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FORAGE AND NUTRITION
Guide 2017
38
Post weaning, the sheep were managed using the leader
follower system whereby lambs were allowed access to the
freshest herbage, grazing paddocks to a post grazing sward
height of 5cm and were followed by the ewes who grazed from
5cm to 4cm post grazing sward height. The ewes continued
grazing until they were winter housed in December.
In 2015, lambs grazing the six-species mixture were weaned
at 36kg, this was 4kg heavier than the lambs grazing the PRG
only sward due to higher growth rates from birth to weaning
(see figure 1). Subsequently they were slaughtered on average
25 days earlier than the lambs grazing the PRG sward. All four
treatments were heavier than the national target of 30kg for
twin lambs at weaning. Furthermore, the lambs grazing the
six-species and the nine-species mix required less frequent
anthelmintic treatment than the lambs grazing PRG and PRG/
white clover swards (see figure 2).
The initial results of this work indicate the potential for
high levels of output from pasture-based sheep production
systems to be supported from reduced inputs of N fertiliser
and anthelmintic drugs. The theory behind the reduction of
anthelmintic input is that some of the species included in
the mixture contain condensed tannin which have natural
anthelmintic properties.
Very little is known about why animals grazing multispecies
swards have higher ADGs than lambs on PRG monocultures
but it is most likely to be a combination of higher nutritional
value in multispecies swards, higher intakes, selective grazing
by the lamb and a reduced parasitic burden.
The results presented in this article are preliminary and in need
of further verification before final conclusions can be drawn but
are initially positive. This experiment is part of the Smartgrass
project funded by the Department of Agriculture, Food and the
Marine: RSF 11/S/147.
3
2.5
2
1.5
1
0.5
PRG
PWC
six-species
mix
Sward treatment
No
. of doses
nine-species
mix
Figure 2. The e ect of sward treatment on the number of anthelmintic
treatments required by each lamb.
AD
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