1h. The Profitable Lifetime Index (£PLI) is a reliable basis for genetic improvement of dairy cattle productivity, health, welfare, longevity and environmental impact
Submitting InstitutionsUniversity of Edinburgh,
Unit of AssessmentAgriculture, Veterinary and Food Science
Summary Impact TypeEconomic
Research Subject Area(s)
Engineering: Food Sciences
Summary of the impact
Impact: Economic / animal health and welfare / environment:
Improved profitability and
sustainability of the UK dairy industry.
Significance: The use of the Profitable Lifetime Index (£PLI)
increased the profitability of the
dairy sector by an estimated £634M in 2008-2013 and reduced the greenhouse
from the sector by an estimated 8.4%.
Beneficiaries: Dairy producers, breeding companies, general
public/environment, dairy cattle
welfare and health.
Attribution: Drs Wall, Mrode (SRUC), and Brotherstone (UoE),
Profs. Coffey, Simm, Stott,
Veerkamp, Oldham (SRUC), and Woolliams (UoE/Roslin)
Reach: UK dairy industry. Tools developed, such as the routine
recording of body condition
score, and using these data in national genetic evaluations, have been
internationally, including in major dairy genetics exporting countries
such as the USA, Canada,
the Netherlands and New Zealand.
This Research is attributed to (Drs Wall (Researcher, employed
2001-onwards), Mrode (Senior
Geneticist employed 2005-onwards), and Brotherstone (researcher, UoE
Profs. Coffey (Team Leader, employed 1998-onwards), Simm (Academic
1983-onwards), Stott (Group Manager, employed 1983-onwards), Veerkamp
employed 1991-2004), Oldham (Principal researcher, employed-onwards), and
(Group Leader, UoE/Roslin employed 1977-onwards), UK dairy cattle genetic
programmes focussed mainly on milk production traits with clear negative
impacts on cow
health, welfare and fertility, and thus economic performance. The research
and dairy industry opinion formers identified that broader breeding goals
encompassing production but also addressing animal health and welfare, and
goals. A significant programme of research was initiated over 25 years ago
government and industry funding. This led to improvements in knowledge and
updated dairy cattle breeding tools, with those elements of research and
impact reported here
occurring in the relevant REF impact period.
Research (from 1993 onwards) focused on two main areas:
- Establishing the biological, environmental and economic consequences
of selection for
milk production, including testing for unforeseen consequences of
selection [3.1]. This
was achieved by: (i) comprehensively measuring and comparing the
cows selected for high milk solids yield with control line cows in our
Langhill experiment &mdsh; the
world's longest running dairy cattle selection experiment; and (ii)
correlations among traits of interest, from both Langhill [3.2] and UK
dairy industry data
[3.3]. This work identified that selection for production had a major
impact on body
condition score change, which in turn, affected reproductive
performance. As a result,
the UK was the first country in the world to routinely record body
condition scores in dairy
herds and was the first to use this information in national genetic
evaluations for dairy
- Developing new `breeding goals' — identifying the most appropriate
combination of traits
to select for, and their relative economic importance — and developing
improvement tools to allow selection for these breeding goals [3.3, 3.4,
included: (i) developing genetic and statistical methodology for
predicting genetic merit in
new breeding goal traits, or proxies for them, including longevity,
fertility, body condition
score, udder health and calving ease, and (ii) producing successive
versions of a new
selection index, the Profitable Lifetime Index (£PLI), which provides a
single score to
identify animals with the highest genetic merit for overall economic
breeding goal traits.
The research provided evidence on the optimal design of breeding schemes
practical selection tools (e.g. estimated breeding values for new traits
in dairy cows and new
statistical models to enhance accuracy of selection decisions [3.3, 3.4])
and the new £PLI [3.5],
which has become widely used in the UK. The index framework developed
additions as new traits are identified and become economically
Further work established valuable environmental co-benefits in terms of
Wider programme on dairy cattle fertility and health involved colleagues
from Universities of
Nottingham (Prof A Flint) and Reading (Dr R J Esslemont).
References to the research
3.1 Veerkamp, R F, Simm, G, & Oldham, J D (1994). Effects of
interaction between genotype
and feeding system on milk production, feed intake, efficiency and body
in dairy cows. Livestock Production Science, 39: 229-241. http://dx.doi.org/10.1016/0301-6226(94)90202-X
3.2 Veerkamp, R. F., & Brotherstone, S. (1997). Genetic correlations
between linear type traits,
food intake, live weight and condition score in Holstein Friesian dairy
cattle. Animal Science,
64: 385-392. http://dx.doi.org/10.1017/S1357729800015976
3.4 Mrode, R, Pritchard, T, Coffey, M and Wall, E (2012). Joint
estimation of genetic parameters
for test-day somatic cell count and mastitis in the United Kingdom.
Journal of Dairy Science.
95 (8): 4618-4628. http://dx.doi.org/10.3168/jds.2011-4971
3.5 Stott, AW, Coffey, MP and Brotherstone, S (2005). Including lameness
and mastitis in a
profit index for dairy cattle. Animal Science. 80: 41-52.
Details of the impact
The major impact of this research is improved profitability and
sustainability of the UK dairy
industry. Adoption of these new indexes has improved production, fertility
performance of dairy cattle. Cattle now live longer (from 3.4 years in
2004 to 4.3 years
productive life in 2009). Cow fertility has improved (average calving
interval has decreased from
431 days in 2008 to 423 days in 2012) and health (somatic cell scores, an
indicator of the
incidence of mastitis, have decreased from 206,000 cells/ml in 2008 to
198,000 cells/ml in 2012)
with milk yields still increasing (8,765 litres/cow/annum in 2008 vs.
