Influences of wet feeding and supplementation with ascorbic acid on performance and carcass composition of broiler chicks exposed to a high ambient temperature.

In two experiments was investigated whether feeding with an air-dry feed mixed with different amounts of water and/or supplemental ascorbic acid affect performance and carcass compositions of broilers exposed to a high ambient temperature (35 to 37 degrees C for 8 h/d and thermoneutral for 16 h/d). In the first trial, 64 one-week-old male broiler chicks were fed ad libitum in four dietary treatment groups for a 6-week period. Experimental mash diets were prepared by mixing a maize-soybean based standard broiler starter or finisher with tap water in the ratios of 0.0:1.0, 0.5:1.0, 1.0:1.0 and 1.5:1.0 (water:air-dry feed, w/w). More water in the diet increased BWG, DMI, abdominal fat and carcass weight, carcass CP, crude fat, but it deteriorated DM conversion efficiency. In the second experiment, 64 one-week-old male broiler chicks were given air-dry or wet (water:feed, 1.5:1) starter or finisher diets without or with ascorbic acid supplementation (0 and 250 mg/kg air-dry feed, resp.) ad libitum for a 6-week period. Ascorbic acid supplementation increased BWG, carcass weight and carcass CP significantly, while reducing carcass crude fat content. However, feeding broilers with a diet mixed with water in a ratio of 1.5:1.0 increased BWG, DMI, carcass weight and carcass lipid markedly, but deteriorated DM conversion efficiency. There was also a significant interaction between ascorbic acid and wet feeding, whereby ascorbic acid supplementation induced a significant reduction in carcass lipid contents of broilers fed on air-dry diets but not on wet diets. It is concluded that wet feeding, especially an addition of 150% water to produce a porridge like consistency, improved growth performance by increasing fat, ash and protein deposition in the body, while reducing DM conversion efficiency. It is also concluded that under heat stress supplemental ascorbic acid in air-dry diets stimulates broiler performance but not in wet diets.     

Comparison of the supplemental effects of Saccharomyces cerevisiae and antibiotics in low-protein and high-fibre diets fed to broiler chickens.

Two experiments were completed to compare the supplemental effects of yeast Saccharomyces cerevisiae and sub-therapeutic antibiotics in high-fibre and low-protein diets for broiler chicks. In experiment 1, yeast was added at 1.5, 3.0 and 6.0 g kg-1 while penicillin, tylosin or neoterramycin were added at 150 mg kg-1 into different batches of a high-fibre diet containing 250 g kg-1 palm kernel meal. Saccharomyces cerevisiae and antibiotics increased BW, BWG, FCR, feed intake, carcass and breast weights above the control. Small intestine weight was reduced by antibiotics, while yeast caused a lower deposition of abdominal fat. Liver weights of different treated broilers were similar. The performance indices were superior on penicillin and 3.0 g kg-1 yeast compared to other supplements evaluated. In the second experiment, 1.5 and 3.0 g kg-1 of yeast, and 0.75 mg kg-1 of procaine penicillin, zinc bacitracin and tylosin were separately added to a 180 g kg-1 crude protein diet. Performance of the chicks with additives was compared with unsupplemented negative and positive controls containing 180 and 210 g kg-1 crude protein respectively. Broilers fed with supplements had superior BW, BWG, FCR and feed intake compared to the negative control, but carcass data were similar. Dietary penicillin increased BW, BWG, feed intake more than other supplements, but yeast stimulated higher FCR. Data from both studies indicated that Saccharomyces cerevisiae comparatively increased growth and carcass weight and reduce abdominal fat, therefore, it can serve as a natural substitute for antibiotics in broiler diet.     

Influence of wheat-based diets supplemented with xylanase, bile acid and antibiotics on performance, digestive tract measurements and gut morphology of broilers compared with a maize-based diet

