Effect of food deprivation during early pregnancy on endocrine changes in primiparous sows

The effect of food deprivation during early pregnancy on maternal plasma endocrine levels and on embryonic survival was studied in primiparous sows. Twelve cross-bred (Swedish Yorkshire × Swedish Landrace) primiparous sows at the same stage of pregnancy were used. Six sows were fasted on Days 10 and 11 of pregnancy, with free access to water. The other six sows were fed as usual and used as controls. Blood samples were collected from Days 7 to 14 of pregnancy for cortisol, corticosteroid-binding globulin (CBG), progesterone (P4), oestradiol-17β (E2), oestrone sulphate and prostaglandin F2α metabolite (PG-metabolite) analysis. The sows were slaughtered on Day 17 of pregnancy and embryos recovered. Cortisol concentrations rose (P < 0.001) during food deprivation and were greater (P < 0.05) than in the control sows. In both groups of sows CBG concentrations were similar and decreased (P < 0.05) from Day 7 to Day 14 of pregnancy. P4 levels increased dramatically during fasting; P4 levels were higher on the first (P < 0.08) and second (P < 0.03) days of fasting than in the control sows. E2 levels decreased (P < 0.05) during fasting, with lower (P < 0.05) levels on the second compared with the first day of fasting. E2 levels on the second day of fasting were lower (P < 0.05) in the fasted compared with the control sows. Oestrone sulphate concentrations were low in both groups of sows and remained unchanged during the experimental period. PG-metabolite concentrations were elevated (P < 0.001) during food deprivation. Mean embryonic survival was 71.4 ± 4.7% and 64.5 ± 5.6% respectively for the control and fasted sows. In conclusion, food deprivation on Days 10 and 11 of pregnancy elevated maternal plasma cortisol, P4 an PG-metabolite levels concomitant with a fall in E2 levels. Neither CBG nor oestrone sulphate levels changed during the experimental period.