The economic benefit of selection on the versions of £PLI produced as a
result of this research
are estimated to be around £634M over the period 2008-2013 [5.10]. Also,
the changes to the
sector brought about by the new selection indexes and breeding goals have
reduced greenhouse gas emissions per breeding animal by an estimated 1.4%
CO2 equivalent) per annum.
Pathways to Impact
The versions of the £PLI index developed in this REF period have become
very widely used in
the UK dairy industry, allowing selection of those breeding animals best
suited to UK needs from
the massive international pool available. The vast majority of dairy cows
in the UK are bred
using artificial insemination (AI), to bulls which rank highly on £PLI. It
is the combination of high
AI use, and the selection of high £PLI bulls by AI companies which
underpins most of the
impact. Additional, smaller gains arise from farmers selecting the best
available AI bulls, and
breeding replacement heifers from the highest ranking £PLI cows.
We have worked to support the dairy industry levy bodies (currently
DairyCo) in encouraging
widespread uptake by breeding companies and farmers, via many workshop and
presentations and with articles for websites, the farming press, and other
media activity. The use
of the tools we have developed has helped dairy producers in the UK become
helping them to breed animals that are more profitable, fertile, healthy,
have longer productive
lives, and reduced greenhouse gas emissions per unit of milk produced.
Our research led to lifespan being included in the national dairy
breeding goal (which became
£PLI in 1999) in 1995. This was the first move away from a production-only
breeding goal for UK
dairy farmers. £PLI was further upgraded in 2003 with the inclusion of
health traits (somatic cell
counts from milk as an indicator of mastitis/udder health, and locomotion
as an indicator of
lameness), and in 2006 with the inclusion of fertility traits; traits that
were all identified as
important and researched by our group.
Genetic evaluation — the process of predicting the genetic merit of
animals from pedigree and
performance data (milk yield, growth, disease incidence etc.) and,
recently, molecular genetic
data — is a mathematically complex, internationally scarce, but key
enabling technology in
delivering the impact described. We established Edinburgh Genetic
(EGENES) in 2005. It provides livestock genetic evaluation and data
handling services, and has
helped to accelerate the transfer of research results into industry
practice. EGENES has been
contracted by DairyCo to provide genetic evaluations for the UK dairy
population since 2005.
The close partnership between our researchers, EGENES and DairyCo in
via genetic evaluation services, and supporting knowledge exchange with
users, has been
instrumental in achieving impact.
The approaches and methodology employed have influenced practice
Interbull — the international agency for quality assurance and technical
developments in cattle
genetic evaluations; see: www.interbull.org.
For example, the genetic evaluation of body
condition score which we pioneered has since been adopted in 15 other
countries, including Canada, the Netherlands and USA and our methods for
condition score as a predictor of dairy cow fertility have been mirrored
in national routine
evaluations for fertility in Belgium, Ireland, the Netherlands, New
Zealand, South Africa, Spain
and the UK.
Sources to corroborate the impact
5.1) Marco Winters (Head of Genetics at DairyCo, firstname.lastname@example.org)
DairyCo fund and disseminate the national dairy genetic evaluations and
responsible for the implementation of research findings into practice.
5.2) Dr David Garwes (former research project manager, Defra, currently
of the research findings described were commissioned by
Defra and managed by Dr Garwes. http://tinyurl.com/lxa3cly
5.3) Wall et al. 2003. Introducing a UK Fertility Index [http://tinyurl.com/o72986c].
relates to an annual meeting of the British Cattle Vet Assoc. and
describes the launch of
the fertility index to UK dairy farmers.
5.4) DairyCo Breeding+ [http://tinyurl.com/qf5ggxm]
The hub for routine provision of breeding
values (and selection indexes) to UK dairy farmers.
5.5) Swanson, G. and Mrode, R. (2001). Reduction in mastitis incidence
from selection for
reduced Somatic Cell Counts — good or bad? [http://tinyurl.com/oqzhc5u].
the British Mastitis Conference on how selection on somatic cell counts
can be used to
genetically select for mastitis reduction.
5.6) Winters, M. (2008). Develop mastitis resistance by exploiting
Article describing how selection on somatic cells has impacted
on mastitis resistance.
5.7) Amer, P R., Wall, E., Nühs, J., Winters, M. and Coffey, M. P.
Sources of benefits from
genetic improvement in the UK dairy industry and their impacts on
consumers. Interbull Bulletin No. 44. Stavanger, Norway, August 26 - 29,
5.8) Winters, M. (2010). Is dairy cow fertility a lost cause? DairyCo
Technical note showing how the genetic decline in dairy cattle
fertility has been turned around since the introduction of the fertility
index as part of routine
national genetic evaluations.
5.9) Performance of UK Holstein-Friesian cows for a range of production
and fitness traits
National statistics for milk recorded pedigree
Holstein-Friesian cows showing how traits have changed over the past
5.10) Pritchard, T., Coffey, M., Mrode, R. and Wall, E. (2013).
Understanding the genetics of
survival in dairy cows. Journal of Dairy Science. 96 (5): 3296-3309. Peer
publication quantifying the improvement in dairy cattle survival.