Heat Load Alleviation in Beef Cattle

171 Pages·2015·2.89 MB·English

Heat Load Alleviation in Beef Cattle:
Water Application During Continuous High Temperature Exposure

Louise Amy Tait
BAppSc (Hons 1) (Animal Science)

A thesis submitted for the degree of Doctor of Philosophy at
The University of Queensland in 2015
School of Agriculture and Food Sciences
Abstract

The live export industry is an integral part of the Australian cattle industry and makes a significant
contribution to the Australian economy. Heat stroke has been a major cause of cattle death on long
haul sea voyages and has the potential to threaten the viability and sustainability of cattle exports.
To mitigate high heat loads on these voyages, it is necessary to implement cooling strategies to
lower the temperature of the microclimate surrounding the cattle. The main cooling method used on
live export voyages is high pressure hosing but no research has been undertaken to evaluate the
efficacy of this or other water application methods. The major focus of this thesis was therefore, to
explore heat load mitigation of confined beef cattle. The initial hypothesis was that the application
of water onto cattle exposed to a continuous high heat load will reduce the severity of heat stress.
As, different breeds of cattle and composites are exported together, the second hypothesis was that
different cattle breeds and composites respond differently to heat exposure and to water cooling.

Climatic conditions for all three studies were based on the conditions encountered on board a live
export vessel travelling from southern Australia to the Middle East (during the northern hemisphere
summer). The first study obtained data on changes in the microclimate and responses of Bos taurus
cattle (Angus) when water was applied via a hose to cattle maintained in single pens under
continuous hot conditions. The results showed that the water application had a positive impact on
cattle comfort (respiratory rate reduced by 50 - 80 bpm; rectal temperature reduced within an hour
after wetting of cattle). The dry-bulb temperature was also reduced following longer duration water
applications. The impact of water application on physiological parameters, such as rate of
respiration and rectal temperature, was a function of water volume applied and ambient conditions.
For all steers mean daily rectal temperatures and respiratory rates were lower (P < 0.01) during
thermoneutral conditions than during the 11 days of hot conditions.

Four water application methods (hosing, overhead sprinklers, leg sprinklers and misters) were
evaluated in the second experiment with the same Bos taurus breed. Volume and frequency of water
application was assessed with the cattle were housed in groups (n = 9) on sawdust bedding. Of the
four methods evaluated, hosing was the most effective in mitigating the heat load on the cattle. The
leg wetting and misting treatments had little to no effect. While not as effective as hosing, overhead
sprinklers did afford heat relief and may have advantages for cooling large numbers of cattle at the
same time. Bedding had to be removed after it became wet due to increased concentrations of
atmospheric ammonia that posed a risk to cattle and human health.

I
As live export ships carry both Bos taurus and Bos indicus cattle, the third experiment investigated
the effects of high heat load conditions on three breeds of cattle and the effect of the three water
application treatments. Duration of exposure to high heat load conditions caused a decrease in the
ability of the Angus cattle to cope. Respiration rates and rectal temperatures of the Angus were
greater (P < 0.05) than the Brahman and Brangus cattle, with the Brahmans having the greatest heat
tolerance. The most effective method for lowering heat load (in terms of rectal temperature) was
hosing, followed by overhead sprinkler and misting. It was found that breed differences in body
surface temperature, in conjunction with respiration rate, may be a good predictor of heat stress

The present studies have highlighted the complexities of investigating beef cattle exposed to
continuous high heat loads and have demonstrated the diversity of data required to assess heat stress
mitigation strategies. Only when comprehensive data is available, following a sustained research
effort, will it be possible to improve the wellbeing of intensively maintained beef cattle, whether in
feedlots or on the high seas.

II
Declaration by author
This thesis is composed of my original work, and contains no material previously published or
written by another person except where due reference has been made in the text. I have clearly
stated the contribution by others to jointly-authored works that I have included in my thesis.

