Response of broiler chicks to threonine‐supplemented diets to 4 weeks of age

1. Two experiments were carried out to determine the response of broiler chicks to threonine‐supplemented diets between 10 and 28 d and 7 and 21 d of age, respectively.

2. In the first experiment female broiler chicks were fed on 11 experimental diets. Two iso‐energetic basal diets (diets 1 and 2) were prepared with 200 and 160 g CP/kg and 7·6 and 6·0 g threonine/kg respectively. Both diets contained 11·5 g lysine and 8·7 g sulphur‐containing amino acids/kg. Diet 3 was composed of diet 2, supplemented with all essential and non‐essential amino acids (EAA and NEAA, respectively) except threonine, to the concentrations of the amino acids in diet 1. The NEAA were added as a combination of glutamic acid and glycine. Diets 4 to 11 had the same compositions as diet 3, but contained increasing amounts of threonine.

3. For birds fed on diet 2, gain was significantly lower and food/gain ratio was significantly higher than for birds fed on diet 1. Supplementation with EAA, NEAA and threonine to the same concentrations in diet 1 resulted in a performance similar to that found on diet 1.

4. In experiment 2, male and female broiler chicks both received 10 experimental diets. Diet 1 contained 220 g CP/kg and 8.5 g threonine/kg, diet 2 contained 160 g CP/kg from natural raw materials and 6 g threonine/kg. Both diets contained 12·4 g lysine and 9·3 g sulphur‐containing amino acids/kg. Basal diet 2 was supplemented with all EAA and NEAA to the concentrations of basal diet 1, except for threonine. Diets 3 to 10 had the same compositions as the supplemented diet 2, but contained increasing amounts of threonine.

5. For male and female chicks on diet 2, gain was significantly lower and food/gain ratio significantly higher than those on diet 1. Diet 10 (160 g CP/kg plus all EAA, including threonine, and NEAA supplemented to the concentrations of diet 1) resulted in the same performance as diet 1.

6. The results indicate that, when low protein maize‐soyabean meal diets supplemented with EAA and NEAA with 13·31 MJ ME/kg were fed to male and female broiler chicks until 21 d of age, improvements in gain and food/gain ratio were obtained when the dietary threonine content was increased to 7·25 g/kg. When female chicks were fed threonine‐supplemented diets to 28 d of age, improvement in gain and food/gain ratio was obtained when the threonine concentrations were increased to 6·32 g/kg diet.

7. Curves have been fitted to the data, from which a cost‐benefit analyses can be made and an optimum threonine dose calculated, using local prices.     

Effects of fermented cottonseed meal on the growth performance,gastrointestinal microflora population and small intestinal morphology in broiler chickens

1. This experiment was conducted to evaluate the effects of replacing dietary cottonseed meal (CSM) or fermented cottonseed meal (FCSM) for soya bean meal (SBM) on growth performance, carcass characteristics, gastrointestinal microbial populations, and intestinal morphology of broiler chickens.

2. CSM was fermented with Bacillus subtilis, Aspergillus niger and A. oryzae for 7 d. A total of 300 one-d-old male Ross 308 broiler chickens were used in a 42-d experiment in which the birds were randomly allotted to one of 5 dietary treatments (containing 0%, 10% and 20% CSM or FCSM) in a completely randomised design. Birds were reared on litter floor and had free access to feed and water during the experiment.

3. Results indicated that the fermentation process significantly reduced crude fibre and free gossypol, while it increased crude protein content and lactic acid bacteria (LAB) count in CSM.

4. The use of FCSM instead of CSM significantly improved growth performance of broilers. The abdominal fat yield in treatments containing FCSM was significantly lower than in the other treatments. The increase in the population of LAB in the crop and decrease in the population of coliforms in the ileum of birds fed on diets containing FCSM were more significant than in other birds. Villi in the duodenum and jejunum of the birds fed on diets containing FCSM were significantly higher than for the other experimental groups.

5. The positive effects of diets containing FCSM on growth performance and intestinal health of broiler chickens showed that this processed source of protein can serve as an appropriate alternative for SBM in diets for 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.     

Immune-modulatory effects of dietary Saccharomyces cerevisiae cell wall in broiler chickens inoculated with Escherichia coli lipopolysaccharide

1. An experiment was conducted to study the effect of yeast (Saccharomyces cerevisiae) cell wall (YCW) supplemented in diets of broiler chickens challenged with Escherichia coli lipopolysaccharide (LPS).

