This document summarizes a maternal productivity project investigating the impacts of selection for body composition and net feed intake (NFI) on breeding herd efficiency under different nutritional environments. The project compared divergent selection lines for fatness and NFI across two sites and nutritional treatments. Key findings included genetically fatter cows being heavier and more fertile, especially under low nutrition, while selection for NFI was associated with changes in cow leanness but had no impact on reproduction or calf performance. The results suggest selection for body composition can influence breeding herd efficiency depending on nutritional conditions.

1. Maternal
Productivity
Project
(Southern Aust)
Jeisane Accioly,
Fiona Jones and
Michael Laurence
(on behalf of a large team)

2. WA Maternal ProductivityWA Maternal Productivity
TeamTeam
Brad
Seib
John
Milligan
Tex
Hann
Nola
Mercer
Ryan Drage
Brian McIntyre Peter Jelinek
Leonarda
Paszkudzka-Baizert
Greg Sawyer

3. CollaboratorsCollaborators

4. Western Australia
• Jane Speijers
Other Researchers
South Australia
• Wayne Pitchford
• Katrina Copping
• Mick Deland
• Nick Edwards
• Ian Carmichael
• Michelle Hebart
• Stephen Lee
New South Wales
• Kath Donehue
•Robert Herd
• Peter Parnell
Victoria
• John Graham

5. Industry Push

6. 386 kg Start wt 398 kg
1.5 kg/d ADG 1.5 kg/d
1640 kg Expected feed 1670 kg
1880 kg Actual feed 1580 kg
+ 240 kg Net feed intake - 90 kg
Low Efficiency High Efficiency

7. 1. Adoption of selection
strategies influencing
body composition (e.g.
RBY and NFI) constrained
by industry concerns
about impact on breeding
herd efficiency, especially
in variable nutritional
environments
Key industry issues

8. 2. The seedstock industry
lacks suitable selection
criteria for effective
improvement of
breeding herd efficiency
(kg cow and calf per MJ
energy consumed by
cow & calf)
Key industry issues

9. Key issue in South
Maternal efficiency:
 Cow feed (75%)
• Maintenance
• Energy storage & retrieval
 Reproductive performance
 Calving ease
 Calf value
 Longevity
 Cow salvage value

10. Improve breeding herd efficiency in temperate Australia
 Impact of selection for body composition on herd efficiency,
especially under variable nutrition
 Efficient use of available feed resources & body reserves to
produce progeny
 Full multi-trait index with measure of maternal efficiency &
optimally weighted composition traits for variable environments
Project aims

11. Key research question …
Does selection for improved NFI or RBY%
influence breeding herd efficiency* ?
Hypothesis: Selection for
reduced NFI and reduced
carcass fatness increase
breeding herd efficiency in
good, but not in poor
nutritional environments
* Kg of cow and calf liveweight
/ MJ energy consumed by the
breeding herd

12. Two approaches:
1. Correlations between traits across large range of production
systems (Industry herds)
2. Differences between divergent single-trait lines in formal
design (Research herds)
Project approach

13. Animal Selection
• 154 “fat line” yearling heifers arrived Jan-Feb 07
sourced from industry seedstock herds in Vic & SA (‘B’
heifers).
• 62 NFI heifers arrived Jan-Feb 08
Sourced from Trangie NFI Selection Herd, NSW.
• 95 “fat line” yearling heifers arrived Feb-Mar 08
sourced from industry seedstock herds in Vic & SA (‘C’
heifers).
Maternal efficiency herds
Angus
Hereford
Research herds

14. Vasse (WA)
Struan (SA)

15. 4 Lines
High Fat
Low FatLow Fat
High NFI
Low NFI
2 Nutrition
High
Low
2 Sites
Vasse, WA
Struan, SA
x x
Intensive measurements and estimation of food intake
Research herds
3 calving seasons

16. EBV differencesEBV differences
between the linesbetween the lines
EBV
High Fat
(n=170)
Low Fat
(n=170)
High NFI
(n=81)
Low NFI
(n=81)
Rib fat 1.2 -1.4 3.2 -0.4
Rump P8 1.4 -1.5 3.0 -0.6
NFIP 0.65 -0.47
NFIF 0.77 -0.87
BWt 3.8 4.9 2.9 4.6
Wt200 31.3 36.3 18.9 25.9
Milk 10.8 10.6 7.8 9.0
Wt600 75.9 83.8 47.6 60.6
MCWT 67.7 81.3 42.0 58.6
DTC -3.3 -1.8 -1.2 0.3
EMA 2.40 2.10 0.42 0.48

17. Heifer managementHeifer management
Nutritional treat’s applied
9 week joining
Calving
SepSep
OctOct
NovNov
DecDec
JanJan
FebFeb
MarMar
AprApr
MayMay
JuneJune
JulyJuly
AugAug
SepSep
OctOct
NovNov
DecDec
JanJan
FebFeb
JuneJune
JulyJuly
AugAug
SepSep
OctOct
NovNov
DecDec
JanJan
FebFeb
MarMar
AprApr
MayMay
JuneJune
JulyJuly
AugAug
SepSep
OctOct
NovNov
9 week joining
Nutritional treat’s applied
Calving
Weaning Weaning
VasseVasse StruanStruan
9 week joining9 week joining