1. The aim of the present study was to compare wheat-based diets supplemented with arabinoxylanase, bile acid and virginiamycin with a maize-based diet in their effects on the performance of broilers. 2. The diets were fed to 5 groups of broilers. Group A received a maize-based diet (control), and groups B, C, D and E were fed on wheat-based diets. Diets C, D and E were supplemented with arabinoxylanase (150 mg/kg), bile acid (500 mg/kg) and virginiamycin (200 mg/kg), respectively. 3. A total of 450 1-d-old Ross 385 chicks were randomly divided into 5 groups, each with three pens as replicates (30 birds per pen). The experimental diets were given for 18 d. On d 18, three chickens from each group were slaughtered by cervical dislocation and the liver weight, and duodenal, jejunal and ileal lengths were measured for length and width of the villi and the height of crypts. 4. Arabinoxylanase, bile acid and virginiamycin supplementation significantly increased feed intake and daily gain but had no significant effect on feed conversion ratio. The liver weight was significantly greater in virginiamycin supplemented chicks as compared with those on the diet containing bile acid. 5. Virginiamycin inclusion increased full and empty caeca weight significantly compared with groups A and D. Group A had the lightest caeca. Significant effects of diets were observed on duodenal, ileal and intestinal length, but jejunal length was not affected by diet. The heights of duodenal and ileal, but not jejunal, villi were significantly affected by the treatments. The lengths of villi in groups B and E were significantly higher than other groups. The mean height of ileal villi in group A was significantly higher than in groups receiving the wheat-based diets. The mean width of duodenal and ileal villi was significantly affected by the ration. The height of crypts in group B was significantly higher than in group E. 6. It could be concluded that supplementation of the wheat-based broiler ration with virginiamycin had significant positive effects on gastrointestinal tract characteristics for absorption. Supplementation with bile acid reduced the weight of liver and caeca and the length of duodenum, jejunum, ileum and in small intestine and the height and width of villi.     

Intestinal function and gut microflora of broiler chickens as influenced by cereal grains and microbial enzyme supplementation

A study was conducted to investigate the effect of the key cereal grains and a microbial enzyme supplement on broiler chicken performance, gut microflora and intestinal function. Ingestion of the barley-based diet was associated with low 28-day body weight, decreased feed intake and high FCR. The supplemental enzyme increased feed intake and weight gain of the chickens on a wheat-based diet. The pH of the gizzard and caecal contents varied with the grain type. Enzyme supplementation reduced ileal viscosity, particularly in birds that received the diet based on wheat. The birds on the barley-based diet had lower ileal digestibility of dry matter, protein and energy than those given maize and sorghum-based diets. The ileal digestibility of starch was increased by enzyme supplementation. Enzyme supplementation increased the number of total anaerobic bacteria in the gizzard of birds fed on sorghum and increased lactobacilli in the gizzard of those fed both sorghum and wheat. The birds fed the sorghum-based diet had the lowest counts of caecal total anaerobic bacteria and lactobacilli. Jejunal villus height and villus:crypt ratio of birds fed the barley-based diet were the lowest when compared with those fed the other diets. Enzyme application induced an increase in villus height and villus:crypt ratio of birds on wheat, crypt depth on barley and a reduction in crypt depth of chickens on the sorghum-based diets. The highest activity of maltase and the lowest activity of sucrase were observed in tissue from birds fed on maize and sorghum-based diets respectively. The differences in the performance of broilers on cereal grains could be explained by changes in intestinal morphology, enzyme activities and gut microflora as well as nutrient digestibility. The improved performance by supplemental enzyme in wheat-fed chickens was associated with beneficial changes in intestinal morphology and digesta viscosity.     

Influence of particle size and xylanase supplementation on the performance, energy utilisation, digestive tract parameters and digesta viscosity of broiler starters

1. The aim of the present experiment was to examine the influence of particle size and xylanase supplementation on the performance, energy utilisation, and gross morphological and histological parameters of the digestive tract of broiler starters fed wheat-based diets. The experimental design was a 2 x 2 factorial arrangement of treatments evaluating two wheat particle sizes (medium and coarse) and two levels of xylanase supplementation (without or with 1000 xylanase units/kg diet). The two particle sizes were achieved by grinding the whole wheat in a hammer mill to pass through 3 and 7 mm screens, respectively. Broiler starter diets, based on wheat and soybean meal, were formulated and each diet was fed ad libitum to 6 pens of 8 male broilers each from d 1 to 21 post-hatch. 2. Wheat particle size had no effect on the performance of broilers. Xylanase supplementation had no effect on weight gain and feed intake. However, a significant particle size x xylanase interaction was observed for feed per unit gain with xylanase lowering feed per gain only in the coarse particle size diet. Xylanase supplementation improved the nitrogen-corrected apparent metabolisable energy at both particle sizes. 3. Xylanase supplementation decreased the relative weight and relative length of all gut components. Villus height and crypt depth and total extent of the mucosal layer were unaffected by both wheat particle size and xylanase supplementation. 4. The apparent viscosity of intestinal digesta, determined over the physiological range of shear rates, was not influenced by xylanase addition or particle size. 5. The findings of this study suggest that the effectiveness of exogenous xylanase in broiler diets is influenced by wheat particle size.     

