Reproduction performances and conditions of group-housed non ...

- Paper I -
However, this does not seem to be a possible explanation for the conflicting results in the
mentioned studies given in Table 2.
Anderson (1975) studied the effect of total starvation from ten days before mating to respectively
14, 18, 22, 26, 30 and 34 days after mating and found no differences in embryo
survival rate in the sows that remained pregnant compared to control animals given a full
diet (2.7 kg). The number of embryos was lower in the starved sows but this was because of
a lower ovulation rate and therefore probably founded before mating.
The effect of energy intake in early pregnancy on pregnancy rate has not been subject for
much research. Dyck & Strain (1983) found that the group with low energy supply (17.6
MJ ME day -1 ) in the entire period from mating to 30/35 days after mating had lower pregnancy
rate (64.3%) than the other groups (86.2-87.1%). This was not the case for sows with
low energy supply only in the first ten days of pregnancy. The conception failure occurred
after day ten and before day 30 and the authors therefore hypothesized that the conception
failure was due to failure of either early embryonic growth or implantation.
It has not been possible to find more recent references about the effect of energy intake in
early pregnancy on conception rate. However, Anderson (1975) investigated the effect of
total inanition in gilts from ten days before mating until 14, 18, 22, 26, 30 and 34 days respectively
after mating. They found that 22 of 36 gilts (61 %) remained pregnant. Of these
gilts, six out of six (100 %) remained pregnant after day 14 after mating whereas 13 out of
18 (72 %) remained pregnant when inanition continued to day 18, 22 and 26 after mating
and inanition longer than that resulted in a pregnancy rate of 25 % (three of 12 gilts).
In summary, there are indications that moderate (31.3 MJ ME day -1 ) compared to low
(17.6-22.8 MJ ME day -1 ) energy supply in the first three days after mating can influence
embryo survival negatively in gilts. However, the results are conflicting. The effect of very
low feed intake in early pregnancy in gilts has almost not been studied, but one study did
not find a negative effect of total starvation compared to moderate feed intake in early
pregnancy (34 days) on embryo survival rate in the sows that remained pregnant. Regarding
pregnancy rate, it seems that low energy intake (17.6 MJ ME day -1 or less) compared to
moderate energy supply (29.4 MJ ME day -1 , 2.7 kg) the first 30/35 days in pregnancy may
have a negative effect.
Sows
High energy supply (50.1, 38.4, 48.6 MJ ME day -1 ) when treatment beginning three days
after mating (Toplis et al., 1983) or immediately after mating (Sørensen, 1994) does not
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