The present study investigated the effect of enzyme inclusion on silage quality using meta-analysis tool. A total of 16 research papers reporting the effect of enzyme application on silage quality were employed in the meta-analysis of this study. Mixed model for integrating quantitative results from multiple studies was used first to calculate the predicted error of each study. Individual error from the estimated model was the applied into standard deviation of each study to calculate the mean difference. Finally, summary effect was determined using standard mean difference (SMD) and inversed variance weighting. Mixed model analysis and SMD analysis showed the same effect patterns in all analysis items. Enzyme inclusion in silage significantly (p < 0.05) altered all silage quality characteristics investigated compared to control when enzyme was not included. Our results showed that enzyme treatment increased dry matter content, preserved crude protein effectively, and elevated water soluble carbohydrate content. However, the pH value, acetic acid, propionic acid, neutral detergent fiber, and acid detergent fiber contents in silage with enzyme inclusion were lower than those of the control.

Ⅰ. INTRODUCTION
 Ⅱ. MATERIALS AND METHODS
  1. Data set
  2. Data analysis
 Ⅲ. RESULTS
  1. Data set
  2. Mixed model evaluation
  3. Summary effect
  4. Publication bias
 Ⅳ. DISCUSSION
  1. Model evaluation, heterogeneity and publicationbias
  2. Effect of enzyme inclusion on silage characteristics
 Ⅴ. CONCLUSION
 Ⅵ. ACKNOWLEDGEMENTS
 Ⅶ. REFERENCES

• Sangbuem Cho(Institute of CALSNBT, Seoul, 08506, Korea) Corresponding author
• Sanghoon Yeom(Institute of CALSNBT, Seoul, 08506, Korea)
• Namhyung Kim(Institute of CALSNBT, Seoul, 08506, Korea)
• Dohyeong Li(DREAMFEED Co Ltd, Youngin, 16817, Korea)
• Jaehoon Lee(Department of Animal Science, Kyungpook National University, Sangju 37224, Korea)
• Sang Moo Lee(Department of Animal Science, Kyungpook National University, Sangju 37224, Korea)
• Ji Hong Lee(Department of Animal Science, Gyeongbuk Provincial College, Yecheon 36830, Korea)
• Su-Jin Shin(Department of Animal Science, Chonbuk National University, Jeonju 54896, Korea)
• Mi-So Kim(Department of Animal Science, Chonbuk National University, Jeonju 54896, Korea)
• Nag-Jin Choi(Department of Animal Science, Chonbuk National University, Jeonju 54896, Korea)