Effects of low protein diet and low protein diet supplemented with synthetic essential amino acids on meat quality of broiler chickens

We investigated the effects of a low crude protein (CP) diet and a low CP diet supplemented with synthetic essential amino acids (EAA) on the meat quality of broiler chickens. Twenty‐one‐day‐old chickens were assigned to one of three diets: control, low CP (LCP), or low CP supplemented with EAA (ELCP). The chickens received these diets for 10 days. The shear force value (SFV) and free glutamate content of the Pectoralis major muscle were measured as indicators of the meat toughness and taste. The collagen and crude fat content of the muscle and the cross‐sectional area of myofibers were measured to evaluate the effects of the LCP and ELCP diets on meat toughness. The SFV of the ELCP group was 47% lower than that of the control group (P < 0.01). However, the LCP diet did not affect the SFV. The collagen and crude fat content were not affected by the dietary treatment. The cross‐sectional area was lower in the LCP and ELCP groups (P < 0.05) than the control group. The free glutamate content of muscle was not affected by the dietary treatment. Thus, a low CP diet supplemented with EAA is an effective means of producing tender meat.     

Nutritional evaluation and utilisation of quality protein maize, Nityashree hybrid maize, and normal maize in broiler chickens

1. Three experiments were conducted to determine the apparent metabolisable energy, apparent digestible amino acid values, and utilisation of three maize varities in chickens: quality protein maize (QPM), hybrid maize Nityashree (HMN) and normal maize (NM).

2. There was no significant difference in the apparent metabolisable energy (AME) content amongst the three varieties of maize.

3. Lysine and threonine digestibilities were significantly higher in QPM compared to either HMN or NM. No difference in the digestibilities of other amino acids occurred among the three different maize varieties.

4. There was no difference between diets containing NM or HMN for body weight gain (21 and 40?d of age) and overall feed conversion ratio (0–40?d), but values were significantly higher for QPM (and Lys-supplemented NM) diets. The relative weights of dressed meat yield and giblets were unaffected by dietary replacement of NM with QPM, HMN, or Lys supplementation of the NM diet. However, abdominal fat content decreased and breast meat yield increased with both dietary replacement of NM with QPM and Lys supplementation of the NM diet.

5. The concentration of protein in serum was significantly increased by dietary replacement of NM with QPM. Adding Lys to the NM based diet significantly increased the Ca concentration in serum compared with NM or HMN diets. However, the highest concentration of Ca in serum was found in the QPM diet. The concentration of total cholesterol in serum significantly decreased by either replacing NM with QPM or adding Lys to the NM based diet, compared with the NM diet.

6. These results suggested that the feeding value of quality protein maize was superior to normal maize, while the feeding value of hybrid maize Nityashree was similar to that of normal maize.     

Whole pearl millet feeding does not impair performance and nutrient digestibility in 28-day-old broiler chickens

The effects of varying inclusion levels of whole grain millet in millet–soya bean-based diets on growth performance, gizzard development, digesta characteristics and nutrient digestion in broiler chicken were investigated. Starter (0–14 days) and grower (15–28 days) broiler chicken diets containing pearl millet at 500 and 540 g/kg diet, respectively, were formulated. The diets comprised of 0%, 20%, 40%, 60%, 80% and 100% of millet incorporated as whole grain. One-day-old unsexed Arbor Acres Plus chicks (n = 540) were allotted to the experimental diets in a completely randomized design with the diets and water provided ad libitum for 28 days. Each treatment was replicated seven times, and each replicate had 12 chicks. Results showed that daily live weight gain and feed conversion ratio of chickens on the whole millet grain diets compared favourably with chicken on the control in both starter and grower phases, while feed intake reduced quadratically (p < .05) with increased whole grain millet levels in the starter phase. Morphological and structural characteristics of the gizzard and small intestine and intestinal digesta pH and viscosity were also unaffected (p > .05) by whole grain millet inclusion levels. However, the weight of intact millet grain in gizzard increased linearly (p < .001) with whole grain millet inclusion in the diets. Dietary whole grain millet inclusion also consistently lowered (p < .05) jejunal and ileal maltase and sucrase activities, but did not influence (p > .05) pancreatic amylase activity. Ileal crude protein and starch digestibility increased, while ileal energy digestibility decreased significantly (p < .05) with whole grain millet inclusion. Whole grain millet inclusion in broiler starter and grower diets up to 500–540 g/kg did not negatively impact on broiler chicken performance.     

