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Phytate-phosphorus and phytase contents on the relative weight of organs, intestinal morphometry and performance of broilers/Teores de fosforo fitico e fitase sobre o peso relativo de orgaos, morfometria intestinal e desempenho de frangos de corte.

INTRODUCTION

Although non-ruminants are fed with vegetal feed (cereals, oil seeds and their byproducts), approximately two thirds of the phosphorus present in such feed is in the PP form (GUENTER, 1997). Therefore, their diet must be complemented with inorganic phosphorus, one of the most expensive and rare minerals, as a greater part of that fraction of phosphorus not used is excreted with the feces, generating environmental pollution. In addition, it can combine with other ions, such as calcium, magnesium, zinc, iron, to form phytate and nutritional deficiencies (GUENTER, 1997; LEESON & SUMMERS, 2005). However, non-ruminants have little or no capacity to utilize PP, as there is little or no natural synthesis of phytase enzyme in the digestive tract of these animals (GREINER & KONIETZNY, 2010).

Exogenous enzymes are being broadly studied and used in animal nutrition with phytase being one of the most widely known. Phytase has an effect on performance, retention and availability of nutrients, reducing the variability of energy from feed stuffs, neutralizing the anti-nutritional effects of phytate; thus, increasing the accuracy of feed formulation (SOUSA et al., 2015).

The effects and benefits of phytase on the performance of broilers have been shown in different studies; however, phytase is basically used to reduce the anti-nutritional effects of phytate (RAVINDRAN et al., 2008; SELLE et al., 2009; OLUKOSI &FRU-NJI, 2014; SOUSA et al., 2015). When such fact occurs, there is an improvement of intestinal integrity and consequently greater absorption of nutrients and better performance of the animal (SMULIKOWSKA et al., 2010).

To improve phytase efficacy, it is important to make available adequate substrate so that the enzyme may work accordingly. Wheat bran is a widely available and economically viable ingredient for use in animal feed, as it contains around 16% crude protein, 4.5% of fat content, 12% crude fiber (LEESON & SUMMERS, 2005). This feed presents a high PP content, around 0.64%, which represents 66% of total phosphorus contained in the raw material, and it may thus be considered a good substrate for the phytase enzyme (ROSTAGNO et al., 2011).

In this way, the aim of this study was to evaluate the efficiency of phytase on diets with low and high PP content and its effects on the relative weight of organs, intestinal morphometry and performance of broiler chicks.

MATERIALS AND METHODS

The study was conducted in a metabolic room under controlled temperature, relative humidity and illumination, according to the lineage manual (COBB500, 2009) at Embrapa Swine and Poultry. Three-hundred and eighty four 1-d old male Cobb500 broiler chicks were kept in metal metabolic cages, equipped with bar feeders and nipple drinkers, where feed and water were supplied ad libitum.

Birds were allocated into four treatments, resulting from a 2x2 factorial scheme (two levels of PP x presence or absence of phytase 500FTU [kg.sup.-1]), in a randomized block design, with eight replicates per treatment and 12 birds per cage (experimental unit). At the beginning of the experiment, birds were weighed individually and sorted out into the blocks according to their initial weight, allowing all treatments to have eight blocks, which corresponded to replicates, with birds of uniform weight within each block, according to table 1.

Diets were prepared so that they would have different levels of PP, one with low (corn and soybean meal) and another one with high PP content (corn and soybean meal with the inclusion of wheat bran). They were formulated according to the nutritional requirements for broiler chickens according to the Brazilian Table for Poultry and Swine (ROSTAGNO, et al., 2011), showing similar levels of metabolizable energy, crude protein, calcium, available phosphorus, sodium and digestible amino acids. Despite the inclusion of inert, wheat bran with high fiber content and vegetable oil, respecting the limits proposed by the literature, it was assumed that the levels were within the physiologically acceptable limits, to the point of not affecting animal performance and the evaluated responses.

Up to 10 days of age, all broilers were fed with the same basal diet. From the 11th day on, two (11-21d and 22-32d) experimental diets were delivered that consisted in: T1-low PP content diet; T2--low PP content diet with phytase (500FTU [kg.sup.-1]); T3--high PP content diet and T4--high PP content diet with phytase (500FTU [kg.sup.-1]), according to table 2.

