Performance,meat quality,meat mineral contents and caecal microbial population responses to humic substances administered in drinking water in broilers

1. This study was conducted to examine the effect of different levels of humic substances (HS) administered in drinking water on caecal microflora and mineral composition and colour characteristics of breast and thigh meats and the growth performance, carcass and gastrointestinal tract (GIT) traits of broiler chicks.

2. A total of 480 3-d-old broiler chickens were randomly allocated to 4 treatments with 4 cages per treatment and 30 bird (15 males and 15 females) chicks per cage. All birds were fed on commercial basal diet. The control birds (HS0) received drinking water with no additions, whereas birds in the other treatment groups received a drinking water with 7.5 (HS7.5), 15.0 (HS15.0) and 22.5 (HS22.5) g/kg HS. Mush feed were provided on an ad libitum basis. Body weight and feed intake of broilers were determined at d 0, 21, and 42, and feed conversion ratio was calculated. On d 42, 4 broilers (2 males and 2 females) from each cage were slaughtered and the breast and thigh meats were collected for mineral composition and quality measurements.

3. Performance, carcass and GIT traits and caecal microbial population of broiler chicks at d 42 were not affected by the dietary treatments. The lightness (L*) of breast and thigh meat decreased in broilers supplemented with 15 and 22.5 g/kg HS in drinking water. Although the redness (a*) of breast meat increased, yellowness of thigh meat decreased in broilers supplemented with 15 and 22.5 g/kg HS in drinking water (P < 0.05).

4. In conclusion, the 15 and 22.5 g/kg HS administration in drinking water can be applied for broiler chicks to maintain growth performance and improve meat quality without changing caecal microflora.     

Influence of increasing slaughter age of chickens on meat quality, welfare, and technical and economic results

Because of the increasing demand for raw cuts and processed products, there is a trend to producing very heavy broilers. Breeds that are used for such kinds of production have been intensively selected for growth rate and breast meat yield, and birds are reared for a longer period than standard broilers. This study was to evaluate the effects of increasing slaughter age on technical and economic factors, including production efficiency and environmental costs, bird welfare, and breast meat quality in a modern heavy broiler line. Five groups of 300 male Ross 708 chickens were reared until slaughter ages of 35, 42, 49, 56, or 63 d. Increasing age at slaughter from 35 to 63 d resulted in a 7.4-fold increase (P < 0.01) in mortality rate (5.21 vs. 0.70%). It also increased (P < 0.001) the slaughter weight and ADFI of birds 2.5- and 1.4-fold, respectively, without affecting their G:F. Under our experimental conditions, economic profit evaluated through the net gain reached a maximum at 42 d. The moisture and ammonium content of litter increased (P < 0.05 and P < 0.01, respectively) rapidly during rearing concomitantly with increased (P < 0.05) occurrence and severity of contact dermatitis and decreased (P < 0.05) walking ability and activity of birds. Thermal comfort also decreased (P < 0.05) greatly as early as 42 d of age. Changes in carcass quality occurred mainly between 35 and 56 d of age, with a progressive increase (P < 0.001) in breast and leg yield, whereas body fatness was barely affected by age. Major changes in breast meat traits were observed between 35 and 49 d of age, with an increase in muscle pH at 15 min (P < 0.01) and 24 h (P < 0.001) postmortem and reduced (P < 0.001) lightness and drip loss. The protein and lipid content of raw breast meat also increased (P < 0.05 and P < 0.01, respectively) with age. Taking into account the main aspects of sustainability, we could recommend slaughtering chickens of heavy line at 42 d of age.     

Characteristics of cold-induced dark,firm, dry broiler chicken breast meat

1. A study was designed to characterise dark, firm, dry (DFD) breast meat resulting from cold exposure of broilers and compare its properties with normal breast meat from cold-stressed and control birds.

2. A total of 140 broilers were selected from 5- and 6-week-old birds exposed to cold temperatures ranging from ?18 to ?4°C, or a control temperature of +20°C for 3?h in an environmental chamber. Half of these birds were slaughtered immediately following the cold exposure and the other half were given 2?h of lairage.

