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gestation. After parturition, the amount of nitrogen lost in the urine increases along with
feed intake and the amount of nitrogen required increases with milk yield throughout
the transition period. Concomitantly, the uterine degradation contributes 19% of the
calculated daily nitrogen requirement on d 2, whereas the uterine supply decreases to
11% on d 7 (Figure 7.7). It is noteworthy that the calculated daily nitrogen requirement
increases much less from gestation to lactation than does the requirement for lysine. This
could indicate that protein may be a limiting factor for sow productivity in late gestation
and that lysine may be limiting after parturition.
7.4.5
Nutrient balances during transition
Transition sows fed a standard gestation diet until one week prior to parturition are
exposed to minor negative balances of lysine and nitrogen, but to a slightly positive
energy balance (Figure 7.8; Feyera and Theil, 2014). If the gestation diet is replaced by
a standard lactation diet at the onset of the transition period, all three balances become
positive until the feed supply is eventually lowered (for instance during the last 3 d
before parturition), as recommended in Denmark. This decreased feed supply leads to
negative balances of lysine, nitrogen and energy until parturition. After parturition, the
nitrogen balance is constantly positive, the lysine balance is close to zero and the energy
balance is negative initially but becomes zero after approximately one week. The slightly
positive balances of energy, lysine and nitrogen after the dietary shift in late gestation
indicate that nutrient requirements of sows are met quite well by the feed composition
and feeding level prior to parturition. In contrast, the positive nitrogen balance along
with the negative energy balance in early lactation indicates that the lactation diet is not
well balanced with nutrients required to support milk production.
Uterus (+ placenta + uids + membranes)
120
Fetal growth
Milk/colostrum
Mammary growth
80
Urine (maintenance + additional loss)
40
0
-10
-8
-6
-4
-2
0
2
4
6
8
10
Day relative to parturition
Figure 7.7. Nitrogen requirement of transition sows. SID = standardized ileal digestible.
 
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