Effect of increasing progesterone concentration from Day 3 of pregnancy on subsequent embryo survival and development in beef heifers

Abstract

Higher systemic progesterone in the immediate post-conception period is associated with an increase in embryonic growth rate, interferon-tau production and pregnancy rate in cattle. The objective of this study was to examine the effect of increasing progesterone concentration on Day 3 on subsequent embryo survival and development. Oestrus (Day 0) was synchronised in beef-cross heifers (n=210) and approximately two-thirds of the heifers were inseminated with semen from a proven sire, while the remainder were not inseminated. In order to produce animals with divergent progesterone concentrations, half of the animals received a progesterone-releasing intravaginal device (PRID) on Day 3 of the oestrous cycle, which was left in situ until slaughter. The four treatment groups were: (i) pregnant, high progesterone; (ii) pregnant, normal progesterone; (iii) non-pregnant, high progesterone; and (iv) non-pregnant, normal progesterone. Animals were blood-sampled twice daily from Days 0 to 8 and once daily thereafter until slaughter on Days 5, 7, 13 or 16, corresponding to the 16-cell stage, the blastocyst stage, the beginning of elongation and the day of maternal recognition of pregnancy, respectively. Embryos were recovered by flushing the tract with phosphate-buffered saline and characterised by stage of development and, in the case of Days 13 and 16, measured. Data were analysed by mixed models ANOVA, Chi-square analysis and Student's t-test where appropriate. Insertion of a PRID on Day 3 increased (P<0.05) progesterone concentrations from Day 3.5 onwards. There was no difference between treatments in the proportion of embryos at the expected stage of development on Days 5 or 7 (P>0.05). While not significantly different, the proportion of viable embryos recovered was numerically greater in the high progesterone group on both Day 13 (58 v. 43%) and Day 16 (90 v. 50%). Elevation of progesterone significantly increased embryonic length on Day 13 (2.24+/-0.51 mm v. 1.15+/-0.16 mm, P=0.034) and Day 16 (14.06+/-1.18 cm v. 5.97+/-1.18 cm, P=0.012). In conclusion, insertion of a PRID on Day 3 of the oestrous cycle increased serum progesterone concentrations on subsequent days, which, while having no phenotypic effect on embryonic development on Days 5 or 7, was associated with an increase in embryonic size on Days 13 and 16.

Evaluation of models to induce low progesterone during the early luteal phase in cattle

“…Blood samples were stored at room temperature for 1 h and at 4°C for a further 16 h. Serum was decanted after centrifugation for 20 minutes at 1600 x g and stored at -20°C until subsequent analysis. Serum progesterone concentrations were measured using a time-resolved fluorescentimmunoassay (FIA) with an AutoDELFIA™ Progesterone kit (Perkin Elmer, Wallac Oy, Turku, Finland) as previously used by Carter et al (2008). All samples were assayed within a single assay.…”

Maternal-embryo interaction leading up to the initiation of implantation of pregnancy in cattle

“…Addition of P4 to culture medium had no effect on blastocyst formation (Clemente et al, 2009;Larson et al, 2011) or elongation after transfer to synchronized recipients (Clemente et al, 2009). Most convincingly, the embryo does not need to be present in the uterus during the period of P4 elevation in order to benefit from it (Clemente et al, 2009;O'Hara et al, 2014), strongly suggesting that the effect of P4 is via advancing the endometrial transcriptome (Forde et al, 2009) resulting in advancing conceptus elongation (Carter et al, 2008;Clemente et al, 2009). In addition reducing the output of P4 from the CL results in a delay in the temporal changes in the endometrial transcriptome resulting in delayed conceptus elongation in vivo (Forde et al, 2011a and2012a).…”

Physiological and practical effects of progesterone on reproduction in dairy cattle

“…These results are consistent with the studies of (Larson et al, 2011) that also failed to find a direct effect of P4 during either days 1 to 3 or days 4 to 7 of culture on percentage of embryos that developed to the morula or blastocyst stage; although small differences in glucose metabolism were observed. Further evidence for a lack of P4 effect in early embryo is found in the studies of Carter et al, 2008 and In the first experiment, 210 crossbred beef Wiltbank, Souza, Carvalho, Cunha, Giordano, Fricke, Baez and Diskin 76 heifers were used to analyze the effects of in vivo supplementation with P4 on embryo development. These researchers observed no difference in early embryo development by day 5 or 7 after AI, however dramatic effects of P4 supplementation on embryonic length could be observed on day 13 and 16 after AI (Carter et al, 2008).…”

“…Further evidence for a lack of P4 effect in early embryo is found in the studies of Carter et al, 2008 and In the first experiment, 210 crossbred beef Wiltbank, Souza, Carvalho, Cunha, Giordano, Fricke, Baez and Diskin 76 heifers were used to analyze the effects of in vivo supplementation with P4 on embryo development. These researchers observed no difference in early embryo development by day 5 or 7 after AI, however dramatic effects of P4 supplementation on embryonic length could be observed on day 13 and 16 after AI (Carter et al, 2008). In an elegant study that continued this research focus (Carter et al, 2010), in vitro produced embryos were transferred to the oviduct of beef heifers that received or did not receive a PRID on day 3 after estrus.…”