Previous exposure to dietary phytase reduces the endogenous energy losses from precision-fed chickens

Investigating possible impact, and interaction, of phytase supplementation during pre-experimental and experimental phases on assay of true phosphorus pre-caecal digestibility and total tract retention

1. Two experiments were conducted to investigate whether the use of phytase in the pre-experimental or experimental phases of true pre-caecal phosphorus digestibility (TPD) assay influenced the assayed TPD values. In experiments 1 and 2, broiler chickens were randomly allocated to 12 treatments in a 2 × 2 × 3 factorial arrangement. The factors were pre-experimental phytase supplementation (+ or -), experimental phase phytase supplementation (+ or -) with varying soybean meal inclusion levels (450, 560, or 670 g/kg).2. The diets in the pre-experimental phase were based on maize-soybean meal, whereas the diet used during the experimental phase was semi-purified, with soybean meal as the only source of P. Both TPD and true phosphorus retention (TPR) were determined using regression for the P output (g/kg, dry matter basis), pre-caecal or total tract, against P intake (g/kg). Data for TPD and TPR were analysed as a 2 × 2 factorial (with or without pre-experimental or experimental phase phytase).3. In both experiments 1 and 2, there were no significant effects for pre-experimental phytase supplementation nor interaction of pre- and experimental phytase supplementation on any of the pre-caecal digestibility responses. Phytase supplementation during the experimental phase increased (P < 0.01) pre-caecal P digestibility and retention, as well as digestible and retained P intake, and decreased (P < 0.01) P output.4. In experiment 1, pre- and experimental phytase supplementation increased (P < 0.01) the coefficient of TPR. In experiment 2, there was no significant effect of pre-experimental phytase supplementation on coefficient of pre-caecal TPD. However, phytase supplementation in the experimental phase increased (P < 0.01) the coefficient of pre-caecal TPD.5. In conclusion, whether or not phytase was supplemented to a P-adequate diet in the pre-experimental phase of the TPD assay, it had no influence on assayed TPD or TPR value.

Feeding dry stevia leaf (Stevia rebaudiana) or xylanase improves the hepatic antioxidative status of broiler chickens

Four diets, formulated with and without stevia and with and without exogenous xylanase, following a 2 × 2 factorial design, were prepared. Each diet was fed ad libitum to birds in eight pens (three birds in each pen) in a randomised block design. It was found that birds fed xylanase grew faster, used the feed more efficiently and had an increased concentration of hepatic α-tocopherol and vitamin E concentrations (P < 0.05). Feeding stevia did not affect growth performance (P > 0.05), but increased hepatic CoQ₁₀ (P = 0.05), lutein, zeaxanthin and total carotenoids (P < 0.001) concentrations. There were no dietary stevia by xylanase interactions (P > 0.05) for any of the studied variables. The results showed that alone, dietary stevia and dietary xylanase can improve the antioxidative status of birds through enhancing dietary antioxidant availability.

Variation in the chemical composition and the nutritive quality of different field bean UK-grown cultivar samples for broiler chicks

1. The chemical composition and physical characteristics of 10 different UK-grown field bean cultivar samples from the same harvest year were determined.2. Diets included each bean sample at a level of 200 g/kg, and were used to compare broiler growth performance and determine N-corrected apparent metabolisable energy (AMEn) and nutrient utilisation. The AMEn and nutrient retention coefficients for the bean samples were obtained via the slope-ratio method. The relationships were examined between variation in nutritive value for broilers and the laboratory analysis of the bean samples.3. The data showed significant differences (P < 0.05) among the bean cultivar samples for feed conversion ratio, AMEn and dry matter retention (DMR) coefficients. Further analysis showed that the feeding quality of different field bean cultivar samples, measured as AMEn, was highly correlated to crude protein (CP) (P < 0.05) and colour (P < 0.001) of the samples. Thus, beans with higher CP and pale colour had superior feeding value for broilers.