I have clearly stated the contribution of others to my thesis as a whole, including statistical
assistance, survey design, data analysis, significant technical procedures, professional editorial
advice, and any other original research work used or reported in my thesis. The content of my thesis
is the result of work I have carried out since the commencement of my research higher degree
candidature and does not include a substantial part of work that has been submitted to qualify for
the award of any other degree or diploma in any university or other tertiary institution. I have
clearly stated which parts of my thesis, if any, have been submitted to qualify for another award.

I acknowledge that an electronic copy of my thesis must be lodged with the University Library and,
subject to the policy and procedures of The University of Queensland, the thesis be made available
for research and study in accordance with the Copyright Act 1968 unless a period of embargo has
been approved by the Dean of the Graduate School.

I acknowledge that copyright of all material contained in my thesis resides with the copyright
holder(s) of that material. Where appropriate I have obtained copyright permission from the
copyright holder to reproduce material in this thesis.

III
Publications during candidature

Gaughan, J.B., Tait, L.A., Mader, T.L. and Sakaguchi, Y. (2004). Changes in respiration rate
pattern of cattle exposed to prolonged heat. International Society of Animal Biometeorology,
Vancouver, Canada, August 2004.

Gaughan, J.B., Tait, L.A., Eigenberg, R. and Bryden, W.L. (2004). The effect of shade on
respiration rate and rectal temperatures of Angus heifers. Australian Society of Animal Production,
Melbourne, VIC, July 2004

Gaughan, J.B. and Tait, L.A. (2005). Effectiveness of evaporative cooling of beef cattle housed in
confinement. In. Livestock Environment VII (ASAE, St. Joseph, Michigan), pp105-114. Presented at
the ASAE conference in China, May 2005.

Tait, L.A. and Gaughan, J.B. (2005). The effect of hosing beef cattle exposed to hot conditions in
confined housing. ICB 2005 - 17th International Congress of Biometeorology, Germany, September
05-09, 2005.

Tait, L.A., Gaughan, J.B. and Bryden, W.L. (2006). Using water to alleviate heat load in cattle
housed in confinement. Horizons in Livestock Science. CSIRO - Livestock Research Sciences
Conference, Gold Coast, QLD, October 08-11, 2006

Publications included in this thesis
No publications included.

Contributions by others to the thesis
No contributions by others.

Statement of parts of the thesis submitted to qualify for the award of another degree
None.

IV
Acknowledgements

The School of Animal Studies on the Gatton Campus and all staff involved have been the
supportive backbone for my continuum of studies. Starting as a Certificate student in 1996 and then
completing successive degrees culminating in the completion of a PhD. I am greatly indebted to the
staff over the years that helped expand my mind into the vast knowledge of Agriculture in
Australia, in particular the production of Beef Cattle.

Between the completion of my Diploma and Degree, I was able to spend a year working on a cattle
ranch in the US and again after the completion of the Degree I went back out into the cattle industry
and worked in the “top end” of Australia. These experiences increased my resolve to return to
University and undertake postgraduate study.

The enduring process of completing Honours and also this PhD could not have been possible
without the support and input by my supervisors, Dr John Gaughan and Professor Wayne Bryden.

My mentor in heat stress in cattle is John Gaughan, who has opened my eyes to this field and is now
leading an assembly of scientists in this highly important area, both in Australia and overseas.
Thankyou John for giving me this wonderful opportunity and I look forward to working with you in
the future.

Thank you, also to Wayne Bryden, I am very glad that you could see the potential in me as I could
not have dreamed of getting to this stage without your support and encouragement. No matter how
often I wanted to “throw the towel in”, I always revisited those stories that you told me of past
students that gave it all in and how I don’t need those regrets, thank you.

To complete this PhD, money to allow day to day survival is paramount. This was achieved through
a Mid-Year Scholarship provided by the University of Queensland and for that I am extremely
thankful.

