The effects of supplementary bacterial phytase on dietary true metabolisable energy, nutrient digestibility and endogenous losses in precision fed turkeys

1. A total of 40 female BUT9 turkeys were used in a precision-feeding assay to investigate the effect of dietary phytase on true metabolisable energy corrected for N retention (TME(N)), coefficients of true dry matter (TDMD), mineral, amino acid and nitrogen (TND) digestibilities and the excretion of endogenous mucin, measured as sialic acid (SA). 2. Five treatments were used in this study: control (C), C + 250 phytase units (FTU) per kg feed, C + 500 FTU, C + 2500 FTU, and glucose only for endogenous losses estimation. Diets were formulated to be nutritionally adequate with the exception that the P content was relatively low (3·6 g/kg non-phytate P). 3. Inclusion of phytase increased TND in a quadratic manner with the optimum being achieved at approximately 500 FTU, at which TND was 37 % greater than in the control. The concentration of SA in the excreta decreased linearly with increased phytase supplementation. Dietary TME(N), TDMD and true mineral digestibility coefficients were not significantly affected by phytase supplementation. 4. Phytase inclusion increased digestibility coefficients for indispensable, dispensable and total amino acids in a linear manner. The scale of the response to phytase was greatest with threonine and least with lysine digestibility, suggesting a specific mechanism of action that benefits gut health. 5. The strong negative relationship between secretion of SA and threonine digestibility suggests that a large part of the threonine benefit may be from reduced mucin synthesis. This supports the hypothesis that dietary phytase may play a role in improving the health status of the intestine and, as a result, reduces the maintenance energy requirements of turkeys.     

The effects of supplementary bacterial phytase on dietary energy and total tract amino acid digestibility when fed to young chickens

1. Four diets were offered to broiler chickens from 7 to 17 d of age; these included a phosphorus-adequate positive control (PC) (4·7 g/kg available P), a sub-optimal P negative control (NC, 2·5 g/kg available P) with (500 and 12500 FTU/kg) and without phytase. Dietary apparent metabolisable energy (AME), dietary net energy for production (NEp), the efficiency of AME retention (Kre), heat production and total tract amino acid digestibility coefficients were determined. The determination of NEp involved a comparative slaughter technique in which growing chickens were fed the experimental diets ad libitum. 2. Feed intake, weight gain and feed conversion efficiency increased significantly in a dose dependent manner in response to dietary phytase activity. Overall, the NEp of the phytase supplemented diets significantly improved by approximately 15·6% compared with the negative control, while dietary AME was unaffected. Although phytase did not affect AME, the large increase in the NEp demonstrated that dietary phytases improves energy utilisation, i.e. diverting more energy, not accounted for in the AME procedure, for production. This is largely a result of the stimulatory effect that phytase has on feed intake rather than on digestibility of the diet. 3. Overall, the diet supplemented with 12500 FTU had 6·4% significant improvement in total tract digestibility coefficients of the total amino acids compared with the negative control. With regard to individual amino acids, the impact of phytase was far more pronounced for threonine, an important component of the gastrointestinal mucin, than for other amino acids. 4. Dietary NEp was more highly correlated with performance criteria than dietary AME and seems to be a more sensitive way to evaluate broiler response to phytase supplementation.     

Response of broiler chickens to microbial phytase supplementation as influenced by dietary phytic acid and non-phytate phosphorous levels. II. Effects on apparent metabolisable energy, nutrient digestibility and nutrient retention

1. Male broilers (n=900) were fed on wheat-sorghum-soyabean meal based diets containing 3 concentrations of phytic acid (10.4, 13.2 and 15.7 g/kg; equivalent to 2.9, 3.7 and 4.4 g/kg phytate P), 2 concentrations of non-phytate (or available) phosphorus (2.3 and 4.5 g/kg) and 3 concentrations of microbial phytase (0, 400 and 800 FTU/kg) from day 7 to 25 post-hatch. The dietary concentrations of phytic acid were manipulated by the inclusion of rice pollards. All diets contained celite (20 g/kg) as a source of acid-insoluble ash. 2. The apparent metabolisable energy (AME) concentrations of the diets were determined using a classical total collection procedure during the 3rd week of the trial. On d 25, digesta from the terminal ileum were collected and analysed for phosphorus, nitrogen and amino acids. Nutrient digestibilities were calculated using acid-insoluble ash as the indigestible marker. 2. Ileal digestibilities of nitrogen and essential amino acids were negatively influenced by increasing dietary levels of phytic acid but these negative effects were overcome by the addition of phytase. 3. Supplemental phytase increased AME, ileal digestibilities of phosphorus, nitrogen and amino acids and the retention of dry matter, phosphorus and nitrogen in broilers. There were no differences in the phytase responses between additions of 400 and 800 FTU/kg. 4. The responses in all variables, except AME, were greater in low non-phytate phosphorus diets. 5. In the case of AME, the response to added phytase was greater in adequate non-phytate phosphorus diets. Supplemental phytase increased AME values from 13.36 to 13.54 MJ/kg dry matter in low non-phytate phosphorus diets and from 12.66 to 13.38 MJ/kg dry matter in adequate non-phytate phosphorus diets.     

