9. Friday Monogastric Sessions dr jeremy cottrell university of melb - betaine reduces heat stress in aust broilers

1. Betaine reduces
heat stress in
Australian broilers
20 September 2018
Shakeri M, Cottrell JJ, Furness JB, Wilkinson S,
Dunshea FR.

2. Heat stress physiology
Cottrell et al. 2015

3. The gastrointestinal tract is a
focal point for heat stress
-50
-40
-30
-20
-10
0
10
20
30
Baseline
37.0
37.5
38.0
38.5
39.0
39.5
40.0
40.5
41.0
41.5
42.0
42.5
43.0
43.5
%Change
Temperature (oC)
Renal
SMA
Adapted from Sils 2001 (rats) Hall et al. (1999)

4. 0 h 2 h
6 h4 h
Pearce et al., 2014
Pearce et al. 2013

5. EB extravasation in HS pigs
0
50
100
150
200
250
TN 1 3 7
EvansBlue(ng/mg)
Kidney
P=0.038
0
50
100
150
200
250
300
TN 1 3 7
EvansBlue(ng/mg)
Liver
P=0.025
Zhao et al (2017)

6. Heat stress compromised intestinal barrier
function
• Heat stress reduced small intestinal resistance and increased
permeability
• Selenium and Vitamin E ameliorated the impacts of heat stress
Liu et al., 2016

7. Summary
• HS is a current and emerging problem
• HS compromises efficient production by
– reducing feed intake
– diverting energy from growth to thermoregulation
• Nutrition strategies are increasingly being
recognised as a useful strategy for
combatting HS

8. Betaine
• Organic osmolyte, protects cell against
stress
• Reduces activity of ATPases, lowering
metabolic heat production
• Serves as a methyl donor for a wide
range of physiological processes
– Synthesis of SAA via methionine cycle
– DNA methylation

9. Two experiments
Quantify the effects of betaine and anti-
oxidants on HS broilers
Experiment 1- Growth rates, “leaky gut?”
Experiment 2- Growth rates, product
quality

10. Methodology
• 144 Chicks received from hatchery @1d
• Fed starter, grower and finisher diets with
– Control
– Betaine 1 g/kg
– Anti-oxidants (Se 0.5 mg/kg, Vitamin E 250 IU/kg)
– Betaine + Anti-oxidants (BAO)
• Grown under thermoneutral and “heat stress”
conditions

11. Temperature profile
D7
D21
33oC
Day
25oC
Night
Starter Grower Finisher
D42

12. 40.4
40.6
40.8
41.0
41.2
41.4
41.6
41.8
42.0
42.2
42.4
Control Bet AO BAO
Rectaltemperature(oC)
TN
HS
Dietary additives reduced rectal temperatures
in HS broilers
Temperature P<0.001
Diet*Temp P=0.018
a
b
b
b
Main effect of weekly RT

13. Betaine reduced respiration rate in HS broilers
a
b ab
b
RR measured at end of the experiment

14. Betaine increased body weight, irrespective of HS
1500
1700
1900
2100
2300
2500
2700
2900
3100
3300
Control Betaine AO BAO
Bodyweight(g)
TN
HS

15. Increases in FCR with HS were ameliorated by
betaine

16. Betaine increased breast weight, in both TN
and HS broilers
0
100
200
300
400
500
600
700
800
900
Control Betaine AO BAO
Breastweight(g)
TN
HS
x x
ya
a
a
b
y

17. HS reduced intestinal resistance (TER),
however no change in permeability (FD4)
0
25
50
75
100
125
150
175
200
TN HS
/cm2
0.00
0.20
0.40
0.60
0.80
1.00
1.20
TN HS
FD4
a
b

18. Betaine increased intestine permeability
overall (P=0.013)

19. Summary
• HS reduced weight gain and increased FCR
• Betaine ameliorated symptoms of HS
• Betaine improved weight gain and breast
muscle weight in TN and HS broilers
• Increase in gut permeability with betaine?
– Relationship with high growth rates?

20. Experiment 2
• Methodology as per experiment 1
• 76 Chicks
• Diets:
– Control
– Betaine
– Betaine + anti-oxidants
• Meat quality assessed at the end of the
experiment

21. Betaine ameliorated heat stress in
broilers
c c c
a
b b
0
50
100
150
200
CON BET BET + AOX
RR(BPM)
TN
HS

22. Betaine diets improved final body
weights overall (no interaction)
0
1000
2000
3000
CON BET BET + AOX
Bodyweight(g)
TN HS

23. Breast muscle weight reduced by HS,
overall improvement with betaine diets
0
300
600
900
CON BET BET + AOX
g
TN HS

24. Betaine diets increased myofibrillar
degradation in HS broilers
a
abc
a
d
cb
ab
0
30
60
90
120
CON BET BET + AOX
MFI
TN HS

25. Betaine diets reduced drip loss in meat from HS
broilers
b
b
b
a
b
ab
0
1
2
3
4
CON BET BET + AOX
Driploss(%)
TN
HS

26. Betaine and anti-oxidant diet reduced lipid
oxidation in meat from thermoneutral broilers
a
b
b
a
a a
0
2
4
6
8
CON BET BET + AOX
TBARS(mg/kg)
TN HS

27. Summary
• Betaine ameliorated the effects of HS
• Betaine improved broiler growth rates
– TN and HS conditions
• Accompanied by improved product
quality
– Higher MFI
– Less drip loss

28. © Copyright The University of Melbourne 2011