Agriculture Reference
In-Depth Information
though the increased litter size may have reduced the mean piglet birth weight. From
a nutritional point of view, the actual litter size should ideally be taken into account to
allow a more optimal nutrient supply to the sow during the transition period. However,
from a practical point of view this is not possible because the litter size is unknown prior
to parturition. After parturition, litters are typically equalized on d 1 or 2 of lactation,
thereby correcting the variation for this biological trait.
7.2.3
Glycogen depots in newborn piglets
Newborn piglets are highly vulnerable to dying from insufficient energy supply (Theil
et
al.
, 2014a). During the colostrum period, neonatal piglets oxidize substantial amounts
of glycogen from the liver and muscles (Pastorelli
et al.
, 2009; Theil
et al.
, 2011) in order
to cope with the low ambient temperature in the extra-uterine environment and with
their very large heat loss due to a high surface to volume ratio of the body. Glycogen
is retained in fetuses during late gestation (not only during the last 10 d) and the main
purpose of these depots is indeed to supply neonatal piglets with energy. Genetic
selection for increased piglet survival seems to have increased glycogen retention in liver
and muscle tissues during fetal life (Leenhouwers
et al.
, 2002). Glycogen retained in a
litter of 17 newborn piglets totals roughly 1 kg (Theil
et al.
, 2011), and this amount is
roughly equivalent to the starch content of 2 kg of standard sow gestation feed. Since
glycogen depots are built-up during the last 2 to 4 wk prior to parturition (Père, 2003)
and sow gestation diets are very rich in starch, the glycogen depots in newborn piglets
may not need to be considered from a quantitative nutritional point of view. However,
from a welfare and economical point of view, it is indeed of interest to study whether the
glycogen depots can be improved by altered sow nutrition. Seerley
et al.
(1974) reported
a greater concentration of glycogen in the liver of newborn piglets when sows were fed
additional energy from cornstarch beginning on d 109 of gestation. According to Jean
and Chiang (1999), hepatic glycogen content of piglets 4 h after birth was greater if
their dam was fed either 10% medium chain fatty acids or 10% coconut oil from d 84 of
gestation until farrowing, as compared with sows fed soybean oil. However, Boyd
et al.
(1978) reported no beneficial effect on liver glycogen concentration in newborn piglets
when sows were fed additional energy from either cornstarch or tallow from d 100 of
gestation until farrowing. Likewise, Newcomb
et al.
(1991) found no effects of feeding
sows with starch, soybean oil, or medium-chain triglycerides for the last 14 d of gestation
on hepatic glycogen of newborn piglets.
7.2.4
Placenta, uterus, fluids and membranes
The placenta and uterus also grow in an exponential fashion in late pregnancy, hence, the
retention of nutrients is high during the last 10 d of gestation. In Contrast, the volume of
amniotic fluid peaks around d 80 of gestation (Noblet
et al.
, 1985) and membranes grow
quite slowly so these traits require negligible amounts of nutrients during late gestation.
The amount of energy required for growth of the placenta and uterus (lean growth) is also
rather low and may be neglected, but the amounts of amino acids required for their lean
growth are substantial (Noblet
et al.
, 1985). During the farrowing process, placenta, fluids
and membranes are expelled from the sow and, consequently, nutrients retained in these