Dietary essential oils improve feed efficiency and hepatic antioxidant content of broiler chickens

The aim of this study was to test the hypothesis of an improved growth, dietary nutrient availability and overall health of broiler chickens reared on recycled litter when fed a standardised combination of essential oils (EO; carvacrol, cinnamaldehyde and capsicum oleoresin). To assess the effect of dietary treatments, feed intake, weight gain, feed efficiency, availability of dietary nutrients and energy, villus morphometry, excreta sialic acid concentration, hepatic antioxidants and serum amyloid A (SAA) when fed to broiler chickens were evaluated. Counts of Eimeria spp. oocysts were also determined in excreta samples. Four experimental diets were offered, including two basal control diets based on either wheat or maize that contained 215 g CP/kg and 12.13 MJ/kg metabolisable energy and another two diets using the basal control diets supplemented with the EO combination at 100 mg/kg diet. Each diet was fed to eight floor pens, containing two birds each, following randomisation. Birds fed the EO-supplemented diets had an improved (P0.05) were observed in villus morphometry, sialic acid secretion, number of oocysts and SAA. Feeding the EO improved (P&lt;0.05) the retention of dietary Ca and Na. Compared with maize, feeding wheat-based diets improved the retention coefficients for Ca, P and Na (P&lt;0.05). Feeding dietary EO improved (P&lt;0.05) the concentrations of the hepatic antioxidants, including carotene, coenzyme Q10 and total vitamin E. The hepatic concentration of carotene of the maize-fed birds was 55.6% greater (P&lt;0.05) compared with the wheat-fed birds. These results demonstrated that the addition of a standardised combination of EO in wheat- and maize-based diets provided benefits in terms of feed efficiency, mineral retention and antioxidant status of the birds when reared on recycled litter.

Effect of high-dose phytase and citric acid, alone or in combination, on growth performance of broilers given diets severely limited in available phosphorus

1. Two trials were conducted to evaluate the effect of high-dose phytase alone or in combination with citric acid (CA) in the diet severely limited in available phosphorus (P) on performance, plasma P and plasma Ca of broilers from 22 to 42 d of age. 2. In Trial 1, 297 21-d-old female chicks were placed into 27 pens and allocated to 9 maize-soybean meal-based dietary treatments, which were a positive control [PC, 4.23 g/kg non-phytate P (NPP)] and 8 negative control (NC, 1.35 g/kg NPP) groups consisting of two concentrations of CA (0 and 20 g/kg) and 4 concentrations of phytase (0, 1000, 2000 and 4000 U/kg) in a 2 × 4 factorial arrangement. In Trial 2, 192 21-d-old male chicks were placed into 24 pens and allocated to 6 wheat-canola meal-based dietary treatments, which were a PC (4.2 g/kg NPP), a NC (1.68 g/kg NPP) and 4 NC groups consisting of two concentrations of CA (0 and 20 g/kg) and two concentrations of phytase (2000 and 4000 U/kg) in a 2 × 2 factorial arrangement. 3. In both trials, birds fed on the PC had significantly higher average daily gain (ADG), average daily feed intake (ADFI), plasma P and lower feed conversion ratio (FCR) and plasma Ca than those of birds fed on the NC. CA supplementation significantly increased ADG and ADFI. There was a significant interaction between CA and phytase on plasma P where CA improved the effect of phytase on plasma P. In Trial 1, phytase addition improved ADG, ADFI, FCR and plasma Ca linearly. 4. Briefly, this research showed the interaction effect between CA and phytase on plasma P when broilers were fed on diets based on maize-soybean meal or wheat-canola meal. The results showed that CA supplementation lowered the concentration of phytase that is needed in low NPP diets to increase plasma P.

Effect of high-dose phytase supplementation in broilers from 22 to 42 days post-hatch given diets severely limited in available phosphorus

