Table Of ContentFORAGE AND ANIMAL RESPONSES IN PASTURE-BASED DAIRY
X PRODUCTION SYSTEMS FOR LACTATING COWS
.'
BY
BISOONDAT MACOON
A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
UNIVERSITY OF FLORIDA
1999
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', To my wife, Yonette, '%
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for her love, patience, endless understanding,
and moral support
To my sons, Ron and Russ,
for providing unconditional love and
inspiration and giving final meaning to my
life
To my mother, Agnes, ' : ' ,- . * ". • i'«'.*/' .-•""
'''' ' '..<"' '--.
for her love and for instilling motivation for
' learning " -* '>' v
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And to all those people, ^
who stretched out a helping hand when I
stumbled and fell as I traveled life's path to
where I am today -?
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ACKNOWLEDGMENTS
The author wishes to express his sincere appreciation and deep gratitude to Dr.
Lynn E. Sollenberger, chairman ofthe supervisory committee, for his constant support,
outstanding guidance, and extraordinary patience prior to and throughout the doctoral
program, for being an excellent mentor, and forhis considerable contributions to the
dissertation research andpreparation ofthis manuscript. Much appreciation is extended to
Dr. Charles R. Staples, co-chair ofthe supervisory committee, for his diligent guidance
and exceptional contribution to the dissertation research and also the preparation ofthis
manuscript. Appreciation and sincere gratitude is extended to Dr. John E. Moore for his
exceptional teaching, outstanding guidance, and for being a significant mentorthroughout
the author's graduate career. Appreciation and sincere gratitude is further extended to Dr.
Kenneth M. Portier, forhis outstanding guidance with statistical matters and for serving
onthe supervisory committee and reviewing this manuscript. Special appreciation and
sincere gratitude is also extended to Dr. Carrol G. Chambliss for his excellent guidance,
encouragement, and support throughout the doctoral program and for serving on the
supervisory committee and reviewing this manuscript. •
Special appreciation is extended to University-wide faculty members who always
encouraged and supported the author's professional development. Prominent among
these are Drs. Kenneth H. Quesenberry, David S. Wofford, Kenneth L. Buhr, the late
J'v
iii
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^ > < Edwin C. French III, Clarence B. Ammerman, and Peter E. Hildebrand. Sincere gratitude
is extended to Dr. Jerry Bennett, Agronomy Department Chairman, and the administrative
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staffofthe department fortheir help and support during the author's graduate program.
The award ofthe teaching assistantship from the Agronomy Department, which made
financial support forthis doctoral program possible, is gratefully acknowledged. The
National Agricultural Research Institute ofGuyana is gratefully recognized for its role in
facilitating the author's graduate studies.
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Many people contributed to the successes ofthe author's program ofStudy and
their assistance is gratefully acknowledged. Special thanks to Richard Fethiere andNancy
Carter ofthe Forage Evaluation Support Laboratory fortheir friendship and help. The
long hours spent inthe field with Sid Jones and Dwight Thomas ofthe Forage Evaluation
Field Laboratory were vital to the successful completion ofthe dissertation research and
the author will always be grateful for their contribution. The help and support ofJohn
Funk, Pam Miles, and Nancy Wilkinson ofthe Animal Science Department and Jocelyn
Jennings ofthe Dairy Science Department are gratefully acknowledged. The support of
the staffofthe Dairy Research Unit, including Farm Manager, Mr. Dale Hissem, Ms.
Mary Russell, and Mr. James Lindsey, and the many people who worked specifically with
the grazing study, including Ryan Richards, Shane Brooks, and Darmy Tomlinson, is
gratefully recognized. The help and friendship ofDr. Masaaki Hanada, a visiting scientist
from Japan, is gratefully acknowledged. The authorwill always be grateful forthe
cooperative research responsibilities and special friendship shared with John Fike,
graduate student in the Dairy and Poultry Sciences Department.
'" iv
The authoris grateful to former and current fellow students, Steve Welch, Renato
Fontaneli, and YoanaNewman, who worked relentlessly to help onthe author's research
project, and also Elide Valencia, Marjatta Eilitta, Nadia Douglas, Brett Wade, Stuart
Rymph, Alberta Chiteka, Liana Jank, Marcos Freire, Jean Thomas, CelinaJohnson, and
many others for their friendship and help during his graduate school life and wishes them
the best in their careers. Gratitude is also extended to visiting scientists, Ricardo Reis and
Dianelis Urbano, forthe sharing ofideas and their friendship. - '-"'' .,
Special gratitude is extended to Dr. Leslie A. Simpson for his friendship and
encouragement in pursuing the opportunity for doctoral studies and to RichardN.
Cumberbatch and Godfrey A. Nurse forbeing friends and mentors. The efforts by Dr.
Ronald W. Rice to help the Macoon family reachthe United States ofAmerica and his
special friendship, moral support, and help will forever be remembered and is recognized
with deepest gratitude. Finally, the author wishes to express his most sincere appreciation,
love, and gratitude to his wife, Yonette, forher love, endless understanding, and support
throughout their life together and more so during the doctoral program, to his sons, Ron
and Russ, for their unconditional love and for being the sources ofhis inspiration, and to
his mother, Agnes, for her love and for instilling the desire to seek knowledge.