3. Breast meat samples were categorised based on ultimate pH (pH_u) and colour L* (lightness) values into normal (5·7?≤?pH_u?≤?6·1; 46?≤?L*?≤?53) breast meat from control (control-normal) or cold-stressed (cold-normal) birds, and DFD (pH_u?>?6·1; L*? 4. Residual glycogen was not different between cold-DFD and control-normal breast meat. Lactate concentration was lower in cold-DFD compared with control-normal breast meat. Lactate concentration almost tripled for all the samples by 30?h post-mortem, which resulted in a drop in pH of normal meat, but did not have any effect on pH of DFD breast meat. Glycolytic potential at both 5?min and 30?h post-mortem was lower in DFD breast meat compared with the normal breast meat from both cold-stressed and control birds.

5. Cold-DFD breast meat was significantly darker, with higher pH_u, lower cook loss, higher water-binding capacity and processing cook yield than cold-normal and control-normal breast meat, which were not different from each other.     

饲粮中添加葛根总黄酮对爱拔益加肉鸡生长性能及肉品质的影响

本试验旨在研究饲粮中添加不同水平葛根总黄酮对爱拔益加(AA)肉鸡生长性能及肉品质的影响。选择健康1日龄AA肉鸡275羽,随机分为5个组,每组5个重复,每个重复11羽鸡。对照组饲喂基础饲粮,试验组分别在基础饲粮中添加10、50、250、1 250 mg/kg葛根总黄酮。试验期42 d。结果表明:1)10 mg/kg添加组AA肉鸡的平均日增重在8~14日龄、15~21日龄和29~35日龄时均显著高于对照组(P0.05),但在22~28日龄时显著低于对照组(P0.05);250 mg/kg添加组AA肉鸡的平均日增重在8~14日龄时显著高于对照组(P0.05)。10 mg/kg添加组AA肉鸡的料重比在15~21日龄、29~35日龄和36~42日龄时显著低于对照组(P0.05),但在22~28日龄时显著高于对照组(P0.05)。各组AA肉鸡的平均日采食量差异不显著(P0.05)。2)与对照组相比,10 mg/kg添加组AA肉鸡胸肌、腿肌的亮度(L*)值显著降低(P0.05),红度(a*)值有升高趋势但差异不显著(P0.05);250 mg/kg添加组腿肌亮度值显著低于对照组(P0.05);50 mg/kg添加组胸肌、腿肌的黄度(b*)值均显著低于对照组(P0.05)。与对照组相比,250、1 250 mg/kg添加组AA肉鸡的胸肌剪切力显著降低(P0.05);250 mg/kg添加组的胸肌水分含量显著高于对照组(P0.05)。结果表明,饲粮中添加10 mg/kg的葛根总黄酮可提高AA肉鸡的生长性能,但添加250 mg/kg的葛根总黄酮可改善肌肉的色泽和嫩度。     

Genetic evaluation of meat quality traits and their correlation with growth and carcase composition in Japanese quail

1. Estimates of heritability, genetic and phenotypic correlations of performance and meat quality traits were obtained in a population of Japanese quail using restricted maximum likelihood (REML) procedures.

2. The heritability estimates for body weight (BW) traits ranged from 0·15 at hatch to 0·42 at six weeks. For carcase composition traits, heritability estimates ranged from 0·12 for carcase yield to 0·26 for abdominal fat yield and for meat quality traits they ranged from 0·18 for drip loss to 0·54 for yellowness of the meat.

3. Negative genetic correlations were found between BW and carcase traits with ultimate pH and drip loss ranging from ?0·01 (BW at hatch) to ?0·40 (skin yield). Redness and yellowness showed negative genetic correlations with BW and carcase traits, whereas the genetic correlations with lightness were positive (from 0·04 to 0·43).

4. Shear force and cooking loss showed positive genetic correlations with carcase, breast, abdominal and skin yield.

5. In conclusion, meat quality traits have the potential to be improved through genetic selection but selection for higher BW and carcase composition may reduce the meat quality of Japanese quail through reducing redness, ultimate pH and intramuscular fat and increasing lightness, shear force and cooking loss of the meat.     