2. One-day-old broiler chicks were randomly distributed into 24 cages (6 replicate cages; 8 birds/cage) and were inoculated with 0 or 1 mg/kg body weight E. coli-LPS (d 4 and 9) and 0 or 500 mg YCW/kg feed, resulting in a 2 × 2 factorial arrangement of treatments. Experimental diets did not include coccidiostats, in-feed antibiotics or enzymes.

3. On d 21, the inoculation of E. coli-LPS reduced weight gain and feed intake and increased feed conversion ratio (FCR) of birds, an effect maintained until 28 d. In contrast, chickens given diets with YCW improved the FCR at both 21 and 28 d of age.

4. E. coli-LPS challenge reduced the relative weight of bursa of Fabricius, except when chickens were given YCW, which resulted in an interaction. Supplementation of broiler diets with YCW exacerbated the cellular immune response as measured by the delayed cutaneous hypersensitivity response test.

5. The results of this study suggested a benefit on feed efficiency when YCW was added to diets fed to broiler chickens challenged with E. coli-LPS. Part of the mode of action of YCW might be related to better maintenance of immune status in response to microbial challenge.     

Urea and aspartic acid supplementation of low‐protein broiler diets1

1. L‐Aspartic acid does not seem useful as a protein surrogate in conventionally formulated low‐protein diets for broiler chicks.

2. Urea as a protein substitute does not enhance the value of conventional broiler diets.

3. Urea does not improve broiler diets that have been supplemented with fish meal or crystalline amino acids to satisfy requirements for all indispensable amino acids.

4. Urea is absorbed into the bloodstream, but is not assimilated into body proteins.     

Evaluation of rabbit excreta as an ingredient in broiler diets

1. Dry rabbit excreta were found to contain 188.1 g crude protein, 6.6 g non‐protein nitrogen, 0.3 g ammonia, 89.8 g moisture, 8.0 g ether extractives, 135.2 g crude fibre, 266.9 g ash and 19.18 MJ gross energy/kg. Methionine and lysine contents were 3.95 and 4.29 g/100 g protein, respectively.

2. In one experiment, 0, 50, 100 or 200 g rabbit excreta/kg were substituted for maize in a broiler diet. Chickens receiving the diet containing 200 g rabbit excreta/kg gained significantly less weight to 8 weeks of age than those receiving other diets.

3. In a second experiment, 0, 100, 150 or 200 g rabbit excreta/kg were substituted primarily for maize in a broiler diet to provide equal energy and protein contents. Weight gains to 8 weeks of birds receiving these diets did not differ significantly. The uncorrected metabolisable energy content of the excreta was 9.15 MJ/kg.

4. There were no gross pathological changes in the birds fed on the experimental diets.     

Welfare assessment of broiler breeder and layer females subjected to food restriction and limited access to water during rearing

1. A factorial experiment was conducted to assess the welfare at different ages of two strains of broiler breeder and one layer strain during rearing using a range of indicators. The birds were fed ad libitum or restricted and provided with free or limited access to water.

2. Food‐restricted birds spent a large proportion of time scratching and pecking the litter compared with birds fed ad libitum.

3. The heterophil/lymphocyte ratio and the proportion of basophils were raised at 8, 12 and 16 weeks, and the plasma concentrations of corticos‐terone were higher at 8 and 12 weeks of age in restricted birds compared with those fed ad libitum.

4. Creatine kinase activity was higher in broiler breeders fed ad libitum compared with layers and restricted broiler breeders. The activity of aspartate transaminase was higher in restricted layers compared with birds fed ad libitum and was similar in broiler breeders.

5. Plasma viscosity was lower in food‐restricted compared with ad libitum‐fed birds.

6. Limiting access to water had little or no effect on the welfare indicators although food‐restricted birds with free access to water spent more time drinking than birds fed ad libitum.

7. There were no important differences between the two broiler strains. Layers spent less time resting than broiler breeders and had higher plasma corticosterone concentrations at 3 and 16 weeks of age.

8. It was concluded that there was evidence for physiological stress associated with restricted feeding at least between 8 and 16 weeks of age. It was suggested that the altered behaviour of broiler breeders kept on litter may indicate that they can cope with food restrictions and that this may be acceptable in relation to the long‐term benefits of limiting body weight during rearing. The same may not be true for layers.     