A commercial phytase, produced from Aspergillus ficuum (3-phytase (EC 3.1.3.8)) was used. The phytase content in each feed was assessed following the method determined by ISO (2008) and the PP content was determined according to DE BOEVER et al. (1994), to determine the PP percentage obtained based on the molecular weight of six phosphorus molecules in relation to the molecular weight of the intact phytate molecule.

At 22 and 32 days of age, two birds per experimental unit were identified, weighed and sacrificed by cervical dislocation (ART.14 OF RESOLUTION No. 1000, CFMV, 2012) to collect gizzard, heart, liver, cecum, cloacal bursa to determine the relative weight of those organs. At 32 days, a portion of duodenum, jejunum and ileum was collected to assess their intestinal morphometry. The gizzard (without its content), heart, liver, cecum and cloacal bursa were weighed with a digital scale (Brand: Bel Engineering, model Mark 5200 and with 0,01g precision), to measure relative weight (%PR = organ weight/body weight x 100) in relation to the body weight of each bird at the time they were sacrificed.

In order to assess intestinal morphometry, a sample of two centimeters long of each of the segments of the thin intestine (duodenum, jejunum and ileum) was collected and then fixed in a 10% formaldehyde solution. After fixation, the samples were dehydrated in ascending concentrations (70, 80, 90 and absolute) of ethyl alcohol, followed by diaphanization with xylol and inclusion in paraffin. Paraffin blocks were sectioned in rotating microtone at a thickness of 5 gm in 10 transversal and semiserial cuts. Blades were stained with hematoxylin and eosin (HE), and then they were mounted between slides and cover slips using Entellan[R] resin (Merk). Histological sections were analyzed using digital images captured by a camera (Zeiss, Axio Cam ICc 3) coupled to a microscope (Zeiss, Scope A1) at 5x magnification. Images were used to measure the heights of 10 villus and depths of 10 intestinal crypts and their measurement was made with a software program (Image Pro-Plus 4.5), and later relations between villus height and crypt depth were calculated.

In the period of 22 to 32 days of age, birds were weighed for average body weight (ABW) and average weight gain (AWG). Feed used and leftovers were also weighed during each phase to determine the average feed intake (AFI) and feed conversion ratio (FCR), which was obtained from the AFI/AWG.

Data were subjected to analysis of variance, with a 5% significance level through the SAS (2008) MIXED procedure. Fixed effects of diets and phytase, and interaction between factors, as well as randomized block effects, according to the statistical model were tested: [Y.sub.ijk] = [mu] + [B.sub.i] + [D.sub.j] + [F.sub.k] + D[F.sub.Jk] + e. where, [Y.sub.ijk] = observed value in i-simal block, at j-simal phytate phosphorus content, at k-simal phytase level; u = general mean; [B.sub.i] = block effect; i = 1, 2, ..., 8; [D.sub.j] = effect of phytate phosphorus content; j = high, low; [F.sub.k] = effect of phytase level; k =0, 500; D[F.sub.jk] = effect of interaction between phytate phosphorus content and phytase level; [[epsilon].sub.ijk] = random error associated to each observation.

RESULTS AND DISCUSSION

Results of the relative weight of organs at 22 and 32 days of age did not show interaction between the PP and phytase factors (Table 3). However, at 32 days of age, there was an isolated effect both of PP content and of phytase. The diet with high PP content provided a greater relative weight for the gizzard and the diet with low PP content presented a greater relative weight for broiler chicks liver.

Regarding the diet with high PP content, it is also important to consider the high dietary fiber content, which according to MATEOS et al. (2012) may have effects on voluntary consumption, size of organs, intestinal motility, enzyme production and microbiota growth. It also resulted in greater development and better functioning of the gizzard, which may be an indication of the good functioning of the gastrointestinal tract.

When broilers were fed with a high phytate phosphorus diet, that is, with the inclusion of wheat bran, there was energetic dilution, which made necessary the inclusion of soybean oil in the diet to keep it isoenergetic. According to SILVA et al. (2014), replacing carbohydrate or protein with lipids implies in the reduction of the diet's calorie increase, which will make the liver work less due to a less complex enzymatic system for digestion and absorption of these molecules. This justifies the lesser relative weight observed in the liver.

