC增殖的作用;氟西汀能明显促进PASMC的凋亡,但氟西汀和5-HT共同作用于细胞,PASMC凋亡率明显少于氟西汀单独处理组。表明5-HTT在调节肉鸡PASMC的增殖和凋亡方面起重要作用,有可能参与肺动脉高压肉鸡肺血管重构的形成。     

Compatibility of dimmers and alternative technology lamps for commercial broiler houses

The use of artificial lighting has become an integral component of the commercial broiler industry, as chickens possess visual acuity superior to that of humans. A variety of new light emitting diode (LED) lamps have become available specifically for use in poultry houses to reduce energy costs, causing many broiler growers to consider implementing LED technology. Lamp dimmers help maximize bird performance by reducing light intensity and often have multiple settings (profiles) used to accommodate different lamps. Because of the investment required to replace lamps in a broiler house, growers have requested information to assist in selecting an appropriate lamp-profile combination. This study evaluated the impact of 8 different commercial dimmers with 21 profiles total on the performance of 15 different LED lamps, one incandescent (INC), and one cold cathode fluorescent lamp (CCFL). Approximately 350 lamp-profile combinations were individually tested for multiple criteria as the lamps were dimmed. A scoring metric was developed that considered linearity, re-fire, luminous output, and efficacy. Dimmer and profile selection impacted lamp luminous output and efficiencies. No one lamp worked effectively with all dimmers and profiles, and no one dimmer or profile worked effectively with all lamps. There were statistically significant differences in scores based on technology, lamp, dimmer, and profile, suggesting that a multifaceted approach is necessary when evaluating the performance of lamps, dimmers, and profiles. A publically available selection tool website allows access to the combination scores. Growers can use this website to make informed decisions, promoting energy savings and agricultural sustainability.     

Effects of methionine and guanidinoacetic acid supplementation on performance and energy metabolites in breast muscle of male broiler chickens fed corn-soybean diets

ABSTRACT

1. Guanidinoacetic acid (GAA) is the single endogenous precursor of creatine, which plays a critical role in energy homeostasis of cells. Since GAA is endogenously converted to creatine by methylation, it was hypothesised that the effects of dietary GAA supplementation might determine the methionine (Met) availability in corn-soybean based diets.

2. A total of 540, one-day-old male Ross 308 broilers were allocated to nine dietary treatments with six replicates (10 birds each) in a 3 × 3 factorial arrangement with three graded levels of supplementary Met (+0.4 g/kg per level), whilst cystine was equal across groups, resulting in a low, medium and high level of total sulphur amino acids, and with three levels of GAA (0, 0.6 and 1.2 g/kg). Birds were fed for 42 days.

3. Increasing levels of supplemental Met enhanced performance indices in all rearing periods, although there was no effect on feed conversion ratio in the grower or feed intake in the finisher periods. Final body weight was 8.8% and 14.6% higher in the birds fed medium and high Met diets, respectively, compared to the low Met level. Relative breast weight and protein content in muscle on d 25 linearly increased with higher levels of Met. At low and high Met levels, growth in the finisher phase was negatively affected by supplementing GAA at 1.2 g/kg. It was suggested that disturbances in methylation homeostasis and/or changes in Arg metabolism might explain these findings. At the end of the grower phase, muscle creatine content was higher when feeding GAA at 0.6 and 1.2 g/kg (4464 and 4472, respectively, vs. 4054 mg/kg fresh muscle in the control group).

4. The effects of dietary GAA supplementation were influenced by the dietary Met level only in the finisher period, which indicates the need for proper sulphur amino acid formulation in diets when feeding GAA.     

Effects of early and late feed restriction or feed withdrawal on growth performance,ascites and blood constituents of broiler chickens

A study was conducted with male broilers to determine the effects of early and late feed restriction or feed withdrawal. In the experiment five treatments were represented by three replicate floor pens, each containing 20 broilers. The experimental procedure was a completely randomized design. The treatments were ad libitum (AL), 25% (FR-25) and 50% (FR-50) feed-restricted or 8 h (FW-8) and 16 h (FW-16) feed withdrawal regimes, respectively. FW-16 regime significantly reduced weight gain to 21 days of age compared to AL or FR-25 regimes (P<0.05). However, the overall weight gains between 9 days and 42 days of age were not significantly affected by the treatments. FW-8 and FW-16 broilers consumed significantly less feed than either AL or FR broilers between 9 and 21 days (P<0.05), however FW-8 and FW-16 broilers had similar feed intake to AL or FR-25 and FR-50 broilers between 9 and 42 days of age. Feed: gain, abdominal fat pad and heart weights, mortality, death due to ascites, and the incidence of leg disorders were unchanged by feeding regimes, although the incidence of ascites in FW-16 was significantly (P<0.05) lower than AL fed broilers. Blood constituents, such as albumin, total cholesterol, ketone bodies, glucose, chlorine, lactate dehydrogenase, alanine aminotransferase and creatine were also significantly affected by feeding regimes (P<0.05).     

