Supplemental progesterone during early pregnancy exerts divergent responses on embryonic characteristics in sows and gilts

Abstract

Progesterone (P4) plays a key role in pregnancy establishment and maintenance; during early pregnancy, P4 stimulates the production and release of uterine secretions necessary for conceptus growth prior to implantation; therefore, exogenous P4 supplementation may improve embryo development. This study evaluated the effects of supplementation during early pregnancy with long-acting injectable progesterone or altrenogest on embryonic characteristics of sows and gilts. Thus, a total of 32 sows and 16 gilts were used. On day 6 of pregnancy sows and gilts were allocated to one of the following groups: non-supplemented; supplemented with 20 mg of altrenogest, orally, from days 6 to 12 of pregnancy; supplemented with 2.15 mg/kg of long-acting injectable progesterone on day 6 of pregnancy. Animals were killed on day 28 of pregnancy, and ovulation rate, embryo survival, embryo weight, crown-to-rump length, uterine glandular epithelium and endometrial vascularization were assessed. Treatments had no effect on pregnancy rate, embryo survival or endometrial vascular density (P > 0.05). Non-supplemented gilts presented larger and heavier embryos compared to gilts from supplemented groups (P < 0.05). Sows in the altrenogest group presented larger and heavier embryos compared to non-supplemented sows and sows supplemented with long-acting injectable progesterone. In conclusion, supplementation of sows and gilts with progestagen from day 6 of pregnancy can be used as a means to improve embryo survival without deleterious effects.

Effect of Exposure to Seminal Plasma Through Natural Mating in Cattle on Conceptus Length and Gene Expression

“…In the pig, this was associated with an increase in CL weight at Days 5-9, which probably explains the increase in P4 secretion that was also observed at this time (O'Leary et al, 2006). Although there is inconsistent evidence on the effect of high P4 on embryo survival in pigs, with some authors reporting a positive effect (Ashworth, 1991;Jindal et al, 1997), others a negative (Mao and Foxcroft, 1998), and others a lack of effect (Muro et al, 2019), P4 prevents embryo resorption (Aisemberg et al, 2013) and is essential for timely progression of early embryogenesis (Zhang and Murphy, 2014) in mice. In cattle, elevated P4 concentrations prior to Day 7 are associated with an altered endometrial transcriptome (Forde et al, 2009) and accelerated conceptus development (Clemente et al, 2009;O'Hara et al, 2014a).…”

Altrenogest during early pregnancy modulates uterine glandular epithelium and endometrial growth factor expression at the time implantation in pigs

“…Likewise, Ravagnani et al (2020) found increased uterine glandular area at 28 days of gestation in gilts with the previous estrus synchronized with 18 days of altrenogest treatment. Muro et al (2020) also reported larger uterine glands at 28 days of pregnancy in gilts supplemented with altrenogest from day 6 to 12 of pregnancy. However, our results are not in agreement with Bailey et al (2010), who did not observe hypertrophy nor hyperplasia in endometrial glands of ovariectomized gilts supplemented with long-acting progesterone.…”

“…Indeed, in bovines, supplemental P4 in early pregnancy affects endometrial gene expression (Forde et al, 2009), which may be the underlying cause of increased embryo development and higher pregnancy rate in cows (Pugliesi et al, 2016). Previously, Muro et al (2020) demonstrated that sows supplemented with altrenogest from day 6-12 of pregnancy had heavier and larger embryos at 28 days of pregnancy. In pigs, there is limited information on the effects of progestagen provided during early pregnancy on the uterine environment.…”

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“…No presente experimento, as fêmeas submetidas à pseudogestação antes da cobertura apresentaram aumento da área glandular média em comparação as fêmeas do grupo controle. Estudos já demonstraram que a hipertrofia das glândulas uterinas foi acompanhada pelo aumento da expressão de IGF-I, VEGF e aumento do peso de embriões coletados no dia 28 da gestação (MURO et al, 2020;2021)…”

“…No dia 5 da gestação fragmentos uterinos de aproximadamente 4 cm 2 foram coletadas da região central do corno uterino esquerdo; a região central foi escolhida para de padronizar a análise. As avaliações do epitélio glandular foram realizadas como descrito por Muro et al (2020). Após a coleta, as amostras foram armazenadas em formalina tamponada a 10% por 24 h e, após esse período, foram processadas para histologia.…”