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

Abstract

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.

How does nutrition influence luteal function and early embryo survival

“…Manipulation of feed ingredients (starch or sugars replacing fat) has only marginal effects (Wientjes et al, 2011) on IGF-1. In this respect it is interesting to note that in gilts on a high feed level, replacement of starch in the diet with a fat source increased progesterone secretion (at d15 of pregnancy), whilst luteal tissue mass (at d35) seemed to be unaltered (Athorn et al, 2012a). No difference in IGF-1 was reported between these diets.…”

“…Embryo survival data obtained during early gestation (up to day 15) have to be interpreted with caution. Efficiency of flushing methods (morulas and blastocysts), and the fragility of embryos and morphological aspects once embryos start to elongate, can complicate the assessment of the number of embryos (Jindal et al, 1997;Ashworth et al, 1999;Athorn et al, 2012a).…”

Latest Advances in Sow Nutrition during Early Gestation

“…This is reflected in the correlation between embryo survival to day 35 (r = 0.48 [5]; r = 0.72 [6]) and systemic progesterone in the first three days of gestation. Beyond these first three days, progesterone does not seem to be correlated to embryo survival [3,7], suggesting that the level of progesterone is mainly limiting in the phase where it is still on the rise. At later stages progesterone receptors in the uterus seem to drop [8,9], which may indicate that the role of progesterone changes.…”

“…Porcine luteal tissue grows rapidly and gains maximum size between day 10 and 12 after ovulation, with a total luteal mass around 6 to 8 g in gilts and 10 to 15 g in multiparous sows [1]. The total luteal mass is correlated to the number of follicles that ovulate (correlation coefficient between 0.45 and 0.62; [2][3][4]), and therefore, older sows have more luteal tissue than gilts and primiparous sows. Embryos start secreting oestrogens at ~12 days, a signal for maternal recognition that ensures that luteolysis does not occur when it would normally occur in non-pregnant animals (day [14][15], and in doing so, maintain luteal function.…”

Reproductive performance of ewes grazing lucerne during different periods around mating

“…Some studies observed increased embryo mortality (Parr et al, 1987;Robertson et al, 2015), while others have not (Athorn et al, 2012;Wilkins, 1997). The timing of increased nutrition may have an impact because the sheep embryo is sensitive to the decreased progesterone concentrations that can be induced by feeding greater than maintenance diets on Days 11 and 12 of pregnancy (Parr, 1992), although the rate of increase in progesterone earlier in pregnancy is also important for embryo survival (Ashworth et al, 1989).…”