Dietary supplementation with pioglitazone hydrochloride and l-carnosine improves the growth performance,muscle fatty acid profiles and shelf life of yellow-feathered broiler chickens

The present study aimed to investigate the effects of dietary pioglitazone hydrochloride (PGZ) and l-carnosine (LC) supplementation on the growth performance, meat quality, antioxidant status, and meat shelf life of yellow-feathered broiler chickens. Five hundred broiler chickens were randomly assigned into 4 experimental diets using a 2 × 2 factorial arrangement with 2 PGZ supplemental levels (0 and 15 mg/kg) and 2 LC supplemental levels (0 and 400 mg/kg) in basal diets for 28 d. The feed-to-gain ratio decreased whereas the average daily gain increased with PGZ supplementation. Greater dressing percentages, contents of intramuscular fat (IMF) in breast and thigh muscles, C18:3n-6, C18:1n-9 and monounsaturated fatty acid (MUFA) percentages of thigh muscle were observed with PGZ addition. Additionally, significant synergistic effects between PGZ and LC on the C18:1n-9 and MUFA contents were found. Supplementation with LC decreased drip loss, cooking loss and total volatile basic nitrogen, and increased the redness (a∗) value, the superoxide dismutase and glutathione peroxidase activities in thigh muscles. Moreover, the malondialdehyde content decreased when diets were supplemented with LC, and there was a synergistic effect between PGZ and LC. Additionally, the mRNA abundance of lipogenesis-related genes, such as peroxisome proliferator-activated receptor γ (PPARγ), PPARγ co-activator 1α and fatty acid-binding protein 3, increased with PGZ supplementation, and relevant antioxidation genes, such as nuclear factor erythroid-2-related factor 2 and superoxide dismutase 1, were enhanced with LC supplementation. In conclusion, the results indicated that the supplementation of PGZ and LC could improve the growth performance, antioxidant ability, IMF content, and meat shelf life of yellow-feathered broiler chickens.     

Randomized control trial to test the effect of a feed additive on Campylobacter contamination in commercial broiler flocks up to slaughter

A randomized controlled trial (RCT) was carried to evaluate the effect of a feed additive on Campylobacter contamination of broilers reared in commercial conditions. Twenty‐four broiler flocks naturally contaminated with Campylobacter were enrolled in the RCT: 12 were assigned to a control group (C) fed with a conventional finishing feed from 4 weeks of age to slaughter (around 35 days), and the other group of 12 flocks (S) was fed with a finishing feed supplemented with 250 ppm of a patented feed additive (an ion‐exchanged clay compound) previously proven to reduce Campylobacter contamination in broiler caeca under experimental conditions. Enumeration of Campylobacter colonies in caeca (8 per flock) was carried out following ISO standards before feed distribution and at slaughter. Before treatment, the caecal Campylobacter load tended to be lower in C flocks (7.1 ± 1.9 log CFU/g, CI_95% [6.6–7.5]) than in S flocks (7.7 ± 1.0 log UFC/g, CI_95% [7.5–7.9]) (p = .05). At slaughter, the bacterial load was similar in the S (7.7 ± 1.0 log CFU/g, CI_95% [7.5–7.9]) and C groups (7.5 ± 1.2 log CFU/g, CI_95% [7.2–7.8]) (p = .73). Therefore, the feed additive had no significant effect on the caecal Campylobacter load at slaughter under the tested conditions. The logistical constraints inherent in field trials and the natural variability of Campylobacter contamination in naturally infected broiler flocks make it difficult to reproduce experimental results in in situ farm conditions. RCT testing of an intervention strategy in commercial situation is therefore a key step in evaluating pre‐harvest interventions against food‐borne pathogens.     

Practical assessment and management of foot pad dermatitis in commercial broiler chickens: A Field Study

Foot pad dermatitis (FPD) is a welfare concern in broiler chickens characterized by ulcerated lesions on the pad of the foot, which results from prolonged contact of foot pads with wet litter. During Canadian prairie winters, barn moisture levels tend to increase due to reduced ventilation as a means of conserving heat and minimizing costs. However, there are no published benchmarks regarding the prevalence of foot pad dermatitis in broilers reared in western Canadian provinces such as Alberta, Canada. As such the objectives of the current study were to evaluate practical means of assessing FPD in Alberta broilers as well as on-farm management practices which correlate with higher prevalence of foot pad dermatitis. A management-practices survey and 3 foot pad assessment methods were used to benchmark foot pad dermatitis in 32 broiler flocks throughout the province of Alberta. Four flocks per farm were sampled from a total of 8 commercial broiler farms. Per flock, 200 birds were assessed on-farm, 3 processor-line scores were taken at the processing plant, and 600 foot pad samples were assessed post-processing. The prevalence of foot pad dermatitis by assessment method was benchmarked on a per-flock basis at 28.65% on-farm, 26.17% on the processing line (processor-line), and 31.83% for samples taken off the processing line (processor-sampled). On-farm and processor-sampled assessment results were highly correlated (r = 0.90) compared with processor-line and on-farm (r = 0.77) and processor-line and processor-sampled results (r = 0.72; P < 0.001). Specifically, processor-line assessments were not found to be reliable when repeated (P > 0.10). On farm, wheat straw was used by the majority of Alberta’s producers (62.5%) and was associated with a higher prevalence of foot pad dermatitis per flock (40.6%). In contrast, pine shavings was associated with lower FPD prevalence (6.4%; P < 0.001), but was used by only 21.9% of producers in Alberta. Primary results from this field study support the use of on-farm FPD assessments rather than processor-line-based assessments, and a shift away from wheat straw as a broiler litter substrate.     

5-羟色胺对肉鸡肺动脉平滑肌细胞增殖和凋亡的影响

采用胶原酶消化法培养原代肉鸡肺动脉平滑肌细胞（PASMC）,检测不同浓度的5-羟色胺（5-HT）对肉鸡PASMC增殖的影响,并用流式细胞仪检测PASMC周期和凋亡情况。结果发现,10-4～10-7 mol/L的5-HT能剂量依赖性地促进肉鸡PASMC的增殖,可能是5-HT加速细胞从G1期向S期过渡,同时5-HT也可促进PASMC凋亡,因此在总体上5-HT促进PASMC增殖的作用更明显。