SCHOOL EDITION 8 MARCH 2023 - Flipbook - Page 32
OCTOBER 28 2021
Firms partner with AFBI
to improve nitrogen-use
efficiency in dairy cows
BY DR CONRAD FERRIS
LIVESTOCK PRODUCTION SCIENCES BRANCH
WO of Northern Ireland’s leading animal
nutrition companies, John Thompsons
and Sons Ltd and Trouw Nutrition Ltd,
are partnering with scientists at AFBI to
develop strategies to improve nitrogen-useefﬁciency by dairy cows.
Dairy cow diets contain nitrogen, mostly in
the form of protein. However, nitrogen-useefﬁciency by dairy cows is low, with only
approximately 30 per cent of nitrogen that is
consumed being converted into milk protein.
Much of the remaining nitrogen is excreted
in manure, and this has a number of
n Nitrogen is lost from manure (during
housing, during manure storage and during
ﬁeld spreading) in the form of ammonia gas,
and when deposited on sensitive habitats
this can lead to biodiversity loss and soil
n Ammonia from manures can react with
pollutants in the atmosphere to form ﬁne
particles, and these can cause respiratory
problems in humans.
n Nitrogen in manure can also be lost as
nitrous oxide, a potent greenhouse gas with
a global warming potential almost 300 times
greater than carbon dioxide.
n Nitrogen losses from manure to
watercourses, primarily via leaching, can
cause nutrient enrichment of fresh and
coastal waters (the EU Nitrates Directive was
established to address this issue).
n Protein is generally the most expensive
component of dairy cows diets, so inefﬁcient
use of dietary nitrogen represents an
economic loss. In addition, growing protein
feeds such as soya bean threaten sensitive
ecosystems in some parts of the world.
Recognising these challenges, DAERA,
supported by co-funding from John
Thompsons and Son Ltd and Trouw Nutrition
Ltd, have commissioned AFBI to conduct a
wide ranging research programme which is
designed to identify strategies to improve
nitrogen-use-efﬁciency in dairy cows.
Work which will be undertaken within this
research partnership includes reviewing
existing scientiﬁc literature to identify the
following: relationships between dietary
protein and ammonia excretion from
manures, recent research on protein feeding,
protein feeding systems adopted in Europe,
and approaches to assess the protein status
of cows based on the analysis of milk, blood
In addition, the research will encompass an
extensive data modelling exercise to examine
RESEARCH: Dr Conrad Ferris (AFBI), Jim Uprichard (Trouw Nutrition) and Gordon Donaldson
(John Thompsons and Son Ltd), discuss the research partnership.
drivers of nitrogen-use-efﬁciency in dairy
cows, with this work involving data collected
from approximately 40 studies conducted at
AFBI over the last 25 years.
The project will also involve a series of full
lactation studies in which the direct effect of
protein nutrition on cow performance will be
These studies will also examine the effects
of diet on milk and blood urea levels, ration
digestibility, and the rumen microbiome (the
latter in partnership with QUB), and will
seek to identify alternative approaches, such
as the use of mid-infrared (MIR) analysis of
milk to predict nitrogen-use-efﬁciency. The
economics of adopting lower protein diets
will also be examined.
There is currently considerable pressure,
which will continue to increase, for the dairy
sector to improve the efﬁciency with which
dairy cows utilise dietary nitrogen.
This major project, through the adoption of
a holistic research approach, has potential to
help improve nitrogen-use-efﬁciency within
the local dairy sector, and to ultimately
reduce nitrogen losses to the environment.
Trial could see more breeding
sheep beneﬁt from red clover
group of farmers grazing
as part of a trial could
overturn old fears about
the legume’s impact on sheep
If successful, it is hoped to
encourage other farmers to make
use of the many environmental
and business beneﬁts of using red
The four farmers, who are based
in the West Midlands and Powys,
are working with ADAS as part of a
ﬁeld lab run through the Innovative
Farmers programme, which is
managed by the Soil Association.
They plan to graze a selected
group of their ewes on herbal leys
containing at least 10 per cent red
clover, before and after tupping, to
test the impact on pregnancy rates.
A growing number of sheep
producers are beginning to reap the
beneﬁts of mixed red clover leys, but
the majority are still reticent due to
research conducted 50-60 years ago
in Australia and New Zealand.
Gillian Preece, a sheep farmer
and senior consultant at ADAS, who
is coordinating the ﬁeld lab trial,
says this research now badly needs
updating to reﬂect how UK farmers
actually use red clover.
“We know there are UK sheep
successfully in their grass leys, but
the science hasn’t caught up with
them, and the research that exists
has relevance issues,” says Mrs
“Red clover contains phytooestrogens, which when fed in
large quantities can trick the ewe’s
body into thinking she’s pregnant,
thereby stopping her from cycling.