1. Two trials were conducted from 22 to 42 d post-hatch to evaluate the effectiveness of high concentrations of supplemental phytase in maize-soya bean meal-based diets severely limited in available phosphorus (P). Growth performance, plasma P and tibia ash (TA) were measured. 2. Each trial used 220 21-d-old male broilers in 20 pens with 11 birds per pen. Dietary treatments included a positive control [PC, 4.3 g/kg nonphytate P (NPP)], negative control [NC, 2.3 g/kg NPP (Trial 1) or 1.4 g/kg NPP (Trial 2)] and NC plus 1000, 2000 or 4000 phytase U/kg of the diet. 3. Birds fed on the PC diet had higher average daily gain (ADG), gain to feed ratio (G:F), plasma P (Trials 1 and 2) and TA (Trial 2) than those fed on the NC. 4. In Trial 1, ADG and G:F values of the NC plus 1000, 2000 or 4000 phytase U/kg reached those of the PC. Plasma P values of the NC plus 2000 or 4000 phytase U/kg reached that of the PC. Although TA values of the NC, NC + 1000 or NC + 2000 reached that of the PC, TA of the NC + 4000 was more than that of the PC. 5. In Trial 2, ADG and G:F values of the NC plus 4000 phytase U/kg reached those of the PC; nevertheless, plasma P values of the NC diets did not come up to that of the PC. While TA values of the NC, NC + 1000 or NC + 2000 did not reach that of the PC, TA of the NC + 4000 was greater than that of the PC. 6. Results of this study showed that, in the diets with 2.3 and 1.4 g/kg NPP, respectively, 1000 and 4000 phytase U/kg can be sufficient to obtain a comparable performance in broilers to those given diets adequate in available P.

Endogenous intestinal losses of calcium and true total tract digestibility of calcium in canola meal fed to growing pigs

An experiment was conducted to test the hypothesis that values for apparent total tract digestibility (ATTD) of Ca in pigs are influenced by endogenous Ca lost from the gastrointestinal tract. The objective was to determine the endogenous loss of Ca, the ATTD of Ca, and the true total tract digestibility (TTTD) of Ca in canola meal without and with microbial phytase. The second objective was to determine the balance of Ca in pigs fed diets based on canola meal without or with microbial phytase. Forty-eight growing barrows (initial BW: 16.72 ± 2.52 kg) were allotted to 8 dietary treatments in a randomized complete block design with 6 pigs per treatment. Diets were based on sucrose, cornstarch, potato protein isolate, corn gluten meal, and canola meal. Diets were formulated to contain 0.08, 0.16, 0.24, or 0.32% Ca from canola meal. All diets were formulated with 0 or 1,500 units/kg of microbial phytase and contained 0.32% digestible P. Feces and urine samples were collected from d 6 to 11. Total endogenous losses of Ca were determined using the regression procedure. Results indicated that ATTD of Ca and Ca retention increased (P < 0.05) if dietary Ca increased and also increased (P < 0.01) when phytase was added to the diets. The estimated total endogenous loss of Ca was 0.160 and 0.189 g/kg DMI for canola meal without and with microbial phytase, respectively, and these values were not different. The TTTD of Ca increased (P < 0.01) if phytase was used but was not affected by the level of dietary Ca. As dietary Ca increased, the amount of Ca absorbed and retained increased (P < 0.01) to a greater extent if phytase was used than when no phytase was included in the diet (interaction, P < 0.05). Fecal P excretion increased (P < 0.01) as dietary Ca increased but was reduced (P < 0.01) by the use of phytase. The ATTD of P decreased (P < 0.01) with increasing dietary Ca to a lesser extent if phytase was used than when no phytase was used (interaction, P < 0.01). In conclusion, endogenous Ca is lost from the gastrointestinal tract of growing pigs, and values for TTTD of Ca are, therefore, different from values for ATTD of Ca. Values for ATTD of Ca are influenced by level of dietary Ca, but that is not the case for values for TTTD of Ca. The ATTD of P decreases as dietary Ca increases, but microbial phytase increases Ca and P digestibility and Ca retention in pigs fed diets based on canola meal whereas it does not influence endogenous losses of Ca.

Extra-phosphoric effects of phytase with and without xylanase in corn-soybean meal-based diets fed to broilers