The presence of phytase provided greater relative weight of the heart. Study conducted by WANG et al. (2013) did not observe such fact. However, SOUSA et al. (2015), upon evaluating diets with reduced nutritional levels, in the presence or absence of phytase, observed an increase in the relative weight of the heart, but with the absence of phytase. Authors noted that cardiac hypertrophy may be caused by hypophosphatemia due to the low supply of phosphorus. Nevertheless, in this study, there was no reduction of nutritional levels and the greater relative weight of the heart occurred with the presence of phytase, which would enable a greater phosphorus release, thus not characterizing a hypophosphatemia.

Birds' cecum had a smaller relative weight in the presence of phytase. HAN (1997) explains that the reduction of weight of the organs through the supplementation of exogenous enzymes may be related to the enzyme's efficiency in degrading anti-nutritive factors.

Table 4 presents the results of variables, villus height ([micro]m), crypt depth ([micro]m), and the villi:crypt ratio in duodenum, jejunum and ileum of broilers, evaluated at 32 days of age. This study did not observe a significant interaction among the factors evaluated, nor their isolated effect. However, when WU et al. (2004) evaluated the influence of phytase on wheat-based diets with adequate levels of phosphorus, they determined that the villus of duodenum of the birds without phytase supplementation were relatively shorter and thicker. Whereas the addition of phytase provided an increase of the villus height when compared to the control treatment, but did not influence the villus height of the jejunum and ileum portion.

Evaluation of the intestinal morphological characteristics, such as villus height and crypt depth, is required due to the absorptive capacity of the intestinal mucosa because the higher the villus, greater is the area of contact of enterocytes with the feed, which increases the absorption area of nutrients. In addition, an adequate and rapid weight gain of birds is directly linked with the morphological and functional integrity of the digestive system (GOPINGER et al., 2014). Therefore, the inclusion of phytase in the diet of non-ruminants in order to reduce the anti-nutritional effects of phytate may also improve intestinal integrity and consequently improve nutrient absorption (SMULIKOWSKA et al., 2010).

Table 5 presents the results obtained for the performance in the period of 22 to 32 days of age, as there was no interaction among the factors analyzed because it is expected that when there is substrate (PP), the magnitude of the effect of the phytase enzyme is greater. However, when the effects were analyzed separately birds fed with a diet with higher PP content presented an AFI 1.64% greater in comparison with birds fed with a diet with low PP content. This is probably due to the high fiber content (3.9%) supplied by the wheat bran. Increasing the fiber in the diet may provide a greater intestinal motility and, consequently increase passage rate, resulting in greater feed intake (MATEOS et al., 2012).

Phytase is well accepted in wheat-based diets (AMERAH, 2015); however, inclusion of wheat bran and phytase in broiler diets did not provide the best response for performance in this study. KLEYN (2013) notes that phytase has an impact mainly on the anti-nutritional properties of PP, and that, although not directly measurable, may have a positive effect on the performance of the birds due to a better absorption of the other nutrients. In addition, PP present in wheat is located in the aleurone and due to its fibrous nature it ends up limiting the access of the phytase to its substrate, thus stopping PP degradation (LIU et al., 2014).

CONCLUSION

Phytase and phytate phosphorus content did not interact for the variables of performance, intestinal morphometry and relative weight of organs in broiler up to 32 days of age. Nevertheless, the feed intake was affected by the phytate phosphorus content. In addition, the relative weight of gizzard, liver, heart and cecum were affected by both, presence of phytate and by presence of phytase separately.

BIOETHICS AND BIOSECURITY COMMITTEE APPROVAL

Animal experiment procedures used in this study were approved by Ethics Committee in Animal Experimentation at Universidade Federal de Pelotas, under number 6866.

http://dx.doi.org/10.1590/0103-8478cr20150892

REFERENCES

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ISO (INTERNATIONAL ORGANIZATION FOR STANDARDIZATION). Animal feeding stuffs: determination of phytase activity. Geneva, 2008. 16p. Accessed: Sept. 17, 2014.

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LIU, S.Y. et al. Effects of phytase supplementation on growth performance, nutrient utilization and digestive dynamics of starch and protein in broiler chickens offered maize-, sorghumand wheat-based diets. Animal Feed Science and Technology, v.194, p.164-175, 2014. Accessed: Dec. 03, 2014. doi: 10.1016/j. anifeedsci.2014.08.005.