Effect of different non-chloride sodium sources on the performance of heat-stressed broiler chickens

1. One hundred and eighty 1-d-old broiler chicks were used to evaluate the effect upon broiler performance during severely hot summer months of three different sodium salts: sodium bicarbonate (NaHCO3), sodium carbonate (Na2CO3) and sodium sulphate (Na2SO4), in starter and finisher diets having an identical electrolyte balance (DEB) of 250 mEq/kg. 2. The non-chloride sodium salts were added to contribute the same amount of sodium and were substituted at the expense of builder's sand in the basal diets containing common salt (NaCl) as Na and Cl source. 3. Each diet was fed to three experimental units having 15 chicks each until 42 d of age. Severe heat-stress conditions, maintained in the rearing room, were indicated by high average weekly room temperature (minimum 29.3 degrees C; maximum 38.0 degrees C). 4. Diets containing sodium salts gave better body weight gain, feed intake and feed to gain ratio than the control diet. Sodium salts also enhanced water intake as well as water to feed intake ratio. This effect was more pronounced in broilers fed NaHCO3 supplement (with NaCl in the basal diets). 5. The increased water intake resulted in lower body temperature in heat-stressed birds fed NaHCO3 supplemented diet than in birds fed other sodium salts. A lower mortality rate was noted with NaHCO3 (15.15%), Na2CO3 (13.64%) and Na2SO4 (15.15%) supplements than with the control (33.33%) treatment. 6. Better carcase and parts yield were observed in sodium supplemented broilers. Sodium salts reduced the alkalotic pH and enhanced the blood sodium content, which ultimately improved the blood electrolyte balance and overall performance of heat-stressed broilers. 7. Supplementing broiler diets with sodium salts improved the live performance of heat-stressed broilers and better productive performance was noted with NaHCO3 than other sodium supplements.     

Effect of wet feeding on growth performance of broiler chickens in a hot climate

1. The Guinea Savanna in the tropics is characterised by high diurnal temperatures, often beyond the thermo-neutral zone of modern poultry, which imposes heat stress on them. 2. An experiment was conducted to determine the effect of partially (12 h wet mash in the day and 12 h dry mash in the night) or wholly (24 h) feeding wet mash on the growth performance of broiler chickens. 3. Three treatments: dry mash (control), wet mash (day) + dry mash (night) and wet mash (day + night) were tested. At 28 d of age, a total of 120 broiler chickens (Hybro, Netherlands) were randomly divided, using a completely randomised design, into 12 groups of 10 birds, each with mean live weight of approximately 800 g/bird. A maize-soybean based grower mash (200 g CP/kg and 12·5 MJ/kg ME) was fed. The wet mash was prepared daily by addition of 1·3 parts of water to 1 part of dry mash and fed from 28 to 56 d of age. The birds were housed in raised-floor pens. Feed and water were given ad libitum and light provided 24 h. Mean daily room temperature was 28-29°C in the morning and 35-41°C in the afternoon. 4. Mean feed intake of birds fed the wet mash (174 g/day) or wet + dry mash (166 g/day) was higher than that of birds fed the dry mash (152 g/day). Mean live weight gain of birds fed the wet mash (64 g/day) or wet + dry mash (64 g/day) was higher than that of birds fed the dry mash (58 g/day). There were no differences in gain/feed ratios (0·38-0·39) of any of the treatments, neither were there any differences between the feeding of wet mash partly or wholly for all variables. 5. It was concluded that wet feeding, particularly during day-time, had the potential to improve growth performance of broiler chickens in a hot climate.     

The influence of feeding crimped kernel maize silage on broiler production,nutrient digestibility and meat quality

1. Two experiments were carried out in parallel with male Ross 308 broilers over 37 d. An experiment with a total of 736 broilers was performed to study the effect of dietary inclusion of crimped kernel maize silage (CKMS) on broiler production and meat quality. Another study with 32 broilers was carried out from 21 to 25 d to investigate the inclusion of CKMS on nutrient digestibility.