Welfare of broiler breeder and layer females subjected to food and water control during rearing: Quantifying the degree of restriction

1. A factorial experiment was conducted with females of two broiler breeder and one layer strains. The birds were fed ad libitum or restricted and were provided with free or limited access to water to simulate commercial rearing practices.

2. There was little difference between the broiler breeder strains except in body weight at 16 and 18 weeks of age.

3. Food intake relative to body weight was higher in the broiler breeders compared with the layer strain.

3. The degree of restriction was defined as the food intake of re‐stricted birds as a proportion of the estimated intake of birds of the same body weight fed ad libitum. The value declined from 0.60 to 0.45 during the rearing period.

5. In the ad libitum treatments broiler breeders drank more than layers, whereas when restricted, layers drank more than broiler breeders.

6. Water intake was 2.50 times higher in restricted compared with ad libitum‐fed layers and 1.25 times higher in restricted than ad libitum‐fed broiler breeders, with free access to water.     

Effect of diets containing raw and extrusion‐cooked rice bran on growth and efficiency of food utilization of broilers

1. Meat strain chicks were fed on diets containing 600 g rice bran/kg for the 7 to 8 week period required to reach broiler weight.

2. Extrusion cooking of rice bran resulted, in improved chick weight gain and food efficiency for the first two weeks of feeding, but this advantage was lost by the end of the feeding period.

3. Addition of 10 g calcium/kg to the stabilised rice bran diet prevented the decline in performance after two weeks of age, and birds fed on this diet continued to gain at an increasing rate until the end of the experiment.

4. Calcium supplementation of stabilised rice bran diets produced significantly greater gains and superior food utilisation compared to stabilised rice bran diets without added calcium.

5. Calcium supplementation did not affect weight gain of chicks fed on diets containing raw rice bran.

6. Taste panel evaluation of meat from birds fed on diets containing raw rice bran, stabilised rice bran, or no rice bran indicated a significant preference in only one combination tested. Any ‘off flavour could not be related to dietary treatment.     

Relationship between monensin and sulphur amino acid requirements IN broiler chickens

1. Diets containing 80, 100, 125, 150, 175 or 200 mg monensin/kg were fed to broiler chickens from 0 to 28 d in cages that prevented access to excreta.

2. Growth was depressed with 125 mg monensin or more/kg and food intake tended to decrease. Feathering was adversely affected with 175 mg or more/kg.

3. In a similar experiment, diets containing 8.8, 9.1, 9.4, 9.7 or 10.1 g total sulphur amino acids (SAA)/kg were supplemented with 125 or 80 mg monensin/kg and compared with a diet containing 8.8 g SAA and 33 mg robenidine/kg.

4. With 125 mg monensin/kg, body‐weight gain was significantly less than that of birds receiving robenidine if dietary SAA content was 9.4 g or less/kg. With 9.7 g SAA or more/kg, gain in birds receiving monensin was similar to that of birds receiving robenidine.

5. Monensin at 125 mg/kg therefore appears to increase the SAA requirement.     

Effect of probiotic supplementation on growth,nitrogen utilisation and serum cholesterol in broilers

1. The effect of dietary probiotic supplementation on the growth, nitrogen utilisation and serum cholesterol content of broiler chickens was studied in 2 trials.

2. In experiment 1, the birds receiving the 0, 75, 100, 125 mg probiotic/kg diets had weight gains of 1204.0, 1272.0, 1268.3 and 1210.5 g, respectively at the end of 8 weeks of feeding. The group of birds fed on the 75 mg probiotic supplemented diet retained significantly (P<0.01) more nitrogen than the control birds. Serum cholesterol content was lower in the probiotic‐supplemented birds (93.3 mg/100 ml) compared to the control birds (132.2 mg/100 ml).

3. In the second experiment the probiotic plus antibiotic‐supplemented group of birds had the maximum weight gain (1148.5 g) followed by antibiotic (1141.3 g), probiotic‐supplemented (1128.4 g) and control birds (1045.6 g) after 6 weeks. Nitrogen retention was greatest in the antibiotic—(48.5%) followed by the probiotic—(46.5%), probiotic plus antibiotic‐supplemented groups (46.3%) compared to 40.2% in control birds.

