Xylanase and xylo- oligosaccharide prebiotic improve the growth performance and concentration of potentially prebiotic oligosaccharides in the ileum of broiler chickens

ABSTRACT

1. The objective of this study was to investigate the effect of supplementing broiler diets with xylanase or xylo- oligosaccharide (XOS) on growth performance, the concentration of non-starch polysaccharide (NSP) hydrolysis products in the ileum and concentration of short chain fatty acids (SCFA) in the caeca of broiler chickens.

2. In total, 500 male Ross 308 broilers were used in this 29-day (d) study. The treatments were organised into a 2 × 2 plus 1 factorial arrangement consisting of two additives (xylanase or XOS) at two levels (low or high) plus a control treatment with no additives. This gave five treatments with 100 birds in each treatment group. The diets were slightly deficient in protein by 20 g/kg and energy by 1 MJ/kg.

3. On d 14 and 28, two birds per pen were euthanised, the caeca content collected and analysed for short chain fatty acid (SCFA) concentration. On d 29, six birds per pen were euthanised and ileal digesta were collected and analysed for the concentration of NSP fractions.

4. On d 14, caecal acetic acid, iso-butyric acid, iso-valeric acid, n-valeric acid and total SCFA concentrations were significantly greater (P ≤ 0.05) when diets were supplemented with XOS compared with xylanase.

5. Ileal concentration of arabinose, galactose and glucuronic acid (GlucA2) were significantly greater (P ≤ 0.05) in the insoluble NSP fraction when diets were supplemented with a high level of xylanase, compared with the control treatment. Ileal concentration of fructose was significantly greater (P ≤ 0.05) in the water soluble NSP when a high level of xylanase or low level of XOS were included in the diet compared with the control.

6. It was concluded that xylanase and XOS had similar effects on NSP concentration and SCFA in the caeca, although there was little effect on performance. This observation demonstrated further benefits of xylanase supplementation in wheat-based broiler diets beyond digesta viscosity reduction and the release of extra nutrients.     

Comparison of single- and multi-strain probiotics effects on broiler breeder performance,egg production,egg quality and hatchability

ABSTRACT

1. This study was conducted to investigate the effect of multi-strain probiotic (containing Lactobacillus acidophilus 2.5 × 10⁷ cfu/g, Lactobacillus casei 2.5 × 10⁷ cfu/g, Bifidobacterium thermophilum 2.5 × 10⁷ cfu/g and Enterococcus faecium 2.5 × 10⁷ cfu/g) and single-strain probiotic (Pediococcus acidilactici 1 × 10¹⁰ cfu/g) on broiler breeder performance and gastrointestinal health.

2. A completely randomised trial was conducted using 300 broiler breeder hens (Ross 308) aged 51 weeks old which were randomly allocated to 1 of 5 dietary treatments with 6 replicates per treatment in a 10 week trial. Treatments included (1) the basal diet a negative control, (2) basal diet supplemented with 0.1 g/kg multi-strain probiotic (MS), (3) basal diet supplemented with 0.1 g/kg single-strain probiotic (SS), (4) basal diet supplemented with 0.1 g/kg of both of probiotics (MS+ SS) and (5) positive control basal diet supplemented with 0.5 g/kg oxytetracycline antibiotic (OX).

3. Body weight, egg production, yolk weight, eggshell thickness and weight, Haugh unit, fertility and hatchability were determined. Results showed that dietary treatments had no significant effect on total hen house or total hatching egg production, egg weight, yolk colour index, shell weight, mortality, body weight, fertility, hatchability, oviduct and stroma weight or number of large and small yellow follicles (P > 0.05). None of the jejunum morphological parameters, apparent ileal digestibility of protein and ileal Lactobacillus population were influenced by supplemental probiotics (P > 0.05), although ileum Escherichia coli count was reduced by inclusion of dietary probiotics (P < 0.05).

4. It was concluded that although both probiotic treatments reduced coliforms, they did not improve broiler breeder performance or gastrointestinal tract (GIT) function.     