Rearing conditions influence nutrient availability of plant extracts supplemented diets when fed to broiler chickens

The effects of a standardised mixture of essential oils, including 5% carvacrol, 3% cinnamaldehyde and 2% capsicum (XT 6930; Pancosma S.A), on dietary apparent metabolisable energy corrected for nitrogen retention (AMEn), nutrient digestibility and mucin secretions, measured as sialic acid (SA) were investigated in broilers fed on the same diet but reared under different conditions, that is, cages and floor pens littered with wood shavings used in previous broiler study. The use of XT reduced (p < 0.05) nitrogen digestibility (0.585 vs. 0.544) and tended (p = 0.072) to reduce dry matter digestibility (0.733 vs. 0.717) of the diet when fed to birds reared in cages. However, XT supplementation improved (p < 0.05) fat digestibility (0.844 vs. 0.862) and tended (p = 0.093) to increase AMEn (14.01 vs. 14.25 MJ/kg DM) of the same diet when fed to broilers reared in floor pens. Essential oils supplementation tended (p = 0.059) to increase the secretion of SA, when fed to birds reared in cages (11.24 vs. 14.18 μg), but did not influence (p > 0.05) the SA secretion from birds reared in floor pens. The results obtained from the cage study tend to be the opposite of those obtained from the floor pen study. This suggests that the efficiency of dietary plant extracts may be influenced by the rearing/hygienic conditions of poultry. Based on the overall results, it can be concluded that information on rearing conditions should be taken into account for more complete interpretation of the experimental data emanating from experiments involving use of essential oils typified by those considered in this study.     

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

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

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

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

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

The effect on performance, energy metabolism and hepatic carotenoid content when phytase supplemented diets were fed to broiler chickens

Two basal diets containing an adequate and a low supply of available P (4.7 vs 2.5 g/kg diet) and three others containing a low available P but supplemented with 250, 500 and 12,500 units of phytase (FTU) per kg diet, respectively, were prepared. Each diet was fed ad libitum to birds in six metabolism cages (five birds in each cage) in a randomised block design. It was found that birds fed a high (12,500 FTU) dosage of phytase grew faster (P < 0.001) and retained proportionally more carotenoids in the liver (P < 0.05) compared to birds fed unsupplemented diet. The results suggest that dietary phytase may improve the anti-oxidative status of birds fed low P diets through enhancing dietary carotenoid availability.     

Effect of dietary energy restriction on retention of protein,fat and energy in broiler chickens

1. Broiler chickens were fed 60–100% of recommended energy intakes to study the effects of energy restriction on protein and fat retention.

2. At an energy retention of 179 kJ/kg W ^0·75 d, only protein was retained. At higher energy intakes, each increment in retention had a rather constant composition: about 85% energy in fat and 15% in protein. At lower energy intakes body fat was mobilised whereas protein was deposited.

3. The efficiencies of energy retention in protein and fat were estimated to be 0·66 and 0·86 respectively.

4. The rather constant composition of additional retained energy after additional energy supply provides an explanation for a linear relationship between energy intake and energy retention.     

Exogenous phytase and xylanase exhibit opposing effects on real-time gizzard pH in broiler chickens

ABSTRACT

1. The current study was conducted to evaluate the influence of high phytase doses and xylanase, individually and in combination, on performance, blood inositol and real-time gastric pH in broilers fed wheat-based diets.

