This study aimed to develop the in vitro method using domestic commercial diets to estimate nutrient digestibility in dogs. The existing in vitro method were tested and compared with literature data to develop new in vitro method. The development of in vitro method progressed as follows: modification of pepsin solution to an activated form and supplementation with 1% lipase. All the in vitro method progressed to 4 hours of stomach simulation and 2 hours of small intestine simulation. In vivo digestibility was measured using the same diets as beagle dogs. The supplementation of lipase methods showed significantly improved (p < 0.05) DM, OM, and EE than the existing and modified pepsin solution methods. The correlation between in vitro and in vivo data in DM, OM, and EE digestibility was high (r2 = 0.889, 0.907, and 0.721, respectively), and the correlation between in vitro and in vivo data in CP and GE digestibility was medium (r2 = 0.681 and 0.536, respectively). The current in vitro method is similar to in vivo digestibility and helps potentially predict digestibility for dogs. In conclusion, this developed in vitro method suggests that it can help estimate the nutrient digestibility of dogs' diets without in vivo experiments.

Introduction
Materials and Methods
    1. Commercial dog diets
    2. Existing in vitro procedure
    3. Developed in vitro Method
    4. Chemical analyses and calculation
    5. Ethics approval and consent to participate
    6. Animals, experimental design, and diets
    7. Nutrient digestibility
    8. Statistical analyses
Results and Discussion
    1. The result of existing in vitro Method
    2. Nutrient digestibility by method
    3. Relationships between in vivo and in vitro
Acknowledgement
References

• Kyeong Ho Jeon(Graduate Student, Department of Animal Sciences, Chungbuk National University, Cheongju, 28644, Korea)
• Min Ho Song(Professor, Department of Animal Science and Biotechnology, Chungnam National University, Daejeon, 34134, Korea)
• Ji Hwan Lee(Postdoctoral researcher, Department of Poultry Science, University of Georgia (UGA), Athens, GA, 30602, United States)
• Se Yeon Chang(Graduate Student, Department of Animal Sciences, Chungbuk National University, Cheongju, 28644, Korea)
• Dong Cheol Song(Graduate Student, Department of Animal Sciences, Chungbuk National University, Cheongju, 28644, Korea)
• Jae Woo An(Graduate Student, Department of Animal Sciences, Chungbuk National University, Cheongju, 28644, Korea)
• Se Hyun Park(Graduate Student, Department of Animal Sciences, Chungbuk National University, Cheongju, 28644, Korea)
• Hyuck Kim(Graduate Student, Department of Animal Sciences, Chungbuk National University, Cheongju, 28644, Korea)
• Jin Ho Cho(Professor, Department of Animal Sciences, Chungbuk National University, Cheongju, 28644, Korea) Corresponding author