2. In both trials, 4 dietary treatments were used: wheat-based feed (WBF), maize-based feed (MBF), maize-based feed supplemented with 15% CKMS (CKMS-15) and maize-based feed supplemented with 30% CKMS (CKMS-30).

3. Compared with MBF, the dry matter (DM) intakes of broilers receiving CKMS-15 and CKMS-30, respectively, were numerically 7.5 and 6.2% higher and feed conversion ratio 6 and 12% poorer (significant for 30% CKMS), although there were no significant differences in AME content between the three diets. At 37 d, the body weight of birds receiving 15% CKMS was similar to birds fed with MBF. However, the inclusion of 30% CKMS decreased broiler growth. Dietary supplementation with CKMS significantly reduced the apparent digestibility of phosphorus. The fat digestibility was significantly lower for CKMS-30 than for the other three diets.

4. Broiler mortality decreased significantly when CKMS was added to the diet.

5. The consumption of drinking water was significantly lower in all maize-based diets as compared to WBF and was lowest in broilers fed with CKMS-30.

6. An improved litter quality in terms of DM content and a lower frequency of foot pad lesions was observed with broilers supplemented with both dietary levels of CKMS.

7. The addition of CKMS to maize-based diets increased juiciness, tenderness and crumbliness of the meat.

8. In conclusion, the dietary supplementation of 15% CKMS had no negative effect on broiler growth and positively influenced bird welfare in terms of mortality and foot pad health. Therefore, the addition of 15% CKMS to maize-based diets is considered an advantageous feeding strategy in broiler production.

     

Effect of hatch location and diet density on footpad dermatitis and growth performance in broiler chickens

The effect of hatch location and diet density on the prevalence of footpad dermatitis and growth performance in broiler chickens was studied. Broilers (Ross 308), incubated at 2 different hatch locations but originating from the same parent stock, were subjected to 2 feeding programs differing in energy content (2,750 vs. 2,950, 2,850 vs. 3,050, 2,900 vs. 3,100, and 2,900 vs. 3,100 kcal/kg for starter, grower I, grower II, and finisher diets, respectively) in a 2 × 2 factorial design (6 replicates per treatment combination). Broilers were housed under conditions and managed according to Dutch practice. Hatch location did not affect hatching results nor the prevalence and severity of footpad dermatitis, but did affect BW gain, feed, and water intake. A significant interaction was found between hatch location and feeding program; broilers fed the low-energy (LE) program had a better performance when hatched at Location 2 than at Location 1, whereas performance was similar for the high-energy (HE) broilers hatched at both locations. Broilers fed the LE program had similar BW gain but a higher feed conversion due to a higher feed intake as compared to broilers fed the HE program. In addition, moisture content of the litter in the pens with LE birds was higher than in pens with HE birds. As a result, broilers fed the LE program had more footpad dermatitis and hock burns at d 36 as compared to broilers fed the HE program. It is concluded that the HE feeding program is preferred to prevent footpad dermatitis and hock burn, and with respect to growth performance. The differences in growth performance between the 2 hatch locations merit further study but indicate the importance of the incubation and hatching environment and posthatch handling in relation to the growth performance of broilers on-farm.     

Effect of intermittent feeding,structural components and phytase on performance and behaviour of broiler chickens

1. Two experiments were conducted to study the effect of intermittent feeding on performance and the efficacy of an exogenous phytase, and to assess whether intermittent feeding changed the activity pattern of broiler chickens.

2. Broiler chickens were given, either ad libitum or intermittently, a phosphorus deficient pelleted diet containing either coarsely or finely ground oat hulls and either no enzyme or a phytase added from 10 d of age, in a 2 × 2 × 2 factorial arrangement. Ad libitum feeding consisted of continuous access to feed in a room with 18 h of light and 6 h of complete darkness, whereas birds on intermittent feeding had restricted access to feed from 7 d of age, with 4 1-h feeding bouts/d and one 2-h feeding bout/d from d 14.

