Agriculture Reference
In-Depth Information
-10
0
10
Figure 7.2. Farms use different strategies when changing sow feed from gestation diet (solid line) to lactation
diet (dotted line) during the transition period (different strategies are shown by arrows; 0 represents the day
of farrowing).
other causes (Papadopoulos
et al.
, 2010). Yet, other farmers choose to shift the diet only
at parturition, a few days after or even up to 7 d after parturition. The farms using these
latter strategies claim that it is optimal because it reduces the pressure on the sow udder
in early lactation when the suckling ability of the piglets is rather low. The time chosen
for this dietary shift relies much more on a strong belief than on scientific evidence. Such
strong belief also characterizes the choice of the feeding curve used during the transition
period (discussed later). As a corollary, some late-gestating sows are fed lactation diets
and some early-lactating sows are fed gestation diets. At present, it is not common to
feed sows a specific transition diet or to mix gestation and lactation diets in different
proportions to match the rapid changes in nutrient requirements, yet this is an avenue
which should likely be considered.
7.3.2
Contents of energy, lysine and nitrogen in the diet of transition
sows
Dietary energy originates from carbohydrates, protein and fat in sow diets and normally
these three nutrient classes account for approximately 87 to 89% of the feed, whereas
water and minor amounts of minerals and vitamins accounts for the remaining 11 to
13%. Of the energy-supplying ingredients, carbohydrates are always the most abundant
in sow diets, and dietary starch is the most abundant energy source in sow feeds.
Normally, starch accounts for more than 50% of the dry matter fraction of sow feeds.
On an energy basis (gross energy), carbohydrates (starch and fiber) constitute 76 and
64% of the energy in gestation and lactation diets, respectively. In comparison, protein
accounts for 16 and 22% of the energy in gestation and lactation diets, respectively,
whereas dietary fat typically accounts for 8 and 14%, respectively. On an ME basis, the
dietary energy contents of sow diets from various countries are quite similar (Table 7.1)
and range from 11.9 to 13.6 MJ ME/kg in gestation diets, whereas the energy density is
often 6 to 10% higher in lactation diets (13.0 to 14.0 MJ ME/kg). The dietary ME content
may be reduced by including more ingredients rich in fibre, and this is commonly done
when formulating gestation diets. Conversely, the dietary ME content may be increased
by including more dietary fat and most lactation diets are actually formulated with 3 to
5% of supplementary fat. However, in general, dietary energy contents vary by less than
20% across both gestation and lactation diets (Table 7.1). A survey carried out during the