The effect of graded inclusions of waxy starch hull-less barley and a multi-component exogenous carbohydrase on the growth performance,nutrient digestibility and intestinal morphometry of broiler chickens

ABSTRACT

1. A 21-d experiment was conducted to investigate the effect of graded inclusions of waxy starch hull-less (WSHL) barley and a multi-component exogenous carbohydrase on the growth performance, nutrient digestibility and intestinal morphometry of broiler chickens. Five levels of WSHL barley inclusion (0, 65, 130, 195 and 260 g/kg) in a wheat-based diet, and two levels of enzyme supplementation (0 and 150 g/tonne of feed) were evaluated in a 5 × 2 factorial arrangement of 10 dietary treatments. All diets were equivalent in metabolisable energy and digestible amino acid content. A total of 400, one-d-old male broilers (five cages/treatment; eight birds/cage) were used in the experiment.

2. Regardless of enzyme supplementation, feed intake declined (P < 0.001) with increasing inclusion of WSHL barley. Increasing levels of WSHL barley (P < 0.001) and supplemental enzyme (P < 0.01) increased gain to feed ratio.

3. Birds fed diets with 0 g/kg WSHL barley showed the lowest (P < 0.001 to 0.01) digestibility for all nutrients except starch. Only starch digestibility was improved (P < 0.05) by enzyme supplementation. The nitrogen-corrected apparent metabolisable energy improved with increasing inclusion of WSHL barley (P < 0.001) and supplemental enzyme (P < 0.001). Increasing inclusion of WSHL barley increased the relative weight of gizzard (P < 0.001) and reduced jejunal digesta viscosity (P < 0.01). Supplemental enzyme (P < 0.001) reduced digesta viscosity.

4. All levels of WSHL barley inclusion improved digestibility of dry matter, nitrogen and fat, whilst energy utilisation improved at inclusions of 130 g/kg WSHL and above, probably due to lowered digesta viscosity and better development of the gizzard. Gain to feed ratio, starch digestibility, energy utilisation and jejunal digesta viscosity can benefit from carbohydrase supplementation in wheat-based diets, regardless of barley inclusion level.     

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.     

A multi-microbe probiotic formulation processed at low and high drying temperatures: effects on growth performance,nutrient retention and caecal microbiology of broilers

1. Two experiments were conducted to evaluate a multi-microbe probiotic formulation processed at low (LT) or high (HT) drying temperature.

2. In both the experiments, 640 d-old Ross male chicks were randomly allotted to 4 treatments on the basis of initial BW for 35 d experiments.

3. In experiment one, dietary treatments were a negative control (NC; basal diet without any antimicrobial); positive control (PC; basal diet +10?mg/kg avilamycin); basal diet with 0·3% probiotic LT; and basal diet with 0·3% probiotic HT.

4. Improved overall weight gain, FCR and retention of CP were observed in birds fed the PC and probiotic diets when compared with birds fed the NC diet. At d 21, birds fed the probiotic and NC diets had more caecal Bifidobacterium and total anaerobes than birds fed the PC diet; while birds fed the PC and probiotic diets had fewer caecal Clostridium than birds fed the NC diet at d 35.

5. In experiment two, a 2?×?2 factorial arrangement of treatments was employed to evaluate the effects of two concentrations of probiotic HT (0·30 or 0·60%) and avilamycin (0 or 10?mg/kg).

6. Birds fed the 0·60% probiotic HT diet showed improved overall weight gain and CP retention, higher Lactobacillus and Bifidobacterium in the caecum, and reduced Clostridium and coliforms in the caecum. Inclusion of avilamycin improved the overall weight gain and feed intake, and reduced the caecal Clostridium and Bifidobacterium population.

7. In conclusion, high drying temperature had no effect on the efficacy of the multi-microbe probiotic formulation; while the probiotic HT formulation was more effective at the 0·60% level. Moreover, inclusion of avilamycin improved performance of birds but did not have any interaction with probiotics.     

Energy and protein utilisation by broiler chickens fed diets containing cottonseed meal and supplemented with a composite enzyme product

ABSTRACT

1. The present study examined the potential of new-generation microbial enzymes to improve the utilisation of energy and protein of cottonseed meal (CSM)-containing diets, with the aim of increasing its inclusion level in broiler chickens diets.

2. Four hundred and eighty, one-day-old Ross 308 male broilers were used to assess the utilisation of energy and protein by broiler chickens fed diets containing four graded levels of CSM – none, low (4, 8, 12%), medium (5, 10, 15%) or high (6, 12, 18%) in the starter, grower, and finisher phases, respectively, supplemented with 100 mg/kg of a composite enzyme product (xylanase and β-glucanase).