Effects of Lactobacillus cultures on growth performance,abdominal fat deposition,serum lipids and weight of organs of broiler chickens

1. The effects of a mixture of 12 Lactobacillus strains (LC) on the growth performance, abdominal fat deposition, serum lipids and weight of organs of broiler chickens were studied from 1 to 42 d of age. 2. One hundred and thirty-six 1-d-old male broiler chicks were assigned at random to two dietary treatments: a basal diet (control), and a basal diet with 0.1% LC. 3. The supplementation of LC in broiler diets improved the body weight gain and feed conversion rate from 1 to 42 d of age and was effective in reducing abdominal fat deposition but only after 28 d of age. 4. The LC diets reduced serum total cholesterol, low density lipoprotein (LDL) cholesterol and triglycerides in broilers from 21 to 42 d of age. However, there was no significant difference in serum high density lipoprotein (HDL) cholesterol between control and LC-fed broilers. There was also no significant difference in the weights of organs of control and LC-fed broilers. 5. The results indicated that the mixture of 12 Lactobacillus strains have a hypolipidaemic effect on broilers.     

Effect of dietary Moringa oleifera leaves on the performance,ileal microbiota and antioxidative status of broiler chickens

In this study, we investigated the effect of Moringa oleifera leaves (MOL) supplements on the performance, ileal microbiota carcass traits and biochemical and antioxidant parameters of broiler chickens. MOL was added to starter, grower and finisher diets at four levels (0%, 0.5%, 1.0% and 5.0%). A total of 320 one-day-old mixed-sex Cobb-500 broiler chicks were divided equally into four treatment groups, with 5 replicates of 16 chicks each until 42 days of age. Compared to the control group, chicks fed 0.5% and 1% MOL exhibited a higher final body weight (FBW), greater weight gain (BWG), and better average daily gain (ADG). Feed intake (FI) gradually decreased as the inclusion rate of MOL in the broilers' diet increased to 5%. The best feed conversion ratio (FCR), protein efficiency ratio (PER) and performance index (PI) were observed in broilers that were fed the MOL diet. The percentage of abdominal fat in broilers decreased significantly in response to dietary supplementation with MOL. The haematological profile in the MOL group revealed a lower WBC count and lymphocyte percentage but higher heterophil and H/L ratio without affecting haemoglobin and RBC count. The inclusion of MOL increased total serum protein, Ca and P levels but decreased glucose, cholesterol, triglycerides, AST and ALT concentrations. Moreover, dietary MOL increased the activities of GSH, CAT and SOD, GPx and GST while decreasing the TBARS level. The pH value decreased in the ileum of broilers fed the 1% and 5% MOL diet compared to the other treatments. Decreased ileal counts of E. coli, Salmonella and Staphylococcus spp. were observed whereas the total ileal Lactobacillus spp. count increased in broilers fed the MOL diet. In conclusion, the MOL supplement can enhance growth performance and antioxidant status, alter ileal microbiota and protect against enteropathogens with no deleterious effects on the broiler chickens.     

Effect of Phytase Supplementation in Diets on Nutrient Digestibility and Performance in Broiler Chicks

A performance trial was conducted with broiler chicks to study the effect of phytase (PHY) supplementation in diets formulated with reduced AME, Ca, and P. The nutrient digestibility was determined during the 14- to 21-d and 28- to 35-d periods. The treatments consisted of 3 diets (NC1, NC2, NC3) differing in nutrient content and each diet with or without supplemental PHY (NC1, 0 or 500; NC2, 0 or 750; NC3, 0 or 1,000 U of PHY/kg feed) and 1 positive control diet (PC). Compared with the PC diet, negative control diets (NC) resulted in lower AME and apparent ileal amino acid digestibility for some amino acids. Phytase supplementation of the NC diets increased AME, apparent ileal amino acid digestibility, and apparent ileal crude protein digestibility. Phytase addition also increased mineral absorption in 21- and 35-d-old broilers fed NC diets. Reduced nutrient digestibility appears to be a factor in the weight gain and feed intake results. Reducing Ca and P content reduced feed intake in a stepwise fashion in the NC diets. Phytase increased feed intake and generally improved nutrient digestibility, which resulted in an increase in digestible nutrient intake. Averaged across NC diets, PHY improved body weight. Bone-breaking strength was the most consistent predictor of Ca and P reduction. All NC diets had significantly lower bone-breaking strength than the PC. Phytase supplementation of the NC diets gave bone-breaking strengths that were comparable to the PC. Diets with PHY had the highest bioeconomic index.     

