1. Effects of pretreatment in all-plant feedstuff with microbial phytase on phosphorous utilization and growth performance of Nile tilapia
Cao, Ling and James Diana
University of Michigan
Wang Weimin
Huazhong Agricultural University
Wuhan China
Yang Yi
Shanghai Ocean University
Shanghai China

2. Development (USAID) Grant No. EPP-A-00-06-00012-00.
Travel funding for this presentation was provided by AquaFish Collaborative Research Support Program
AquaFish CRSP
USAID
The Aquaculture CRSP is funded in part by United States Agency for International
Development (USAID) Grant No. EPP-A
The opinions expressed herein are those of the authors and do not necessarily reflect the views of the US Agency for International Development.

3. Outline Background Experimental design Results Conclusions
Acknowledgement

4. 1. Background Decrease of annual fishmeal production
Fishmeal substitution by plant proteins
High concentration of phytate in plant proteins

5. Phytate 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.

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

7. Phytase:
An enzyme specific to hydrolyze phytate, naturally found in animals, plants and microorganisms

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

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

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

12. 2. Experimental design 2.1 Pretreatment trial Objectives:
＊ Find out the most efficient phytase dose for treating plant ingredients

13. Enzyme solution (10 U/ml)
pH 5.5
Citric acid buffer
Phytase (5000 U/g)
Enzyme solution (10 U/ml)
Mix with plant ingredients (W:V=1:1)
Oven 55 ℃
5～6 h
Sampling
Chlorine anion mesh AG1-X4 （Bio-Rad Laboratory, USA）

14. 2.2 Growth trial
Objectives:
＊Find out the optimum addition dosage for growth performance of tilapia juveniles.
＊Determine the best replacing amount for inorganic phosphorous by phytase.

17. 3. Results
3.1 Pretreatment
Soybean meal
Mix plant ingredients

20. 3.2 Growth performance

23. 4. 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.

24. Thanks for your attention!