Lipogenesis and pancreatic insulin release in fetal pigs

Body composition, liver and adipose lipogenesis, and pancreatic insulin release were examined in intact and decapitated fetal pigs on d 110 of gestation. Decapitation was on d 45 of gestation. Decapitated fetuses deposited more body lipid and less body ash compared with intact fetuses. Body weight, water, dry matter and protein remained similar in intact and decapitated fetuses. Hepatic fatty acid esterification and synthesis were two- and threefold greater, respectively, in decapitated than in intact fetuses. Fatty acid synthesis in subcutaneous adipose tissue of decapitated fetuses was three times greater than values obtained in intact fetuses. The data supported the concept that substrate availability from the dam was not the rate-limiting step in fetal pig lipid synthesis and storage. High growth hormone levels in normal fetal pigs may be responsible for inhibiting lipogenesis, while fetal decapitation would remove this inhibition and be associated with greater lipid deposition. However, pancreatic insulin release was greater in decapitated than in intact fetuses; an indication that elevated lipid deposition may also be due to greater fetal insulin secretion.     

Hematopoiesis in the feline fetal liver: an assessment by flow cytometry

The domestic cat is an excellent model for the development of therapeutic protocols that target hematopoietic stem cells (HSCs) because it is relatively resistant to complications related to bone marrow transplantation. To identify a plentiful source of HSC that could be used as targets for gene transduction and transplantation, the livers of 28 mid-gestation fetuses (28-52 days) and late-gestation fetuses (53 days-term) were analyzed for erythroid, myeloid, lymphoid, and uncommitted hematopoietic progenitor cells by flow cytometry. We found that the fetal liver mononuclear cells (FLMCs) contained 57% erythroid progenitors during mid-gestation, but this percentage declined to 43% as gestation progressed. Myelomonocytic cells within FLMC were more numerous in late-gestation (31%) than in mid-gestation (18%). Two monoclonal antibodies (mAb), CH 152 and CH 755, which recognize cells with the potential to reconstitute multilineage hematopoiesis in cats, were tested. Approximately, 32% of FLMC from late-gestation fetuses expressed the epitope recognized by mAb CH 152, a significant increase above the 12% positive cells in mid-gestation fetuses. Approximately, 33% of hepatic mononuclear cells expressed the epitope recognized by mAb CH 755 in both mid-term and late-term fetuses. When expressed in absolute numbers, medians of 2.7 x 10(7) CH 152-positive cells and 3.2 x 10(7) CH 755-positive cells were extracted from the late-term fetal livers of individual cats. T-lymphocytes were a minor component (<3%) of FLMC, despite their presence in the thymus and spleen. These data suggest that the late-term feline fetal liver is a suitable source of mutipotential hematopoietic cells that could be used for gene therapy protocols in the cat.     

Relations between maternal and fetal plasma concentrations of placental lactogen and placental and fetal weights in well-fed ewes

The concentration of ovine placental lactogen (oPL) in maternal plasma varies with litter size and nutritional status, making it difficult to compare these concentrations across studies. In this study, 27 Dorset and Finn-Dorset crossbred ewes with litters of known size and gestational age were used to relate concentrations of oPL in maternal plasma to placental and fetal weights. Fetal oPL concentrations also were correlated to these variables in 12 chronically catheterized singleton fetuses. The concentration of oPL in maternal plasma increased with increasing placental weight across litter sizes ranging from 1 to 3 (r = .716). When expressed per gram of placenta, oPL was greater (P less than .05) in those ewes carrying multiple fetuses. There was no correlation between maternal and fetal oPL in time-matched samples or in average values between individuals for ewes carrying singleton pregnancies. Within the singleton group, placental weight and fetal weight were well correlated (r = .761), as were the concentration of fetal plasma oPL and fetal weight (r = .699). Placental weight plus fetal oPL could explain 81% of the variation seen in fetal weight. These results imply that maternal and fetal oPL release are controlled independently and that fetal oPL affects fetal growth by a mechanism not directly related to placental size.     

Relationship of fetal position within the uterus to fetal weight, placental weight, testosterone, estrogens, and thymosin beta 4 concentrations at 70 and 104 days of gestation in swine.

