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PARALLEL SESSION 3C: SHEEP AND DAIRY PRODUCTION SYSTEMS 8 th Int. Conference on LCA in the
Parallel session 3c: Sheep and Dairy Production Systems
304
Agri-Food Sector, 1-4 Oct 2012
A systems-LCA model of the stratified UK sheep industry
Adrian Williams * , Eric Audsley, Daniel Sandars
Centre for Environmental Risks and Futures, School of Applied Sciences, Cranfield University, Bedford, MK43 0AL, UK.
Corresponding author. E-mail: adrian.williams@cranfield.ac.uk
ABSTRACT
A systems model of the stratified UK sheep industry was developed to provide the activity data inputs for life cycle assessment
(LCA) in the Cranfield systems-LCA model. It includes the biophysical performance of the lowland, upland and hill sheep flocks,
which are economically interlinked and provide meat and wool as outputs. The sheep metabolisable energy requirements are calculated
from standard formulae and the grazing needs are determined from the feed supplied by grass coupled with a bespoke grass
production model. This calculates the N requirements and productivity over a wide range of climatic and soil zones.
Baseline results were compared with alternative scenarios. The potential for improvement under reasonable changes in management
and technology could reduce main burdens by about 14% and about 24% with more demanding changes. Changes in the industry
structure have major effects on land occupation, but smaller effects on energy use and greenhouse gas emissions.
Keywords: lamb, systems model, greenhouse gases, enteric methane, wool
1. Introduction
The UK sheep industry can be divided into hill, upland and lowland flocks. The overwhelming purpose is to
produce meat (of which lamb is economically dominant), with wool as a co-product. The milking flock is
negligible and not addressed in this paper. There are many breeds ranging from the smaller breeds most
suited to the severe conditions of hill farming, which struggle to produce a lamb each year, to the larger
breeds associated with lowland farming. These include very local traditional breeds (e.g. Herdwick) to more
recently-imported breeds, such as the Texel. The system that has developed combines the qualities of these
different breeds to develop hybrid vigour and make best use of the available land at different altitudes (Figure
1).
Hill
Upland
Lowland
Male
lambs
Pure bred hill
Male
lambs
Draught
ewes
Finished lambs
Ewe lambs
retained
Halfbreds Rams Longwool
Cross-bred
ewes & lambs
Lowland Rams Downland
Figure 1. Simplified structural model of sheep production in the UK.
Thus, hill farms produce ewes that are sold to upland farms where they are crossed with high genetic merit
rams to produce ewes that are, in turn, sold for breeding to lowland farms. In addition, there are purebred
flocks with intermediate characteristics. Whilst most male lambs on lowland farms can be finished (i.e. reach
slaughter weight and condition) before the autumn, a decreasing proportion on upland and hill farms can
achieve this and many must be sold to lower land farms, where they are grown and finished over winter or
kept as “stores”, typically kept on maintenance rations until being finished the next spring. A small proportion
of lowland flocks lamb very early and lambs are reared with a high concentrate diet to meet the Easter
market (high prices). Lambing then proceeds with the rest of the lowlands, upland and hills in sequence.
Sheep are major emitters of enteric methane and so contribute about 8% the UK national agricultural methane
emissions and about 7% of direct agricultural N2O emissions (Sneddon et al., 2010). The sheep sector
has historically operated at the margins of livestock production in the UK, but is important in supporting
rural communities as well as particular grassland ecosystems and utilising these relatively poor grasslands.
Surplus
lambs
Surplus
lambs