4. The apparent metabolisable energy was greatest in birds receiving the probiotic plus antibiotic‐supplemented diet (12.37 MJ/kg) followed by antibiotic—(12.00 MJ/kg), probiotic‐supplemented birds (11.92 MJ/kg) than in control birds (11.62 MJ/kg). Serum cholesterol was significantly (P<0.01) lower in probiotic‐supplemented birds (86.1 mg/dl) compared to 118.4 mg/dl in control birds.     

Rapeseed meals in broiler diets: Effect on performance and sensory evaluation of carcasses

1. The effect of including rapeseed meal (RSM) in lieu of soyabean meal in broiler diets was determined.

2. Live‐weight gains, from 8 to 63 d, were depressed when the diet contained 150 g RSM/kg and there was a highly significant negative correlation between weight gain and inclusion rate of RSM over this period.

3. The efficiency of food utilisation was worse when the diet included 150 g solvent RSM/kg than when it contained no RSM: food efficiency was consistently poorer whenever RSM was included in the diet but the difference was significant only when the diet contained 10 g tallow/kg.

4. Carcasses from birds fed on diets containing 10 g tallow/kg had a better appearance than those from birds on diets containing 30 g tallow/kg, while the flavour of meat from birds fed on a diet containing 150 g solvent RSM/kg treatment was adversely affected. However, up to 100 g solvent RSM/kg may be included in broiler diets without affecting appearance, taste, texture or acceptability of the meat.

5. Inclusion of 50 g or more, solvent RSM/kg reduced growth rate and worsened food efficiency.     

The response of cage‐reared broiler cockerels to dietary supplements of nitrovin,zinc bacitracin or penicillin used singly or in paired combinations

1. The effect of feeding diets supplemented with procaine penicillin (50 mg/kg), zinc bacitracin (25 mg/kg) or nitrovin (20 mg/kg) singly or in combinations on the performance of broiler cockerels from 1 to 56 d was assessed.

2. The growth of treated birds was significantly better than that of controls fed on a basal diet, but no combination of additives was significantly superior to the additives given singly.

3. Performance up to 56 d of birds fed continuously on a diet supplemented with zinc bacitracin (25 mg/kg) from 1 d old was better than that obtained when the supplement was either introduced or withdrawn at different ages.     

Trace mineral interactions in broiler chicken diets

1.?The aim of the present study was to demonstrate trace mineral interactions among organic copper, iron, manganese and zinc (Cu, Fe, Mn and Zn) in broiler chickens.

2.?Three experiments were conducted using a control diet which was deficient in Cu, Fe, Mn and Zn.

3.?In experiment 1, the control diet, supplemental organic Cu, Fe alone and combined diets, were randomly fed to 4 groups of one-day-old Cobb broilers (each group had 6 replicates of 4 birds).

4.?In experiment 2, the control diet, supplemental organic Mn and Zn alone or combined with Cu, Fe diets and corresponding inorganic combined diet, were randomly fed to 6 groups (each group had 8 replicates of 6 birds).

5.?In experiment 3, the depletion of organic Zn, the depletion of inorganic Zn and normal Zn treatments were carried out in three groups of one-day-old Cobb broilers (each group had 8 replicates of 6 birds).

6.?Adding organic Cu, Fe and Mn alone or combined to Zn deficient diets did not significantly improve bird performance and were mostly excreted. Supplemental organic Zn alone or combined with other elements significantly increased feed intake, body weight gain and tibia bone length. However, supplemental organic Fe alone or combined with Cu significantly increased feed intake but had no obvious effect on body weight gain. The organic Fe supplementation resulted in a wider tibia.

7.?Depletion of organic and inorganic Zn resulted in decreased feed intake, body weight gain and total tibia bone Zn content. Zinc deficiency did not affect the uptake of organic Fe by tibia bone but reduced its total Fe content.

8.?Zinc is the first limiting element among these 4 trace minerals. Adding Mn, Cu and Fe to Zn deficient diets did not stimulate bird performance. Surplus organic Fe and Cu resulted in increased feed intake and increased tibia bone Fe content but did not contribute to bird performance.     

The effect of dietary cooked potato flake on performance of broilers and on litter quality

1. Broiler chicks, reared on litter, were given diets containing either 40% maize, 40% cooked potato flake, or 20% of each, in crumb form ad libitum from 1 to 21 d and 21 to 63 d in five dietary treatments.

2. Birds receiving the diet with 40% cooked potato flake grew more slowly than birds receiving the other diets during both periods but their food consumption was the same.