Fetal intrauterine position relative to the sex of adjacent fetuses has an effect on reproductive performance in rodents. An experiment was conducted to determine whether sex of adjacent fetuses in utero has an influence on fetal and placental weights and whether the hormonal mechanisms documented in rodents are similar in fetal pigs. Sows were slaughtered at 70.1 +/- 1.7 d (n = 123) and 104.5 +/- .05 d (n = 135) of gestation. The fetuses and placentas were removed from the uterus and the position and sex of each fetus was recorded to indicate whether the fetus was between two males, two females, or a male and a female. Fetal blood was sampled for later hormonal analysis. At 70 d of gestation, male fetal and placental weights were heavier than those of females (P less than .05), but no differences were detected relative to the sex of adjacent fetuses. At 104 d of gestation, a fetus surrounded on each side in utero by fetuses of the opposite sex (two males or two females) was lighter in weight than a fetus surrounded by fetuses of the same sex (P less than .01). Differences in fetal weight due to the sex of adjacent fetuses were not related to placental function because placental weights were generally not different at 104 d of gestation. By 104 d of gestation, most placentas were not separated by necrotic regions and were in close apposition with surrounding placentas. No differences in growth or development could be related to hormonal effects (testosterone, estrone, or estrone sulfate) from surrounding fetuses.(ABSTRACT TRUNCATED AT 250 WORDS)     

The relationship of fetal weight to serum albumin and alpha-fetoprotein in swine

The within-litter relationship of fetal weight to fetal serum albumin and alpha-fetoprotein (AFP) was investigated at d 30 to 40, 45 to 50, 50 to 60, 75 to 85 and 90 to 105 of gestation in swine. Regression equations were calculated on individual litters and regression coefficients pooled across litters within each gestational age group. Coefficients for the regression of albumin on fetal weight (microgram . ml-1 . g fetus-1) were significant over all groups and ranged from 22.5 +/- 6.6 to d 45 to 50 to .7 +/- .2 at d 95 to 105. There was no significant relationship between AFP levels and fetal weight at any gestational age. Unilateral ovariectomy-hysterectomy was performed before mating to study effects of uterine crowding on the relationship of fetal weight to AFP and albumin. Although the total number of ovulations was not different from controls, this treatment resulted in only about 1.3 more fetuses/uterine horn compared with controls at either d 40 or 60 of gestation. Fetal weights in crowded litters were not different from controls. However, AFP levels in fetuses from crowded litters were lower than in control fetuses at d 40 (4.5 +/- .1 vs 6.7 +/- .5 mg/ml). Albumin levels in crowded fetuses were significantly lower than in controls at d 60 (342 +/- 50 vs 653 +/- 41 micrograms/ml). Because none of these differences in albumin or AFP could be attributed to variation in fetal weight or fetal number at the time of sample collection, it is possible that more extreme uterine crowding earlier in development resulted in these differences. These results demonstrate that fetal serum albumin concentrations are related to fetal weight when analyzed on a within-litter basis and that unilateral ovariectomy-hysterectomy may affect serum concentrations of both AFP and albumin early in fetal development. Future studies involving the regulation of synthesis of these proteins at the cellular level during development should provide information as to how factors affecting overall fetal growth and development influence the expression of a single gene. Previously, such markers that are amenable to study early in development have been lacking.     

Neospora caninum and complex vertebral malformation as possible causes of bovine fetal mummification

Bovine neosporosis, caused by Neospora caninum is a leading cause of abortion in cattle. We postulated that neosporosis could lead to fetal death and mummification. Fifteen mummified fetuses were tested by polymerase chain reaction (PCR) for the mutation in the bovine SLC35A3 gene that causes complex vertebral malformation (CVM) and the pNC-5 gene which identifies N. caninum infection. DNA was extracted from the mummified fetuses and the sex of the mummies was determined by PCR. The CVM mutation was not detected in the mummified fetuses, but 4 fetuses were positive for N. caninum infection. The ages of the mummies with N. caninum infection were 100, 113, 123, and 131 days. Twelve of the 15 mummified fetuses were male. To our knowledge, this is the first detection of N. caninum as a possible cause of bovine fetal mummification.     

Experimental fetal infection with bovine viral diarrhea virus. I. Virological and serological studies.

