Agriculture Reference
In-Depth Information
uterine tissues are also well characterized (Noblet et al. , 1985). However, studies on the
nutrient requirements for colostrum production are lacking and it is presently unknown
when colostrum is actually being produced and at which rate (Theil et al. , 2014b). For
simplicity it is assumed that colostrum is being synthesized uniformly during the last
10 d of gestation. Also, the growth rate, and hence nutrient requirements, for mammary
growth in late gestation is unknown, although it is known that mammary growth is faster
before parturition than after (Kim et al. , 1999b; Noblet et al. , 1985). For late gestating
sows, the unknown dynamics of nutrient requirements are of minor importance from an
energetic point of view because most of the energy is required by the sow body and not by
reproductive tissues. In contrast, the production of colostrum is important for evaluating
the requirements of protein and essential amino acids.
After parturition, nutrients are required for milk production, maintenance, mammary
growth and heat loss associated with these reproductive traits. The regressing uterus has
a considerable impact on the amounts of amino acids and protein required by the sow.
Since no information is available in the literature on how fast regression of the uterus
occurs, it is assumed in this mathematical model that the uterus regresses during the first
week of lactation. The assumptions that colostrum is being produced uniformly over 10 d
and that the uterus regresses over 7 d are clearly too simple and further research is needed
to better evaluate the timing of these processes.
7.4.2
Energy requirement
Sow maintenance is the major contributor to the energy requirement in late gestation
(Figure 7.5). From d 105 to 115 of gestation, sows require approximately 39 MJ/d of
metabolizable energy (Feyera and Theil, 2014) and, by far, the highest proportion (79%)
is lost as heat (30.5 MJ/d; Noblet et al. , 1985, Theil et al. , 2002). The remaining 21% is
retained in reproductive tissues or products, such as colostrum (3.6 MJ/d), fetal growth
Uterus (+ placenta + uids + membranes)
80
Fetal growth
Milk/colostrum
60
Mammary growth
Additional heat loss
40
Maintenance
20
0
-10
-8
-6
-4
-2
0
2
4
6
8
10
Day relative to parturition
Figure 7.5. Energy requirement of transition sows. ME = metabolizable energy.
 
Search WWH ::




Custom Search