Feeding level and dietary energy source have no effect on embryo survival in gilts, despite changes in systemic progesterone levels

This study was designed to assess the effect of feeding level and dietary energy source on luteal function, systemic progesterone concentration and embryo survival in gilts during early gestation. At Day 0 of pregnancy, 104 gilts were allocated to one of four experimental diets (LStarch: 1.2 × maintenance requirement (M) Starch diet (43.3% starch), n = 31; HStarch: 2.4 × M Starch diet (43.3% starch), n = 21; HFat: 2.4 × M Fat diet (13.5% fat), n = 23; and HFibre: 2.4 × M Fibre diet (7.2% fibre), n = 23). On Day 5 of gestation, no significant difference in circulating concentration of systemic progesterone was seen among the treatments. However, on Day 15 of pregnancy, gilts on the HStarch diet had a significantly lower concentration of systemic progesterone than did gilts on both the LStarch and HFat diets (P < 0.05; 24.8 ± 2.4 v. 32.7 ± 2.4 and 36.1 ± 2.1 ng/mL, respectively). At Day 35 of gestation, there was also a tendency for gilts on the HStarch and HFat diets to have a higher total luteal weight than for gilts on the LStarch diets (7.2 ± 0.2 and 7.1 ± 0.2 v. 6.7 ± 0.2 g (P < 0.05)). No difference in embryo survival was seen among the treatments. From the present study, we can conclude that altering feeding level and dietary energy source did not affect embryo survival, despite the fact that systemic progesterone concentrations were affected on Day 15 of gestation. Also, luteal weight was greater for those gilts on the high feeding level than for those on the low feeding level when fed the same energy source.R. Z. Athorn, P. Stott, E. G. Bouwman, A. C. Edwards, M. A. Blackberry, G. B. Martin and P. Langendij