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

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sol in oestrus cycle impaired the pre-ovulatory oestrogen surge, the preovulatory LH surge
and the timing between oestrus behaviour and LH surge in female pigs (Turner et al.,
2002). Likewise did administration of AdrenoCorticoTrophic Hormone (ACTH), followed
by an increase in cortisol in very early pregnancy impede the cleavage rate of the embryos
(Razdan et al., 2002).
Furthermore, there are also indications that the endocrine regulation may be influenced by
energy intake. A positive correlation is believed to exist between the levels of the energy
related hormones, insulin and IGF-1, and the levels of LH and FSH (Hughes & Pearce,
1989; Peltoniemi et al., 1995). Finally, there are indications that a high level of feed intake
may reduce the level of progesterone (Hughes & Pearce, 1989; Foxcroft, 1997).
It therefore seems that both stress and energy intake may influence the reproduction physiology
of the sow. These factors might be very much affected by the group housing system.
In commercial group housing systems, mixing of unfamiliar sows often occur and in a
number of studies, mixing of unfamiliar sows have lead to a more or less long-lasting elevated
level of cortisol in plasma (Pedersen et al., 1993; Tsuma et al., 1996; Olsson &
Svendsen, 1997b). Likewise, there are several indications that group housing may lead to
individual variation in energy intake between sows (Brouns & Edwards, 1994; Olsson &
Svendsen, 1997a; Andersen et al., 1999).
References
Andersen, I.L., Bøe, K., Kristiansen, A.L., 1999. The influence of different feeding arrangements and food
type on competition at feeding in pregnant sows. Appl. Anim. Behav. Sci. 65, 91-104.
Anderson, L.L., 2000. Pigs. In: Hafez, E. S. E., Hafez, B. (Eds.), Reproduction in farm animals. Lippincott
Williams & Wilkins, New York, pp. 182-191.
Ashworth, C.J., 1991. Embroyo development. Pig News and Information 12[4], 551-554.
Bazer, F.W., Geisert, R.D., Thatcher, W.W., Robert, R.M., 1982. The establishment and maintenance of
pregnancy. In: Cole, D. J. A., Foxcroft, G. R. (Eds.), Control of Pig reproduction. Butterworth Scientific,
London, pp. 227-252.
Bazer, F.W., Marengo, S.R., Geisert, R.D., Thatcher, W.W., 1984. Exocrine versus endocrine secretion of
prostaglandin F2a in the control of pregnancy in swine. Animal Reproduction Science 7, 115-132.
Britt, J.H., Armstrong, J.D., Cox, N.M., Esbenshade, K.L., 1985. Control of follicular development during
and after lactation in sows. Journal of Reproduction and Fertility, Suppl. 33, 37-54.
Brouns, F., Edwards, S.A., 1994. Social rank and feeding behaviour of group-housed sows fed competitively
or ad libitum. Applied Animal Behaviour Science 39, 225-235.
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