Blood Chemistry, Nutrient Metabolism, and Organ Weights in Fetal and Newborn Calves Derived from In Vitro-Produced Bovine Embryos1

Abstract

Calves born after in vitro production (IVP) of embryos often show reduced perinatal viability. The present experiment investigated a series of physiological variables in the immediate prenatal and postnatal period of IVP dairy calves. Fetal IVP and control calves (each n = 7) were prepared with vascular catheters at 248+/-1 day gestation (term = 280 days), and blood samples were taken for five days before premature delivery by cesarean section. IVP fetuses compared with controls had significantly elevated arterial hemoglobin and oxygen content (8.41 vs. 7.52% and 5.75 vs. 3.79%, respectively) whereas lactate level was lowered (1.89 vs. 2.26 mM). The umbilical venous-arterial concentration differences in oxygen, lactate, and glucose indicated that IVP fetuses relied more on lactate and less on glucose as oxidative substrates. The fetal glucose tolerance, and the basal and adrenocorticotropin-stimulated cortisol levels were similar between the groups. In the immediate postnatal period, IVP calves showed elevated venous blood pH (7.294 vs. 7.270), hemoglobin (9.06 vs. 8.25%), oxygen contents (6.33 vs. 4. 64%), K(+) levels (4.89 vs. 4.56 mM), and rectal temperature (38.9 vs. 37.4 degrees C), and lowered blood Na(+) (139.9 vs. 141.0 mM), Cl(-) (100.2 vs. 103.1 mM) and glucose levels (2.86 vs. 3.11 mM). There were no differences in body dimensions and organ weights, except that the fore legs and hind legs were slightly longer in the IVP group (76.1 vs. 72.4 cm and 93.4 vs. 88.8 cm, respectively). Although prenatal and neonatal IVP calves differed from control calves in a number of variables, the effects were relatively minor and provide no direct evidence for the hypothesis that IVP calves have an impaired capacity to adapt to life ex utero. In fact, several parameters indicated enhanced rather than retarded maturation of IVP calves when data from premature calves were compared with data from a group of control calves delivered at term.

Evidence of increased substrate availability to in vitro-derived bovine foetuses and association with accelerated conceptus growth

“…Values for blood chemistry in animals examined in this study were somewhat similar to those reported by Jacobsen et al (2000) and Sangild et al (2000) for IVP calves, and by Garry et al (1996) and Chavatte-Palmer et al (2002) for clone calves. From this and the results of the aforementioned studies, deviations in blood chemistry appeared to be influenced by calving ease and birth weight.…”

The monitoring of bovine pregnancies derived from transfer of in vitro produced embryos

“…Under experimental conditions a surgical method (installing catheters in the foetal umbilical vessels) has been used to investigate the differences between IVP and A.I. control foetuses with respect to blood chemistry and hormone levels during the final days before delivery [49]. While IVP foetuses had an elevated haemoglobin (and as a consequence a higher oxygen content) and lower lactate levels compared to arterial samples of A.I.…”

“…Besides many (ongoing) studies to unravel the cellular and molecular mechanisms of deviant development of IVF-derived and cloned embryos [11,41,53,64], several authors have reported on placental and foetal growth and pathophysiological events during the perinatal period [18,19,22,26,29,30,47,49,51,59,60]. The bovine foetus and placenta are not easily accessible for (on farm) investigations, especially during the second and third trimester of gestation.…”

Estrone Sulfate and Progesterone Profiles During Late Gestation in Recipient Cows Transferred Embryos Produced by Nuclear Transfer and In Vitro Fertilization

“…It has also been reported that some physiological mechanisms are perturbed as a result of in vitro manipulations apart from changes in imprinting status [44,45]. Studies on fetuses resulting from the transfer of IVP embryos have demonstrated disproportionate organ development in some cases [13,46] but not in others [47,48]. In addition, alterations in the histological development of fetal muscle [49,50] and placental tissue [51,52] have been reported for pregnancies from embryos produced in vitro.…”