3. Inclusion of CSM improved (P < 0.01) apparent metabolisable energy (AME), with further improvement (P < 0.001) seen in the enzyme-supplemented diets. Inclusion of CSM reduced (P = 0.002) the metabolisable energy intake (MEI), but this was increased (P < 0.05) with enzyme supplementation.

4. Enzyme addition increased (P < 0.001) the net energy of production (NEp), while heat production (HP) decreased (P < 0.001) with CSM inclusion. More energy was retained as fat (P < 0.05) and protein in birds fed diets with the enzyme, but this was reduced (P < 0.029) by CSM.

5. There was an increase (P < 0.05) in efficiencies of ME use for energy, lipid and protein retention, with higher CSM levels. The enzyme improved (P < 0.013) efficiency of ME use for lipid retention.

6. Feeding diets containing CSM to the broilers enhanced (P < 0.05) protein intake (PI) and protein efficiency ratio (PER). Positive effects (P < 0.05) of enzyme were observed on protein gain (PG) and net protein utilisation (NPU).

7. Results obtained from this study suggested that nutrient utilisation of diets containing CSM by broiler chickens can be improved by enzyme supplementation.     

In vitro bile acid-binding capacity of dietary fibre sources and their effects with bile acid on broiler chicken performance and lipid digestibility

1. A 4 × 2 factorial experiment was conducted to study the effect of feeding diets-containing dietary fibre (DF) sources and a source of bile acid (BA) on growth performance and lipid metabolism. In addition, in vitro BA-binding capacity of fibre sources was investigated.

2. A total of 256 one-d-old male broiler chickens (Ross 308) were assigned to DF sources [maize-soybean meal (control, C), or 30 g/kg of wheat bran (WB), barley bran (BB) or soybean hulls (SH)] and BA (with or without 1.5 g Na-deoxycholate/kg). Each treatment was replicated 4 times with 8 broiler chickens per cage.

3. The highest in vitro BA-binding capacity was observed with BB (8.76 mg/g BB). From 0 to 21 d, with the addition of BA, the average daily feed intake (ADFI) decreased in broiler chickens fed on the C, WB or BB diets, while there was no difference with the SH diet. With added BA, the average daily gain decreased in broiler chickens fed on the C or SH diets, but it did not change in those fed on the other diets. The addition of BA decreased feed conversion ratio (FCR) in broiler chickens fed on the BB or WB diets, but it increased in those fed on the C or SH diets. Interaction results indicated that the apparent ileal digestibility of lipid increased in broiler chickens fed the C and other DF diets with BA compared to those fed the diets without BA. The addition of BA decreased the pancreas lipase activity (PLA) in broiler chickens fed on the C diet compared to those fed the C diet without BA, while no changes observed in those fed the DF diets with or without BA. No interaction was observed in total liver bile acid (TLBA).

4. The WB, BB and SH with little Na-deoxycholate-binding capacity (<10 mg/g of DF) under in vitro conditions had particular effects with BA on the measured criteria in broiler chickens. The magnitude of improvement in digestibility of lipid with the addition of BA depends on the source of fibre used and the addition of BA in DF diets had little effect on growth performance in young broiler chicken diets.

     

膨化陈化早籼糙米添加外源酶对生长猪表观养分消化率及消化酶活性的影响

选用6头平均体重(18.00±0.60)kg的健康去势公猪,在回肠末端安装T型瘘管后按6×6拉丁方设计分别饲喂高、低糊化度(分别为86.5%和42.6%)膨化和未处理3种陈化早籼糙米,并在其基础上添加或不添加外源α-淀粉酶(2500U/kg日粮)和糖化酶(20000U/kg日粮)共计6种试验日粮,研究膨化处理陈化早籼糙米添加外源酶对生长猪表观养分消化率和食糜碳水化合物消化酶活性的影响。结果表明:膨化有提高猪表观回肠淀粉消化率的趋势(P=0.075),但未能显著改善猪能量、粗蛋白和氨基酸表观回肠消化率(P>0.05);添加外源酶显著提高猪赖氨酸、苏氨酸和异亮氨酸表观回肠消化率(P<0.05);适度膨化显著提高试猪食糜碳水化合物消化酶活性(P<0.05)。     

Phytate degradation,intestinal microbiota,microbial metabolites and immune values are changed in growing pigs fed diets with varying calcium–phosphorus concentration and fermentable substrates