MATEOS, G.G. et al. Poultry response to high levels of dietary fiber sources varying in physical and chemical characteristics. Journal Applied Poultry Research, v.21, p.156-174, 2012. Accessed: May. 30, 2014. doi: 10.3382/japr.2011-00477.

OLUKOSI, O.A.; FRU-NJI, F. The interplay of dietary nutrient specification and varying calcium to total phosphorus ratio on efficacy of a bacterial phytase: 1. Growth performance and tibia mineralization. Poultry Science, v.93, p.3037-3043, 2014. Accessed: Dec. 16, 2014. doi: 10.3382/ps.2014-03978.

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SMULIKOWSKA, S. et al. Effect of an organic acid blend and phytase added to a rapeseed cake-containing diet on performance, intestinal morphology, caecal microflora activity, and thyroid status of broiler chickens. Journal of Animal Physiology and Animal Nutrition, v.94, p.15-23, 2010. Accessed: Jun. 02, 2015. doi: 10.1111/j.1439-0396.2008.00876.x.

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WU, Y.B. et al. Influence of phytase and xylanase, individually or in combination, on performance, apparent metabolisable energy, digestive tract measurements and gut morphology in broilers fed wheat-based diets containing adequate level of phosphorus. British Poultry Science, v.45, p.76-84, 2004. Accessed: Oct. 16, 2014. doi: 10.1080/00071660410001668897.

Aiane Aparecida da Silva Catalan (I) Everton Luis Krabbe (II) Valdir Silveira de Avila (II) Leticia dos Santos Lopes (II) Ana Paula Nunes (I) Marcos Antonio Zanella Mores (II) Victor Fernando Buttow Roll (I) Eduardo Goncalves Xavier (I)

(I) Programa de Pos-graduacao em Zootecnia, Universidade Federal de Pelotas (UFPEL), 96010-000, Pelotas, RS, Brasil. E-mail: aianec@yahoo.com.br. * Corresponding author.

(II) Empresa Brasileira de Pesquisa Agropecuaria (EMBRAPA)--Suinos e Aves, Concordia, SC, Brasil.

Received 06.18.15

Approved 04.04.16

Returned by the author 07.04.16

CR-2015-0892.R1
Table 1--Experimental blocks according to the weight of
broilers in the housing.

Block     Average weight in the housing (g)

1                        51.3
2                        48.5
3                        46.9
4                        46.4
5                        44.9
6                        43.6
7                        42.6
8                        40.0

Table 2--Centesimal and nutritional composition of experimental
diets for broilers.

Ingredients (kg)            1-10d          11-21d (Initial)
                            Basal
                            Diet    Low     Low    High   High
                                     PP     PP      PP     PP
                                    NP *   WP **    NP     WP

Corn (7.5%)                 50.7    63.9   63.9    48.7   48.7
Soybean meal (45%)          42.0    30.2   30.2    25.4   25.4
Wheat bran (14%)             0.0    0.0     0.0    20.0   20.0
Soybean oil                  3.1    0.0     0.0    2.9    2.9
Kaolin                       0.0    2.8     2.8    0.1    0.1
Dicalcium phosphate (1)      1.8    1.0     1.0    0.8    0.8
Limestone (2)                1.0    0.7     0.7    0.8    0.8
Iodized salt                 0.5    0.4     0.4    0.6    0.6
DL-melthionine               0.3    0.2     0.2    0.2    0.2
L-lysine                     0.2    0.3     0.3    0.4    0.4
Vitamin premix (3)           0.1    0.1     0.1    0.1    0.1
Mineral premix (4)          0.05    0.05   0.05    0.05   0.05
L-threonine                  0.1    0.1     0.1    0.2    0.2
Phytase (5)                 0.00    0.00   0.05    0.00   0.05
TOTAL                        100    100     100    100    100