TABLE OF CONTENTS
page
ACKNOWLEDGMENTS
iii
LIST OF TABLES ^ ':. ix
LIST OF FIGURES xvii
ABSTRACT
xviii
CHAPTERS
INTRODUCTION
1 1
2 LITERATURE REVIEW 8
Pasture-based Milk Production Systems 8
Economic Aspects ofPasture-based Milk Production 9
Animal Responses to Management Variables 12
Forage Responses on Grazed-pasture Dairy Systems 16
Plant-animal Interactions 21
Factors Influencing Intake ofGrazing Animals 22
Role ofGrazing Time in the Plant-animal Interface 34
Coat Color Relationships with Grazing Behavior and
Animal Performance 39
Estimation ofIntake on Pasture 42
GRAZING MANAGEMENT EFFECTS ON FORAGE PRODUCTION
AND ANIMAL PERFORMANCE OF LACTATING DAIRY
COWS ON SUBTROPICAL WINTER PASTURES
53
Introduction 53
Materials and Methods 57
Pasture Variables 60
Plant-animal Interface Variables 62
Animal Response Variables 65
VI
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Statistical Analysis 66
Results and Discussion 69
Herbage Mass 69
Herbage Disappearance 74
Herbage Allowance 78
Forage Nutritive Value 81
Organic Matter Intake 86
Milk Production per Cow 96
Milk Production per Hectare 101
4% Fat Corrected Milk Production per Cow 103
4% Fat Corrected Milk Production per Hectare 104
Milk Composition 105
Animal Body Weight Changes 113
Body Condition Score Changes 115
Blood Glucose Concentration 116
Summary and Conclusions 117
4 GRAZING MANAGEMENT, COAT COLOR, AND SEASON
EFFECTS ON GRAZING BEHAVIOR AND PERFORMANCE
OF LACTATING DAIRY COWS
122
Introduction 122
Materials and Methods 125
Statistical Analysis 130
Results and Discussion 133
Responses to Grazing Management 133
Coat Color Effects on Grazing Behavior 168
Coat Color Effects on Animal Responses 175
Summary and Conclusions 181
5 COMPARISON OF THREE TECHNIQUES FOR ESTIMATING
FORAGE INTAKE OF LACTATING DAIRY COWS
ON PASTURE
187
Introduction 187
Materials and Methods 191
Statistical Analysis 194
Results and Discussion 196
Forage DMI Data for 1996 196
Forage DMI Data for 1997 206
Summary and Conclusions 214
6 GENERAL DISCUSSION AND SUMMARY 219
vu
APPENDIX
TABLES OF CLIMATOLOGICAL DATA, VARIABLE LISTS,
RAW DATA AND PROBABILITY VALUES ASSOCIATED
WITH RESPONSES REPORTED IN THE DISSERTATION 232
REFERENCES 291
BIOGRAPHICAL SKETCH 305
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LIST OF TABLES
Table page
3 Period by stocking rate (SR) interaction effect on pregraze herbage mass
.
during winter 1996 70
3.2 Period by forage system (FS) by stocking rate (SR) interaction effect on
pregraze herbage mass during winter 1997 71
3.3 Forage system (FS) by stocking rate (SR) by concentrate supplement (CS)
interaction effect on pregraze herbage mass during winter 1997 74
3.4 Period by forage system (FS) by stocking rate (SR) interaction effect on
herbagedisappearanceduring winter 1997 75
3.5 Period by stocking rate (SR) interaction effect on herbage allowance
during winter 1996 78
3.6 Forage system (FS) by stocking rate (SR) by concentrate supplement (CS)
interaction effect on herbage allowance during winter 1997 79
3.7 Period by forage system interaction effect on herbage allowance during
winter 1997 80
3.8 Period by stocking rate (SR) interaction effect on pasture in vitro digestible
organic matter concentration during winter 1996 82
3.9 Period by stocking rate (SR) interaction effect onpasture neutral detergent
fiber concentration during winter 1996 85
3.10 Period by stocking rate (SR) interaction effect on forage organic matter
intake (OMI) and total OMI during the 1996 winter grazing season 87
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3.11 Period by stocking rate (SR) interaction effect on average daily forage
organic matter intake (OMI) and total OMI relative to cow body
weight, during the 1996 winter grazing season 88
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3.12 Period by concentrate supplement (CS) interaction effect on forage
organic matter intake (OMI) and total OMI during the 1996 winter
grazing season 89
3.13 Period by concentrate supplement (CS) interaction effect on average daily
forage organic matter intake (OMI) and total OMI, relative to cow
body weight, during the 1996 winter grazing season 90
3.14 Period by forage system interaction effect on forage organic matter intake
(OMI) and total OMI during the 1997 winter grazing season 91
3.15 Period effect on forage organic matter intake (OMI) and period by forage
system interaction effect total OMI, both relative to cow body weight,
during the 1997 winter grazing season 92
3.16 Forage system by stocking rate (SR) interaction trend on forage organic
matter intake (OMI) and total OMI during the 1997 winter grazing
season 94
3.17 Period by stocking rate (SR) interaction effect on milk production per
cow during winter 1997 97
3.18 Period by stocking rate (SR) interaction effect on milk production per
hectare during winter 1997 102
3.19 Period by stocking rate (SR) interaction effect on 4% fat corrected milk
productionper cow during winter 1997 104
3.20 Period by stocking rate (SR) interaction effect on 4% fat corrected milk
production per hectare during winter 1997 105
3.21 Period by stocking rate (SR) interaction effect on milk fat concentration
during winter 1997 106
3.22 Period by stocking rate (SR) interaction effect on milk crude protein
concentration during winter 1996 108
3.23 Period by forage system interaction effect on milk urea nitrogen
concentration during winter 1997 110
3.24 Forage system (FS) by stocking rate (SR) by concentrate supplement (CS)
interaction effect on milk urea nitrogen concentration during winter
1997 Ill
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