Cao, Ling and James Diana University of Michigan Wang Weimin Huazhong Agricultural University

Effects of pretreatment in all-plant feedstuff wiEffects of pretreatment in all-plant feedstuff with microbial phytaseth microbial phytase

on phosphorous utilization and growth perforon phosphorous utilization and growth performance of Nile tilapiamance of Nile tilapia

Cao, Ling and James DianaCao, Ling and James Diana

University of MichiganUniversity of Michigan

Wang WeiminWang Weimin

Huazhong Agricultural UniversityHuazhong Agricultural University

Wuhan ChinaWuhan China

Yang YiYang Yi

Shanghai Ocean UniversityShanghai Ocean University

Shanghai ChinaShanghai China

AquaFish CRSPAquaFish CRSPUSAIDUSAID

Travel funding for this presentation was provideTravel funding for this presentation was provide

d byd by AquaFish AquaFish

Collaborative Research SuCollaborative Research Support Programpport Program

The Aquaculture CRSP is funded in part by United States Agency for The Aquaculture CRSP is funded in part by United States Agency for International International

Development (USAID) Grant No. EPP-A-00-06-00012-00.Development (USAID) Grant No. EPP-A-00-06-00012-00.

The opinions expressed herein are those of the authors and do not The opinions expressed herein are those of the authors and do not necessarily reflect the views of the US Agency for International necessarily reflect the views of the US Agency for International

Development.Development.

OutlineOutline

BackgroundBackground Experimental designExperimental design ResultsResults ConclusionsConclusions AcknowledgementAcknowledgement

1. Background1. Background

Decrease of annual fishmeal productionFishmeal substitution by plant proteinsHigh concentration of phytate in plant proteins

Phytate and phytase enzymePhytate and phytase enzyme

Phytate = phytin = phytic acid

Up to 80% of the total P content in plants may be present in the form of phytate and is practically not available for monogastric or agastric aquatic animals.

Table 1. Phytate contents in plants or plant products (NRC, 1993)

Phytase: Phytase: An enzyme specific to hydrolyze phytate, naturAn enzyme specific to hydrolyze phytate, natur

ally found in animals, plants and microorganisally found in animals, plants and microorganismsms

Figure 1. Action of phytase (Baruah et al. 2004)

Table 3. Commercial information of microbial phytase Table 3. Commercial information of microbial phytase (Cao (Cao et alet al. 2007). 2007)

Table 4. Optimum dose of phytase addition in diets of different fish species (Cao et al. 2007)

2. Experimental design2. Experimental design

2.1 Pretreatment trial2.1 Pretreatment trial

Objectives:Objectives:

＊＊ Find out the most efficient phytase dose for trFind out the most efficient phytase dose for treating plant ingredientseating plant ingredients

Citric acid bufferCitric acid bufferPhytase (5000 U/g)Phytase (5000 U/g)

pH pH 5.55.5

Enzyme solution Enzyme solution (10 U/ml)(10 U/ml)

Mix with plaMix with plant ingrediennt ingredients (W:V=1:1)ts (W:V=1:1)

Oven 55 Oven 55 ℃℃ 55 ～～ 6 h6 h

SamplinSampling g

Chlorine anion 100-200 mesh AGChlorine anion 100-200 mesh AG1-X4 1-X4 （（ Bio-Rad Laboratory, USBio-Rad Laboratory, USAA ））

2.2 Growth trial2.2 Growth trial

Objectives: Objectives:

＊＊ Find out the optimum addition dosage for groFind out the optimum addition dosage for growth performance of tilapia juveniles. wth performance of tilapia juveniles.

＊＊ Determine the best replacing amount for inorDetermine the best replacing amount for inorganic phosphorous by phytase.ganic phosphorous by phytase.

3. Results 3. Results

3.1 Pretreatment3.1 Pretreatment

Soybean mealSoybean mealMix plant ingredientsMix plant ingredients

3.2 Growth performance3.2 Growth performance

4. Conclusion4. Conclusion

The optimal dose of phytase for the pretreatment of plant ingredients is 1,000 U kg -1, which can efficiently convert phytate P to available P and replace 50% of the inorganic P supplementation to the diets for Nile tilapia juveniles without affecting their growth performance, apparent digestibility coefficients of both crude protein and phosphorous.

The addition of phytase in the diets can reduce the use of inorganic P, enhance the utilization of P in plant ingredients, and thus minimize the P discharge to the environment.