2. In a 42-d experiment, a total of 576 male Ross 308 broiler chicks were allocated to 4 dietary treatments. Treatments consisted of a 2 × 2 factorial arrangement, with 500 or 2500 FTU/kg phytase and 0 or 16 000 BXU/kg xylanase, fed in two phases (starter 0–21; grower 21–42 d). Heidelberg pH capsules were administered to 8 birds from each treatment group, pre- and post-diet phase change, with readings captured over a 5.5-h period.

3. At 21 and 42 d, birds fed 500 FTU/kg phytase without xylanase had on average 127 and 223 g lower weight gain than all other treatments, respectively (P < 0.05). At 42 d, body weight-corrected feed conversion ratio (_bwcFCR) was reduced (P < 0.05) by supplementing 2500 FTU/kg phytase or xylanase, with the combination giving a 12 point reduction in _bwcFCR compared to birds fed 500 FTU/kg phytase without xylanase. Inositol content of plasma was twice that of the erythrocyte (P < 0.001), with 2500 FTU/kg phytase tending to increase (P = 0.07) inositol content in both blood fractions.

4. Across all treatments, capsule readings ranged from pH 0.54 to 4.84 in the gizzard of broilers. Addition of 2500 FTU/kg phytase to the grower diet reduced (P < 0.05) average gizzard pH from 2.89 to 1.69, whilst feeding xylanase increased (P < 0.001) gizzard pH from 2.04 to 2.40. In contrast, digital probe measurements showed no effect of xylanase on gizzard pH, while addition of 2500 FTU/kg phytase increased (P = 0.05) pH compared to 500 FTU/kg phytase with or without xylanase.

5. These findings suggested that xylanase and high phytase doses have opposite effects on real-time gastric pH, while similarly improving performance of broilers.     

The effect of dietary supplementation with globin and spray-dried porcine plasma on performance,digestibility and histomorphological traits in broiler chickens

This study evaluated the effects of globin and spray-dried porcine plasma (SDPP) on growth performance, digestibility, nitrogen retention, energy retention efficiency (ERE) and intestinal morphology of broiler chickens. A total of 336-day-old male broiler chickens were reared from 1 to 40 days of age and fed 3 diets (8 replicates/diet, 14 birds/replicate) during 3 feeding phases: starter (1–12 days), grower (12–25 days) and finisher (25–40 days). Isonitrogenous diets were formulated by replacing gluten protein isolate contained in the control diet (C diet) with 2% (starter) or 1% (grower and finisher) spray-dried porcine plasma in the plasma diet (SDPP diet). The globin diet (G diet) was obtained by adding globin on the top of C diet at a dose of 0.08% for the whole rearing period. Total tract apparent digestibility (aD), nitrogen retention and ERE were assessed during the three growing phases. At 12  and 40 days of age, one bird per pen was slaughtered to sample gut, liver, spleen and bursa of Fabricius for histomorphological investigations. The SDPP diet increased body weights of chickens at 12 (+60 g; p < .001), 25 (+101 g; p < .001) and 40 days (+130 g; p = .018) of age compared to C and G diets. Also SDPP improved crude protein aD (+9.7%) and ERE (+12.3%) during the starter phase (p < .001). Dietary globin and SDPP inclusion did not affect either the gut morphology or the histopathological findings in birds at 12 and 40 days of age, despite a numerical (+6.90% and +7.40% respectively) villus height improvement in the SDPP group. Overall, these results confirm that dietary supplementation with SDPP and, to a lesser extent, with globin can improve growth performance and dietary protein and energy utilization in broiler chickens without effect on gut functionality.     

Effects of dietary metabolisable energy, calcium and phosphorus on bone mineralisation, leg weakness and performance of broiler chickens

1. Performance, gait score (GS), tibial dyschondroplasia (TD), and tibia bone mineralisation and breaking strength were determined in 2880 male and female Ross 208 broilers fed on diets with two different concentrations of dietary metabolisable energy (ME) (11.00 or 12.00 MJ/kg) and 4 different concentrations of available phosphorus (aP) adjusted for dietary ME content (4.0, 4.5, 5.0 or 5.5 g/kg aP in starter and 3.5, 4.0, 4.5 or 5.0 g/kg aP in finisher diets containing 12.00 MJ/kg). 2. Tibia ash, calcium (Ca) and phosphorus (P) contents in broilers given diets with low ME (11.00 MJ/kg) were greater than those of broilers given diets with higher ME (12.00 MJ/kg). Tibia ash, Ca and P contents increased curvilinearly with increasing dietary aP content. The dietary aP level had no effect on GS. 3. Dietary concentration of ME or aP had no effect on tibia breaking strength. 4. Walking ability, as measured by GS, was negatively correlated with the body weight (BW) of tested birds at 23 and 35 d of age, but the dietary ME content or aP level had no significant effect on GS at 35 d of age. 5. The results indicated that bone mineral content had no clear correlation with the walking ability of broilers.     

