An increased supply of amino acids to
sows in late gestation is being suggested
to improve litter birthweights.
on to a lactation-type amino acid profile. In
this instance, the extra feeding produced no
additional litter weight at farrowing, nor was
there any less variability for size between the
individual pigs.
But Danish advisers insist from practical
experience that sows receiving more protein
or amino acids in their feed in the last four
weeks before farrowing go on to give birth
to heavier piglets.
Strong support for this view can be
seen in recently revised recommendations
in Germany. Since its revision completed in
2006, the German animal feeding authority
Gesellschaft für Ernährungsphysiologie or
GfE has advocated feeding to promote the
growth of fetuses by adding to the amino
acid levels for sows from Day 85 of gestation. In a similar direction, Canadian studies
at the University of Alberta were reported to
the Banff seminar to have demonstrated a
doubling of the sow’s requirement for threonine in the final third of gestation, in order
to achieve maximum synthesis of protein
for the litter.
Recommendations
Of course, in a North American context,
such remarks will always be judged alongside the published recommendations of the
National Research Council. Alberta’s indications on the late-stage gestation needs for
threonine are considerably above those cited
by NRC in 1998. Other work at the same
center has reported that whereas NRC-98
said non-pregnant sows needed 36 mg/
kg0.75 of lysine per day for maintenance, the
daily lysine requirement in a high-productivity
population of Hypor sows was determined to
be about 30% greater at 49 mg/kg0.75.
There is also a seasonal factor to be taken
into account. In Alberta’s results, the heat
production of the sows was shown to be at its
lowest when their dietary lysine was at least
adequate, at 46.8 mg/kg0.75. The risk of heat
stress on sows in the summer months often
is addressed by an adjustment of the nutrient
density of their diet as compensation for any
downturn in daily feed intake. While feeding
less crude protein to the sow in hot times
certainly works, however, the percentage
reduction achievable in practice is limited by
the necessity of maintaining the balance of
amino acids available through the feed.
A common way of judging the essential
amino acids (apart from lysine) required by
the lactating sow depends on determining
how much she secretes in her milk. But
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