EFFECT OF ENERGY SOURCE, TIMING OF PROVISION, AND DAYS ON FEED ON FEED EFFICIENCY OF FINISHING BEEF CATTLE A Thesis Submitted to the College of Graduate and Postdoctoral Studies in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in the Department of Animal and Poultry Science University of Saskatchewan Saskatoon, Saskatchewan By Faustin Joy ©Copyright Faustin Joy, December 2019, All rights reserved PERMISSION TO USE STATEMENT In presenting this thesis in partial fulfillment of the requirements for a Postgraduate degree from the University of Saskatchewan, I agree that the Libraries of this University may make it freely available for inspection. I further agree that permission for copying of this thesis in any manner, in whole or in part, for scholarly purposes may be granted by the professor or professors who supervised my thesis work or, in their absence, by the Head of the Department or the Dean of the College in which my thesis work was done. It is understood that any copying or publication or use of this thesis or parts thereof for financial gain shall not be allowed without my written permission. It is also understood that due recognition shall be given to me and to the University of Saskatchewan in any scholarly use which may be made of any material in my thesis. DISCLAIMER This report was exclusively created to meet the thesis requirements for the degree of Doctor of Philosophy at the University of Saskatchewan. Reference in this thesis to any specific commercial products, process, or service by trade name, trademark, manufacturer, or otherwise, does not constitute or imply its endorsement, recommendation, or favoring by the University of Saskatchewan. The views and opinions of the author expressed herein do not state or reflect those of the University of Saskatchewan, and shall not be used for advertising or product endorsement purposes. Requests for permission to copy or to make other uses of materials in this thesis in whole or part should be addressed to: Head of the Department of Animal and Poultry Science 51 Campus Drive University of Saskatchewan Saskatoon, Saskatchewan S7N 5A8 Canada OR Dean College of Graduate and Postdoctoral Studies University of Saskatchewan 116 Thorvaldson Building, 110 Science Place Saskatoon, Saskatchewan S7N 5C9 Canada i ABSTRACT The objective of this research was to evaluate if the decline in gain-to-feed ratio (G:F) during finishing in beef cattle could be due to a reduction in nutrient digestion, short chain fatty acid absorption, or post-absorptive nutrient utilization, and those responses were influenced by the dietary energy source or timing of provision. A high-lipid byproduct pellet (HLP) was used as a partial replacement for barley grain in a high concentrate finishing diet to partially replace starch with lipid as the energy source. Yearling steers were used for performance evaluations and ruminally cannulated Hereford crossbred heifers were used for nutrient metabolism studies. The dry matter (DM), organic matter (OM), crude protein (CP) and neutral detergent fibre (NDF) digestibility of HLP diets were lower than the barley-based control diet (CON). Utilizing a phase- feeding strategy and partially replacing barley grain and canola meal with a high-fibre high-lipid byproduct pellet in the latter part of the finishing period may improve carcass yield grade without affecting average daily gain and G:F. With advancing days on feed, diet DM digestibility (P = 0.02) and insulin resistance (P = 0.04) increase without changes in ruminal pH and plasma metabolite clearance rates. A marginal increase in forage inclusion with the HLP diet increased ADG (P = 0.04). Increasing dietary lipid supply up to 6% of DM using HLP did not affect the digesta flow and rumen fermentation parameters, therefore, increased lipid content is not associated with reduced feed efficiency of the HLP diet. In conclusion, decreasing feed efficiency in the later stages of finishing in beef cattle is most likely due to changes in the post absorptive nutrient metabolism, and these changes are not influenced by the dietary energy source. The small particle size of feed ingredients within the byproduct pellet may be the factor associated with decreased feed efficiency of HLP pellet rather than lipid content. ii ACKNOWLEDGEMENTS I thank Almighty God for all his blessings and giving this opportunity to work with a bunch of wonderful people at the Department of Animal Science, University of Saskatchewan as part of my Doctoral program. I would like to extend my heartfelt gratitude to my supervisor Dr. Greg Penner for all his amazing support, guidance and encouragement throughout my study. I will always cherish his encouragement and support as an invaluable experience in my academic career. I thank my committee members Dr. John McKinnon, Dr. Steve Hendrick, Dr. Luis Burciaga and the graduate committee chair Dr. Fiona Buchanan for their continued assistance with my research project and thesis writing. My sincere appreciation to Dr. Pawel Górka, who patiently devoted his time for numerous discussions regarding this project. A special thanks to Team Rumen, Gillian Gratton, Kasia, Coral, Katie, Dan, Silvia, Keshia, Rodrigo, Larissa, Jordan, Brittney, Liam, Tyler, Brittany, JK, Brittney Schurmann and numerous others for all their dedication and assistance with this research project. I would also like to extend my sincere thanks to the Manager and staff of Livestock Research Building and Beef Cattle Research and Teaching Unit at the University of Saskatchewan for assisting me with the sample collection. I also extend my gratitude to the Alberta Crop Industry Development Fund Ltd. (Lacombe, AB, Canada), Agriculture Development Fund administered through the Ministry of Agriculture in Saskatchewan (Regina, SK, Canada), and the Beef Cattle Research Council of Canada (Calgary, AB, Canada) for funding my projects. I thank Natalia, lab manager for her guidance with the laboratory work of this project. I dedicate this work to my parents, Joy and Annamma, and my dear sisters for their constant motivation and strength in my academic career. I thank my dear wife Divya for always being there to support me in all the ups and downs of life, and instilling in me the confidence to go ahead and succeed in life. I also thank my son Enric for cooperating with my studies and writing and making my world more meaningful and beautiful each day. iii TABLE OF CONTENTS PERMISSION TO USE STATEMENT .......................................................................................... i ABSTRACT .................................................................................................................................... ii LIST OF TABLES ........................................................................................................................ vii LIST OF FIGURES ........................................................................................................................ x LIST OF ABBREVIATIONS ........................................................................................................ xi 1.0 INTRODUCTION .................................................................................................................... 1 2.0 LITERATURE REVIEW ......................................................................................................... 3 2.1 Feeding management in North America ............................................................................... 3 2.2 Feed efficiency in feedlot finishing diets .............................................................................. 5 2.2.1 Patterns of feed efficiency .............................................................................................. 6 2.2.2 Importance of feed efficiency (Sustainability) ............................................................... 9 2.2.3 Physiological factors affecting feed efficiency ............................................................ 13 2.2.4 Strategies to increase feed efficiency ........................................................................... 27 2.3 Alternative diets in feedlot cattle ........................................................................................ 29 2.3.1 Single byproduct substitution- Advantages .................................................................. 30 2.3.2 Disadvantages of byproducts in feedlot diets ............................................................... 30 2.3.3 Blended byproducts ...................................................................................................... 31 2.3.4 Rumen fermentation and feed efficiency with byproduct diets .................................... 32 2.4 Global hypothesis and objectives ........................................................................................ 34 3.0 EVALUATION OF A PHASE-FEEDING STRATEGY UTILIZING A HIGH- LIPID HIGH-FIBRE BYPRODUCT PELLET IN DIETS FOR FEEDLOT STEERS ............... 36 3.1. Introduction ........................................................................................................................ 37 3.2. Materials and methods ....................................................................................................... 38 3.2.1 Study 1 .......................................................................................................................... 38 3.2.2 Study 2 .........................................................................................................................