植酸酶对肉鸡生长性能及饲粮养分利用率的影响

饲养试验选用1日龄的良凤花鸡600羽,随机分为4组(每组设3个重复,每个重复50羽),A组为对照组,饲喂玉米-豆粕型基础饲粮,B、C、D组的饲粮为分别以300、500、700 U/kg的植酸酶取代基础饲粮中的30%、50%、70%的磷酸氢钙。结果表明:0～4周龄,与对照组相比,C和D组平均日增重(ADG)分别极显著提高6.29%(P<0.01)和8.27%(P<0.01);平均料重比(F/G),组间差异不显著(P>0.05)。5～8周龄,与对照组相比,B、C和D组的ADG分别有所提高,F/G有所下降,但组间差异不显著(P>0.05)。B、C、D组鸡血清钙、磷、白蛋白、总蛋白、球蛋白含量随着植酸酶添加量的增加呈上升趋势,但差异不显著(P>0.05);血清碱性磷酸酶活性随着植酸酶的添加而呈降低趋势,但差异不显著(P>0.05)。消化代谢试验结果表明,添加不同水平的植酸酶替代饲粮不同比例的磷酸氢钙,肉鸡饲粮干物质、粗蛋白、粗脂肪、粗纤维、粗灰分、钙和能量的表观代谢率虽然比对照组有所改善,但差异不显著(P>0.05);而磷的表观吸收率分别比对照组显著提高了25.39%～32.48%(P<0.01)。     

蛋用鸡连续饲喂低蛋白低有效磷饲粮的安全性和添加植酸酶效果的评价

对蛋用鸡连续饲喂低蛋白低有效磷饲粮的安全性及添加植酸酶的效果进行了探讨。结果表明,2～36周龄蛋用鸡在2～8、9～15、16～18和19～36周龄连续饲喂粗蛋白为17．0％、13．5％、13．0％、15．0％和有效磷为0．35％、0．3％、0．3％、0．3％的低蛋白中磷饲粮,除蛋重降低外,其他生产性能指标与粗蛋白为19．0％、15．0％、14．5％、16．5％和有效磷为0．45％、0．4％、0．4％、0．4％的高蛋白高磷饲粮无显著差异,并使8、15、36周龄鸡的氮、磷排泄量分别减少9．50％（P〈0．01）、18．81％（P〈0．01）、13．42（P〈0．05）和15．93％（P〈0．01）、16．18％（P〈O．01）、19．21％（P〈0．01）。连续饲喂粗蛋白为17．0％、13．5％、13．0％、15．0％和有效磷为0．25％、0．2％、0．2％、0．2％的低蛋白低磷饲粮,可显著降低2～18周龄生长鸡平均日增重和饲料利用率,但添加300IU／kg植酸酶后可达到高蛋白高磷的饲养效果,并使8、15、36周龄鸡的总磷和粗蛋白表观利用率分别提高12．55％（P〉0．05）、7．24％（P〉0．05）、32．66％（P〈0．01）和26．23％（P〉0．05）、15．70％（P〈0．01）、7．77％（P〈0．05）,而氮、磷排泄分别减少17．70％（P〈0．01）、25．19％（P〈0．01）、17．63（P〈0．05）和37．41％（P〈0．01）、36．71％（P〈0．01）、43．17％（P〈0．01）。     

Effect of dietary phytate and phytase on metabolic change of blood and intestinal mucosa in chickens