The serological and virological results of an experimental infection of bovine fetuses with bovine viral diarrhea virus are presented. Four fetuses, 120-165 days gestational age, were inoculated in utero with a second passage virus strain. Two fetuses received a sham-inoculum. A humoral immune response in the virus-inoculated fetuses, was demonstrated three weeks later. In three fetuses only IgM and IgG1 were detectable. The serum from the fourth fetus also contained IgG2 and IgA. Bovine viral diarrhea virus-neutralizing antibodies were detected in two fetuses. These two fetuses inoculated at 135-150 days gestational age, represent the youngest reported bovids, giving a specific response in three weeks following an experimental infection with bovine viral diarrhea virus. The fetal sera did not contain heat-labile factors, which could mediate the neutralization. The virus was not reisolated from any of the fetuses, but viral antigen was nevertheless demonstrated by immunocytochemical methods in sections of several of the fetal organs, primarily lymphoid tissues.     

Laparoscopy guided Doppler ultrasound measurement of fetal blood flow indices during early to mid-gestation in pigs

The objectives of this study were to obtain relevant blood flow indices of umbilical arteries (UmA) of porcine fetuses using a laparoscopic ultrasound probe and to relate these data with fetal size at early to mid gestation. Fetal parameters and flow indices, i.e., fetal length and area, fetal heart rate (FHR), systolic pulse duration (T1), interpulse duration (T2), T2/T1 ratio, peak systolic velocity (PSV), time averaged velocity (TAV), resistance index (RI) and pulsatility index (PI), were measured in 182 fetuses of 26 pregnant Landrace gilts on pregnancy day (PD) 36 (122 fetuses from 17 gilts), PD42 (19 fetuses from 3 gilts) and PD51 (42 fetuses from 6 gilts). Fetal heart rate was higher on PD36 than on PD42 (P<0.05). No differences (P>0.05) were obtained concerning systolic pulse duration, flow velocities and RI. On PD42, the PI was lower (P<0.05), while the interpulse duration (P=0.06) and T2/T1 ratio tended (P=0.08) to be higher on PD42 compared with PD36 and to PD51. To find differences in UmA blood flow parameters concerning fetal size, i.e., fetal length, fetuses were retrospectively grouped as follows: small (lower 25%), medium (mean 50%) and large (upper 25%), respectively. Although, fetuses differed in size (P<0.001) within and between days of pregnancy, FHR, PSV, TAV, RI and PI did not differ (P>0.05) among the size classes. Only systolic pulse duration tended to be longer (P=0.05) in large compared with small fetuses on PD36, and interpulse duration was lower in large fetuses on PD36 in comparison with PD51 (P<0.05). Though there was no link between fetal blood flow indices and fetal intrauterine growth retardation (IUGR), with further studies based on these flow indices, it might be possible to evaluate nutrient- or stress-related influences on fetal growth and development, particularly in the case of IUGR.     

Evaluation of fetal growth and estimation of fetal age based on skeletal growth in Hokkaido sika deer (Cervus nippon yesoensis Heude, 1884)

We investigated fetal development and the estimation of fetal age of 127 Hokkaido sika deer fetuses, categorizing them into three groups according to the nutritional condition of populations. The order and time of the appearance of ossification centers were clarified, and fetal age was determined based on bone length and the appearance of ossification centers. Then we observed the differences in fetal growth among three populations, and discussed the effect of poor nutrition on the fetal growth. The results suggest that fetal diaphysial length of the femur was affected very little by nutritional conditions, whereas conception dates were delayed and fetal weight was restricted as the nutritional condition became poorer. Although it is impossible to know the exact accurate fetal age in wild populations, it was possible to create a standard to estimate fetal age more precisely by the method described in this study. Both the bone length and the appearance of ossification centers are reliable indices to estimate fetal age precisely in measurements available from fetuses of unknown age, and can be applied to estimate the fetal age of other populations of sika deer, whereas estimation of fetal age based on weight is prone to great errors.     