木聚糖酶在肉鸡小麦型日粮中的作用机理

小麦作为主要能量作物之一在粮食工业中已得到广泛应用,其在饲料工业上的应用也越来越受到人们重视,但其含有的抗营养因子在一定程度上限制了其在饲料工业中的应用。小麦中主要的抗营养因子是阿拉伯木聚糖,而向小麦型基础日粮中添加木聚糖酶是消除其抗营养特性的有效办法。文中介绍了小麦型基础日粮中木聚糖的抗营养特性及其对肉鸡生产性能的负面影响,木聚糖酶的作用机理及在肉鸡小麦型日粮中添加木聚糖酶的作用效果,以期为小麦合理地应用于肉鸡日粮提供参考。     

Nutritional approaches to ameliorate pulmonary hypertension in broiler chickens

This article reviews recent nutritional approaches for counteracting the development of pulmonary hypertension syndrome (PHS; ascites) in broiler chickens especially when they are reared at high altitudes. High altitudes impose the sustained stress of hypobaric hypoxia, which reduces the availability of atmospheric oxygen to red blood cells passing through the lungs, thereby causing systemic arterial hypoxaemia (undersaturation of haemoglobin with oxygen), pulmonary arterial hypertension and PHS/ascites in susceptible broilers. Proper nutritional strategies are needed to reduce metabolic activity and prevent the development of ascites especially when modern broilers are reared in regions where the existing altitudes limit the availability of atmospheric oxygen. This article also addresses controversies with regard to broiler nutrition in relation to PHS. For example, the catabolism of protein from feed ingredients incurs increased oxygen consumption, suggesting that feeding reduced‐protein diets to broiler chickens may result in reduced PHS incidences. However, experimental and field data indicate that feeding reduced‐protein diets to broilers subjected to hypobaric hypoxia increases the development of PHS. Controversies on the nutrition of unsaturated fat in relation to PHS are also discussed. In conclusion, hypoxia, acidosis, vasoconstriction and enhanced metabolic rate are triggers of PHS. Feeding reduced‐protein diets might promote the susceptibility of broilers to PHS by decreased dietary intake of arginine, decreased uric acid production and increased lipogenesis. Feeding high‐protein diets, dietary arginine supplementation, partial substitution of sodium bicarbonate for sodium chloride, feeding low‐fat diets and effective feed restriction programmes can be considered as nutritional approaches to prevent PHS.     

日粮中添加酵母培养物对肉仔鸡生长性能、肉品质和肠道菌群的影响

试验旨在研究日粮中添加不同水平酵母培养物对肉仔鸡生长性能、肉品质和肠道菌群的影响。选用432只1日龄、初始体重为（41.73±0.15）g的AA商品代肉仔鸡公雏,随机分为4个处理组（分别在基础日粮中添加0、0.1%、0.2%和0.3%的酵母培养物）,每组6个重复,每个重复18只鸡。试验期42 d,分为1~21和22~42 d两个阶段,试验期间记录采食量、体重和死淘率,试验结束时每个重复选择1只与平均体重接近的肉仔鸡空腹12 h后进行屠宰,测定其屠宰性能和肠道微生物数量。结果显示,与对照组相比,日粮中添加0.2%和0.3%酵母培养物能够显著提高肉仔鸡42 d的体重和试验全期平均日增重（P< 0.05）。且当添加量为0.2%时,能显著提高肉仔鸡22~42 d平均日增重（P< 0.05）,显著降低料重比（P< 0.05）;显著提高试验全期平均日增重和平均日采食量（P< 0.05）,显著降低试验全期料重比（P< 0.05）。同时,添加酵母培养物还可显著降低鸡肉的滴水损失和大肠杆菌数量（P< 0.05）,并显著增加盲肠双歧杆菌数量（P< 0.05）。综上所述,肉仔鸡日粮中添加0.2%酵母培养物的效果最佳,能够显著提高肉鸡生长性能,提高肌肉的系水力,改善其肌肉品质。同时,还能有效增加肉鸡盲肠中有益菌双歧杆菌数量和减少有害菌大肠杆菌数量。     