Effects of humic substances supplementation provided through drinking water on performance,carcass traits and meat quality of broilers

The present study aimed at evaluating the effects of different doses of humic substances (HS) in waterer pan on broiler performances and meat quality. For the trial, 480 chicks (ROSS 308) were allocated into four groups (HS0, HS150, HS300 and HS450) of 120 equally mixed‐sex birds, each receiving a drinking water supplemented with 0, 150, 300 and 450 ppm of a humic acid (provided by 0.0%, 0.5%, 1.0% and 1.5% of HS, v/v) respectively. At the age of 21 and 42 days, feed consumption and live weight were taken. At the age of 42 days, 16 birds per treatment were slaughtered, dressing percentages, digestive tract traits were evaluated and samples of breast (pectoralis major) and thigh (iliotibialis) meat were taken to evaluate the changes in colour characteristics (CIE L*, a* and b*) and chemical composition. The body weight gain increased by the HS300 in relation to the HS0 and HS450, and decreased by the HS450 in relation to the HS0. The feed consumption of birds in the HS450 and feed efficiency of birds in the HS300 were lower and higher than those in the other treatments respectively. The carcass weight of broilers in the HS150 and HS300 were higher than those of in the HS0 and HS450. The carcass weight decreased by the HS450 in relation to the other treatments. The dressing percentage increased by the HS150 in relation to the HS450. The HS450 resulted in breast and thigh meat colour that were lighter than those found in the HS0 birds. The HS450 increased fat content of thigh meat in relation to the HS0. It was concluded that the humic acid supplementation at 300 ppm and 450 ppm appears to have a measurable impact on live performance improving feed efficiency and lightness of breast and thigh meat colours in broilers respectively.     

The effect of a diet containing grasshoppers and access to free-range on carcase and meat physicochemical and sensory characteristics in broilers

1. Research was conducted to evaluate the impact of a diet containing grasshoppers on the carcase, physicochemical and sensory characteristics in a free-range, grassland-based broiler production system.

2. A total of 80, 28-d-old male broilers were reared on grassland containing a large population of grasshoppers (treatment PB). Control birds were reared intensively on a maize-soybean diet (treatment CB). At 91?d of age, 24 birds from each treatment were slaughtered to evaluate carcase, meat and sensory characteristics.

3. Treatment PB produced birds with significantly lower live weights, breast, wing, thigh and drum weights, and higher dressing percentage and breast percentage of carcase, compared with CB. Treatment PB produced breast meat with significantly higher redness values, shear force and protein content, and lower pH values, cooking loss, moisture and fat content compared with CB. Sensory panel results for breast and thigh meats showed no treatment effect on colour and juiciness, but significantly higher scores for chewiness, flavour, aroma and overall appreciation, and lower scores for tenderness from treatment PB compared with CB.

4. Rearing chickens on rangeland may provide an alternative way to produce poultry meat which is considered superior by modern consumers.     

玉米型饲粮和小麦型饲粮对肉仔鸡生长性能、肉品质、血浆生化指标和脂质代谢的影响

本试验旨在研究玉米型饲粮和小麦型饲粮对肉仔鸡生长性能、肉品质、血浆生化指标和脂质代谢的影响。选取健康的1日龄爱拔益加肉仔鸡公雏180只,随机分成2个组,分别采食玉米型饲粮和小麦型饲粮,每组6个重复,每个重复15只鸡。试验期42 d。结果表明:与玉米型饲粮相比,饲喂小麦型饲粮的肉仔鸡,1)生长前期(1~21日龄)和全期(1~42日龄)平均日增重(ADG)显著增加(P0.05),生长前期死亡率显著降低(P0.05);2)42日龄的腹脂率显著降低(P0.05);3)42日龄胸肌肌肉的红度(a*)45 m in和a*24 h值显著降低(P0.05),亮度(L*)45 m in值增加(P=0.096);4)21和42日龄血浆总胆红素含量显著降低(P0.05);21日龄血浆总蛋白和白蛋白含量显著增加(P0.05),21日龄血浆谷氨酸氨基转移酶活性显著降低(P0.05);42日龄血浆尿酸含量显著增加(P0.05);5)21和42日龄血浆甘油三酯含量显著降低(P0.05);42日龄血浆总胆固醇含量显著降低(P0.05)。由此可见,本试验条件下,与玉米型饲粮相比,小麦型饲粮改善了肉仔鸡的生长性能、脂质代谢和健康状态,降低了腹脂率。     

Dietary Apparent Metabolizable Energy and Amino Acid Density Effects on Growth and Carcass Traits of Heavy Broilers

