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8/6/2019 Uso de Enzimas Para Aumetar La Disponibilida de Fosforo en Aves

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USING ENZYMES TO INCREASE PHOSPHORUSAVAILABILITY IN POULTRY DIETS

AUSTIN H. CANTOR

Department of Animal Sciences, University of Kentucky, Lexington,Kentucky, USA

Introduction

There has been considerable interest in recent years in examining waysto decrease the amount of phosphorus excreted by animals in order tominimize water pollution. Much of the phosphorus in feed ingredientsobtained from plants is in the form of phytic acid, a compound notdegraded by the endogenous enzymes found in animals. Consequently,approximately two-thirds of this phosphorus is considered unavailablefor monogastric animals. Thus, it is often necessary to add sources ofinorganic phosphorus to diets for poultry and swine in order to meet theanimals’ requirements for this element.

One method of reducing the amount of phosphorus added to dietsis to increase the availability of the phosphorus in the feed ingredientsby the addition of microbially produced enzymes to the diet. This idea

was introduced over 25 years ago, but was not applied in the feedindustry for a variety of practical reasons. However, in the past severalyears, because of increasing environmental concerns and regulations,this concept has received considerable attention among researchers andapplication in the field.

We recently conducted a study to compare the efficacy of acidphosphatases from yeast and Aspergillus niger with that of a commercialphytase (from A. niger) for improving availability of phosphorus in acorn/soybean meal broiler starter diet. The organisms used for pro-duction of acid phosphatase were genetically modified to increase theiryield of the enzyme.

Methods

The study involved 468 day-old male broiler chicks housed in cages (61x 51 cm). Four replicate groups of nine chicks were assigned to each of

13 dietary treatments. A basal broiler starter diet was formulated (Table1) to meet all of the broilers’ nutrient requirements except for calciumand available phosphorus (calcium = 0.65%, available phosphorus =

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Using enqmes to increase phosphorus availability in poccltry diets

Table 1. Composition of the basal diet.

Ingredient Per cent of diet

coinSoybean mealLimestoneDicalcium phosphateVitamin-mineral mixCelluloseVegetabIe oilCalculated nutrient composition

ME, mcaVkgProteinMet f CysP, total (analyzed)

P, availableCa

57.0035.00

1.000.700.251.354.00

3.1221.90

0.910.54

0.270.65

0.27%). This diet was fed alone or with graded levels of calcium andphosphorus (providing 0.74, 0.83 and 0.92% calcium and 0.33. 0.39and 0.45% available phosphorus) to establish standard dose responsecurves for the variables measured in the trial. The levels of calciumand phosphorus were adjusted by varying the amounts of limestone,dicalcium phosphate and cellulose in the diet. In addition to these fourstandard diets, there were nine experimental diets which consisted ofthe basal diet supplemented with 400, 800 or 1200 phytase units perkg provided by yeast acid phosphatase, A. niger acid phosphatase orAlfzyme Phytase. Chicks were fed the diets on a free-choice basis for14 days.

Results

Variables measured in this study included weight gain, feed intake, feedefficiency (gain:feed ratio), plasma inorganic phosphorus, % toe ash, %tibia ash and tibia breaking strength. Compared with the basal diet (noadded phosphorus or enzyme), weight gain to 14 days was significantly(P < 0.05) increased by 1200 units per kg of al1 three enzymes (Table2). Feed intake was also increased by supplementing the diet with thethree enzymes. There were no differences among these treatments infeed conversion.

Adding inorganic phosphorus to the basal diet did not result inlinear responses in plasma phosphorus and toe ash. Therefore, theseparameters were not useful in evaluating the efficacy of the threeenzymes. However, enzyme supplementation at 1200 units per kg re-sulted in plasma phosphorus levels equivalent to that obtained with the

highest level of dietary phosphorus ( Table 3). The addition of enzymes to the basal diet led to significant improvements in both breaking strength and per cent ash of the tibia ( Table 4).

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Austin H. Cantor

Table 2. Effect of dietary phosphorus and enzymes on broikrgrowth performance.

Dietary supplement

(none)*0.18% PtY‘QSANAPPPHYISEM

Weight gain, Feed Gain/feedg intake, g

320b 391b 0.82336=b 4248 0.79349= 428a 0.82348a 422= 0.82339a 418a 0.80

6 7 0.01

*Basal diet: 0.27% availabIe P, 0.54% total P, 0.65% CaiProvided 0.45% available P, 0.70% total P, 0.92% Ca*Yeast acid phosphatase, 1200 units/kg

§A. niger phosphatase, 1200 units/kgIA. niger phytase, 1200 units/kga,V’ < 0.05

Table 3. Effect of dietary phosphorus and enzymes onplasma phosphorus and toe ash.