The present study assessed effects of diets containing varying calcium–phosphorus (CaP) concentration and fermentable substrates on digestibility of diets, intestinal microbiota and immune system using 32 crossbred pigs (initial BW 54.7 kg). In a 2 × 2 factorial arrangement, pigs were fed either a corn–soybean meal (CSB) or corn–field pea (CFP) diet with either low [‐] (4.4 g Ca/kg; 4.2 g total P/kg) or high [+] (8.3 g Ca/kg; 7.5 g total P/kg; supplemented with monocalcium phosphate) CaP content for a period of 9 weeks. In week 8, blood samples were taken, and at the end of the trial, all pigs were euthanized to collect digesta and mesenteric lymphoid tissue. Apparent total tract digestibility (ATTD) of P was greater (p < 0.05) for pigs fed the CaP+ and CFP diets than CaP‐ and CSB diets. The myo‐inositol 1,2,3,4,5,6‐hexakis (dihydrogen phosphate) (InsP₆) concentration in jejunal digesta was higher (p < 0.05) for CaP+ than in CaP‐ fed pigs. In addition, caecal and faecal InsP₅ isomer concentration were greater (p < 0.05) for CSB than CFP diets. In the caecum, gene copy numbers of saccharolytic bacteria, such as Eubacterium rectale and Roseburia spp., as well as SCFA concentration were higher (p < 0.05) for CaP+ than CaP‐ diets. In particular, innate immune cell numbers, such as natural killer cells, dendritic cells, monocytes and neutrophils, were greater (p < 0.05) for CaP+ than CaP‐ fed pigs. Diets high in CaP resulted in higher abundance of potential beneficial bacteria and might promote the first line of defence enhancing the activation of the cellular adaptive immune response, thereby possibly decreasing the risk for intestinal disturbances. These results strongly suggest that both, CaP supply and dietary ingredients differing in fermentability, may beneficially affect gut health through increase in SCFA‐producing bacteria and/or bacteria with anti‐inflammatory properties.     

The effect of protease and Bacillus licheniformis on nutritional value of pea,faba bean,yellow lupin and narrow-leaved lupin in broiler chicken diets

ABSTRACT

1. This study investigated the nutritional value (digestibility of ileal crude protein and amino acids (AAs)) and the AME_N value of legumes (pea, faba bean, yellow lupin, and narrow-leaved lupin) with or without protease.

2. Two hundred, one-day-old, male Ross 308 broiler chickens were randomly allocated to ten groups. Each group received one of five different protein raw materials – either peas, faba beans, yellow lupins or narrow-leaved lupins, with or without protease produced from Bacillus licheniformis. The birds were kept in individual cages. Nutrient digestibility was calculated using the difference method. The total duration of the study was 23 d, and the study involved two phases – accommodation phase (d 1–18) and experimental phase (d 18–23).

3. The effect of protease on response traits was not consistent between the legumes. The enzyme increased the digestibility of some AAs in the pea (arginine, leucine, phenylalanine, histidine, tyrosine, alanine, and proline), faba bean (lysine, arginine, glycine, and asparagine), and yellow lupin diets (lysine, valine, and serine), but this effect was not observed in the narrow-leaved lupin diet. The change in AME_N values due to protease addition was only statistically significant for the pea diet (P < 0.05), whereas in the case of other legume species, the difference was insignificant (P > 0.05).

4. Exogenous protease increased the digestibility of AAs present in pea, faba bean, and yellow lupin seeds but not in narrow-leaved lupin diets. The AME_N value of peas increased with protease supplementation, but no effect of protease was found for the AME_N values of faba bean and both the lupin diets.     

Influence of graded inclusion of white lupin (Lupinus albus) meal on performance,nutrient digestibility and intestinal morphology of broiler chickens

1. The aim of this study was to investigate the effect of white lupin (Lupinus albus) meal (WLM) addition on the intestinal viscosity, bird performance, nutrient utilisation and villi morphology of growing broiler chicks.

2. The experiment was conducted with 480 broiler chicks divided into 6 dietary treatments, including a maize-soybean meal control diet (CON) and 5 experimental diets containing 100, 150, 200, 250 and 300 g/kg WLM.