Two experiments (EXP) were conducted to evaluate the interactive effects of dietary AME and amino acid (AA) density (total basis) on broiler chickens from 42 to 56 d of age. In EXP 1, diets were formulated to contain low AME (3,140 kcal/kg) and moderate AME (3,240 kcal/kg) in combination with moderate AA (16.2% CP, 0.88% Lys, and 0.75% TSAA) and high AA (18.0% CP, 0.98% Lys, and 0.83% TSAA) and fed to male broilers. Dietary treatments in EXP 2 were diets formulated to contain moderate AME (3,220 kcal/kg) and high AME (3,310 kcal/kg) combined with moderate and high AA concentrations used in EXP 1 and fed to male and female broilers. In general, dietary AME and AA did not interact to influence growth and meat yield responses. Broilers provided the low AME diet in EXP 1 consumed more feed and had poorer feed conversion but had higher total breast meat yield than birds fed the moderate AME diet. In EXP 2, broilers fed the high AME diet from 42 to 56 d had increased BW gain, decreased feed consumption, and improved feed conversion. Feeding the high AA diets in both EXP decreased feed consumption, improved feed conversion, and increased total breast meat yield. Nutritionists establishing nutritional programs for heavy broilers late in development from 2.5 to 3.6 kg may need to consider increasing AA density to optimize breast meat yield. Increasing the AME content of the diet improves feed conversion but not breast meat yield.     

Effect of Monascus Compound Additive on Growth Performance and Meat Quality of Broiler

This trial was conducted to study the effect of Monascus compound additives on growth performance and meat quality of broilers.The total of 400 one-day-old Avian broilers were randomly allotted into 4 groups with 5 replicates per group and 20 birds per replicate.The broilers in group Ⅰ(control group),were fed a basal diet,and those in experimental groups Ⅱ,Ⅲ and Ⅳ were fed the basal diet supplemented with 0.5%,1% and 1.5% Monascus compound additives,respectively.The experiment lasted for 42 d.At the ending of the experiment,all the birds were weighted and two of each replicate were slaughtered,the samples from breast and leg muscles were taken for meat quality measurement.The results showed as follows:Compared with control group,the ADG increased significantly（P<0.05),and F/D decreased significantly（P<0.05）in group Ⅲ and Ⅳ,but the differences were not significant between group Ⅲ and Ⅳ(P>0.05);Compared with the control group,the muscle redness（a^*）and yellowness（b^*）in all the experimental groups increased significantly（P<0.05),and the drip loss rate decreased significantly（P<0.05),but the muscle lightness（L^*),cooking loss rate and shear force had no significant change（P>0.05),and pH_{24 h} of muscles in groups Ⅲ and Ⅳ reduced significantly（P<0.05).In conclusion,adding Monascus compound additives in diets could improve growth performance and meat quality in broiles, and the appropriate level should be 1%.     

Effect of dietary protein regime on meat quality traits and carcase nutrient content of broilers from two commercial genotypes

1. The present study aimed to evaluate breast muscle quality and muscle myofibre density in two broiler genotypes given three dietary protein feeding regimes. 2. A total of 1440 Ross 308 and 708 broilers (720/genotype) were given one of three dietary protein regimes (Low: 192, 166 and 155 g/kg, Control: 229, 199 and 182 g/kg and High: 266, 235 and 207 g/kg for starter, grower and finisher diets respectively). On d 21 and 42, initial protein solubility, DNA and myofibre density were determined. On d 42, breast meat samples were collected for meat quality analyses. 3. There were no genotype effects on pH(24), L*, a* or b* values. Thawing loss was higher in meat from the 708 than the 308 genotype. 4. Broilers given the low protein feeding regime had highest carcase fat, lowest pH(24) and palest meat. The low regression coefficients between dietary protein content and changes in pH(24) and lightness, however, demonstrated that dietary protein was not the principal factor influencing these traits. 5. Although sarcoplasmic protein solubility was similar among protein feeding regimes on d 21, the highest sarcoplasmic protein solubility on d 42 was in broilers on the high protein regime. 6. Myofibre density was highest in meat from broilers given the low protein regime. 7. It was concluded that dietary-protein content contributes significantly to both protein solubility and myofibre density.     