ECG and heart rate determination in fetal cattle using a digital signal processing method

A method of recording the fetal electrocardiogram (ECG) and heart rate (HR) is described. An abdominal lead and a thoracic lead were used to measure the fetal ECG and maternal ECG, respectively. The maternal component in the abdominal lead measurement was estimated by a digital adaptive filter using the thoracic lead measurement as a reference. By suppressing the estimated maternal components in the abdominal lead, the fetal ECG could be detected. The beat‐by‐beat fetal QRS complex peaks were determined by a digital matched filter from the fetal ECG enhanced in this way. The method was trialed in 10 pregnant Holstein cows at gestational periods ranging from 136 to 224 days. The results show that this method can extract the fetal ECG and determine the fetal HR from the raw noisy measurement data. The results suggest that the method would have applicability in monitoring fetal ECG as well as providing a non‐invasive, continuous HR profile during gestation, which will enable better understanding of the development of cattle fetuses before delivery.     

Maternal obesity upregulates fatty acid and glucose transporters and increases expression of enzymes mediating fatty acid biosynthesis in fetal adipose tissue depots

Maternal nutrient restriction leads to alteration in fetal adipose tissue, and offspring from obese mothers have an increased risk of developing obesity. We hypothesized that maternal obesity increases fetal adipogenesis. Multiparous ewes (Columbia/Rambouillet cross 3 to 5 yr of age) carrying twins were assigned to a diet of 100% (Control; CON; n = 4) or 150% (Obese; OB, n = 7) of NRC maintenance requirements from 60 d before conception until necropsy on d 135 of gestation. Maternal and fetal plasma were collected and stored at -80°C for glucose and hormone analyses. Fetal measurements were made at necropsy, and perirenal, pericardial, and subcutaneous adipose tissues were collected from 7 male twin fetuses per group and snap frozen at -80°C. Protein and mRNA expression of fatty acid translocase [cluster of differentiation (CD) 36], fatty acid transport proteins (FATP) 1 and 4, insulin-sensitive glucose transporter (GLUT-4), fatty acid synthase (FASN), and acetyl-coA carboxylase (ACC) was evaluated. Fetal weight was similar, but fetal carcass weight (FCW) was reduced (P < 0.05) in OB versus CON fetuses. Pericardial and perirenal adipose tissue weights were increased (P < 0.05) as a percentage of FCW in OB versus CON fetuses, as was subcutaneous fat thickness (P < 0.001). Average adipocyte diameter was greater (P < 0.01) in the perirenal fat and the pericardial fat (P = 0.06) in OB fetuses compared with CON fetuses. Maternal plasma showed no difference (P > 0.05) in glucose or other hormones, fetal plasma glucose was similar (P = 0.42), and cortisol, IGF-1, and thyroxine were reduced (P ≤ 0.05) in OB fetuses compared with CON fetuses. Protein and mRNA expression of CD 36, FATP 1 and 4, and GLUT-4 were increased (P ≤ 0.05) in all fetal adipose depots in OB versus CON fetuses. The mRNA expression of FASN and ACC was increased (P < 0.05) in OB vs. CON fetuses in all 3 fetal adipose tissue depots. Fatty acid concentrations were increased (P = 0.01) in the perirenal depot of OB versus CON fetuses, and specific fatty acid concentrations were altered (P < 0.05) in subcutaneous and pericardial adipose tissue because of maternal obesity. In conclusion, maternal obesity was associated with increased fetal adiposity, increased fatty acid and glucose transporters, and increased expression of enzymes mediating fatty acid biosynthesis in adipose depots. These alterations, if maintained into the postnatal period, could predispose the offspring to later obesity and metabolic disease.     

The effect of breed and intrauterine crowding on fetal erythropoiesis on day 35 of gestation in swine