                                    Nutritional composition

Metabolizable Energy        2950    2850   2850    2850   2850
  (kcal [kg.sup.-1])
Crude Protein (%)           23.0    18.6   18.6    18.6   18.6
Crude Fiber (%)              --     2.7     2.7    4.1    4.1
Ether Extract (%)            --     2.8     2.8    5.8    5.8
Calcium (%)                 0.92    0.60   0.60    0.60   0.60
Sodium (%)                  0.22    0.15   0.15    0.15   0.15
Digestible lysine            --     1.10   1.10    1.10   1.10
Digestible methionine        --     0.46   0.46    0.46   0.46
Available phosphorus (%)    0.47    0.30   0.30    0.30   0.30
Total phosphorus (%)        0.73    0.54   0.54    0.62   0.62
Calculated PP (%) (6)        --     0.24   0.24    0.32   0.32
Analyzed PP (%) (7)          --     0.22   0.22    0.33   0.33
Added phytase                --      0      500     0     500
Determined phytase (8, 9)    --      0      690    640    1315

Ingredients (kg)                   22-32d (Growth)

                            Low    Low    High   High
                             PP     PP     PP     PP
                             NP     WP     NP     WP

Corn (7.5%)                 72.4   72.4   52.9   52.9
Soybean meal (45%)          24.7   24.7   20.3   20.3
Wheat bran (14%)            0.0    0.0    20.0   20.0
Soybean oil                 0.0    0.0    4.4    4.4
Kaolin                      0.6    0.6    0.0    0.0
Dicalcium phosphate (1)     0.8    0.8    0.5    0.5
Limestone (2)               0.6    0.6    0.7    0.7
Iodized salt                0.3    0.3    0.3    0.3
DL-melthionine              0.2    0.2    0.2    0.2
L-lysine                    0.2    0.2    0.3    0.3
Vitamin premix (3)          0.1    0.1    0.1    0.1
Mineral premix (4)          0.05   0.05   0.05   0.05
L-threonine                 0.05   0.05   0.1    0.1
Phytase (5)                 0.00   0.05   0.00   0.05
TOTAL                       100    100    100    100

                                Nutritional composition

Metabolizable Energy        3000   3000   3000   3000
  (kcal [kg.sup.-1])
Crude Protein (%)           16.5   16.5   16.4   16.4
Crude Fiber (%)             2.5    2.5    3.9    3.9
Ether Extract (%)           3.1    3.1    7.3    7.3
Calcium (%)                 0.50   0.50   0.50   0.50
Sodium (%)                  0.15   0.15   0.15   0.15
Digestible lysine           0.89   0.89   0.90   0.90
Digestible methionine       0.37   0.37   0.39   0.39
Available phosphorus (%)    0.25   0.25   0.25   0.25
Total phosphorus (%)        0.48   0.48   0.56   0.56
Calculated PP (%) (6)       0.24   0.24   0.31   0.31
Analyzed PP (%) (7)         0.25   0.25   0.33   0.33
Added phytase                0     500     0     500
Determined phytase (8, 9)   135    725    330    1175

* PP NP--phytate phosphorus no phytase; ** PP WP--phytate phosphorus
with phytase: (1) Calcium: minimum 210g[kg.sup.-1], maximum
250g[kg.sup.-1]; Phosphorus: 180g[kg.sup.-1]; (2) Calcium: minimum
33%; (3) Levels of guarantee per product kg: Vitamin A: 9000000.
000UI, Vitamin D3: 2500000. 00UI, Vitamin E: 20000. 00UI, Vitamin K3:
2500. 00mg, Vitamin B1: 1500. 00mg, Vitamin B2: 6000. 00mg, Vitamin
B6: 3000. 00mg, Vitamin B12:12000. 00mcg, Pantothenic Acid: 12g,
Niacin: 25g, Folic Acid: 800. 00mg, Biotin: 60. 00mg, Selenium: 250.
00mg. (4) Levels of guarantee per kg of product: Copper: 20g, Iron:
100g, Manganese: 160g, Cobalt: 2000. 00mg, Iodine: 2000. 00mg, Zinc:
100g. (5) Natuphos, 10000 FTU[g.sup.-1]; (6) Calculated Phytate
Phosphorus = total phosphorus--available phosphorus. (7) Levels
obtained according to the report Enzyme Services and Consultancy--AB
Vista; (8) Level of phytase (FTU [kg.sup.-1] of feed) according to
the CBO Essay certificate--Lab analysis; (9) The expected levels do
not normally coincide with the supplemented levels because of the
natural phytase present in the raw material, but it is assumed that
natural phytase is not active in the gastrointestinal tract (GUENTER,
1997).