3. Performance, characteristics of the anterior digestive tract and phosphorus retention were assessed in experiment 1, while in experiment 2, birds were observed during 4-h periods to quantify different behaviours.

4. Intermittent feeding and phytase improved performance, but intermittent feeding did not improve the efficacy of the enzyme added. Ad libitum fed broiler chickens ate and drank on average twice per hour, and spent close to three-quarters of their time resting. Apart from an increased standing and feed searching activity for intermittently fed birds compared to ad libitum fed birds during the last hour before feed was presented, no differences in activity was detected.

5. It was concluded that broiler chickens quickly adapt to intermittent feeding without reduction in final body weight and with improvements in feed efficiency, but without improving the efficacy of dietary phytase. Only small changes occur in the behaviour of intermittently fed birds compared to ad libitum fed birds.     

叶酸对肉仔鸡营养物质利用的影响

选用艾维茵商品代白羽肉鸡120只,随机分成4组,按叶酸添加水平不同分为4个不同处理组,分别为0、0.75、1.5、3.0mg/kg,于35～42日龄用全收粪法进行消化代谢试验,研究叶酸对肉仔鸡营养物质利用率的影响。研究结果表明,添加叶酸可以不同程度地提高饲料养分表观利用率,1.5mg/kg组的干物质、粗蛋白、粗脂肪、粗纤维、有机物和无氮浸出物的表观代谢率最高,分别比对照组提高10.33%、19.83%、14.32%、13.89%、6.07%和16.09%,差异显著,而其余各养分的代谢率各组间均差异不显著。     

Growth performance and carcase quality in broiler chickens fed on bacterial protein grown on natural gas

1. The effects of increasing concentrations (0, 40, 80 or 120 g/kg) of bacterial protein meal (BPM) and bacterial protein autolysate (BPA) grown on natural gas on growth performance and carcase quality in broiler chickens were examined. 2. Adding BPM to diets reduced feed intake and improved gain: feed from 0 to 21 d and overall to 35 d, but did not significantly affect weight gain compared to the soybean meal based control diet. 3. Increasing concentrations of BPA significantly reduced growth rate, feed intake, gain: feed, carcase weight and dressing percentage, but significantly increased carcase dry matter, fat and energy content. 4. Adding BPM to diets had no effect on viscosity of diets and jejunal digesta, and minor effects on litter quality, whereas BPA increased the viscosity of diets and jejunal digesta, improved litter quality at 21 d, but decreased litter quality at 32 d. 5. To conclude, broiler chickens performed better on a BPM product with intact proteins than on an autolysate with ruptured cell walls and a high content of free amino acids and low molecular-weight peptides.     

Effect of feeding whole cereals on performance,starch digestibility and duodenal particle size distribution in broiler chickens

1. An experiment was conducted to study the effects of whole wheat, oats and barley at different inclusion levels on performance, starch digestibility, duodenal particle size distribution, gizzard weight and pH of gizzard contents for broiler chickens. 2. Feed consumption and weight gain were significantly reduced when ground cereals were replaced by whole cereals (P < 0.05). However, feed conversion efficiency was not affected by inclusion of up to 440 g/kg of whole wheat, and up to 300 g/kg of whole oats and barley. 3. Duodenal particle size was measured by laser diffraction to below 1 micron in size. A remarkably large proportion of particles were below 100 microns, with as much as 50% of the particles in the duodenum being below 40 microns in size. Inclusion of moderate amounts of whole cereals reduced the duodenal mean particle size. Large inclusions of whole cereals decreased (P < 0.05) the proportion of particles up to 40 microns in size, and increased (P < 0.05) the proportion with size between 100 and 300 microns. 4. Starch digestibility was improved (P < 0.05) by replacing ground wheat or barley with whole wheat or barley. 5. There was no consistent effect of cereal species or feed form on the pH value of the gizzard contents.     

