Pregnancy development from day 28 to 42 of gestation in postpartum Holstein cows that were either milked (lactating) or not milked (not lactating) after calving

Abstract

The objective was to determine if lactation affects fetal and placental development from day 28 to 42 of gestation. Bos taurus Holstein cows were assigned to one of the two treatments immediately after parturition (lactating (nZ23) or nonlactating (dried off immediately after calving; nZ20)). Cows were inseminated at w60 days postpartum with semen from a single ejaculate. Pregnant cows were slaughtered at 1 of 3 days of gestation (day 28, 35, or 42) and tissues were collected. The interval to first insemination, services per conception, and days to pregnancy were similar for lactating and nonlactating cows. Lactating cows had greater plasma GH and nonesterified fatty acids. Nonlactating cows had greater plasma glucose, insulin, and IGF1. There was no effect of lactation on plasma progesterone or estradiol concentrations. Lactation had a negative effect on the weight of the fetus and placenta (weights were less in lactating cows). Fetuses collected from cows that became pregnant after first insemination were heavier than fetuses collected from cows that became pregnant after second or third insemination. Pregnancy after first insemination was associated with greater blood glucose and IGF1 during the first 30 days postpartum. The conclusions were that lactation negatively affects the growth of fetal and placental tissues perhaps through a mechanism that involves hormones and metabolites that are affected by lactation. Fetal growth within cows conceiving at first insemination compared to second or third insemination was more rapid and was associated with greater blood glucose and IGF1 early postpartum (before day 30).

Endocrine and metabolic mechanisms linking postpartum glucose with early embryonic and foetal development in dairy cows

“…Insulin may have mediated stimulatory effects of glucose on postpartum IGF1 through its capacity to recouple the somatotropic axis. The magnitude of the IGF1 increase in response to glucose that was observed (10 to 15 ng/ml) approximated the magnitude of IGF1 difference reported elsewhere for cows that have or have not commenced oestrous cycles (Beam and Butler, 1998) or postpartum pregnant v. non-pregnant cows (Taylor et al, 2004;Green et al, 2012). The infusion studies demonstrated that a single molecule (glucose) could rapidly reverse the metabolic profile that typifies early lactation.…”

“…Later postpartum (30 to 60 days postpartum) there was no relationship between plasma concentrations of glucose and pregnancy. Green et al (2012) and Garverick et al (2013) examined association between postpartum blood glucose and pregnancy at first AI. In separate studies performed in Ireland (Cummins et al, 2012;Moore et al, 2014), blood concentrations of glucose were examined in dairy cows with similar genetic merit for milk production but with good or poor genetic merit for fertility (Fert + or Fert − , respectively).…”

“…This latter phenomenon is known as the 'Warburg effect' and typifies proliferating cells (Vander Heiden et al, 2009). Green et al (2012) either milked cows normally or dried them off (not milked) immediately after calving. Cows were inseminated at~60 days postpartum and the foetus and placenta were collected on day 28, 35 or 42.…”

Effect of Some Factors on Number of Services per Conception in Dairy Cows

“…High-yielding cows show a higher ability to mobilize energy reserves during the early lactation period [8,9]. This may result in metabolic changes, leading to a decrease in reproductive parameters due to functional changes of the reproductive system [10], which translate into lower conception rate and increased likelihood of pregnancy loss [11].…”

Circulating beta-hydroxybutyrate concentration may be a predictive measurement for young cows that have a greater probability to conceive at a fixed-time artificial insemination

“…Garverick et al (2013) reported an increase in circulating glucose concentrations in postpartum dairy cows that were pregnant at first AI compared with cows that failed to conceive at first AI. Similarly, Green et al (2012) reported decreased plasma glucose concentration during the first 30 d postpartum in dairy cows that did not conceive at first AI when compared with pregnant dairy cows. However, Mulliniks et al (2013) reported elevated serum glucose and reduced insulin concentrations with late conception cows compared with early conception cows.…”