3. During the period from d 0 to 35, birds fed on 200 or higher WLM/kg were characterised by lower body weight gain and feed intake than CON. The use of 150 g of WLM/kg increased feed conversion ratio (FCR) compared to CON treatment. Apparent metabolisable energy corrected to zero N balance (AME_N) and apparent ileal digestibility of dry matter, ether extract, crude protein and starch, linearly decreased as WLM increased from 0 to 300 g/kg.

4. There was a quadratic effect of WLM dose on sialic acid excretion. A strong negative linear correlation was found between the excretion of sialic acid and AME_N. The viscosity of ileal digesta was linearly increased as WLM increased. The effect of WLM dose on ileum villus height (VH) was linear, while that on ileum villus area (VA) was quadratic. Both parameters decreased as WLM increased from 0 to 300 g/kg.

5. In conclusion, the use of over 150 g/kg of WLM in broiler diets depressed performance results. However, depression of nutrient utilisation was only observed when 250 or 300 g/kg of WLM was used.

     

Dietary effects of commercial probiotics on growth performance,digestibility, and intestinal morphometry of broiler chickens

This study compared five commercially available probiotics vis-à-vis antibiotic growth promotant (AGP) supplementation and absence of feed additive based on efficiency, intestinal morphometry, and energy digestibility in improving broiler chicken production. A total of 630 straight run (Cobb) day-old broiler chicks were distributed to seven treatments following a completely randomized design, with ten replicates per treatment and nine birds per replicate per cage. Dietary treatments consisted of basal diet in combination with the following: without probiotics and AGP supplementation (treatment 1); 75 ppm each of chlorotetracycline (CTC) and Zn bacitracin (treatment 2); probiotic A, Bacillus subtilis (treatment 3); probiotic B, Bacillus subtilis (treatment 4); probiotic C, Enterococcus faecium (treatment 5); and probiotic D, Bacillus subtilis (treatment 6); probiotic E, Enterococcus faecium, Bifidobacterium spp., Pediococcus spp., and Lactobacillus spp. (treatment 7). At day 42, energy digestibility was determined by fasting three randomly selected birds from each treatment for 12 h and then subjecting them to their corresponding dietary treatments. Excreta were collected and pooled after 24 h of feeding. Pooled excreta were weighed, oven-dried, and subjected to energy analyses after 3-day collection. Apparent total tract metabolizable energy was then computed. At day 47, three birds were randomly selected per treatment for intestinal morphometry (villi height and crypt depth) of the duodenum, jejunum, and ileum. Dietary supplementation using probiotics showed no significant effect on overall body weight, weight gain, feed consumption, feed efficiency, dressing percentage, mortality, harvest recovery, carcass quality parameters (e.g., meat to bone ratio and abdominal fat content), intestinal morphometry, and energy digestibility. Birds under treatment 7 (basal feed + probiotic E) generated the highest income over feed and chick cost.

     

Performance and nutrient digestibility in growing pigs fed wheat dried distillers’ grain with solubles‐containing diets supplemented with phytase and multi‐carbohydrase

Effect of supplementing wheat dried distillers’ grain with solubles (DDGS)‐containing diet with enzymes on nutrient utilization by growing pigs was evaluated in two experiments. In Experiment 1, 60 pigs weighing ~30 kg were fed five diets that included a corn‐based diet (Control), Control with 10% wheat DDGS (DDGS‐PC), DDGS‐PC without inorganic P source (DDGS‐NC), and DDGS‐NC plus phytase alone or with multi‐carbohydrase for 4 weeks to determine average daily gain (ADG), average daily feed intake (ADFI) and gain‐to‐feed ratio (G:F). In Experiment 2, 30 barrows weighing 22 kg were fed five diets fed in Experiment 1 to determine nutrient digestibility and retention. Pigs fed DDGS‐PC and Control diets had similar ADG and G:F. The ADG and G:F for DDGS‐PC diet were higher (P < 0.05) than those for DDGS‐NC diet. Phytase improved (P < 0.05) ADG, G:F, total tract P digestibility and P retention by 6.6, 8.7, 86.0 and 85.5%, respectively. Addition of multi‐carbohydrase to phytase‐supplemented diet did not affected growth performance, but reduced (P < 0.05) P retention. In conclusion, inclusion of 10% wheat DDGS in growing pig diet may not affect growth performance of growing pigs. Phytase supplementation to wheat DDGS‐containing diet can eliminate the need for inorganic P supplement in pig diets.     