Influence of a microbial phytase on the performance and the utilisation of energy,crude protein and fatty acids of young broilers fed on phosphorus-adequate maize- and wheat-based diets

1. The effects of microbial phytase on the performance and nutrient utilisation in broilers fed on phosphorus-adequate starter diets were examined in this study. The effect of phytase on the apparent ileal digestibility of fatty acids was of particular interest. Two grain types (maize and wheat) and two inclusion concentrations of a phytase enzyme from Escherichia coli expressed in Schizosaccaromyces pombe (0 or 500 phytase units (FTU)/kg of feed) were evaluated in a 2 × 2 factorial arrangement of treatments.

2. Supplemental phytase improved the weight gain and feed per gain, but had no effect on the feed intake of young broilers receiving phosphorus-adequate diets.

3. Phytase supplementation improved the apparent ileal digestibility of nitrogen and phosphorus in both diet types. Phytase supplementation tended to improve the apparent ileal digestible energy in wheat-based diets, but had no effect on the apparent metabolisable energy in both diet types.

4. Supplementation of phytase increased the apparent ileal digestibility of fat, with similar effects for the different fatty acids measured. Increments on ileal fat digestibility due to phytase were not dependent on the type of diet.

5. Dietary supplementation of microbial phytase enhanced not only the digestibility of phosphorus, but also that of nitrogen and fat, exhibiting increased ileal digestibility for all fatty acids in P-adequate maize- and wheat-based diets.     

Influence of whole wheat inclusion and a blend of essential oils on the performance, nutrient utilisation, digestive tract development and ileal microbiota profile of broiler chickens

1. The aim of the present experiment was to examine the influence of whole wheat inclusion and a blend of essential oils (EO; cinnamaldehyde and thymol) supplementation on the performance, nutrient utilisation, digestive tract development and ileal microbiota profile of broiler chickens. 2. The experimental design was a 2 × 2 factorial arrangement of treatments evaluating two wheat forms (ground wheat [GW] and whole wheat [WW]; 100 and 200 g/kg WW replacing GW during starter [1 to 21 d] and finisher [22 to 35 d] diets respectively) and two levels of EO inclusion (0 or 100 g/tonne diet). All dietary treatments were supplemented with 2000 xylanase units/kg feed. Broiler starter and finisher diets based on wheat and soybean meal were formulated and each diet fed ad libitum to 6 pens of 8 male broilers. 3. During the trial period (1-35 d), wheat form had no significant effect on weight gain or feed intake. However, WW inclusion tended (P = 0.06) to improve feed per gain. Essential oil supplementation significantly improved weight gain in both diets, but the improvements were greater in the GW diet as indicated by a significant wheat form × EO interaction. 4. Main effects of wheat form and EO on the relative weight, length and digesta content of various segments of the digestive tract were not significant. Significant interactions, however, were found for relative gizzard and caecal weights. Essential oil supplementation significantly increased the relative gizzard weight and lowered relative caecal weight in birds fed on the GW based diet, but had no effect in those fed on the WW based diet. 5. Whole wheat inclusion and EO supplementation significantly improved apparent ileal nitrogen digestibility. Apparent ileal digestible energy was not significantly influenced by the dietary treatments. 6. Ileal microbiota profiling, using denaturing gradient gel electrophoresis, showed that the ileal microbiota composition was influenced by feed form. The mean numbers of bacterial species in the ileal contents of birds fed on the GW diet supplemented with EO tended (P = 0.07) to be higher than those of the ileal contents of birds fed on unsupplemented GW based diet. 7. The present data suggested that dietary addition of EO improves broiler weight gain and ileal nitrogen digestibility both in GW and WW based diets, but that the magnitude of the response to EO for weight gain was greater in GW based diet. Whole wheat feeding was found to be beneficial in terms of feed efficiency.     