Table 3--Relative weight (%) of gizzard, heart, liver, cecum and
cloacal bursa of broilers male Cobb 500 broilers, at 22 and 32 days
of age, fed with low and high phytate phosphorus (PP) content diets
and without or with phytase (mean [+ or -] standard error).

Age    Variables   PP     Phytase (FTU [kg.sup.-1])
       (1)

                                   0                    500

       Gizzard     Low    2.20 [+ or -] 0.09    2.15 [+ or -] 0.05
                   High   2.31 [+ or -] 0.07    2.19 [+ or -] 0.09

       Heart       Low    0.477 [+ or -] 0.01   0.472 [+ or -] 0.01
                   High   0.473 [+ or -] 0.02   0.481 [+ or -] 0.01

22     Liver       Low    2.50 [+ or -] 0.08    2.55 [+ or -] 0.09
days               High   2.40 [+ or -] 0.08    2.51 [+ or -] 0.10

       Cecum       Low    0.73 [+ or -] 0.06    0.74 [+ or -] 0.05
                   High   0.81 [+ or -] 0.04    0.84 [+ or -] 0.04

       Cloacal     Low    0.20 [+ or -] 0.01    0.20 [+ or -] 0.02
       bursa       High   0.21 [+ or -] 0.02    0.20 [+ or -] 0.01

       Gizzard     Low    1.39 [+ or -] 0.06    1.51 [+ or -] 0.06
                   High   1.58 [+ or -] 0.05    1.60 [+ or -] 0.06

       Heart       Low    0.42 [+ or -] 0.01    0.43 [+ or -] 0.01
                   High   0.38 [+ or -] 0.02    0.42 [+ or -] 0.01

32     Liver       Low    2.25 [+ or -] 0.05    2.33 [+ or -] 0.10
days               High   2.02 [+ or -] 0.09    1.96 [+ or -] 0.06

       Cecum       Low    0.70 [+ or -] 0.04    0.66 [+ or -] 0.04
                   High   0.70 [+ or -] 0.04    0.54 [+ or -] 0.05

       Cloacal     Low    0.22 [+ or -] 0.02    0.22 [+ or -] 0.02
       bursa       High   0.21 [+ or -] 0.01    0.22 [+ or -] 0.02

Age    Variables   p-value for the principal
       (1)         effect and inter action

                   Principal Effect  Interaction

                   PP       Phytase

       Gizzard     0.3254   0.2901   0.7110

       Heart       0.8510   0.9436   0.6248

22     Liver       0.3299   0.2513   0.7058
days

       Cecum       0.0534   0.5926   0.8347

       Cloacal     0.9389   0.8632   0.8858
       bursa

       Gizzard     0.0109   0.1833   0.2903

       Heart       0.0540   0.0398   0.4738

32     Liver       0.0010   0.8581   0.3811
days

       Cecum       0.2109   0.0346   0.1694

       Cloacal     0.5198   0.4845   0.6118
       bursa

(1) Averages obtained from eight replicates with two birds
per experimental unit.

Table 4--Villus height (VH), crypt depth (CD) and villus:crypt ratio
(V:C) of duodenum, jejunum and ileum of broilers male Cobb 500 at 32
days of age, fed with low and high phytate phosphorus (PP) content
diets and with or without phytase (mean [+ or -] standard error).

Variables               PP     Phytase (FTU [kg.sup.-1])
(1)

                                           0

AV           Duodenum   Low     1336.87 [+ or -] 48.54
([micro]m)              High    1431.03 [+ or -] 43.86
             Jejunum    Low      966.02 [+ or -] 64.75
                        High    1019.16 [+ or -] 50.99
             Ileum      Low      623.65 [+ or -] 34.18
                        High     745.59 [+ or -] 54.76
CD           Duodenum   Low      113.14 [+ or -] 7.80
([micro]m)              High     113.63 [+ or -] 6.49
             Jejunum    Low      126.34 [+ or -] 8.29
                        High     133.61 [+ or -] 3.81
             Ileum      Low      110.10 [+ or -] 5.20
                        High     114.78 [+ or -] 4.99
V:C Ratio    Duodenum   Low       12.73 [+ or -] 0.77
                        High      13.26 [+ or -] 1.15
             Jejunum    Low       8.44 [+ or -] 0.71
                        High      8.21 [+ or -] 0.48
             Ileum      Low       6.01 [+ or -] 0.29
                        High      6.83 [+ or -] 0.49