Effect of a novel microbial phytase on production performance and tibia mineral concentration in broiler chickens given low-calcium diets

1. In a 42-d feeding trial, 264 one-d-old, as hatched, Cobb 400 broiler chickens (6 pens per group, n = 11 per pen in a 2?×?2 factorial arrangement) were fed on two concentrations of dietary calcium (Ca) (9.0 and 7.5 g/kg in starter, 7.5 and 6 g/kg in grower phases) and supplemental phytase (0 and 500 U/kg diet).

2. During d 0–21, the high Ca + phytase diet improved body weight. During d 0–42, feed intake was increased by the low Ca diet and decreased by phytase supplementation. Feed conversion ratio during d 0–21 was improved by the high Ca + phytase diet.

3. At d 42, Ca in duodenal digesta was reduced by low dietary Ca and supplemental phytase. High dietary Ca reduced P in duodenal and jejunal digesta. Phytase reduced digesta P and increased serum P concentration.

4. Relative tibia length decreased with low dietary Ca and increased with phytase. The robusticity index of tibia was improved by the low Ca diet and phytase supplementation. Phytase supplementation increased tibia ash and concentrations of Ca, magnesium (Mg), manganese (Mn), copper (Cu), zinc (Zn) and iron (Fe) in tibia. The low Ca diet increased Mg, Mn and Fe and reduced Cu and Zn in tibia.

5. It was concluded that 7.5 g Ca/kg during weeks 0–3 and 6 g Ca/kg during weeks 3–6 sustained broiler performance and bone ash, while phytase supplementation facilitated tibia mineralisation, particularly during the grower phase.     

Effect of feeding different sources of selenium on growth performance and antioxidant status of broilers

ABSTRACT

1. This study was conducted to determine the effect of different sources of selenium (Se) on breast and liver tissue deposition, apparent metabolisable energy (AME), growth performance and antioxidant status of broilers, measured as Se content in liver and breast tissues and glutathione peroxidase (GSH-Px) in blood, when used in 0–35 d broiler chicken diets.

2. A total of 200 male Ross 308 broilers were used in the feeding trial, which comprised two dietary phases, a starter from 0 to 21 d and finisher from 21 to 35 d of age. Four treatments with 10 replications each were used. A control diet (C) was formulated that was sufficient in protein and energy (230 and 215 g/kg of crude protein and 12.67 and 13.11 MJ/kg of metabolisable energy, respectively), for both phases, but contained background Se only from the feed ingredients. Diet 2 (IS) was supplemented with 10.35 g/t inorganic, elemental source of Se. Diet 3 (SY) was supplemented with 136.36 g/t selenised yeast, an organic source derived from Saccharomyces cerevisiae. Diet 4 (SS) was supplemented with 0.666 g/t sodium selenite, an inorganic source.

3. Birds fed the SY diet consumed less and weighed less than those fed IS or C (P < 0.05; 0–35 d of age), but there was no difference compared to birds fed SS diets. There were no differences in FCR or dietary AME between broilers fed different Se sources. All diets containing supplementary Se increased concentrations in the liver and breast muscle, and for GSH-Px levels in blood compared to birds fed the C diet (P < 0.001). Birds fed SY diets had greater Se levels in liver and breast tissues compared to birds fed any of the other diets (P < 0.001).

4. Diets supplemented with Se had variable effects on broiler growth performances and antioxidant status. Feeding Se from a yeast source has higher transfer into breast tissues. Feeding different sources and levels of Se to birds in a more challenging situation to induce oxidative stress may bring more conclusive results.     

Effects of A Multi-Enzyme Complex or Probiotic Supplementation on Performance and Nutrient Digestibility of Broiler Chicks

