Agriculture Reference
In-Depth Information
display reduced sow longevity and are an economic hardship to the producer. Improper
nutrition can exacerbate early culling of sows for a variety of reasons. The effects of
improper nutrition on sow longevity can begin early in the sow's life. Some researchers
have suggested that nutritional and physiological factors during gilt development can
influence lifetime productivity and longevity of breeding sows (Hoge and Bates, 2011;
Johnston
et al.
, 2007; Nikkila
et al.
, 2013) This is covered in more details in Chapter 1
(Rozeboom, 2015) and Chapter 19 (Caldéron Díaz
et al.
, 2015). Sows that are fed too
generously during pregnancy and(or) wean small litters while allowed
ad libitum
access to
feed become fat and overweight. Fat, overweight sows typically have increased farrowing
problems, and locomotion disorders which result in a shorter herd life than sows in
trimmer body condition (Dourmad
et al.
, 1994). Conversely, sows that become too thin
due to inadequate energy and nutrient intake experience reduced time in the breeding
herd (Anil
et al.
, 2006; Knauer
et al.
, 2010) and increased culling rates (Hughes
et al.
,
2010). Proper development and maintenance of the skeleton is important for long herd
life of sows. Nutrition, particularly mineral nutrition, has important effects on proper
development and maintenance of bone, articular cartilage, and associated joints (Van
Riet
et al.
, 2013). Insufficient supply of bioavailable Ca and P, and vitamin D, among
other nutrients can predispose sows to claw lesions and lameness (Van Riet
et al.
, 2013)
(see also Chapter 18; Friendship and O'Sullivan, 2015) which ultimately leads to culling
(Anil
et al.
, 2007).
Usually, negative effects of improper nutrition seem to have a cumulative effect on
sow performance and longevity. With each successive reproductive cycle, even slight
nutritional deficiencies in previous parities are accentuated; eventually functionality of
the sow is compromised and she is culled from the herd. This phenomenon contributes
to the concept that feeding in one stage of the sow's reproductive cycle influences current
and future sow productivity.
6.3
Energy feeding
6.3.1
Energy systems and methods of expressing energy needs:
digestible, metabolizable and net energy
Dietary formulations based on digestible energy (DE) and metabolizable energy (ME)
systems are increasingly replaced with formulations based on the net energy (NE) system.
The NE system provides a closer estimate of the 'true' energy available from feed ingredients
for the synthesis and retention of proteins and fats (Payne and Zijlstra, 2007). Figure 6.1
illustrates the flow of energy from feed energy to retained energy in proteins, fats, and
fetal glycogen in the gestating sow or milk components (lactose, proteins and fats). The
DE is the energy digested based on apparent total tract digestion and absorption of the
energy yielding nutrients including proteins, carbohydrates and fats. Hence the difference
between feed energy and DE represents the energy of undigested nutrients excreted in the
feces (i.e. fecal energy). The main products of protein, carbohydrate and fat digestion that
appear as absorbed nutrients in the blood circulation are amino acids, monosaccharide's
plus (volatile) organic acids, and fatty acids, respectively. These nutrients are used either