Effects of Yeast Culture on Growth Performance,Meat Quality and Intestinal Microflora of Broilers

The experiment was conducted to study the effects of yeast culture on growth performance, meat quality and intestinal microflora of broilers. A total of 432 1-day-old AA commercial broiler chicks with initial body weight of (41.73±0.15)g were randomly divided into 4 groups with 6 replicates per group and 18 broilers per replicate,receiving diets supplemented with 0,0.1%,0.2% and 0.3% yeast culture, respectively. The trial lasted for 42 days which was divided into two periods with 1 to 21 d and 22 to 42 d,respectively.The feed intake,body weight,death and culling rate were recorded in each period. At the end of the experiment,1 chickens in each replicate with the weight close to the average value were slaughtered after fasting for 12 h. The slaughter performance and intestinal microflora counts were determined.The results showed that compared with control group,the supplementation of 0.2% and 0.3% yeast culture significantly increased the body weight at 42 d and the average daily gain (ADG) during the whole trial (P< 0.05).The diet supplemented with 0.2% yeast culture significantly improved the ADG,decreased the F/G of broilers during 22 to 42 d (P< 0.05),and it also significantly increased the average daily feed intake (ADFI) and ADG (P< 0.05),decreased the F/G of the whole period (P< 0.05).Moreover,the supplementation of 0.2% yeast culture significantly decreased the drip loss of meat and the count of Escherichia coli (P< 0.05),and significantly increased the count of Bifidobacterium(P< 0.05). In summary, the supplementation of 0.2% yeast culture could significantly improve the growth performance and the muscle quality of broilers.The intestinal microflora in broiler cecum were effectively optimized after inclusion of yeast culture in the study.     

Polysaccharidase preparations added to a wheat-based diet: effects on performance and digestive parameters of broiler chickens held at three different locations

1. Three experiments of 39 d were simultaneously conducted to assess the efficacy of three carbohydrase combinations on performance, apparent nutrient digestibility, intestinal morphology and digestive organ relative weights of chickens fed on a wheat-based diet. 2. Experiment 1 was performed under laboratory conditions, with the birds housed in cages. In experiment 2, the birds were placed in floor pens built in a commercial farm, and raised with their contemporaries at the farm. In experiment 3, broilers were reared under industrial management circumstances in commercial farms. A two-phase feeding programme was used: starter from 1 to 21 d of age and finisher from 22 to 39 d. The basal diet without supplementation (BD) and three enzyme preparations (BDF, BDP and BDR) were evaluated. 3. No differences in growth traits were observed among treatments in experiments 1 and 2. 4. When overall growing period was evaluated, all enzyme combinations improved apparent DM ileal digestibility of feed in the three experiments, but significant differences were only found in experiments 2 and 3. For this same period, an increase in apparent CP ileal digestibility of broiler chickens fed supplemented diets against the control group was found in experiment 3. Moreover, a significant greater apparent ileal fat digestibility in the enzyme treatments compared with the control group was shown when broilers were raised under industrial conditions (experiment 3). 5. Enzyme combinations had no effect on villus heights and crypt depths of broilers in experiment 1, whereas, in experiment 2, a greater villus height was found in BDF and BDP treatments than in control birds. 6. There were no differences in digestive organ relative weights among dietary treatments except for pancreas in experiment 1.     

Effects of dietary phytase on performance and nutrient metabolism in chickens

1. A broiler growth study was conducted to compare the effect of different concentrations of an Escherichia coli-derived phytase on performance, apparent metabolisable energy (AME), nitrogen (N), amino acid and mineral metabolisability, sialic acid excretion and villus morphology when fed to broiler chickens. 2. Female Ross 308 broilers (480) were reared in floor pens from 0 to 28 d of age. All birds were fed on nutritionally complete starter (0 to 21 d of age) and grower diets (21 to 28 d of age) with the exception that they were low in P (28 and 23 g/kg available P, respectively). These maize-soy diets were supplemented with 0, 250, 500 or 2500 phytase units (FTU)/kg feed. 3. Between 21 and 28 d of age, two birds from each floor pen were selected, and each pair placed in one of 32 metabolism cages (two birds per cage). Feed intake was recorded and excreta collected for the last 2 d of the feeding period, and AME, N, amino acid and mineral metabolisability coefficients and endogenous losses were determined following a total collection procedure. 4. Feed intake and weight gain increased in a linear manner in response to phytase dose, with an average increase of approximately 11.7 and 13.5%, respectively, compared with chickens fed on the low-P diet. Birds given diets with 2500 FTU weighed 6.6% more and had a 2.4% higher feed conversion efficiency (FCE) than those fed on diets containing 500 FTU. 5. Enzyme supplementation increased the intake of AME and metabolisable N by 10.3 and 3.9%, respectively, principally through increases in feed intake. Birds given enzyme-supplemented diets also improved their intake of metabolisable amino acids and P by approximately 14 and 12.4%, respectively, compared with birds fed on the control diet. Enzyme supplementation did not affect ileal villus morphometry of the birds.     