In a previous report, it was suggested that intrauterine crowding impaired fetal erythropoiesis and that fetal erythropoiesis was accelerated in Meishan pigs during early pregnancy. Because these conclusions were based on limited numbers of observations, the present experiment was undertaken to provide a more extensive investigation of these phenomena. Intact white crossbred gilts, unilaterally hysterectomized-ovariectomized (UHO) white crossbred gilts, and intact Meishan gilts (n = 13 to 16 per group) were mated after at least one estrous cycle of normal duration (17 to 23 d). Gilts were laparotomized at d 35 of pregnancy, the uterine horns were exteriorized and opened near each fetus, and a blood sample was collected from each fetus. The uterine horn was then surgically removed, and each fetus and placenta was weighed. All fetal blood samples were measured for hematocrit, red blood cell number, and hemoglobin. Erythropoietin and the percentages of nucleated cells and reticulocytes were also measured in blood samples from the largest and smallest living fetus in each litter. Fetal hematocrits were not affected by treatment. Blood cell counts were greater (P < 0.01) in fetuses of Meishan gilts than in White crossbred intact or UHO gilts. Hemoglobin was less (P < 0.01) in fetuses of Meishan gilts than in fetuses of White crossbred intact or UHO gilts. The percentages of nucleated (immature) cells and reticulocytes were both less (P < 0.01) in fetuses of Meishan intact gilts. Erythropoietin was also lower (P < 0.01) in fetuses of Meishan gilts. As observed previously, fetal weight was correlated (r = 0.38; P < 0.01) with blood hemoglobin concentration. These results confirm that fetal erythropoiesis in Meishan gilts is accelerated compared with White crossbred gilts. These results are consistent with the hypothesis that faster blood cell development could be beneficial to fetal survival in swine.     

The Neospora caninum-Spain 7 isolate induces placental damage, fetal death and abortion in cattle when inoculated in early gestation

The Nc-Spain 7 isolate of Neospora caninum, which was newly obtained from an asymptomatic congenitally infected calf, demonstrated a similar virulence as Nc-1 strain in mouse models. The aim of this study was to characterize the pathogenesis of Nc-Spain 7 isolate in cattle after experimental infection at 65 days of gestation. For this purpose, thirteen pregnant heifers were divided into three groups as follows: group A: 7 heifers inoculated with 1×10(8) tachyzoites of Nc-Spain 7 isolate; group B: 4 heifers inoculated with 1×10(8) tachyzoites of Nc 1 strain; and group C: 2 heifers received PBS. Serum samples were collected weekly and heparinized blood samples were collected three times (0, 28 and 42 days after inoculation) by jugular venipuncture. Placenta and fetal tissue samples were collected at time of necropsy. Specific antibody response in the dams was tested by IFAT, indirect ELISA, and rNcGRA7 and rNcSAG4 based-ELISA. Specific antibody response in fetal fluids was tested by IFAT. IFN-γ production was measured after in vitro culture of PBMC and the supernatant was assessed using a commercial kit (BOVIGAM). A significant increase in N. caninum antibody responses was detected in groups A and B by IFAT and by i-ELISA from day 14 after inoculation onwards. Besides, antibody response against rNCGra7 protein was also detected in all inoculated heifers by rNcGra7-based ELISA. Four fetuses from group A and one from group B were aborted between 3 and 5 weeks after infection. In the recovered fetuses, only 3 out of 4 fetal fluids from fetuses of group A and 1 out of 3 of group B were seropositive by IFAT, but all of them were positive by PCR. Transplacental transmission could be determined in all fetuses from groups A and B by PCR and/or IHC. Heifers of group C and their fetuses remained negative by all techniques. The results of this study demonstrate that the NC-Spain 7 isolate could be transmitted transplacentally, and produced fetal death and abortion in cattle.     

Relationships between uterine and fetal traits in rabbits selected on uterine capacity

The aim of this study was to investigate whether uterine capacity (UC) in rabbits was related to uterine horn length and weight and whether these uterine traits and vascular supply were related to fetal development and survival. Data from 48 unilaterally ovariectomized (ULO) does of the High and 52 ULO does of the Low UC lines of a divergent selection experiment on UC were used. Does were slaughtered on d 25 of fifth gestation. The High line showed higher ovarian weight (0.08 g, P < 0.05) linked to a higher ovulation rate (1 ovum, P < 0.05) and greater length of the empty uterine horn. There were no differences between lines in the remaining doe traits. The number of implanted embryos and live fetuses, fetal survival, and uterine weight and length were positively associated and explained most of the observed variation. Average weights of the live fetuses and their fetal and maternal placentae were not related to uterine weight and length. The linear regression coefficient of full uterine horn length on the number of live fetuses was 2.43 +/- 0.21. The weight of the full uterine horn showed a small quadratic relationship (P < 0.05) with the number of live fetuses. Full uterine horn length, after adjusting for the number of embryos, was negatively associated (P < 0.001) with the number of dead fetuses. The linear regression coefficient of average fetal placental weight of the live fetuses on number of implanted embryos was higher (P < 0.10) in the Low line (-0.23 +/- 0.04 vs. -0.12 +/- 0.04). The linear regression coefficient of average weight of the live fetuses on the average weight of their fetal placentae was higher (P < 0.10) in the High line (2.56 +/- 0.47 vs. 1.27 +/- 0.57). The High line was more efficient, most likely because an increase in intrauterine crowding has a lesser effect on the development of fetal placentae and fetuses. The fetal position within the uterus did not affect the proportion of dead embryos. Fetuses with placentae receiving a single blood vessel had a higher probability of death (P < 0.001) and the lowest weight. There was no difference between lines for individual weight of the live fetuses, but the High line showed higher individual weights of fetal (P < 0.01) and maternal placentae (P < 0.10). Live fetuses in the midportion of the uterus were lighter in weight (P < 0.05) than in the oviductal and cervical regions (20.3 vs. 21.6 and 21.7g). Increasing uterine capacity increases uterine length and decreases weights of fetus and fetal placenta in rabbits.     

