Download Nutritional value of wheat for livestock

Background
Nutritional
value of
wheat for
livestock
Topic Sheet No. 9
Winter 1997
A large proportion of UK
wheat is fed to livestock to
provide dietary energy, crude
protein and nutritionallyessential amino acids. This
Topic Sheet reports research
on pigs and poultry led by Dr
Julian Wiseman of the
University of Nottingham.
Based on several projects, it
has examined the nutrient
and energy values of wheats
as a function of variety, site
and agronomic practice.
Livestock groups and
consumption
Figure 1. Compound feed sales in
Great Britain, 1996-97 (million tonnes)
Horses
& others (0.4)
Poultry
(3.6)
Sheep
(0.6)
Pigs
(2.4)
Cows &
calves
(3.7)
Animal feed is the largest market
for wheat in the UK but much is
incorporated within compound
diets. Figure 1, which is based on
survey data, provides some idea
about the breakdown of sectors.
The figures neither include wheat
used on-farm, nor data on
compounds for Northern Ireland.
Total UK wheat usage in 1996 to
1997 was around 5.5 million
tonnes and is estimated at 6 million
tonnes for 1997 to 1998.
Pigs and poultry are nonruminants. Digestive processes in
cattle, sheep and horses, which are
ruminants, are very different and
rather more complex. Most of the
HGCA-funded project work to
date has been on non-ruminants
but some research - yet to be
reported - has recently started on
ruminants.
Dietary energy
The standard measure of dietary
energy in poultry is apparent
metabolisable energy (AME). A
series of trials, in collaboration
with NIAB, sought to identify possible causes of variation in AME in
different wheat varieties. The
results (Figure 2) confirmed that
AME varies, particularly with
younger poultry. Some varieties
usually had lower and some higher
AME values than others. Reasons
for differences were not apparent.
Location, which includes climatic
and soil factors, did not have a
major effect, although there was
evidence that season might.
Nitrogen fertiliser, which ranged
from 0-200 kg a hectare, had
minimal influence on AME. There
was in general no relationship
between bushel weight and AME
above 69 kg/hl.
More detailed investigations
concentrated on biochemical
differences. Pure wheat starch fed
to poultry is almost completely
digested, which suggests that
there may be something unusual
about the poorly digested starch
of wheat grains. A component of
wheat called ‘non-starch polysaccharide’ (NSP) has been implicated
in the poor starch digestibility
and low AME. A laboratory assay
is currently being developed
which aims to separate ‘good’
(high AME) from ‘poor’ (low
AME) quality wheats for poultry.
Parallel studies have shown that
extended in collaboration with
the John Innes Centre,
Nickersons Seeds and
BOCM/Pauls, to examine the
influence of specific wheat
characteristics. Some factors have
been identified which are
associated with lower nutritional
value. As a result, for the first
time, farmers are being encouraged
by the animal feed industry to
grow specific varieties.
AME (MJ/kg DM)
Figure 2. Variation of AME in 22 wheat varieties
fed to poultry
14.0
13.5
13.0
12.5
12.0
11.5
11.0
10.5
10.0
9.5
9.0
Nutritional value of
wheat for livestock
Topic Sheet No. 9
Winter 1997
Action:
●
Choose the highest yielding
wheat variety on the UK
Recommended List if it is
suitable for your area and if you
can grow it.
●
Grow specific varieties if
required to do so by the animal
feed industry.
●
Grow and store wheat which is
to be used for feeding to animals
as a ‘quality’ wheat; not as a bulk
commodity.
●
Aim for high specific weight
(bushel weight) grain, but be
aware that there does not
appear to be a correlation
between AME and bushel weight
above approximately 69 kg/hl.
Downgrading because of specific
weight below this is possible.
●
Apply optimum nitrogen rates
for maximum yield. Only apply
more than this to improve
protein quality. AME will not be
affected and the crop will be
more likely to lodge.
A B CD E F GH I J K LMNO P QR S T U V
Variety
dietary energy differences
between samples are relatively
unimportant with growing and
finishing pigs.
Preliminary studies on starch
digestibility in ruminants are
continuing.
Dietary protein/amino
acids
Nitrogen fertiliser improved
protein and amino acid content
and digestibility. Thus higher
levels of fertiliser appear
appropriate for feed wheats.
Recent research has been
The future
Current project work is utilising
‘isogenic’ lines. These are lines
which are identical for all varietyspecific characteristics but which
differ in relation to specific genes
which influence nutritional value,
for example grain hardness,
starch structure, protein units.
This will allow us to build a
picture of the likely nutritional
value of individual varieties and
will help plant breeders select
high feeding-value varieties.
Further information:
Project Reports 43, 86, 111
Ongoing projects 0005/1/90,
0014/1/92, 0016/1/92, 0014/1/95
Home-Grown Cereals Authority
Research & Development
Caledonia House
223 Pentonville Road
London N1 9NG