红曲复合添加剂对肉鸡生长性能及肉质性状的影响

试验旨在研究日粮中添加红曲复合添加剂对肉鸡生长性能及鸡肉品质的影响。选用1日龄艾维因肉鸡400只,随机分为4组,每组设5个重复,每个重复20只鸡,Ⅰ组为对照组,饲喂基础日粮,Ⅱ~Ⅳ组为试验组,分别在基础日粮中添加红曲复合添加剂0.5%、1%和1.5%,试验期42 d,试验结束时肉鸡称重,每个重复选取2只屠宰,测定胸肌和腿肌肉质性状。结果表明,与对照组相比,Ⅲ和Ⅳ组平均日增重显著提高（P<0.05）,料重比显著降低（P<0.05）,但这两个指标在Ⅲ和Ⅳ组间无显著差异（P>0.05）;各试验组与对照组相比,肌肉红度（a^*）和黄度（b^*）显著提高（P<0.05）,滴水损失显著降低（P<0.05）,肌肉亮度（L^*）、蒸煮损失和剪切力差异不显著（P>0.05）,Ⅲ和Ⅳ组pH_{24 h}显著降低（P<0.05）。以上结果说明,日粮中添加红曲复合添加剂可以提高肉鸡生长性能、改善鸡肉品质,其添加量以1%为宜。     

Effect of dietary vitamin E on broiler meat qualities,color, water‐holding capacity and shear force value,under heat stress conditions

This study was conducted to evaluate the effect of dietary vitamin E (VE) on broiler meat quality, especially focused on PSE (pale color, soft and exudative), under chronic heat stress (HS) conditions. Twenty‐eight‐day‐old female Ross broilers were kept in independent cages with a controlled temperature of 24°C (normal temperature: NT) or 30°C (high temperature: HT). The NT chickens were fed basal feed. The HT chickens were fed basal feed (HT) or VE (200 mg/kg) added feed (HT + E). Broilers were weighed and slaughtered at 38 days old. The breast muscle was removed immediately and then the samples were used for determination of meat color, pH, water holding capacity (WHC) and shear force value (SFV). Body weight gain and feed intake were significantly decreased in the HT and HT + E groups compared to the NT group. VE supplementation did not affect the growth performance. Chronic HS at 30°C for 10 days may cause deterioration of meat quality such as PSE. The effects of chronic HS on meat quality were most significant in the toughness of broiler breast meat. Supplementation of VE in broiler feed would be effective to prevent the extent of PSE on broiler meat by chronic HS.     

Interaction of transport distance and body weight on preslaughter stress and breast meat quality of broilers

1. The objective of the study was to investigate the effect of transport distance on blood metabolites and breast meat quality of broilers slaughtered at different weights.

2. The study was conducted on Ross 308 broilers from 27 different flocks reared under similar conditions. Slaughter weight was classified as <2·0?kg, 2·0–2·4?kg, and >2·4?kg. Transport distance was categorised as short (65?km), medium (115?km) and long (165?km) distance representing 90, 155 and 220?minutes at an average 45?km/h speed, for each slaughter weight.

3. Higher heterophils and heterophil:lymphocyte (H/L) ratios were obtained for broilers transported over a long distance. Long distance transport increased blood albumin, glucose, and triglycerides levels for <2·0?kg broilers, which did not differ from broilers slaughtered at >2·4?kg after long-distance transport.

4. Broilers slaughtered at >2·4?kg after long-distance transport had lower pH_u, and paler and tougher breast meat, than those broilers slaughtered at <2·0?kg after long-distance transport.

5. A negative correlation was obtained between pH_u and L*, thawing loss and texture. The L* value was negatively correlated with a*; and positively correlated with b*, thawing and cooking losses.

6. It was concluded that the effect of transport distance could not be evaluated independently of slaughter weight. The interaction between transport distance and slaughter weight contributes to preslaughter stress and meat quality.     

Evaluation of probiotics in diets with different nutrient densities on growth performance,blood characteristics,relative organ weight and breast meat characteristics in broilers

1. A total of 720 1-d-old broilers were used in a 28 d experiment to determine the effects of probiotic supplementation in diets with different dietary nutrient densities.

2. Birds were randomly allotted to one of the 4 treatments in a 2 × 2 factorial arrangement (12 replicateswith 15 broilers per replicate) with two levels of nutrient density [high nutrient density (metabolisable energy (ME) 12.7 MJ/kg and crude protein (CP) 230.3 g/kg for 1–7 d; ME 13.2 MJ/kg and CP 220.3 g/kg for 8–28 d) or low nutrient density (ME 12.1 MJ/kg and CP 220.2 g/kg for 0–7 d; ME 12.6 MJ/kg and CP 209.8 g/kg for 8–28 d)] and 0 or 2 g/kg probiotics (1.0 × 10¹⁰ viable spores/g of Bacillus subtilis endospores and 1.0 × 10⁹ viable spores/g of Clostridium butyricum).