Two experiments were conducted to evaluate the extra-phosphoric effects of phytase on amino acid (AA) and energy digestibility (experiments 1 and 2) and growth performance (experiment 2) of broilers fed diets adequate in Ca and nonphytate P supplemented with xylanase. Ross × Ross 708 broiler chicks (864 males in experiment 1 and 1,152 females in experiment 2) were randomly distributed into battery cages (6 replicate cages per treatment) with 12 birds per cage at 1 d of age. In both experiments, factorial arrangements of treatments were evaluated consisting of 6 phytase [0, 1,000, 2,000, 4,000, 8,000, or 16,000 phytase units (FTU)/kg] and 2 xylanase [0 or 16,000 birch xylan units (BXU)/kg] concentrations in experiment 1 and 4 phytase (0, 500, 1,000 or 2,000 FTU/kg) and 4 xylanase (0, 8,000, 16,000, or 32,000 BXU/kg) concentrations in experiment 2. Treatments were provided from 27 to 32 d of age in experiment 1 and from 1 to 32 d of age in experiment 2. Digesta contents of the terminal ileum were collected at 32 d of age (experiment 1 and 2), and growth performance was measured at 1, 14, and 25 d of age in experiment 2. There was no interaction of phytase and xylanase; only main effects of phytase were observed. In experiment 1, broilers fed diets supplemented with phytase at 1,000 FTU/kg had increased (P < 0.05) apparent ileal digestibility (AID) of all AA with the exception of Ala and Met. Diets fed to broilers supplemented with higher concentrations of phytase did not further increase AID of any AA (P > 0.05) above the addition of 1,000 FTU/kg of phytase. Phytase supplementation did not affect ileal digestible energy (P > 0.05). For all variables measured, significant log-linear or log-quadratic effects of phytase (P > 0.05) were not observed. In contrast, broilers fed diets supplemented with phytase in experiment 2 exhibited log-linear (P < 0.05) increases in AID of AA but not apparent ileal digestible energy. However, supplementation with 2,000 FTU/kg of phytase increased (P = 0.05) ileal digestible energy by 36 kcal/kg compared with the basal diet. Broilers fed diets with 1,000 FTU/kg of phytase had improved growth performance (P < 0.05) in comparison with broilers fed diets containing 0 or 500 FTU/kg of phytase. The addition of 500 FTU/kg of phytase in diets fed to broilers did not affect ileal digestibility or growth performance (P > 0.05). Data obtained from these experiments demonstrated extra-phosphoric effects in broilers fed diets supplemented with 1,000 FTU/kg of phytase and diminishing returns with higher concentrations.

Energy utilisation and growth performance of chicken fed diets containing graded levels of supplementary bacterial phytase

A total of 364 female Ross 308 chicks (1 d old) were used in the present study conducted in floor pens to investigate the effects of graded levels of supplementary bacterial phytase on dietary energy utilisation and growth performance. For this purpose, four maize-soyabean-based diets were offered to the birds from 0 to 21 d of age. These included a suboptimal P negative control (NC, 3.0 g/kg non-phytate P), NC+250 phytase units (FTU)/kg feed, NC+500 FTU and NC+2500 FTU. The effect of phytase activity on bird growth performance was best described as a linear relationship between increasing dose and increased feed intake (P< 0.001), but was quadratic for body-weight gain (P= 0.002) and feed efficiency (P= 0.023). There was no significant response (P>0.05) of dietary apparent metabolisable energy (AME) to supplementary phytase. The birds fed phytase increased their retention of total carcass energy in a linear fashion (P= 0.009) with increased phytase dose. The efficiency of dietary AME used for overall carcass energy retention also improved (P= 0.007) in a linear manner with increased dietary phytase activity. Dietary net energy for production (NEp) increased (P= 0.047) with an increase in phytase dose following a linear pattern, as an increase of 100 FTU increased dietary net energy by 15.4 J (estimated within the range of doses used in the present experiment). Dietary NEp was more highly correlated with performance criteria than dietary AME, and it seems to be a more sensitive way to evaluate broiler response to phytase supplementation.

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 effect of previous exposure to dietary microbial phytase on the endogenous excretions of energy, nitrogen and minerals from turkeys

1. A precision feeding experiment was conducted with turkeys, which had previously been fed diets with or without phytase, to study the effects on the excretions of endogenous energy (EEL), nitrogen (ENL), amino acids (EAAL) and minerals. 2. Female turkeys (BUT 6) which had been fed one of 4 experimental diets (low P maize-soya diets (control, C), C + 250 international units of phytase/kg diet (FTU), C + 500 FTU and C + 2500 FTU) were used in this study. All birds were fasted and then given 50 mL of glucose solution at 46 d of age. Birds were allocated to individual metabolism cages in a randomised block design with 8 replicates for each of the 4 previously-fed diets. 3. The response of EEL and ENL to phytase pre-exposure was linear. An increase of 100 FTU reduced the EEL and ENL by approximately 1·6 kJ and 20 mg respectively. The results suggest that a minimum activity of phytase of 500 FTU is needed to initiate the reduction of these losses. 4. Pre-exposure to phytase reduced the EAAL, which was best described as a linear response with increasing phytase dose in the pre-study period. An increase of 100 FTU reduced the losses of total endogenous amino acids by approximately 225 mg. 5. In contrast to the results for endogenous energy losses, turkeys pre-exposed to phytase linearly increased their excretions of Ca and Mg with increasing phytase activity in the pre-study period. 6. The effects of feeding turkeys with supplementary phytase continued for at least 4 d after the diets were withdrawn. This suggests that exposure to phytase alters the functionality and secretions of the gastrointestinal tract, which may influence the nutritive value of diets fed immediately after.