Variables               PP     Phytase (FTU [kg.sup.-1])
(1)

                                          500

AV           Duodenum   Low     1391.21 [+ or -] 41.05
([micro]m)              High    1359.28 [+ or -] 68.38
             Jejunum    Low      947.86 [+ or -] 72.99
                        High    1096.04 [+ or -] 99.80
             Ileum      Low      699.12 [+ or -] 41.82
                        High     749.14 [+ or -] 50.83
CD           Duodenum   Low      113.57 [+ or -] 8.26
([micro]m)              High      99.86 [+ or -] 3.60
             Jejunum    Low      131.44 [+ or -] 5.05
                        High     132.65 [+ or -] 8.42
             Ileum      Low      116.19 [+ or -] 6.79
                        High     122.91 [+ or -] 6.08
V:C Ratio    Duodenum   Low       14.01 [+ or -] 1.21
                        High      14.88 [+ or -] 0.80
             Jejunum    Low       7.60 [+ or -] 0.65
                        High      8.93 [+ or -] 0.92
             Ileum      Low       6.49 [+ or -] 0.53
                        High      6.48 [+ or -] 0.30

Variables               PP     p-value for the principal effect
(1)                            and interaction

                               Principal Effect   Interaction

                               PP       Phytase

AV           Duodenum   Low    0.5090   0.8823    0.1978
([micro]m)              High
             Jejunum    Low    0.1994   0.6760    0.5403
                        High
             Ileum      Low    0.0670   0.3848    0.4283
                        High
CD           Duodenum   Low    0.3588   0.1805    0.1709
([micro]m)              High
             Jejunum    Low    0.5660   0.7110    0.6055
                        High
             Ileum      Low    0.2990   0.1980    08505
                        High
V:C Ratio    Duodenum   Low    0.3467   0.0671    0.8726
                        High
             Jejunum    Low    0.4516   0.9318    0.2914
                        High
             Ileum      Low    0.3448   0.8875    0.3350
                        High

(1) Averages obtained from eight replicates with two birds per
experimental unit.

Table 5--Average feed intake (AFI--g-bird), average body weight
(ABW-g-bird) on 32 days of age, and average weight gain (AWG -g-bird)
and feed conversion ratio (FCR--g:g) at the period of 22 to 32 days of
age, for broilers male Cobb 500, fed with low and high phytate
phosphorus (PP) content diets, and with or without phytase (mean
[+ or -] standard error).

Variables   PP     Phytase FTU [kg.sup.-1])
(1)
                             0                       500

AFI         Low    1395.17 [+ or -] 15.29   1390.27 [+ or -] 20.23
            High   1413.45 [+ or -] 17.91   1418.55 [+ or -] 19.41
ABW         Low    1659.12 [+ or -] 23.14   1633.17 [+ or -] 31.56
            High   1613.69 [+ or -] 23.43   1605.45 [+ or -] 20.59
AWG         Low    843.04 [+ or -] 11.22    830.51 [+ or -] 22.89
            High   856.74 [+ or -] 17.69    846.75 [+ or -] 12.69
FCR         Low    1.656 [+ or -] 0.013     1.679 [+ or -] 0.031
            High   1.652 [+ or -] 0.020     1.677 [+ or -] 0.025

Variables   PP     p-value for the principal effect
(1)
                     PP     Phytase   Interaction

AFI         Low    0.0319   0.9924    0.6266
            High
ABW         Low    0.0771   0.3948    0.6572
            High
AWG         Low    0.3221   0.4542    0.9323
            High
FCR         Low    0.8992   0.3056    0.9807
            High
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Title Annotation:produccion animal; texto en ingles
Author:Catalan, Aiane Aparecida da Silva; Krabbe, Everton Luis; de Avila, Valdir Silveira; Lopes, Leticia d
Publication:Ciencia Rural
Date:Oct 1, 2016
Words:5012
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