This experiment was conducted to determine whether the performance of broilers fed diets based on corn and soybean meal could be enhanced with enzymes or probiotics.A total of 120 male broilers,three days of age,were assigned to one of four treatments in a completely randomized design,and housed in groups of five with six cages per treatment.The control diet was based on corn and soybean meal while the three experimental diets consisted of the basal diet supplemented with 0.1% of enzyme I,enzyme II,or probiotic.Enzyme I provided α-galactosidase and β-mannanase,while enzyme II provided protease,amylase,α-galactosidase,xylanase,and cellulase.The probiotic was composed of Bacillus coagulance,Bacillus lichenformis,Bacillus subtilis,and Clostridium butyricum.Over the 28 day experiment,the weight gain of birds fed the probiotic treatment was superior(P=0.03)to the control,while gains for the enzyme treatments were intermediate to those of the control and probiotic.Feed intake and feed conversion did not differ among treatments(P0.05).Ammonia production was significantly(P0.01)higher in the control compared with either of the enzyme or probiotic treatments.Compared with the control,supplementation with enzyme II significantly reduced the digestibility of arginine,isoleucine,and lysine(P0.05).In contrast,the digestibility of energy was higher(P0.01)for birds supplemented with enzyme II than the control.Digestibility coefficients did not differ for any other parameter with the exception of energy which was significantly higher for birds fed the probiotic treatment than the control(P0.01).In summary,the performance of broilers was significantly enhanced by the addition of a probiotic to the diet.However,under the conditions of this experiment,supplementation with a multi-enzyme complex containing either α-galactosidase and β-mannanase or the combination of protease,amylase,galactosidase,xylanase,and cellulase failed to improve broiler performance.     

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.     

Performance and intestinal microbiota of chickens receiving probiotic in the feed and submitted to antibiotic therapy

The purpose of this study was to verify the ability of a probiotic in the feed to maintain the stability of the gut microbiota in chickens after antibiotic therapy and its association with growth performance. One thousand six hundred twenty 1‐day‐old Cobb male were housed in floor pens (36 pens, 45 birds/pen) and were fed corn‐/soya bean meal‐based diets supplemented with or without probiotic (Bacillus subtilis) during the entire rearing phase. From 21 to 24 days of age (three consecutive days), the chickens were submitted to antibiotic therapy via drinking water (bacitracin and neomycin) in order to mimic a field treatment and induce dysbiosis. Growth performance was monitored until 42 days of age. At 2, 4 and 6 days after antibiotic therapy, three chickens from each pen were euthanized and the contents of the small intestine and caeca were collected and pooled. The trial was conducted with four treatments and nine replicates in a 2 × 2 factorial arrangement for performance characteristics (with and without probiotic × with and without antibiotic therapy); for the intestinal microbiota, it was in a 2 × 2 × 3 factorial arrangement (with and without probiotic × with and without antibiotic therapy × 2, 4 and 6 days after the antibiotic therapy) with three replicates per treatment. Terminal restriction length polymorphism (T‐RFLP) analysis showed that the structure of gut bacterial community was shaped by the intestinal segment and by the time after the antibiotic therapy. The number of 16S rDNAs copies in caecum contents decreased with time after the therapeutic treatment. The antibiotic therapy and dietary probiotic supplementation decreased richness and diversity indexes in the caecal contents. The improved performance observed in birds supplemented with probiotic may be related to changes promoted by the feed additive in the structure of the intestinal bacterial communities and phylogenetic groups. Antibiotic therapy modified the bacterial structure, but did not cause loss of broiler performance.     

Evaluation of bee venom as a novel feed additive in fast-growing broilers

1. The present study was designed to evaluate purified bee venom (BV) as an alternative to antibiotics in broiler chickens. The experimental treatment diets were formulated by adding BV into a maize-soybean meal-based diet to give 0, 10, 50, 100, and 500 μg BV per kg of diet.

2. Dietary BV quadratically improved (P < 0.05) feed conversion ratio and increased body weight gain at 1–21 d as level in diet increased. Higher BV levels lowered relative weight of spleen (linear and quadratic, P < 0.05), bursa of Fabricius (quadratic, P < 0.05), and liver (linear and quadratic, P < 0.05) at 21 d of age. Relative breast meat yields were increased quadratically at 21 d and linearly at 35 d with supplementation levels. Dietary BV increased (linear and quadratic, P < 0.05) lightness (L*) value for meat at 21 d, decreased (linear, P < 0.05) ileal villus height and narrowed (quadratic, P < 0.05) width.

3. Dietary BV inclusion linearly increased the concentration of secretory immunoglobulin A (sIgA) on ileal mucosa at 21 d and decreased (quadratic, P < 0.05) nitric oxide contents in serum samples at 21 d and 35 d. Total short-chain fatty acids (SCFA) in caecal digesta were reduced with increasing venom in diets at 21 d of age. None of the serum parameters except for creatinine was affected by dietary BV.

4. It was concluded that dietary BV exhibited wide range of in vivo biological properties in broiler chickens and could be incorporated into feed to promote growth and animal health.     

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.