USE OF BOVINE SOMATOTROPIN TO HASTEN PUBERTY ACHIEVEMENT OF BOS INDICUS-INFLUENCED BEEF HEIFERS By MATHEUS BETELLI PICCOLO A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2018 © 2018 Matheus Betelli Piccolo To my loving parents, Teresa e José Alberto ACKNOWLEDGMENTS First, I would like to thank God, without him nothing of this would be possible and to my parents, Teresa Cristina Betelli Piccolo and José Alberto Piccolo; all my grandparents, which I am blessed to have present in my life. To my brothers, Thomas e Rafael Betelli Piccolo; for all the support, guidance and encouragement, and love given to me throughout my life. Each one of them has a special meaning to this accomplishment in my life, and all are majorly responsible for me being able to fulfill my education goals. My family and in special, my parents, provided all the opportunities for me to become the person I am today. I would like to thank all my committee members, Dr. Philipe Moriel, Dr. John Arthington and Dr. João Vendramini for the patience, friendship and trust beyond measure that they putted on me. Dr. Philipe Moriel deserves especial thanks, for guiding me since 2015 and giving me so many opportunities and for pushing me to become a better student and person, despite of all the headache that I gave to him. His teachings went beyond the academic and therefore I will always have a great respect for him. Appreciation is also extended to Dr. Reinaldo Cooke, who always made himself available to help me and in several occasions give me valuable advices, and for that I am extremely thankful. I would like to thank Dr. Corwin Nelson for the help during the laboratory analysis of my experiment, and Dr. Geoffrey Dahl for the help and patience with me when I needed. I would like to thank my former advisor Dr. José Luiz Moraes Vasconcelos for introducing me to science, for the career opportunities he provided, for his many teachings and even for his annoying way of doing things but in special for his support. Along with Dr. Vasconcelos, I am extremely thankful for having made part of the study group that he advises; 4 Conapec was the best part of my undergraduate carrier in terms of developing skills, acquiring experience in the field and making many friends and important contacts in the agribusiness. I am also deeply grateful to all the staff at the Range Cattle Research and Education Center. In particular, Mrs. Julie Warren, for her help on field and on the lab and also for being a friend; Mrs. Andrea Dunlap for always being helpful and available when I needed the most; Mr. Austin Bateman, Mr. Clay Newman, Mr. Tom Fussell, and Mr. Ryann Nevling for all their help when working with cattle and friendship. Special thanks for my friends Achilles Vieira Neto, Umberto Pardelli and Miguel Miranda for being always present when needed, and always pushing me to get my head up. Great thanks to everybody of my fraternity: “Karca 1 Gole”, for all the friendship and support during the last 8 years of my life, nothing would be the same without them. I would like to thank Juliana Ranches for all her help, teaching me lab procedures or helping me in the field and support as a friend, becoming her friend was a great surprise that living in Ona provided to me. Also, I would like to thank all the friends that I made in Ona, João Sanchez, José Dias, Pedro Mamede, Hiran Marcelo, Gleise Silva, Marcelo Vedovatto, Aline Moraes, Kely Koriaken, JK, Caio, YanYan, Amanda, Nayara, Jhone, Rhaiza, and others for all the help and friendship during my period here. Last but not least, to my friends in Gainesville, Luara, Felipe, Hendyel, Paula, Roney, André, Amanda, Fernanda, Jason, Camilo and everybody else that as them made Gainesville a little happier even if just for a moment. 5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................4 LIST OF TABLES ...........................................................................................................................8 LIST OF FIGURES .........................................................................................................................9 LIST OF ABBREVIATIONS ........................................................................................................10 ABSTRACT ...................................................................................................................................12 CHAPTER 1 INTRODUCTION ..................................................................................................................14 2 LITERATURE REVIEW .......................................................................................................16 Metabolic Imprinting ..............................................................................................................16 Potential Mechanisms .............................................................................................................16 Organ structure ................................................................................................................16 Cell number .....................................................................................................................17 Clonal selection ...............................................................................................................17 Epigenetics ......................................................................................................................18 Evidences of Metabolic Imprinting in Beef Heifers ...............................................................18 Somatotropic Axis ..................................................................................................................19 Nutrition vs. Somatotropic Axis vs. Puberty Achievement ....................................................24 Exogenous Bovine Somatotropin – Structure, Synthesis and Secretion ................................26 Strategies to Explore the Effects of Metabolic Imprinting in Beef Cattle Production Systems ...............................................................................................................................31 3 PRE-WEANING INJECTIONS OF BOVINE ST ENHANCED REPRODUCTIVE PERFORMANCE OF BOS INDICUS-INFLUENCED REPLACEMENT BEEF HEIFERS. ...............................................................................................................................32 Introduction .............................................................................................................................32 Material and Methods .............................................................................................................33 Animals and Diets ...........................................................................................................33 Sample and data collection ..............................................................................................35 Laboratory analyses .........................................................................................................37 Statistical analyses ...........................................................................................................39 Results.....................................................................................................................................40 Discussion ...............................................................................................................................42 Conclusion ..............................................................................................................................48 LIST OF REFERENCES ...............................................................................................................60 6 BIOGRAPHICAL SKETCH .........................................................................................................75 7 LIST OF TABLES Table page 3-1 Average nutritional composition of concentrate offered during the post-weaning phase (d 127 to 346) to beef heifers ...................................................................................50 3-2 Primer sequences and accession number for all gene transcripts analyzed by quantitative real-time PCR1. ..............................................................................................51 3-3 Pre- and post-weaning growth performance of beef heifers ..............................................52 3-4 Pre- and post-weaning plasma IGF-1 concentrations of beef heifers ................................53 3-5 Liver mRNA expression (fold increase1; yr 3 only) of beef heifers .................................54 3-6 Reproductive performance of beef heifers .........................................................................55 8 LIST OF FIGURES Figure page 3-1 Pre- (A) and post-weaning (B) body weight of beef heifers that received a s.c. injection of saline solution (SAL; 5 mL; 0.9% NaCl) or 250 mg of sometribove zinc (BST; Posilac, Elanco) on d 0, 14, and 28 (n = 15 heifers/treatment annually; 3 yr).. ......56 3-2 Percentage of pubertal beef heifers during the post-weaning phase. .................................58 3-3 Calving distribution (% of heifers that calved) of beef heifers ..........................................59 9 LIST OF ABBREVIATIONS ADG Average daily gain AI Artificial insemination AKT Protein kinase B or PKB bST Bovine somatotropin BW Body