Circadian characterization of
thyroid hormones, methane and
heat production profiles across
physiological stages in
replacement beef heifers
Yuri Montanholi, Brock Smith, Stephen Miller
Outline
Introduction
Material and methods
Results and discussion
Conclusions
Acknowledgments
Introduction
Feed efficiency
Feed efficiency
Eating experience
Eco-footprint
Competiveness
Measure of feed efficiency
Titus et al 1927
Feed intake =
BW + BWvariation + eggproduction
Measure of feed efficiency
Koch et al 1963
Feed intake = BW + BWvariation
Measure of feed efficiency
Source: Owens et al. 1995.
Feed intake = BW + Bwvariation + Backfat
+ Marbling + Rump_fat + Ribeye
Measure of feed efficiency
Feed intake = BW + Bwvariation + Backfat
+ Marbling + Rump_fat + Ribeye + Age +
Gestation
Variability in feed efficiency
Biological basis feed efficiency
RFI
“Indirect” feed efficiency
Rumen microbiology
Liver metabolism
Digestion physiology
Immunology
HPA axis
Bio-climatology
Cardiac function
Behavior
Theriogenology
CALORIMETRY
Thyroid function
Heat – Indirect calorimetry
Dulong’s apparatus - 1841
“Life is a slow burning process.” (Max Kleiber, 1961)
Heat: micro-calorimetry
Liver metabolic rate
1.2% of body weight
25% of basal energy
Thyroid hormones
T3
&
T4
Hypothesis
There are evidence supporting variation in
feed efficiency in the bovine. These
differences result in metabolic fluctuations,
which can be captured through indirect
calorimetry and thyroid hormone profile.
Objectives
To verify the associations between feed efficiency
with oxygen consumption and CH4 production.
To study the associations between thyroid
hormones with efficiency and metabolic rate.
Material and methods
Experimental design
48 yearling heifers
38 1st third of gestation
Extensive training to “calorimetry”
Over 500 days of feed intake assessment
Biweekly body weight assessment
Monthly assessment for body composition
Known days in gestation and age
Known breed composition
Standing/laying time
36 45 d before due date
Residual feed intake
Feed_intakeobserved
Feed_intakepredicted = Body_weight + Body_weightvariation
+ Back_fat + Marbling + Rump_fat + Rib_eye
+ Age + Days_gestation
RFI = Feed_intakeobserved - Feed_intakepredicted
Heat, CO2 and CH4 measures
Position and activity sensors
Heat, CO2 and CH4 measures
Data collection and handling
Room
Chamber
4
Chamber
1
Chamber
2
Flush
Sample
Chamber
3
Dwelling =
1800/5 sec.
Dataset/ heifer
= 48 (cycles) x
210 sec/cycle
Sample =
360-150 sec.
O2 consumption
CO2 production
CH4 production
STP
Room [ ]
Blood collection and T3 &T4
ELISA tests for T3 & T4 (Siemens®)
Liver oxygen consumption
Liver oxygen consumption
Oxygen probe
Water heater
Chamber
LoggerPro
Liver oxygen consumption
Statistical analysis
n = 18
Categorical analysis: n = 18
Vs.
Repeated measures:
proc mixed;
class ID group hour RFIg;
model Xtrait = group RFIg hour RFIg*hour
Room_Temperature Room_Humidity
Time_Stand Time_Lay
Age Days_gestation
Breed_composition
Body_weight / ddfm=betwithin;
lsmeans RFIg*hour;
lsmeans hour;
repeated hour / type=CS subject=ID;
run;
Liver oxygen consumption: GLM
Results & discussion
Productive performance
Circadian:
* Heat
* CH4
* T4
* T3
Heat production
Vs
10%
Oxygen consumption - liver
61.8%
2.54
1.57
μmol/min/g DM
μmol/min/g DM
P = 0.03
Thyroid: T3
Vs
Thyroid: T4
Vs
CH4 production
Vs
25%
CH4 production
 Freetly & Brown-Brandl 2013 - USMARC
CH4
CH4 production: rumen microbiology
Ruminal fluid DNA analysis:
Methanogen
Fungi
Bacteria
Protozoa
Methanogen
Fungi
CH4 production: rumen microbiology
10.3 vs. 11.4
Hristov et al. 2014, JAS:91:5045-5069
Modelling in the farming system
Conclusions
Conclusions
Improved feed efficiency in beef heifers fed ad libitum
and during late gestation is associated with increased
metabolic rate and methane production.
Thyroid hormones (T3, T4) are increased in cattle with
improved feed efficiency.
Acknowledgments
Acknowledgments
Acknowledgments
Luiz Vicente + Livia Haas + Ricardo Ventura + Linxi Li +
Melissa Lim + Michael Bernardo + Patrick Kelly +
Samantha Medeiros + Lisa Wormsbecher + Sarah Wright +
Padma Mullick + Stephanie Cukier + Amy Earle + Heather
Longhorn + Michael Chouster + Dena Fowler + Kelsey
McDonald + Carly Isenberg + Amy Patrick + Madeleine
Cosentino + Kyle Nazareth + Natasha Janke + Kate
Sweetman + Bethany Storey + Benjamin Potvin + Ananda
Fontoura + Jessy-Marie Hawkes + Adam Gate + Andrea
Faltynek + Ashley Mitton + Kevin Colliver + Emerald
Saldanha + Stephanie Lam + Vanessa Peripolli + Ahmad
Zahraee + Stephanie Bourgon = 7,000 h volunteer work
Acknowledgments
[email protected]