3. The high-nutrient-density diet increased body weight gain (BWG), feed conversion ratio (FCR), serum cholesterol and triglyceride concentration relative to the low-nutrient-density diet. High-nutrient-density diet reduced water loss ratio of breast muscle, liver and fat relative to body weight compared to low-nutrient density-diet. The inclusion of probiotics increased BWG and feed intake throughout the experiment. Dietary probiotics increased the percentage of blood lymphocytes and relative weight of spleen and bursa of Fabricius when compared to the non-probiotic treatment. The inclusion of probiotics decreased serum cholesterol and triglyceride concentrations and lightness (L*) value of breast meat compared to the non-probiotic-supplemented diet.

4. In conclusion, high dietary nutrient density increased growth performance and serum cholesterol and triglyceride concentrations in broiler chickens. The inclusion of probiotics increased growth performance but reduced serum cholesterol and triglyceride concentrations. The positive effect of probiotic supplementation on growth performance was reduced by the high-nutrient-density diet during the first week of life.     

谷氨酰胺对肉鸡小肠组织结构和吸收能力的影响

本试验旨在研究饲粮不同添加水平谷氨酰胺(Gln)对热应激肉鸡小肠组织结构和吸收能力的影响.选用1日龄科宝- 500肉鸡240只,随机分为6个处理,每个处理4个重复,每个重复10只.Ⅰ组为对照组,饲喂玉米-豆粕型基础饲粮,Ⅱ、Ⅲ、Ⅳ、Ⅴ和Ⅵ组为试验组,分别饲喂在基础饲粮中添加0.4％、0.8％、1.2％、1.6％和2.0...     

Nutrient density and slaughter age have differential effects on carcase performance,muscle and meat quality in fast and slow growing broiler genotypes

1. A 2?×?2 factorial design was used to investigate the differences in carcase, muscle and meat characteristics between fast and slow growing genotypes fed on low nutrient (LND) or high nutrient diets (HND) at their respective slaughter ages.

2. The birds were randomly assigned to treatments with 5 replicates of 145 birds for Wens Yellow-Feathered Chicken (WYFC, 5·75 birds/m²) or 115 birds for White Recessive Rock Chicken (WRRC, 7·25 birds/m²), according to the commercial recommendations for the two breeds and were fed on HND or LND. Birds were slaughtered at 63?d and 105?d of age.

3. The results showed WRRC had higher carcase yield and meat yield than that of WYFC, lower fat content, higher moisture content and lower cooking loss. The meat from WRRC was less tender and contained lower levels of polyunsaturated fatty acids (PUFA).

4. Birds fed on HND had higher breast meat yield, myofiber area and protein content in the breast muscle and lower fat content than birds fed on LND. The thigh muscle of birds fed on HND had higher levels of PUFA. Age had a positive effect on carcase parameters, but a negative effect on pH, meat tenderness and cooking loss, and the two genotypes exhibited different responses to the influence of nutrient density and age.

5. Genotype and age had the largest effect on carcase performance and meat quality. LND benefited meat quality and WRRC had larger responses in meat yield and shear force when fed on HND.     

Effect of three mycotoxin adsorbents on growth performance, nutrient retention and meat quality in broilers fed on mould-contaminated feed