Effect of dietary xylanase on energy, amino acid and mineral metabolism, and egg production and quality in laying hens

1. The aim was to examine the effect of dietary xylanase on the availability of nutrients for laying hens when fed on wheat-rye-soy-based diets. The basal diet was formulated to contain 11.03 MJ/kg apparent metabolisable energy (AME), and the experimental diets were formulated by supplementing the basal diet with four different activities of xylanase (400, 800, 1200 and 1600 xylanase units (XU)/kg). 2. The AME and nitrogen metabolisability coefficients of xylanase-supplemented diets were 1.2% and 7.1%, respectively, greater than in the control diet. 3. Supplementary xylanase significantly improved the coefficients of metabolisability of indispensable, dispensable and total amino acids by 8.2%, 6.9% and 7.8%, respectively, and led to a significantly linear response of total amino acid metabolisability coefficient to xylanase. There was a range of effects within the indispensable amino acids with xylanase supplementation (1600 XU/kg) significantly improving the metabolisability of threonine by 4.9%, but having no have effect on lysine. The response of total amino acid retention to added xylanase was a significant quadratic function and suggests that 800 XU/kg is the optimum supplementary dosage. 4. Supplementary xylanase significantly improved sulphur metabolisability in a linear fashion to a maximum of 2.3% higher than that of the control diet. In terms of daily retention, most of the minerals responded in a quadratic manner to dietary xylanase, as the suggested optimal supplementary level was between 800 and 1200 XU/kg. 5. The yolk colour of the birds receiving 1200 and 1600 XU/kg was 0.33 and 0.28 units (Roche score); these were 4.1% and 3.5%, respectively, darker than the yolk of the birds given the control diet. 6. Birds receiving xylanase had a significantly higher weight gain than those fed on the unsupplemented diet. Feed intake, the number of eggs per hen per d, dirty and cracked eggs, and feed conversion ratio for egg production were not affected by xylanase. These data suggest that use of a xylanase may improve the metabolisability of many nutrients, but that such effects may not always benefit production parameters.

The effect of supplementary bacterial phytase on dietary metabolisable energy, nutrient retention and endogenous losses in precision fed broiler chickens

Thirty-two Ross 308 male broiler chickens were used in a precision feeding assay to investigate the effect of exogenous phytase (EC 3.1.3.26) on dietary apparent metabolisable energy (AME), dry matter digestibility (DMD) coefficient, nitrogen (NR), amino acid and mineral retentions. The excretion of endogenous losses measured as sialic acid (SA) was also determined. Four dietary treatments (control (C), C + 250 FTU (phytase units per kg feed), C + 500 FTU, and C + 2500 FTU) were studied with each treatment replicated eight times in randomised complete block design. Diets were formulated to be nutritionally adequate with the exception of available P content (2.3 g/kg non-phytate P). Over the 48-h collection period, the phytase fed birds retained 29.3 mg more Na and 2.3 mg more Zn (p < 0.05) than the control fed birds, with the relationship between phytase dose and Na and Zn retention being best described by a linear function (p < 0.05 and p < 0.001, for Na and Zn, respectively). Phytase supplementation did not have an effect on dietary AME, DMD and NR. However, increasing the dose of phytase led to a linear increase in dietary amino acid retention (p < 0.05). Dietary phytase decreased total sialic acid excretion in a linear fashion (p < 0.05). It can be concluded that supplementary phytase increases the retention (reduces the excretion) of dietary Zn and Na in broiler chickens. The beneficial effects of the addition of exogenous phytases to poultry diets seems to be mediated through improved dietary nutrients absorption and reduced endogenous losses.