The objective of this study was to investigate the effect of dietary phytate and phytase on the metabolic parameters of lipid, protein, enzyme, electrolyte in the blood or intestinal mucosa of broiler chickens. Diets containing phytate phosphorus (0.22% or 0.44%) with phytase supplementation (0, 500 or 1000 U/kg) were administrated to 504 Cobb chicks for 4 weeks. Results showed that the serum concentrations of total cholesterol (T‐CHO), albumin, albumin/globulin, total superoxide dismutase (T‐SOD), total antioxidant capacity (T‐AOC) and glutamic pyruvic transaminase (GPT) were decreased by 9–41% in high phytate diets (p < 0.05) and the concentrations of blood P, K, Fe, Cu, Zn and Mg were decreased by 4–14% for birds fed high phytate diets (p < 0.05), whereas inclusion of phytase compensated these adverse influences. In the duodenum, phytate decreased the level of T‐AOC by 13% (p < 0.05), whereas phytase increased the levels of T‐SOD, T‐AOC and alkaline phosphatase (ALP) by 9–16% (p < 0.05). Also, in the jejunum, diets with high phytate showed lower activity of T‐SOD, T‐AOC and glutamic oxaloacetic transaminase (GOT) (p < 0.05), and phytase increased T‐SOD, T‐AOC and ALP (p < 0.05). However, phytase decreased transaminase activity in the low phytate basal diets (p < 0.05). This study suggests that dietary phytate can adversely interfere with the metabolisms of lipid and protein, as well as the antioxidation of blood and intestinal cells, while phytase supplementation may compensate these effects for broiler chickens.     

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.     

Effects of different dietary phytase activities on the concentration of antioxidants in the liver of growing broilers

One‐hundred and fifty male chickens were used to evaluate the effects of different activities (0, 250, 500, 12 500 FTU/kg) of phytase on their performance and antioxidant concentration in the liver. The chicks were housed in 30 cages and were allocated to six replicates of five dietary treatments. All diets were formulated to be adequate in energy and protein (12.90 MJ/kg metabolizable energy, 214 g/kg crude protein), however, the negative control (NC) was lower in available P compared with the positive control (PC) (2.5 vs. 4.5 g/kg diet). The other three diets were the NC supplemented with phytase at 250, 500 and 12 500 FTU/kg (NC + 250, NC + 500 and NC + 12 500 FTU respectively). The concentration of antioxidants in the liver of the birds was determined using HPLC at 21 days of age. Low P diets (NC) reduced weight gain, however, supplementation with phytase improved weight gain to the extent that it was better than the PC at the 12 500 FTU treatment (p < 0.05). Feed conversion ratio was also improved by the high level of phytase supplement more than other treatments (p < 0.05). Feed consumption was not affected either by dietary phosphorus concentration or by different phytase supplementation. The antioxidant data showed that the unsupplemented diet with low phosphorus (NC) decreased the concentration of coenzyme Q₁₀ and retinol‐linoleate in the liver compared with that of birds on the adequate phosphorus treatment (PC). Phytase supplementation, especially at the higher doses (500 and 12 500 FTU) increased the level of coenzyme Q₁₀ to the same level as the PC treatment. In addition, the highest dose (12 500 FTU) of phytase increased retinol concentration in the liver of chickens compared with those on the NC treatment. The highest inclusion level of phytase increased the α‐tocopherol level in the liver compared with the lower levels of phytase (NC + 250 and NC + 500 FTU).     

The efficiency of energy retention of broiler chickens and turkeys fed on diets with different lysine concentrations

1.?An experiment determined the effect of 6 different lysine concentrations (40, 52, 58, 65, 90 and 130 g/kg CP) in two protein concentrations (210 and 260 g/kg) on the efficiency of energy utilisation of broiler chickens and turkeys. Ninety-six male Ross 308 broiler chicks and 96 male BUT Big 6 turkey poults were fed at 90% of ad libitum during a 12 d bioassay period. At the end of the bioassay, birds were slaughtered and carcase crude protein, fat and gross energy were measured and nutrient metabolisability determined.

2.?Broiler chickens had lower AME and AME_N than turkeys. AME was higher in the 260 g/kg than in the 210 g/kg protein diet; however, no difference was evident in AME_N between any of the diets in both species. A significant species × lysine interaction indicated that the decrease in AME and AME_N with increasing lysine was greater in turkeys than in broiler chickens.

3.?Turkeys had lower weight gains and efficiencies of energy retention than broiler chickens. The effects of different lysine concentrations on growth and the efficiency of energy retention were significant and growth responses were quadratic but there were negative linear responses in the efficiency of energy retention in both species at both crude protein concentrations. The efficiency of energy retention was increased with decreasing lysine concentrations throughout the wide range of concentrations used in the experiment.