18. 0
100
200
300
400
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
PastureEnergySupply
(MJ/ha/day)
0.0
100.0
200.0
300.0
400.0
CattleEnergyDemand
(MJ/head/day)
Energy Supply & Demand: Early Calvers & Late CalversEnergy Supply & Demand: Early Calvers & Late Calvers

19. Rainfall (mm)
2006: 577 mm 2007: 810 mm 2008: 671 mm 2009: 679 mm
2010: 464.1mm
0
50
100
150
200
250
300
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
2006 2007
2008 2009
2010

20. Nutritional control

21. Fat lines

22. Weight of Fat cowsWeight of Fat cows
0
100
200
300
400
500
600
700
PM1 W0 PM 2 W1
CowWeight(kg)
High Fat Low Fat High Fat High Nut Low Fat High Nut High Fat Low Nut Low Fat Low Nut

23. P8 FatP8 Fat
0
2
4
6
8
10
12
PM1 W0 PM 2 W1
Cowp8Fat(mm)
High Fat Low Fat High NFI High Nut Low NFI High Nut High NFI Low Nut Low NFI Low Nut

24. 11stst
calvers pre-matingcalvers pre-mating
and pregnancy testand pregnancy test
Line
Age
(days)*
Weight
(kg)
P8 fat
(mm)***
Conception
rate*
Adjusted
conception
rate*
High Fat 473 370 6.5 93.5 93.4
Low Fat 465 367 4.9 85.1 86.8

25. Pre-mating and pregnancyPre-mating and pregnancy
test 2test 2ndnd
calvingcalving
Line Nutrition
Weight
(kg)***
P8 fat
(mm)**
Conception
rate
High Fat High 531 8.3 94.9
High Fat Low 488 5.4 88.4
Low Fat High 575 7.6 93.5
Low Fat Low 491 4.2 85.7

26. Days to calving forDays to calving for
heifersheifers
260
270
280
290
300
310
320
330
High Nutrition Low Nutrition
DaysToCalving(days)
High Fat Low Fat
*

27. Days to Calving 2Days to Calving 2ndnd
calverscalvers
295
297
299
301
303
305
307
309
311
313 High Fat - High Nut" High Fat - Low Nut
Low Fat- High Nut Low Fat - Low Nut

28. MessagesMessages
• Low fat cows were bigger / heavier (ave. 50kg)
• Low fat cows were leaner (>3mm)
• Fat difference was consistent across seasons
• Low fat cows seem to have poorer reproduction??

29. Birth weightBirth weight
0
5
10
15
20
25
30
35
40
1st calf 2nd calf
BirthWeight(kg)
High Fat High Nut Low Fat High Nut High Fat Low Nut Low Fat Low Nut

30. Calf weaning weightCalf weaning weight
from 1from 1stst
calverscalvers

31. Messages (calves)Messages (calves)
• No effect of fat genotype on birth or weaning
weight
• Nutrition effect on weaning weight

32. Net Feed
Intake
lines

33. Weight of NFI cowsWeight of NFI cows

34. P8 Fat – NFI cowsP8 Fat – NFI cows
0
2
4
6
8
10
12
14
16
PM1 W0 PM 2 W1
Cowp8(mm)
High NFI Low NFI High NFI High Nut Low NFI High Nut High NFI Low Nut Low NFI Low Nut

35. 11stst
calvers pre-matingcalvers pre-mating
and pregnancy testand pregnancy test
Line
Age
(days)
Weight
(kg)
P8 fat
(mm)***
Conception
rate
Adjusted
conception
rate
High NFI 493 306 10.4 91.9 91.8
Low NFI 492 315 8.2 91.6 91.6

36. Pre-mating and pregnancyPre-mating and pregnancy
test 2test 2ndnd
calvingcalving
Line Nutrition
Weight
(kg)
P8 fat
(mm)***
Conception
rate
High NFI High 478 11.9 95.1
High NFI Low 441 8.7 96.1
Low NFI High 488 8.8 87.4
Low NFI Low 438 6.1 88.7

37. Days to calving forDays to calving for
heifersheifers
260
270
280
290
300
310
320
330
High Nutrition Low Nutrition
DaysToCalving(days)
High NFI Low NFI

38. Days to Calving 2Days to Calving 2ndnd
calverscalvers
310
312
314
316
318
320
322
324
326
High NFI High Nut High NFI Low Nut Low NFI High Nut Low NFI Low Nut

39. Birth weightBirth weight
0
5
10
15
20
25
30
35
40
1st calf 2nd calf
BirthWeight(kg)
High NFI High Nut Low NFI High Nut High NFI Low Nut Low NFI Low Nut

40. Calf weaning weightCalf weaning weight
from 1from 1stst
calverscalvers

41. MessagesMessages
• No difference in weight of cows
• Trend for Low NFI cows to be leaner
• No effect of NFI in reproduction
• No effect of NFI in birth or weaning weight
• Effect of nutrition on
weaning weight

42. Main messagesMain messages
• Genetically fatter cows seem to be more fertile,
especially under low nutrition
• Selection for body composition holds across seasons
and nutrition treatments
• No effect of cow fatness or NFI EBV on weaning
weight of her calf
• Selection for NFI is associated with changes in
fatness

43. o be continued …