Effects of inulin on growth performance,nutrient digestibility and metabolisable energy in broiler chickens

1. A 35 d feeding trial with 480 d-old male broiler chickens (Cobb) was conducted to evaluate the effects of graded levels of inulin (0, 5, 10, 15 and 20 g/kg diet) in a maize-soybean meal based diet on growth performance, AME_N and apparent ileal digestibility (AID) of crude protein, amino acids, starch, crude fat and fatty acids. A commercial product (Inulina 95®) containing 914?0 g/kg of inulin and a degree of polymerisation (DP) ranging from DP 1–10 to DP 51–60 was used.

2. The performance of birds (feed intake, BW gain and feed to gain ratio) was not affected by the different dietary inclusions of inulin.

3. Dietary inulin significantly improved the AID coefficient of crude protein and crude fat. Also, there was a significant effect of inulin on the digestibility of most amino acids (10 out of 15) and major fatty acids (oleic and linoleic acids). The AID coefficient of starch and the AME_N content of diets were not affected by inulin inclusion.

4. In conclusion, the current study showed that inulin supplementation improved the digestibility of protein and fat in a maize-soybean meal based diet, but had no effect on the performance of broiler chickens.     

Increased iron level in phytase-supplemented diets reduces performance and nutrient utilisation in broiler chickens

1. The effect of different levels of dietary iron on phytase activity and its subsequent effect on broiler performance were investigated in a 3 × 2 factorial arrangement. A total of 360 day-old Ross 308 male broiler chicks were distributed to 6 experimental diets, formulated with three levels of Fe (60, 80 and 100 mg/kg) and two levels of phytase (0 and 500 FTU/kg).

2. Phytase supplemented to mid-Fe diets increased feed consumption more than the non-supplemented diet at d 24. From hatch to d 35, Fe × phytase interaction significantly influenced the feed intake (FI), body weight gain (BWG) and feed conversion ratio (FCR). The high-Fe diet supplemented with phytase significantly reduced FI and BWG of broilers than those supplemented with low- or mid-Fe diets. The overall FCR was significantly better in birds fed on the mid-Fe diets with phytase supplementation.

3. A significant improvement in ileal digestibility of N, P, Mg and Fe was observed in birds feed diets containing 60 mg Fe/kg, with significant interaction between Fe and phytase.

4. Phytase improved the bone breaking strength when supplemented to low- or mid-Fe diets, compared to the non-supplemented diets. There was a significant Fe × phytase interaction effect. Tibia Fe content was higher in birds fed on phytase-free diets with high Fe but the reverse was the case when phytase was added and their interaction was significant. High dietary Fe significantly increased the accumulation of Fe in liver.

5. Phytase improved Ca-Mg-ATPase, Ca-ATPase and Mg-ATPase activities in jejunum when supplemented to the diet containing 80 mg Fe/kg.

6. This study indicates that high (100 mg/kg) dietary Fe inhibited phytase efficacy and subsequently reduced the overall performance and nutrient utilisation of broilers.     

Effect of feeding regimen and lighting pattern on the performance of broiler chickens in the hot,humid tropics

1. A food restriction study in conjunction with light control was conducted with commercial broiler chicks in a tropical environment.

2. Chicks on treatments 1 and 2 were fed continuously while those on treatments 3 and 4 were fed during the day (from 06.00 h to 18.00 h) and night (from 18.00 h to 06.00 h) respectively. Chicks on treatment 1 received only natural light during the day, while those on treatments 2, 3 and 4 received supplementary lighting during the night in addition to natural light during the day.

3. Food consumption by birds on treatment 2 was significantly higher at 56 days of age, followed by birds on treatments 1, 4 and 3.

4. The pattern of body weight gains was similar to the order of food consumption.

5. Efficiency of food utilisation was poorest for birds on treatment 2.

6. Mortality rates were not influenced significantly by the feeding regimen and lighting pattern.

7. Dressing percentage and proportion of abdominal fat were greatest for birds on treatment 2.     

Wheat particle size,insoluble fibre sources and whole wheat feeding influence gizzard musculature and nutrient utilisation to different extents in broiler chickens

