DIFFERENTIAL GESTATION FEEDING LEVELS ON SOW AND LITTER PERFORMANCE, NUTRIENT DIGESTIBILITY AND ENERGY HOMEOSTASIS A DISSERTATION SUBMITTED TO THE FACULTY OF THE GRADUATE SCHOOL OF THE UNIVERSITY OF MINNESOTA BY PING REN IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY ADVISED BY SAMUEL K. BAIDOO November 2016 © Ping Ren, 2016 Acknowledgements First and foremost, I want to praise the Lord and give all the thanksgivings to Him for His wonderful salvation, unconditional love and eternal hope He has revealed to me. Thanks God for preparing the people and circumstances around me to help me to experience His presence and complete my research smoothly. I would like to express my sincere and deep gratitude to my major supervisor Dr. Samuel Baidoo. Thank you for providing me this opportunity to study in U.S., and thank you for your guidance and encouragement during the past four years, and thank you for giving me so much freedom and allowing me to put my idea into practice during my research. I would also like to extend my thanks to my examining committee members, Drs. Daniel Gallaher, Milena Saqui-Salces, Chi Chen and Hansoo Joo. Thanks for Drs. Daniel Gallher, Milena Saqui-Salces and Chi Chen for opening your lab to allow me to do the lab work and thanks for your advice on the sample analysis. Special thanks to Dr. Hansoo Joo for your willingness to serve on my committee, although you have already retired. I would like to express my thanks to Dr. Crystal Levesque for driving from South Dakota State University to teach us to conduct cephalic vein catheterization. It would be impossible to finish this project without your dedication and support. I am also grateful to Dr. Shiquan Cui for your help on the proximate analysis. Your help really save me a lot of time so that I could focus on other lab work and thesis writing. I would like to thank the staff working in the sow unit at Southern Research and Outreach Center in Waseca, MN (Richard Goetz, Gary Dobberstein, Brain Lewer and Perry Rieck) for your friendship and assistance during the animal experiments. The experiments in this dissertation are truly a collaborative effort which would not be possible without the assistance and support from so many dedicated people in the swine nutrition group. I want to express my deep thanksgiving to Dr. Xiaojian Yang. Thanks for all your help during my PhD program, not only in experiment execution, but also in data analysis, manuscript preparation and thesis writing. Thanks for your advice and guidance during these years. You are invaluable in our group. I would like to thank Dr. Jinsoo Kim for your friendship and so much assistance you gave me during my animal experiments. I am also grateful to Dr. Deepa Menon, Devi Pangeni, Hayford Manu, Abel Tekeste and Blair Tostenson for your friendship and support during these years. I would like to thank Dr. Andrea Hanson for your friendship and encouragement during my PhD program. Special thanks to Dr. Pedro Urriola for your willingness to offer help when I needed. i I would like to thank U.S. Department of Agriculture-Agriculture and Food Research Initiative for their financial support on the projects in this dissertation. It would not be possible to finish these studies without their support. Finally, I want to express my great gratitude to my mother and father. Thank you for your constant love, support, encouragement and all of the sacrifices that you have made on my behalf during these four years. Without your support, I could not have completed my doctorate degree smoothly. ii Table of Contents Acknowledgements .............................................................................................................. i Table of Contents ............................................................................................................... iii List of Tables ..................................................................................................................... vi List of Figures .................................................................................................................... ix Chapter 1. Literature review ............................................................................................... 1 Introduction ..................................................................................................................... 1 Maternal nutrition on reproductive performance ............................................................ 4 Energy intake during gestation .................................................................................... 5 Energy intake during lactation ................................................................................... 11 Protein intake during gestation .................................................................................. 12 Protein intake during lactation ................................................................................... 17 Interaction between gestation and lactation protein intake ....................................... 17 Feeding level during gestation ................................................................................... 18 Feeding level during lactation ................................................................................... 21 Factors affecting voluntary feed intake during lactation ........................................... 24 Gestation housing systems ............................................................................................ 30 Effects of gestation housing systems on sow performance ....................................... 33 Effects of gestation housing systems on litter performance ...................................... 36 Effects of gestation housing systems on progeny development ................................ 37 Effects of gestation housing systems on sow welfare ............................................... 39 Factors affecting apparent digestibility of energy and nutrients ................................... 42 Age, BW and physiological stage .............................................................................. 42 Genotype .................................................................................................................... 44 Dietary factor ............................................................................................................. 46 Food intake regulation ................................................................................................... 49 iii Gastrointestinal hormones ......................................................................................... 50 Adiposity signals ....................................................................................................... 71 Interaction among long-term adiposity signals and short-term satiation signals ...... 74 Summary ....................................................................................................................... 75 Chapter 2. Effects of different feeding levels during four short periods of gestation and housing systems on sows and litter performance .............................................................. 86 SUMMARY .................................................................................................................. 86 INTRODUCTION ......................................................................................................... 87 MATERIALS AND METHODS .................................................................................. 88 RESULTS...................................................................................................................... 94 DISCUSSION ............................................................................................................. 102 CONCLUSION ........................................................................................................... 109 IMPLICATIONS ......................................................................................................... 109 Chapter 3. Effect of different feeding levels during three short periods of gestation on sow and litter performance over two reproductive cycles .............................................. 129 SUMMARY ................................................................................................................ 129 INTRODUCTION ....................................................................................................... 130 MATERIALS AND METHODS ................................................................................ 131 RESULTS.................................................................................................................... 138 DISCUSSION ............................................................................................................. 142 CONCLUSION ........................................................................................................... 149 Chapter 4. Effects of different feeding levels during three short periods of gestation on gilt and litter performance, nutrient digestibility and plasma hormones related to energy homeostasis in gilts ......................................................................................................... 168 SUMMARY ................................................................................................................ 168 INTRODUCTION ....................................................................................................... 169 MATERIALS AND METHODS ...............................................................................