In previous studies, ewes were
grazed on leys containing 100 per
cent red clover, so they would have
got a big hit of oestrogen.
“But most farmers in the UK would
hardly ever do this and would be
much more likely to include red
clover in smaller quantities as part
of a mixed herbal ley,” explains Mrs
“Without up-to-date research on
this, many sheep farmers are missing
out on the multiple beneﬁts of red
clover, including for soil fertility,
drought resistance, environmental
stewardship payments, and reduced
feed and fertiliser costs.”
One of the farmers taking part in
the trial is Tim Teague, a Romney
sheep producer who farms around
500 acres of mainly grass in
Shropshire. Mr Teague is expecting
to lamb 1,800 - 2,000 ewes next
Spring and has selected 360 of them
for the ﬁeld lab.
Red clover contains phyto-oestrogens,
which when fed in large quantities
can trick the ewe’s body into thinking
she’s pregnant, thereby stopping her
Gillian Preece, senior consultant at ADAS
BENEFITS OF RED CLOVER
Red clover offers a host of benefits, which many sheep producers
are currently missing out on, says Mrs Preece. These include:
n Soil fertility: Red clover is a nitrogen-fixing legume, and so helps
improve soil fertility for the next crop in the rotation.
n Drought resilience: With deep roots, red clover helps with soil
structure and creates a pasture more resilient to drought.
n Protein source: Red clover offers an alternative source of protein
to bought-in feeds.
n Lower input costs: By helping to build soil fertility naturally, red
clover reduces reliance on nitrogen fertilisers.
n Greater flexibility: Being able to graze livestock on mixed red
clover leys throughout the year offers greater grazing flexibility to the
farmer and lowers the risk of running out of grass.
n Farm income: Legume and herb rich swards are currently part of
Countryside Stewardship schemes (e.g. GS4 £309/ha) and are likely
to be part of Environmental Land Management Schemes (ELMS) due
to their many environment benefits.
n Increased biodiversity: Flowering red clover leys encourage
pollinating insects and other wildlife which depend on them.
n Lower emissions/carbon footprint: Less use of nitrogen fertilisers
and bought-in feed lowers green-house-gas emissions, and helps
build a circular economy on farm.
“I’d read lots of conﬂicting advice
about grazing breeding ewes on
red clover,” says Mr Teague. “I
asked everyone I could about it and
everyone who was experienced in
using it said they hadn’t had any
problems with fertility.”
Last year, before the ﬁeld lab
began, Mr Teague tried his breeding
ewes on a ley containing about 25
per cent red clover, with successful
results. “The ewes took the tup
really well – we had a very high
scanning percentage at 188 per
cent,” he says.
Mr Teague says he hopes the trial
will conﬁrm what he has already
found and give other farmers the
conﬁdence to use red clover.
“Red clover really opens up a lot
of opportunities,” says Mr Teague.
“It provides a really high-quality
feed, and so we now ﬁnish as many
lambs as possible on it and tup on it
too. It also helps deal with drought.
Thanks to red clover, we now don’t
buy in any nitrogen fertiliser or
feed other than a bit of fodder beet,
and my business is as resilient as it
could be as a result.”
HOW THE TRIAL WILL WORK
Four farmers, who have ﬂocks of
between 500 and 2,000 breeding
ewes each, have selected at least
160 of their ewes for the trial, which
will then be split in half on their
farms. One group will graze the leys
containing red clover, and the other
(the control group) will graze grass
lays with no clover.
The two groups of ewes will
contain a similar mix of ages, body
conditioning scores and breeds.
Both groups will be grazed for
three weeks before tupping and
throughout the mating season.
They will then be scanned, and
pregnancies recorded. The swards
will be assessed for clover content
when the sheep are initially put on
the ﬁelds, when the rams are put in,
and when the mating period ends.
Samples of both swards will also be
sent off for nutritional analysis.
“Our hypothesis is that if farmers
can use red clover in mixed
leys then they can have all the
beneﬁts without any negative
consequences,” says Mrs Preece.
“There might even be a positive
effect on fertility because such leys
offer high feed quality.
“We hope that by updating the
science we can give farmers the
conﬁdence to use red clover
again, and vets the conﬁdence to
encourage it,” says Mrs Preece.
questions are exactly what farmerled research is designed to answer,”
says Innovative Farmers Manager,
“By giving sheep farmers the
scientiﬁc support to robustly test
red clover leys, this ﬁeld lab is
helping the knowledge and technical
understanding in this area develop
in real time.
“We look forward to seeing
the results, which hopefully
will give farmers conﬁdence in
agroecological farming practices
that can improve their bottom line,
build farm resilience, and protect
The ﬁrst results are expected in
early January 2022.
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