1. A study was conducted to investigate the effects of an esterified glucomannan (EGM), a hydrated sodium calcium aluminosilicate (HSCAS) and a compound mycotoxin adsorbent (CMA) on performance, nutrient retention and meat quality in broilers fed on mould-contaminated feed. Mould-contaminated diets were prepared by replacing half of the non-contaminated maize in the basal diets with mould-contaminated maize, which contained 450·6 μg/kg of aflatoxin B1, 68·4 μg/kg of ochratoxin A and 320·5 μg/kg of T-2 toxin. 2. The mould-contaminated diet significantly decreased body weight gain (BWG) between 10 and 21 d, feed intake (FI) between 35 and 42 d, the apparent retention of crude lipid and phosphorus, and the lightness (L*) value of breast and thigh muscle. It also significantly increased the redness (a*) and yellowness (b*) value in breast muscle and the b* value in thigh muscle. 3. The addition of 0·2% HSCAS significantly increased FI between 35 and 42 d and the apparent retention of phosphorus. Supplementation with 0·1% CMA in the contaminated diet significantly improved BWG from 10 to 21 d, and increased FI from 35 to 42 d and from 10 to 42 d. CMA also significantly increased the apparent retention of crude lipid, crude protein, ash and phosphorus. All three mycotoxin-adsorbent treatments significantly improved the L* values of breast and thigh muscle when compared with the mould-contaminated group. Supplementation with 0·1% CMA in the contaminated diet significantly decreased b* value and improved tenderness in thigh muscle. 0·05% EGM significantly decreased b* value of thigh muscle compared to mould-contaminated group. 4. The results indicated that mycotoxins in contaminated feed retard growth, nutrient retention and meat quality, whereas the addition of 0·05% EGM, 0·2% HSCAS or 0·1% CMA prevents the adverse effects of mycotoxins to varying extents, with 0·1% CMA being the most effective adsorbent treatment.     

高粱饲粮中添加复合酶制剂和益生菌对肉鸡饲粮表观代谢能、屠宰性能和肉品质的影响

本试验旨在研究高粱饲粮中添加复合酶制剂和益生菌对良凤花肉鸡屠宰性能、肉品质、表观代谢能和主要营养物质表观消化率的影响。试验选取900只1日龄体重相近的健康良凤花公鸡,随机分为5个组,分别为对照组(基础饲粮)、高粱组、高粱+复合酶组、高粱+益生菌组和高粱+复合酶+益生菌组,每组6个重复,每个重复30只鸡。试验全期为68 d。分为前期(1~28日龄)、后期(29~56日龄)和代谢试验期(57~68日龄)3个阶段进行。试验组前期用高粱替代约30%的玉米,复合酶制剂添加量为200 g/t;后期用高粱替代约50%的玉米,复合酶制剂添加量为300 g/t;全期益生菌添加量为100 g/t。结果表明:1)与对照组相比,高粱+复合酶组和高粱+复合酶+益生菌组粗纤维(CF)表观消化率显著提高(P0.05),各试验组表观代谢能(AME)及其余营养物质表观消化率差异不显著(P0.05)。2)与对照组相比,高粱+益生菌组和高粱+复合酶+益生菌组半净膛率显著提高(P0.05),各组其他屠宰性能指标均无显著差异(P0.05)。3)与对照组相比,高粱+复合酶+益生菌组胸肌亮度(L*)值显著提高(P0.05),试验组腿肌红度(a*)值显著降低(P0.05)。综上,在高粱饲粮中添加复合酶制剂和益生菌可以提高CF的表观消化率,对肉鸡屠宰性能和肉品质均无不良影响。     

Modulation of glycogen and breast meat processing ability by nutrition in chickens: effect of crude protein level in 2 chicken genotypes

The aim of the study was to evaluate the impact of 2 isoenergetic growing diets with different CP (17 vs. 23%) on the performance and breast meat quality of 2 lines of chicken divergently selected for abdominal fatness [i.e., fat and lean (LL) lines]. Growth performance, breast and abdominal fat yields, breast meat quality parameters (pH, color, drip loss), and muscle glycogen storage at death were measured. Increased dietary CP resulted in increased BW, increased breast meat yield, and reduced abdominal fatness at slaughter regardless of genotype (P < 0.001). By contrast, dietary CP affected glycogen storage and the related meat quality parameters only in the LL chickens. Giving LL chickens the low-CP diet led to reduced concentration of muscle glycogen (P < 0.01), and as a result, breast meat with a higher (P < 0.001) ultimate pH, decreased (P < 0.001) lightness, and reduced (P < 0.001) drip loss during storage. The decreased muscle glycogen content observed in LL receiving the low-CP diet compared with the high-CP diet occurred concomitantly with greater phosphorylation amount for the α-catalytic subunit of adenosine monophosphate-activated protein kinase and glycogen synthase. This was consistent with the reduced muscle glycogen content observed in LL fed the low-CP diet because adenosine monophosphate-activated protein kinase inhibits glycogen synthesis through its action on glycogen synthase. Our results demonstrated that nutrition is an effective means of modulating breast meat properties in the chicken. The results also highlighted the need to take into account interaction with the genetic background of the animal to select nutritional strategies to improve meat quality traits in poultry.