1. Friday - Ruminant Sessions mr ian sawyer feedworks - heat stress update

1. Heat stress…
again , but better !
THI evolves into AHLU for better indicators...
And our tools at Feedworks are more valuable then
ever

2. Heat stress and Feedworks… its our 18th birthday ,
so we can have a beer with heat stress !
• Mal kicked off heat stress work in 2000 with
betaine in ruminants
• We have been operating in this heat stress
space ever since, with plenty of commitment to
heat stress research at universities both local
and also in USA
• We happen to think we can claim some first
hand skills and experience as well, so recognise
there is some intellectual capacity here

3. The key happenings in heat stress
A. DMI drop decreases available ME/Nutrients
B. Increase in requirement of ME and Nutrients as
maintenance needs increase
C. Drop on efficiency of metabolism of ME and Nutrients
that are taken in
D. Change In preference for ME sources Glucose is king !!!

4. The double whammy of heat stress!
0
5
10
15
20
25
30
20 25 30 35 40
Temperature °C
KilogramsofDryMatter
Dry Matter
Intake
Maintenance
Req.
1 Holter, West, and McGilliard. 1997. Journal of Dairy Science 80:2188.
40 Litres
potential
27 Litres
potential

5. The double whammy of heat stress!
0
5
10
15
20
25
30
20 25 30 35 40
Temperature °C
KilogramsofDryMatter
Dry Matter
Intake
Maintenance
Req.
1 Holter, West, and McGilliard. 1997. Journal of Dairy Science 80:2188.
And we have not yet
accounted for losses
in:
• diet digestibility
• nutrient efficiency
use or
• glucose preferences

6. Progressing to a better way of predicting how
hard we get hammered…
Accumulated Heat load Units
• Is it a bad day… a bad week… a bad month !
• This matters to our stock a great deal.
• I am now a Victorian, so it matters to me too living in the Macedon ranges
and being a big WOOOZ.
• Lets look at the PROGRESSION in measuring the hit from heat

7. A: THI Chart- In Common use, but only measures a given moment
Relative Humidity
Temp oC
(oF)
30 40 50 60 70 80 90
25 (77) - - 72 73 74 75 76
30 (86) 75 77 78 80 81 83 84
35 (95) 80 83 85 87 89 91 93
40 (104) 86 89 91 94 96 - -
45 (113) 92 95 96 - - - -
50 (122) 97 - - - - - -

8. A-THI- a good start but not a complete story
• Temperature / humidity index
• Tells us what’s happening outside at this moment in time
• Doesn’t capture history of weather or pressure on the stock
• Doesn’t tell us a lot about how the cows physiology will be reacting
• Doesn’t tell the full story
Kind of like hitting your thumb with a hammer once… I can tell you it
hurts… but it doesn’t capture the real pain/damage of doing it
repeatedly

9. B- Dairy heat load index: Better, but still a moment in time
Kind of like THI but with
some extra Benefits as it
captures the impacts of:
• direct sunlight
ie: Radiation load

10. B- Dairy heat load index: still a moment in time
Kind of like THI but with
some extra Benefits as it
captures the impacts of:
• direct sunlight
ie: Radiation load
• Air movement
ie: Convection and
evaporation disapation

11. THI and Dairy heat index are not ideal for
predicting heat stress: no a period of exposure
Thanks to the Beef industry lads on this one…well ahead

12. C- Accumulated heat load units
• A more complete picture describing GAIN of heat vs DISSIPATION OF
HEAT
• Captures the balance of the LOAD ON THE ANIMAL
• Also WHAT DIRECTION it is going in
• Far better idea of HEAT STRESS implications

13. Gain of heat is shown in red
Loss of heat in blue…..and its at a point 10 units UNDER the gain point
can only Loose heat at half the RATE that we gain it…..its slower in recovery
Thats why Night time temperatures are crucial

15. This is really well sorted in Beef, but less so in
a pure number for dairy herds
• Dairy herds are likely to
respond with panting and
other “negative outcomes” at
a lower AHLU rating then our
beefy mates
Reasons:
• Higher DMI typically + Fibre =
more fermentation heat
• Higher metabolic levels of
activity (multiples of
maintenance)

16. SIGN UP TO KATESTONE: CHLT.katestone.com.au

17. Yes Its for Beef: but in summer some of
our dairy country ain’t that much
different to a yard

18. EFFECTIVE NUTRITIONAL INTERVENTIONS ARE VALUABLE
•Its just that not all interventions are effective !
•Here’s three that are effective and well proven
1- Diamond V
2-Acidbuf
3-betaine

19. Diamond V: 1.3L Milk in 10 out of 10 heat stress
specific pieces of trial work ( 9 published)

20. Diamond V: why it works = many irons in the fire
• Promotion of Dry matter intake
• Improved fibre digestibility ( the first thing to crash in heat stress)
• Improved microbial protein yields
• Improved resilience of rumen stability
• Happier and more productive rumen at a time when it is prone to
tanking
• A tool for use every day , and one even more valuable in heat

21. Acidbuf: because SARA becomes a big hassle
• Rumen stability is invariably compromised in heat incidents
• Panting reduces blood carbonate, and salivary buffering is reduced
• Decreased blood flow to gut viscera slows removal of VFA from rumen into
blood… so they accumulate in rumen reducing pH, and less energy sources
• Stock select against fibre and in favour of fermentable carbohydrates
• Stock eat in slugs early in morning and late in afternoon
• Decline in rumen contraction rates
•BIG challenges to rumen stability, rumen health , feed intake
and digestibility… SARA!!!! ACIDBUF EXCELS FOR SARA

22. And we can put some data behind that SARA claim!

23. Betaine: We still love it, and it works in beef, dairy,
lambs, etc… because it works on the fundamentals
• Spares maintenance energy requirements
• Promotes dry matter intake
• Reduces metabolic indicators of heat stress
• Most here probably have never seen the older research: lets look
back 15 years to the early stuff at UQ

24. Early swine work here in Australia.
Betaine reduces the maintenance
energy requirement
686
766
Control BK
kJ DE/kg0.75/day
(kcal DE/kg0.75/day)
(183)
(164)
-10%

25. 2
2.5
3
3.5
4
4.5
5
5.5
6
1 2 3 4 5
Day of HOT
Feedintake(kg/head/day)
BK
CON
a
b
a
b
a
b

26. 70
75
80
85
90
95
100
105
1 2 3 4 5
Day of Hot
respirationrate(breathsperminute)
CON
BK

27. 39
39.2
39.4
39.6
39.8
40
40.2
40.4
1 2 3 4 5 6 7 8
Days
RectalTemperature(oC)
CON BK
a
b
a
b
a
b
a
b
a
b
Hot Days
cool days
cool

28. Betaine ain’t Betaine:
• All the good data is on NATURAL BETAINE that comes from
sugar beet growth for sugar
• Synthetics and Hyrdochloride versions seem not to work, and
have not got data sets in any case

29. SUMMARY:
• Heat stress remains one of the most significant challenges we face each
year in our ruminant sectors
• We should move forward with prediction and quantification of the
challenge on stock with AHLU to better show real challenge, not stay with
old THI that is a simple moment in time
• We can make nutritional interactions with DIAMOND V, ACIDBUF and
NATURAL BETAINE