Acta vet. scand. 2001, 42, 45-55. Impact of Postovulatory Food Deprivation on the Ova Transport, Hormonal Proﬁles and Metabolic Changes in Sows By P. Razdan, A.M. Mwanza, H. Kindahl, F. Hultén and S. Einarsson Department of Obstetrics and Gynaecology, Centre for Reproductive Biology, Swedish University of Agricultu- ral Sciences, Uppsala, Sweden. Razdan P, Mwanza AM, Kindahl H, Hultén F, Einarsson S: Impact of post- ovulatory food deprivation on the ova transport, hormonal proﬁles and metabolic changes in sows. Acta vet. scand. 2001, 42, 45-55. – The effect of food deprivation on ova transport, hormonal proﬁles and metabolic changes was studied in 20 crossbred multiparous sows during their second oestrus after weaning. To determine the time of ovulation, transrectal ultrasonographic examination was performed. The sows were di- vided into 2 groups, one control group (C-group), which was fed according to Swedish standards, and one experimental group (E-group). The E-group sows were deprived of food from the ﬁrst morning meal after ovulation until slaughter. Blood samples were collected every second hour from about 12 h before expected ovulation in the second oestrus after weaning until slaughter and were analysed for progesterone, prostaglandin F2α-metabolite, insulin, glucose, free fatty acids and triglycerides. All sows were slaughtered approximately 48 h after ovulation and the genital tract was recovered. The isthmic part of the oviduct was divided into 3 equally long segments and ﬂushed separ- ately with phosphate buffered saline (PBS). Uterine horns were also ﬂushed with PBS. A signiﬁcantly greater number of ova were found in the ﬁrst and second part of the isth- mus in the E-group (p = 0.05) while in the C-group most of the ova were found in the third part of the isthmus or the uterus (p = 0.01). The level of prostaglandin F2α-metab- olite was signiﬁcantly higher in the E-group compared with the C-group. The concen- tration of progesterone increased in both groups after ovulation but there were no sig- niﬁcant differences between the groups. The other blood parameters showed that the food-deprived sows were in a catabolic state. The 48 h period of fasting results, directly or indirectly in an delayed ova transport, which may be due to a delayed relaxation in the smooth circular muscle layer of the isthmus. sow; isthmus; ova transport; prostaglandin F2a; progesterone; metabolism; stress; re- production; nutrition. Introduction Due to welfare considerations, as well as the urge for a more efﬁcient production, group housing of sows has been an overall common management practice in modern pig produc- tion. Mixing of the sows in these regimes is in general done after mating and, when a new rank order is established among sows aggressive interactions are common (Mendel et al. 1992, Tsuma et al. 1996b). It is not unusual for the more submissive animals to have less or no ac- cess to food (Brouns et al. 1994). This means that the sows are exposed to stress in perhaps the most sensitive stage of gestation since it has been shown that most embryo mortality occurs Acta vet. scand. vol. 42 no. 1, 2001