A 21‐day experiment was conducted to investigate the effects of wheat particle size, insoluble fibre source and whole wheat (WW) inclusion on the gizzard musculature, intestinal architecture and nutrient utilisation of broiler chickens. The following seven treatments, all in mash form, were tested: control diet using finely ground wheat (Fine); control diet using medium‐ground wheat (Medium); control diet using coarsely ground wheat (Coarse); fine diet diluted with 10 g/kg lignocellulose (LC); fine diet diluted with 30 g/kg oat hulls (OH); fine diet diluted with 30 g/kg wood shavings (WS); and ground wheat in the fine diet replaced with 50 and 100 g/kg WW during the second (day 8–14) and third (day 15–21) weeks of the study respectively. Except for the LC diet, all treatments increased (p < 0.05) the thickness of the caudodorsal thick muscle of gizzard compared to the fine diet. The highest (p < 0.05) caudoventral thin and cranioventral thick muscle diameters in the gizzard walls were achieved with the OH and WS diets. Feeding OH, WS and WW diets improved (p < 0.05) starch digestibility compared with the fine diet, while medium, coarse and LC diets had no effect (p > 0.05). All diets containing fibre sources (LC, OH and WS) reduced (p < 0.05) the energy digestibility compared to the fine diet. Birds fed OH and WS diets gained the lowest (p < 0.05) weights. Feeding LC, OH, WS and WW diets increased (p < 0.05) the feed per gain compared with the fine diet. The current results suggest that there is a potential for coarse particles, insoluble fibre sources and WW feeding to improve the gizzard musculature and digestibility of some nutrients, with the effect being more pronounced with the inclusion of structural fibre sources.     

Effect of dietary protein and environmental temperature on growth performance and water consumption of male broiler chickens

1. Male broilers were reared in individual cages from 23 to 44 d of age. The effect of 2 temperatures (22° and 32°C) and 2 crude protein (CP) levels (160 and 200 g/kg) were studied. The low protein diet was supplemented with lysine, methionine, arginine, threonine and valine in order to meet requirements.

2. At 22°C, a reduced CP content did not affect growth rate and breast muscle but slightly increased adiposity and food to gain ratio (FCR). Water consumption was reduced.

3. High temperature reduced growth rate and absolute and proportional breast muscle weight, and increased adiposity and FCR. These effects were more pronounced with the low CP diet. Water consumption was also reduced.

4. It was concluded that reducing CP content did not seem a good way to help broilers to withstand hot conditions. This experiment suggests that amino acids other than lysine, methionine and cystine are probably involved in the detrimental effect of high temperature.     

纤维素酶对肉鸡生产性能和营养物质消化利用率的影响

研究添加不同水平纤维素酶对肉鸡生产性能和营养物质消化利用率的影响,表明加入纤维素酶可提高饲料表观消化率、蛋白质利用率、能量利用率和代谢能值,低能饲料较高能饲料显著;加入纤维素酶可提高肉鸡的增重和饲料利用率,减少饲料消耗;为达到最佳的增重,低能组10~18日龄加纤维素酶0.3%,19~40日龄加纤维素酶0.2%为宜;高能组均加纤维素酶0.2%;为达到较好的料肉比,低能组和高能组均以加纤维素酶0.3%为宜。     

Effects of chitosan on growth performance and energy and protein utilisation in broiler chickens

1. Two experiments were conducted to investigate the effects of dietary chitosan on growth performance, energy availability and protein retention in broilers. 2. Experiment 1 was a 42-d growth assay, in which 294 1-d-old male broilers were given one of 7 dietary treatments. A control feed was supplemented with 5 levels of chitosan (0.2, 0.5, 1.0, 3.0 and 5.0 g/kg) or 50 mg/kg chlortetracycline (CTC). 3. Increasing chitosan inclusion gave a nonlinear increase (P< 0.001) in feed conversion efficiency (FCE). Optimal growth and feed conversion were obtained with 0.5-1.0 g/kg chitosan. 4. In experiment 2, 42 1-d-old male broilers (6/treatment) were individually housed but fed on the same diets as in experiment 1. Excreta were collected from d 19-21 and d 40-42. 5. The addition of 0.5-1.0 g/kg chitosan increased nitrogen retention compared with the control group (P< 0.01), while apparent metabolisable energy in the diets was not altered.