3. Including cooked potato flake in diets decreased the dry matter of the litter: with 40% in the diet the litter dry matter was decreased to 26% in 49 d at a stocking rate of 11 birds/m².

4. If the litter was kept dry, 20% of cooked potato flake was found to be an acceptable inclusion rate for broiler diets.     

Influence of graded levels of meals from three lupin species on growth performance and nutrient digestibility in broiler chickens

1. This study investigated the effect of different levels of seeds of lupin species (Lupinus angustifolius, Lupinus luteus and Lupinus albus) on broiler growth performance, nutrient digestibility and apparent metabolisable energy of poultry diets.

2. A control diet containing corn–soybean meal and test diets containing 50, 100, 150, 200 and 250 g/kg of three lupin species were fed to broiler chickens during a 35-day study period. There were 10 replicate cages of 8 broiler chickens per treatment.

3. Growth performance of the birds fed with yellow and white lupin diets was found to be similar to that of the birds in the control group. The use of narrow-leaved lupin seeds in the diet quadratically decreased the body weight gain of birds and increased feed conversion ratio during all the experimental periods (0–14, 15–35 and overall 0–35 days of age).

4. A significant interaction between lupin species and their inclusion levels for apparent metabolisable energy and apparent ileal digestibility of starch was observed, showing a negative effect of increasing levels of narrow-leaved lupin. Pearson correlation coefficients demonstrated that the presence of raffinose and non-starch polysaccharides is a key factor affecting the nutritive value of lupin,

5. Yellow and white lupins could be utilised as an alternative ingredient for soybean meal in the diet of broiler chickens without any adverse effects on growth performance. The narrow-leaved counterpart diet reduced broiler performance, and hence did not provide a satisfactory outcome.     

Comparative study of the effects of organic selenium on hen performance and productivity of broiler breeders

1. A 10-week experiment was conducted with Ross 308 broiler breeder chickens in cages to evaluate the influence of organic and inorganic sources of selenium (Se) supplementation. A total of 600 birds at 29 weeks of age were divided at random into 4 groups and fed on a maize–soya basal diet supplemented with different forms of Se.

2. The first (control) group was given the basal diet without Se supplementation, whereas the second, third and fourth groups were given, respectively, the basal diet with 0.3 mg/kg of inorganic Se in the form of sodium selenite or 0.3 and 0.5 mg/kg of organic Se in the form of Se enriched yeast (Se-yeast).

3. The experiment was carried out for 10 weeks to compare and evaluate the influence of Se supplementation on breeder performance, egg production, hatchability and the quality of eggs. Samples were collected for analysis at weeks 0, 5 and 10 of the experimental period.

4. At the end of the experiment (39 weeks), there was a reduction in mortality in breeders given diets supplemented with 0.5 mg/kg of Se-yeast. Supplementation of feed with 0.5 mg/kg organic Se increased egg production, percentage of settable eggs and hatchability.

5. Selenium supplementation increased egg weight and specific gravity compared to the control diet. However, no significant variation was found in albumen or yolk protein content at the end of week 10.

6. Selenium accumulation and glutathione peroxidase (GSHPx) activity were lower in the egg albumen and yolk of control compared with Se-supplemented treatments. Se accumulation and GSHPx activity were higher in the group given 0.3 mg/kg organic compared to 0.3 mg/kg of inorganic Se.

7. The results favour the use of Se-yeast at the dose of 0.5 mg/kg in broiler breeder diets for better productivity of eggs, settable eggs, hatchability and higher Se accumulation and antioxidant status in eggs.     

Valine,isoleucine, arginine and glycine supplementation of low-protein diets for broiler chickens during the starter and grower phases

1. Two experiments were performed to study the supplementation of valine, isoleucine, arginine and glycine (Val, Ile, Arg, Gly) in low-protein diets for broiler chickens in the starter (1–21 d; Exp. 1) and grower (22–42 d; Exp. 2) phases.

2. A low-crude protein (CP) diet was formulated to meet the requirements of all amino acids (AA) supplied by the control diet except for Val, Ile, Arg and Gly. The other experimental diets were obtained by the isolated or combined supplementation of the studied AA in the low-CP diet.

3. Growth, serum parameters and litter characteristics were taken in both of the experiments. Carcass measurements were taken in Experiment 2.

4. In the starter and grower phases, low-CP diets without supplementation resulted in birds with a poorer weight gain and feed conversion than those of the birds that received the control diet.

