Agriculture Reference
In-Depth Information
be enhanced piglet vitality, although that is more likely to improve survival of liveborn
piglets rather than reducing stillbirth rate (Baxter
et al.
, 2008).
7.2.7
Colostrum synthesis
Sows start to synthesize colostrum prior to parturition, although it is not known exactly
when this occurs. The first known colostrum component (β-lactoglobulin) was detected
in sow plasma around d 80 of gestation (Dodd
et al.
, 1994), whereas α-lactalbumin (a
part of the enzyme complex that catalyses lactose synthesis) increases in sow plasma
during the last week of gestation. In line with that, Hartmann
et al.
(1984b) reported that
the lactose content of sow plasma increased considerably starting 4 d before parturition,
and these studies indicate that colostral lactose is produced mainly during these last
days of gestation. In contrast, it is not known when colostral fat is produced or when
immunoglobulins and growth factors are being synthesized. From a nutritional point
of view, the production of lactose and the amount of energy secreted via colostrum are
not a major maternal investment, but in terms of protein and amino acids, colostrum
production is clearly a major investment. It was recently found that colostrum yield is
on average 30% higher than previously reported (Theil
et al.
, 2014b) and, consequently,
the maternal investment in terms of protein and amino acids is even greater than
previously believed. The colostrum yield of sows was reported to be on average 5.9±0.1
kg (n=126 sows), but on an individual basis it ranged from 2.7 to 8.5 kg (Theil
et al.
,
2014b; Vadmand
et al.
, unpublished data). It is currently believed that the majority of
colostrogenesis occurs during the last 7 to 10 d of gestation (Theil
et al.
, 2014a). However,
colostrum may potentially also be produced after the onset of farrowing when colostrum
is removed by the piglets. Sow nutrition in late gestation affects the colostrum yield of
sows, and further details on the impact of feed composition on colostrum yield can be
found in Chapter 8 (Quesnel
et al.
, 2015) and in a recent review (Theil
et al.
, 2014a). It is
important to stress that colostrum production does not seem to have a great impact on
the energy requirement by the sow because it is produced over many days, whereas the
impact of colostrum yield on maternal protein and amino acid balances (discussed later)
is much larger. Besides the amount of colostrum produced, colostrum quality may also
be of importance for the piglets, and hence sow productivity, because the total transfer of
nutrients and bioactive components via colostrum is determined both by the volume and
the composition of colostrum. Colostrum contains lactose and fat which are important
for supplying energy to the neonate. In addition, colostrum is very rich in proteins mainly
due to high concentrations of immunoglobulins, but growth factors are also present
(Hurley and Theil, 2011). For a more detailed description of colostrum composition
please see Chapter 9 (Hurley, 2015). Sow nutrition may increase the concentration of
fat or potentially change the concentrations of immunoglobulins and growth factors,
whereas it is not likely that sow nutrition may alter the lactose concentration because
lactose draws water into the alveolar lumen via osmosis. The impact of sow nutrition on
colostrum quantity has been described in details in Chapter 8 (Quesnel
et al.
, 2015)
.
From
a nutritional point of view, the yield of colostrum is more important than its composition
because colostrum yield may vary 3-fold between individual sows whereas colostral
protein concentration varies to a much lesser extent (Theil
et al.
, 2014b; Vadmand
et al.
,
unpublished data).