Dietary supplement Plasma inorganic P, Toe ash, %

mg/dl

(none) * 5.61 10.70.18% Pt 6.61 11.9YAP+ 7.01 11.0ANAP§ 6.48 10.9PHYI 7.49 12.2SEM 0.45 0.5

*Basal diet: 0.27% available P, 0.54% totar P, 0.65% Caj-Provided 0.45% available P, 0.70% total P, 0.92% CafYeast acid phosphatase, 1200 units/kg§A. niger phosphatase, 1200 units/kgIA. niger phytase, 1200 units/kg

Table 4. Effect of dietary phosphorus and enzymes ontibia breaking strength and tibia ash.

Dietary supplement Breaking strength, kg Tibia ash, %

(none)* 5.53” 38.3”0.18% Pt 10.06= 46.laYAP$ 7.84b 42.7bANAPI 7.98b 42.7b

PlWl 8.4P 43.6bSEM 0.34 0.5

*Basal diet: 0.27% available P, 0.54% total P, 0.65% CaTProvided 0.45% available P, 0.70% total P, 0.92% Ca

*Yeast acid phosphatase, 1200 units/kg§A. niger phosphatase, 1200 units/kgflA. niger phytase, 1200 units/kga.bG’ < 0.05.

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Usipag enzynm to increase phosphorus availability in poultry diets

However, the improvements noted with the highest levels of enzymesupplementation were not as great as those obtained with the additionof 0.18% inorganic phosphorus.

We were interested in calcuiating the increase in available phosphorusdue to using the enzymes. Per cent tibia ash was the parameter thathad the most line ar respons e to graded levels of supplemental calciumand phosphorus ( Figure 1). Based on a linear regression equation fortibia ash vs. % available phosphorus in the diet (Y = 4.16X + 27.5,1-2 = OK?), the equivalent available phosphorus was calculated for thevarious enzyme supplements. Supplementing the basal diet with 1200units of yeast acid phosphatase, A. niger acid phosphatase and phytaseincreased the available phosphorus in the diet by 0.10, 0.10 and 0.12%,

50

c 453

g.-l-8 40

350.27 0.33 0.39

% Available P

Figure 1. Tibia ash as a function of dietary available phosphorus.

Table 5. Calculated incr eased available phosphorusbased on tibia variabtes.

Increased available P(%) based on:

Enzyme Breaking strength* Per cent ash?

YAW 0.09 0.10ANAPB 0.10 0.10-J W l 0.11 0.12

*Strength = 28.4 X (available P) - 2.4; P < 0.001,r = 0.89t% ash = 41.6 X (availabIe P) + 27.5; P c 0.001,r = 0.90*Yeast acid phosphatase, 1200 units/kg§A. niger phosphatase, 1200 units/kgTA. niger phytase, 1200 unit&g

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Austin H. Cantor

respectively (Table 5). A similar calculation was made using the resultsobtained with tibia breaking strength. Increases of 0.09, 0.10 and 0.11%available phosphorus were obtained from using 1200 units of yeast acidphosphatase, A. aiger acid phosphatase and phytase, which is in closeagreement with the values calculated from the tibia ash data.

The basal diet was calculated to contain 0.27% available phosphorusand 0.52% total phosphorus. Therefore, the unavailable phosphorus,which was presumably mostly in the form of phytic acid, was equalto 0.25%. Based on the assumption that the increases in availablephosphorus were due to hydrolysis of phytate, we then calculated thepercentage of p hytate p hosphorus liberated by the three enzymes usingthe values from Table 5. This value ranged from 36 to 44% and from 40to 48% using breaking strength and ash data, respectively (Table 6).

Table 6. P ercentage of phytate phosphorushydrolyzed based on tibia variables.

% Phytate phosphorus hydrolyzedbased on:

Enzyme Breaking strength Per cent ash

YAP?ANAP+PHYP

36 4040 4044 48

*Calculated phosphorus values: total = 0.52%,available = 0.27%, phytate = 0.25%TYeast acid phosphatase, 1200 units/kg$A. niger phosphatase, 1200 units/kg§A. niger phytase, 1200 units/kg

Conclusions

The commercial phytase and the two experimental acid phosphataseswere all effective in increasing phosphorus availability in the presentstudy. The increases in available phosphorus due to enzyme supple-mentation were approximately O.lO%, which corresponds to roughly40% of the phytate phosphorus. Thus, it appears that enzyme supple-mentation can be an effective method of replacing some of the supple-mental phosphorus in poultry diets.

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uso de enzimas para aumetar la disponibilida de fosforo en aves

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