Influence of conditioning temperature on the performance, nutrient utilisation and digestive tract development of broilers fed on maize- and wheat-based diets

1. The influence of conditioning temperature on the performance, nutrient utilisation and digestive tract development of broilers fed on maize- and wheat-based diets was examined up to 21 d of age. The experimental design was a 2 × 3 factorial arrangement of treatments evaluating two grain types (maize and wheat) and three conditioning temperatures (60°C, 75°C and 90°C). Broiler starter diets, each based on one grain (maize or wheat), were formulated and pelleted at the three temperatures. 2. Increasing conditioning temperature decreased the body-weight gain and feed intake in wheat-based diets, but birds fed on maize-based diets conditioned at 60°C and 90°C had higher body-weight gain and feed intake than those fed on the diet conditioned at 75°C. Increasing conditioning temperature increased feed per body-weight gain in both grain-type diets but improved pellet durability index (PDI) only in wheat-based diets; PDI was unaffected in maize-based diets. 3. In wheat-based diets, increasing conditioning temperature decreased the ileal digestibility of nitrogen and starch. Ileal nitrogen digestibility of maize-based diets conditioned at 60°C and 90°C was higher than at 75°C. Starch digestibility was unaffected by conditioning temperature in maize-based diets. No effect of conditioning temperature was found for apparent metabolisable energy (AME). Increasing conditioning temperature decreased digestible protein and AME intakes in wheat-based diets but, in maize-based diets, birds fed on the diet conditioned at 75°C had lower digestible protein and AME intakes compared to those fed on diets conditioned at 60°C and 90°C. 4. Small intestine was longer in birds fed on diets conditioned at 75°C and 90°C compared with those fed on diets conditioned at 60°C. 5. Overall, the data suggest that while the effects of conditioning temperature on body-weight gain and feed intake of broilers to 21 d of age differed depending on the grain type, feed per body-weight gain was adversely affected by higher conditioning temperatures.     

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.

     

Higher lipid accumulation in broilers fed on saturated fats than in those fed on unsaturated fats

1. Two experiments were conducted to assess the effect of fat sources differing in degree of saturation on the performance of and fat deposition in broiler chickens fed on isocaloric and isonitrogenous diets. 2. There were no differences in initial body weight between sexes but female broilers had lower daily gains (P <0.0001), final weights (P <0.0001) and food intakes (P <0.0001) than males. Abdominal fat pad weight was lower in male broilers than in female (P <0.001). 3. There were no significant differences in intake, weight gain, final body weight or food-to-gain ratios between birds fed on diets differing solely in the degree of fat saturation. Broilers fed on diets containing an animal fat blend or tallow had higher abdominal fat pad weight (P <0.001) and intramuscular lipid content (P =0.0085) than those fed on diets containing sunflower oil. 4. It was concluded that dietary fat saturation affects fat accumulation in broiler chickens.     

不同配伍酶制剂添加于小麦日粮中对肉仔鸡生长和血液生化指标的影响

选择14日龄肉仔鸡,研究小麦日粮中添加不同配伍酶制剂对鸡生长和一些血液生化指标的影响。结果表明:(1)添加酶制剂可显著提高鸡的增重(P<0.05),不同配伍间差异不明显,但有一定的增加趋势;(2)小麦日粮添加酶制剂有提高鸡血清总蛋白量的趋势(P>0.05);(3)小麦日粮添加酶制剂可显著提高鸡血清谷丙转氨酶和尿酸的量(P<0.05),不同配伍间有出现差异的趋势;(4)小麦日粮添加酶制剂可显著提高鸡血清总胆固醇和甘油三酯的量(P<0.05),不同配伍间有出现差异的趋势。结果显示,酶制剂可提高肉仔鸡生长、采食量和利用日粮营养的能力,适宜配伍酶制剂的效果更为显著。