ABSTRACT
BIOGRAPHICAL NOTES
Detection of estrus in dairy cows is challenging, partly because of poor
behavioural expression. Automated activity monitors allow quantification of estrus
expression based on restlessness. The main goals of this thesis were to use automated
measurements and visual observation of behaviour to increase understanding of estrus
characteristics, variation among animals, risk factors for poor expression, and its
association with fertility. In the first study, the behaviour of heifers was video-recorded
and activity peaks were identified from accelerometer data; estrus was validated by
ovarian ultrasonography. Chin rest, sniff, back mount, crossover, and follow had the
largest increase in frequency during estrus. Estrus relative increase in activity (290 
160%) and duration (14  4 h) varied greatly and were affected by estrus order, season
and time of the day. The second study investigated how estrus affected automated
measurements of lying and standing behaviour, a less explored aspect of estrus. At
estrus, bout frequency was lower, daily standing time was greater, and heifers stood
uninterruptedly for twice longer than at baseline. Relative changes in standing
behaviour at estrus were smaller for estrus starting between 1200 h and 0300 h. The
third experiment investigated the agreement between estrus characteristics in heifers
fitted with two accelerometers. Both systems were precise (PPV = 84.7% [Heatime]
and 98.7% [IceTag]) and provided similar characterization and timing. Plasma estradiol
was not correlated with follicle diameter, duration, intensity, or presence of estrus signs.
Finally, estrus lying behaviour of lactating cows and its associations with fertility were
studied. Daily lying time and bout frequency were reduced at estrus (65  21% and 65
 24% of baseline). Ovulation and pregnancy (d 32 after AI) were 4.9 and 1.6 times
more likely if estrus lying time was < 75% of baseline. Collectively, results suggest
potential application of lying behaviour towards fertility prediction. We have also
highlighted features such as variability, risk factors and basal activity that can contribute
to assessment of methods and practices for increased expression. Additional future
directions include investigation of physiological bases of estrus-fertility association and
real-time applications of characterization data.
Place of Birth:
Belo Horizonte, Brazil
Academic Studies:
B. Vet. Med. Universidade Federal de Minas Gerais, 2010
M.Sc. Universidade Federal de Minas Gerais, 2012
GRADUATE STUDIES
Field of Study:
Courses
AANB504
APBI504
Reproduction of Dairy Cows
Research Methodology in Agricultural
Sciences
Research Methodology in Applied
Animal Biology
Instructors
Dr. D. Weary
Dr. B. Franks
AWARDS
Science Without Borders Scholarship (Brasília, Brazil; 48 months of funding - tuition
and stipend - for PhD degree abroad)
Ursula Knight Abbott Travel Scholarship in Agricultural Sciences (2016)
James A. Shelford Memorial Award (2015)
2013 People’s Choice Oral Presentation Award - First Annual Faculty of Land and
Food Systems Graduate Student Conference (2013).
John and Mary Young Award (2013 & 2014)
SELECTED PUBLICATIONS
Diagnosis of uterine and vaginal disorders by different methodologies is affected
by concentration of estradiol in plasma from lactating Holstein cows. B.F. Silper,
A.M.L. Madureira, T.A. Burnett, A.C.C. Fernandes, F.M. Abreu, D.M. Veira, J.L.M.
Vasconcelos, R.L.A. Cerri. Journal of Dairy Science. 2016. 99:4795.
Automated and visual measurements of estrous behavior and their sources of
variation in Holstein heifers. I: Walking activity and behavior frequency. B.F.
Silper, I. Robles, A.M.L. Madureira, T.A. Burnett, M.M. Reis, A.M. de Passillé, J.
Rushen, R.L.A. Cerri. 2015. Theriogenology. 84:312-320.
Automated and visual measurements of estrous behavior and their sources of
variation in Holstein heifers. II: Standing and lying patterns. Bruna F. Silper, Liam
Polsky, John Luu, Tracy A. Burnett, Jeffrey Rushen, Anne Marie de Passillé, Ronaldo
L.A. Cerri. 2015. Theriogenology. 84:333-341.
Short communication: Comparison of estrus characteristics in Holstein heifers
by 2 activity monitoring systems. B.F. Silper, A.M.L. Madureira, M. Kaur, T.A.