During these trials I could not have managed all of the technical aspects without the assistance of
Bob Engelbright. Thank you Bob for your support and for all of those last minute jobs that I know
you love doing……….You are a man of many talents and I believe that anyone involved in
research with the School of Animal Studies should be very grateful for the time and effort that you
put into each individual trial.
V
Allan Lisle, well what can I say, except thank you so much for guiding me through complexities of
multivariate analysis. All of the number crunching, hair pulling (?), and sleepless nights of yours is
what has made this thesis complete. Although we have spent a lot of the time doing this by
correspondence it was also very exciting to come into your office not only for the brief amount of
time spent on the actual data but for the long conversations about geography, photography,
computers, government and of course the weather. Thankyou Allan, your time spent on the data sets
was priceless.

Thanks to Clint Stephens and Luyanda Themba Khumalo for your commitment to data collection
and expert cattle handling skills, the experimental periods in the climate control rooms ran smoothly
and your diligence even in the hot conditions was astounding.

Last but not least, to my family and friends. Yes it has been a long haul, however, I do promise that
this will be the last………..maybe! I only have my parents to blame, both have a yearning to
continue expanding their knowledge of the world around us and encouraging me to do the same.
Thank you for supporting me financially and lovingly over these years and I am forever in your
debt (until I find a well-paying job of course!). Mum, my clone, your patience and willingness to
help even when you’re not well has provided me with the time to finish; words alone cannot express
how grateful I am. I also thank my siblings, although we are spread out across the globe, your
presence is still felt when sitting at my computer egging me on to finish.

I am grateful that I have been able to share this journey with my closest PhD colleague and friend
Julia. Without you by my side this would have been very difficult if not impossible, I cannot thank
you enough and hold you very dear to my heart.

My deepest appreciation goes to James, who has not only listened to my whinging or tolerated the
bad days that can occur when completing a thesis, but who has also provided me with incredible
support, understanding and encouraged me to excel. Thankyou James for your support and patience
and I look forward to the next adventure we share……which in time became our two beautiful
boys. Hamish and John, welcome to the world of science!

To all of the above without your support and input into my studies this thesis would not be
complete and therefore I dedicate this to all of you.

VI
Keywords
Beef cattle, heat stress, water application, physiological and climatic responses, live export.

Australian and New Zealand Standard Research Classifications (ANZSRC)
ANZSRC code: 070203, Animal Management, 80 %
ANZSRC code: 070207, Humane Animal Treatment, 20 %

Fields of Research (FoR) Classification
FoR code: 0702, Animal Production, 100 %

VII
TABLE OF CONTENTS

ABSTRACT I

DECLARATION BY AUTHOR III

PUBLICATIONS IV

ACKNOWLEDGEMENTS V

CHAPTER 1 INTRODUCTION AND OBJECTIVES OF THE STUDY 1

CHAPTER 2 REVIEW OF LITERATURE 5

CHAPTER 3 THE EFFECT OF WATER APPLICATION ON HEAT
STRESSED CATTLE 43

CHAPTER 4 EVALUATION OF DIFFERENT WATER APPLICATION
METHODS 69

CHAPTER 5 WATER APPLICATION METHODS AND HEAT
STRESS ALLEVIATION OF DIFFERENT BEEF
GENOTYPES 91

CHAPTER 6 GENERAL DISCUSSION AND IMPLICATIONS OF THE
STUDIES 131

BIBLIOGRAPHY 137

APPENDICES 157

VIII
LIST OF ABBREVIATIONS USED IN THESIS

Description Abbreviation Unit
Ammonia NH ppm
3
Breaths per minute Bpm -
Day D -
Degrees Centigrade ºC ºC
Dry bulb temperature T °C
DB
Dry matter intake DMI kg/d
Excessive heat load EHL -
Heat load index HLI -
Hot Conditions HOT -
Hour H -
Kilogram Kg Kg
Minute Min -
Panting score PS -
Parts per million Ppm -
Percentage % %
Rectal temperature RT °C
Relative humidity RH %
Respiratory rate RR bpm
Surface temperature ST °C
Temperature humidity index THI -
Thermoneutral Conditions TNC -
Wet-bulb Temperature T °C
WB

IX