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

- Paper I -
Gilts
When it comes to gilts, the effect of flushing is confirmed in several studies (Cox et al.,
1987; Flowers et al., 1989; Beltranena et al., 1991). The experiments mentioned, have all
been investigating the effect of high (41.7 MJ ME day -1 -ad libitum) contra low (22.6-25 MJ
ME day -1 ) energy intake. A moderate restriction in energy intake (34.0 MJ ME day -1 ) during
day 8-15, but not during day 1-7, in oestrus cycle, seems to impair embryo survival,
however, the number of embryos at day 28 in pregnancy were not affected significantly
(Almeida et al., 2000).
The effect of more restricted feeding of gilts before mating has, as far as we know, not been
studied in the recent years but Anderson (1975), who investigated the effect of total starvation
of gilts in ten days before mating, found that the ovulation rate was reduced compared
to control animals given a full diet (2.7 kg). The question is, however, whether this lower
ovulation rate will result in lower litter size because a positive correlation between the ovulation
rate and the embryo mortality seems to exist (Toplis et al., 1983). In the study by Cox
et al. (1987), the number of fetuses 60 days after mating tended to be decreased in the sows
fed the low energy intake (P