5. In the starter phase, individual supplementation with Val and Gly, but not Ile and Arg, restored the weight gain of the birds, while diets with the addition of Val + Gly, Val + Ile + Arg, Val + Ile + Gly and Val + Ile + Arg + Gly restored their feed conversion.

6. In the grower phase, weight gain was re-established at the same rate as the control diet for the diets supplemented with Val + Ile, Val + Ile + Arg, Val + Ile + Gly and Val + Ile + Arg + Gly. However, the feed conversion was restored only in birds that received the diet supplemented with all studied AA.

7. The supplementation of Val and Gly in low-CP diets was sufficient to avoid adverse effects in the performance and serum parameters of broilers in the starter phase. However, birds in the grower phase required the combined supplementation of Val, Ile, Arg and Gly, to prevent compromised performance.     

Influence of dietary peas and organic acids and probiotic supplementation on performance and caecal microbial ecology of broiler chickens

1.?The effect of dietary pea and addition of organic acid blend (OA) or probiotic (Pro) on performance and caecal microbial ecology of broiler chickens was studied.

2.?A growth trial was conducted with 160 Ross 308 female broilers from d 1 to 35 of age. There were 8 treatment groups based on either control (S) or white pea (P). Both S and P were supplemented with OA (Galliacid – fumaric acid, calcium formate, calcium propionate and potassium sorbate coated with plant triglycerides, Vetagro) and or with Pro (LABYuc-Probio – lactic acid bacteria, Saccharomyces cerevisiae and Yucca schidigeri extract, Mifarmex GmbH).

3.?Inclusion of peas in the diet increased feed intake and decreased gain:feed ratio in comparison to the control diet. Neither probiotic nor OA supplementations affected broiler performance.

4.?The caecal microbiota was characterised in 37-d-old birds by fluorescent in situ hybridisation (FISH) and terminal-restriction fragment length polymorphism (T-RFLP). Total bacterial counts in caecal contents were slightly higher for birds fed the pea diets, but were not affected by OA or Pro supplements.

5.?Neither pea nor Pro affected the Lactobacillus/Enterococcus and Streptococcus/Lactococcus counts in caecal contents, whereas OA supplementation slightly increased the Lactobacillus/Enterococcus counts. The composition of the Lactobacillus/Enterococcus population was altered by inclusion of peas as revealed by the T-RFLP patterns.

6.?The DNA fingerprint further suggested that the caecal microbiota was dominated by the lactic acid bacterium Streptococcus alactolyticus.

7.?In ileal contents, the concentration of short-chain fatty acids (SCFA) was decreased only by Pro supplementation. In caecal contents, the SCFA concentration was higher for birds fed on the pea diets, and increased significantly with Pro supplementation

8.?In conclusion, the results indicate that the use of pea and probiotics in broiler feed may stimulate the caecal commensal microbiota (growth and/or activity) to some extent and hence prevent establishment of pathogenic and zoonotic enterobacteria in these segments of the gut.     

The effects of lactoferrin on the intestinal environment of broiler chickens

1. The influence of in-feed lactoferrin (Lf) on bird production, intestinal microbiota, mucosal immune system and gut microarchitecture was assessed in male Cobb 500 broiler chickens.

2. Birds were given one of four diets from day of hatch: Control (basal diet with no additives), ZnB (basal diet?+?50?mg/kg zinc bacitracin), Lf 250?mg/kg (basal diet?+?250?mg/kg Lf) and Lf 500?mg/kg (basal diet?+?500?mg/kg Lf); n?=?24 birds/treatment. An apparent metabolisable energy study was performed between d 25-32.

3. Lf did not affect growth rate or feed conversion in the period 0-21?d of age, nor performance or energy metabolism during the 7?d metabolism experiment which commenced at 25?d of age.

4. The profiles of caecal microbial communities were significantly different in birds given ZnB compared with birds given a diet with no additives, or supplemented with 250?mg/kg Lf. Birds given 250?mg/kg Lf also had a different microbial profile compared with birds given 500?mg/kg Lf.

5. In comparison to control birds, Lf treated birds showed some differences in the T cell proportions in caecal tonsil and spleen. No differences in ileal villus height, crypt depth or goblet cell proportions were observed amongst dietary treatments.

6. Whilst Lf had little effect on the measured parameters, the use of an integrated approach to study the influence of novel feed additives may facilitate a greater understanding of the relationships between nutrition, gut health and bird performance.