1. The document summarizes research into the relationships between genetic traits and maternal productivity in beef cattle from industry herd data and breeder interviews. 2. Breeder management approaches differed in their control of inputs, with some targeting leaner cattle better suited to variable resource environments. 3. Higher estimated breeding values (EBVs) for traits like rib and rump fat were found to decrease days to calving and increase pre-calving fat depth, with a larger effect in autumn-calving herds.

1. Reporting outcomes
from social science
and industry herd data
analysis
Stephen Lee
Ian Nuberg
Wayne Pitchford

2. Maternal Productivity
Difficult to define:
 the outputs in the beef production system relative to the inputs
• weight of calf weaned / MJ energy cow calf unit
• cow weight change (kg)
Traits include:
Reproductive performance (no. of calves weaned per cow exposed)
Pre-weaning growth of progeny
Change in size and body composition of the cow
Motivating concern
 How does increasing production potential impact on breeding herd
efficiency?

3. Research Approach
In-depth interviews with seedstock breeders on
role and key influencers of maternal productivity
Maternal Productivity Data from 4500
industry animals over first and second parity
•hypotheses generating – logic of
breeding and management
Management and breeding implications for
cows differing in genetic potential
1. associations between performance
potential (EBVs) and body energy
reserves
2. genetic parameter estimates
3. reproduction differences
4. output traits (calf weaning weight,
cow weight change)

4. Breeding goals
• Majority of breeders had similar goals:
– low cost of production
– high quality product (marbling and yield)
– multiple end market specifications
– structural soundness
– temperament
• Contrasting on-farm animal management
approach

5. Diverse management

6. Controlled input
‘I have a real problem with fat and I touched on this
before in regard to cow condition. Fat is expensive to put
on, you put it on, the animal goes to the processor and
they cut if all off. When you feed it (fat) on and it costs
you somewhere in the vicinity of 40% of every mega-
joule you end up using in the process of putting it on and
then re-metabolising it again, that’s just crazy’
‘If you couldn’t do it any other way and we were
dropping 10% conception rate, then you have to have
that fat there. If you can have yield and have efficient
cows, then to me the wrong thing for a seedstock
business to do is to push positive fat.’

7. Variable input
‘We have done a study of what it costs us to produce dry matter
during the year and it is about 4 times as cheap during spring
compared to autumn. So that says a lot about when you put
condition on and when you can let the cows coast through. The ones
that have stayed in the system have this ability where they can put
weight on quickly in spring when there is compensatory growth and
they can draw down on those reserves when things are tougher and
then gain weight quickly when the feed is available.’
‘I use the carcass traits more for maternal productivity than for
carcass. It is huge, rib and rump, whenever I use an AI sire I have a
really good look at his fat EBVs. When I use a negative fat bull the
drop out rate in our maternal side is too high.’ ‘I know the feedlot
buyer wants high yielding steers but I can’t afford that in the cow
herd.’

8. Maternal Productivity
Fertility – 365 day breeding cycle
Calving ease
Calf growth
Pre-calving
energy reserves
P8 and
Rib EBVs
600d Wt EBV
EMA EBV
Feed Intake (energy)
Milk EBVFrame Maturity pattern

9. EBV Standard Deviations
P8 RIB 600d
Wt
MILK EMA IMF DC
EBV
Mat
Pat.
Angus 1.1 1.0 13.2 3.9 1.9 0.7 1.4 1.0

10. Sire 600d
Wt
MCWt Milk
(kg)
DC
(days)
Rib
Fat
(mm)
Rump
Fat
(mm)
RBY
(%)
IMF
%
Long
Fed
Index
($)
1 +122 +119 +20 -8.7 -3.2 -3.2 +1.6 +0.6 +103
2 +57 +50 0 -4.7 +4.5 +3.6 -2.0 +3.7 +98
Breed
Av.
+86 +80 +12 -2.5 -0.1 -0.1 +0.2 +0.8 +87
962 progeny
77 herds
623 progeny
in 20 herds

11. Percentage increase in P8 fat
depth for 1mm increase in P8 EBV
%change in P8 fat depth
A 1mm increase in P8 fat EBV for Angus at pre-calving first parity
(PC1) increased scanned P8 fat depth by 14.6%
13.1
12.3
11.9
14.6
0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0
W2
PC2
W1
PC1
P8
P8

12. Maternal Productivity
Fertility – 365 day breeding cycle
Calving ease
Calf growth
Pre-calving
energy reserves
P8 and
Rib EBVs
600d Wt EBV
EMA EBV
Feed Intake (energy)
Milk EBVFrame Maturity pattern

13. Relationship between Rib and P8
EBVs and observed days to calving
A 1mm increase in P8 EBV resulted in reduced observed DTC by
0.95 days in Spring and 2.45 days in Autumn
-2.93
-2.45
-1.22
-0.95
-4.00 -3.00 -2.00 -1.00 0.00
Rib
P8
Days to calving
Spring
Autumn

14. -4 -3 -2 -1 0
Rib
Days
Autumn
Spring
Relationship between pre-calving rib
fat depth and observed days to calving
In Spring calving cows for every extra millimetre pre-calving scan
rib fat depth, observed days to calving was reduced by 0.39 days,
this effect was larger in Autumn calving cows (-2.89).

15. Summary
Cow management approach differed between breeders
(CONTROL vs. VARIABLE)
Cow management approach was linked with attitude to
optimal EBVs for traits including fat, growth and milk
Body composition
• EBVs for P8 and Rib impact cow fat depth at pre-
calving and weaning (approx 15% per standard
deviation)
• Body composition traits are phenotypically
repeatable for pre-calving and weaning

16. Summary
Days to calving and Rib and P8 EBVs
Approx 1.0 days shorter DTC in spring
Approx 2.5-2.9 days shorter DTC in autumn
Pre-calving but not weaning cow fat depth impacts subsequent days to
calving
Approx 2.89 days/mm rib fat in autumn and
Approx 0.39 days/mm rib fat in spring.
For control input management, where it is cost effective to increase inputs
(feed), the effect of increasing genetic potential for yield (leanness) is
unlikely to compromise observed pre-calving energy reserves
However, in variable input systems, the ability for young cows with high
potential for leanness and growth to attain sufficient pre-calving energy
reserves in adverse seasons may be compromised

17. Acknowledgements
Ian Nuberg
Wayne Pitchford
Angus Australia
Herefords Australia
Collaborating herds!