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separately for gestation and lactation instead
of providing a single diet for the whole period
(Dourmad et al ., 1999). In practice, this is al-
ready achieved in most farms. Nevertheless,
excretion could be reduced even further by
using two- or multiphase feeding programmes
during gestation. However, this requires a
precise evaluation of requirements, which
can be achieved using modelling approaches.
Using InraPorc, we simulated the utiliza-
tion of SID lysine by sows over four parities,
with three different feeding strategies that dif-
fered in nutrient supplies during gestation. In
the first feeding strategy the sows received a
single gestation diet during the entire gesta-
tion period and a lactation diet during lacta-
tion. The feeding level during gestation was
adjusted according to body condition, and in-
creased by 400 g/day during the last 3 weeks
of gestation. During lactation, feed intake was
assumed to be close to ad libitum . Diets were
formulated on a least-cost basis and their
composition is given in Table 4.5. From the
results presented in Fig. 4.5a , it is clear that
the digestible lysine requirement is much
higher at the end than at the beginning of ges-
tation. Moreover, the lysine requirement de-
creases with parity and this decrease is even more
marked when the requirement is expressed
per kilogramme of feed rather than per day.
This means that when the same diet is fed to
all gestating sows, the amino acids and pro-
tein supplies exceed the requirement, espe-
cially during the beginning of gestation and in
older sows. This can be improved by feeding
two different diets to gestating sows, depend-
ing on parity and gestation stage.
This strategy was evaluated ( Fig. 4.5b )
and two gestation diets were formulated dif-
fering in their amino acid and protein con-
tents. The first diet contained 3.8 g of digest-
ible lysine and 102 g of crude protein (CP)
per kilogramme of feed. It was used during
the first 80 days of gestation, except for first
parity sows. The second diet contained 5.5 g
of digestible lysine and 145 g of CP per kg
of  feed and was used in first parity sows
throughout gestation, and in other sows
from day 80 of gestation. Other amino acids
were supplied according to the ideal pro-
tein requirement. This two-phase feeding
strategy allowed for a much better adjust-
ment of amino acids supplies to sows' re-
quirements. With this strategy total con-
sumption of CP and SID lysine were reduced
by 10% and 11%, respectively. This resulted
Table 4.5. Effect of different feeding strategies (one phase, two-phase and multiphase) of sows on nitrogen
and phosphorus excretion and the cost of feed ingredients.
One-phase
Two-phase
Multiphase
Diet composition (g/kg)
Crude protein
Gestation 1
-
102.1
99.7
Gestation 2
145.0
145.0
145.0
Lactation
160.0
160.0
160.0
Digestible lysine
Gestation 1
-
3.80
3.00
Gestation 2
5.50
5.50
5.50
Lactation
8.75
8.75
8.75
Cost of feed (€/sow) a
Per cycle
80.7
76.0
74.4
Per day
0.550
0.518
0.507
% of strategy 1
100%
94%
92%
Nitrogen excretion (g/sow)
Per cycle
8309
7071.5
6718
Per day
56.6
48.2
45.8
% of strategy 1
100%
85%
81%
a 2009 prices for feed ingredients in Western France.
 
 
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