Burnett, R.L.A. Cerri. 2015. Journal of Dairy Science. 98:3158-3165.
SELECTED PRESENTATIONS
Using activity monitors for estrus detection and reproductive management of
dairy cattle. Silper, B.F. April 2016. Invited Speaker, 6o Simpósio Internacional Revista
Leite Integral (Curitiba, Brazil).
Effects of modification of proestrus length and duration of progesterone
exposure on automated measurements of estrous expression in lactating
Holstein cows. Silper, B.F., T.A. Burnett, P.F.M.P. Souto, M.S. Baylao, A.P.O. Santos,
and R.L.A. Cerri. 2016. Poster presented in: ADSA-ASAS Joint Annual Meeting, Salt
Lake City, UT. *Selected for presentation at the 2016 Dairy Cattle Reproduction Council
Annual Meeting.
Association between the circulating progesterone during the luteal phase in
dairy cattle and the estrus activity detected by automated activity monitoring
systems. Denis-Robichaud, J., S. LeBlanc, A. Jones-Bitton, B.F. Silper, and R.L.A.
Cerri. 2016. Poster presented in: 18th International Congress on Animal Reproduction,
Tours, France
Estrus lying behavior of Holstein cows: Risk factors for estrus expression,
ovulation risk and pregnancy per AI. Silper, B.F., A.M.L. Madureira, L.B. Polsky, E.L.
Drago Filho, J.L.M. Vasconcelos, and R.L.A. Cerri. 2015. Poster presented in: ADSAASAS Joint Annual Meeting, Orlando, FL
Comparison of estrus parameters in nulliparous heifers by two automated
activity monitoring systems. Silper, B.F., A.M.L Madureira, T.A. Burnett, M. Kaur,
E.L. Drago Filho, J. Rushen, A.M. de Passille, and R.L.A. Cerri. 2014. Poster presented
in: ADSA-ASAS Joint Annual Meeting, Kansas City, MI. *Selected for presentation at
the 2014 Dairy Cattle Reproduction Council Annual Meeting.
Resting pattern of nulliparous dairy cows changes with estrus. Silper, B. F., L.B.
Polsky, J. Luu, J. Rushen, A.M. de Passille, and R.L A. Cerri. 2014. Poster presented
in: Proceedings of the 48th Congress of the International Society for Applied Ethology,
Vitoria-Gasteiz, Spain
PROGRAMME
The Final Oral Examination
For the Degree of
DOCTOR OF PHILOSOPHY
(Animal Science)
BRUNA FIGUEIREDO SILPER
B. Vet. Med. Universidade Federal de Minas Gerais, 2010
M.Sc. Universidade Federal de Minas Gerais, 2012
Wednesday, March 22, 2017, 9:00 am
Room 200, Graduate Student Centre
Latecomers will not be admitted
“Characteristics of Estrous Behaviour in Heifers and Lactating Cows
and its Associations with Fertility”
EXAMINING COMMITTEE
Estrus behavior in young Holstein heifers. Silper, B.F., M.M. Reis, A.M.L.
Madureira, T.A. Burnett, A.M. de Passillé, J. Rushen, and R.L.A. Cerri. 2013. Poster
presented in: ADSA-ASAS Joint Annual Meeting, Indianapolis, IN
Chair:
Dr. Mark MacLachlan (Chemistry)
Relationships between pre and post weaning growth on estrus behavior and
reproductive parameters of Holstein heifers. Silper, B.F., A.M.L Madureira, T.A.
Burnett, A.M. De Passillé, J. Rushen, and R.L.A. Cerri. 2013. Oral presentation in:
ADSA-ASAS Joint Annual Meeting, Indianapolis, IN
Supervisory Committee:
Dr. Ronaldo Cerri, Research Supervisor (Animal Science)
Dr. Daniel Weary (Animal Science)
SUPERVISORY COMMITTEE
Dr. Ronaldo Cerri
Dr. Daniel Weary
Dr. Zhaoming Xu
University Examiners:
Dr. Jean-Sébastien Blouin (Kinesiology)
Dr. Colin Brauner (Zoology)
External Examiner:
Dr. John Kastelic
Department of Production Animal Health
University of Calgary
Calgary, Alberta