Time of appearance of esterase-positive alveolar macrophages in bovine fetal lung

Bovine fetal lung tissue was examined histochemically, using alpha-naphthyl butyrate (nonspecific method), to detect the presence of esterase-positive pulmonary alveolar macrophages (PAM). Positively stained PAM were first seen in the alveolar septa and lumina of the lungs of 4 of 8 fetuses 240 days old. Macrophages (n = 100) in 240-day-old fetuses were 6.74 +/- 0.07 microm, and in most cells, esterase-positive granules were sparsely distributed in the cytoplasm. In 10 fetuses 250 days old, the alveolar septa and lumina of lungs contained positively stained macrophages, as did those of all older fetal lungs examined. Compared with macrophages of the 240-day-old fetuses, those (n = 50) of 250-day-old fetuses were significantly larger, 7.32 +/- 0.10 micron (P less than 0.0001), and esterase-positive granules were heavily distributed throughout the cytoplasm. In all fetal lungs, T lymphocytes contained a single, small, esterase-positive granule, compared with the numerous diffuse esterase-positive granules in PAM. Type-II pneumonocytes with well-developed lamellar bodies had no evidence of positive nonspecific esterase reaction in lungs.     

Effect of pregnancy and fetal development on sheep liver superoxide dismutase activity

Liver cytosolic CuZn SOD activity of four-week and 12-week pregnant sheep was twice as high as that of their fetuses and almost equal to that of control, barren ewes. By the 20th week of pregnancy activity had decreased by about 70 per cent in the maternal liver and increased to a value similar to that of the controls in the fetuses. The lysosomal CuZn SOD activity remained almost unchanged during pregnancy both in the maternal and fetal livers. Cytosolic and lysosomal CuZn SOD activities of 20-week pregnant sheep and their fetuses showed a similar electrophoretic pattern and low electrophoretic mobility. Hepatic Mn SOD activity increased sharply during fetal development but remained lower than that in both the control and maternal livers. It is proposed that the changes in CuZn SOD and Mn SOD activities are associated with changes in copper metabolism and oxygen utilisation, respectively. The low electrophoretic mobility of CuZn SOD is assumed to be a species specificity.     

Maternal and fetal influences on uterine and conceptus development in the cow: II. Blood flow and nutrient flux

Objectives of this study were to evaluate maternal and fetal influences on uterine and umbilical blood flows and nutrient fluxes of gravid uterine tissues of cows. Brahman cows with Brahman or Charolais fetuses and Charolais cows with Brahman or Charolais fetuses were used. Indwelling catheters were placed into a uterine artery and vein, an umbilical vein, and a fetal femoral artery and vein at 220 +/- .4 d after mating. Uterine and umbilical blood flows (liters/min) and net uptakes of oxygen, glucose, lactate, alpha-amino N, urea N, ammonia N, and estrone sulfate by the gravid uterus, fetus, and uteroplacenta were determined on d 227 +/- .4. Uterine blood flows in Brahman cows with Brahman (5.01) or Charolais (4.66) fetuses were similar but less (P less than .001) than in Charolais cows with Brahman (7.14) or Charolais fetuses (9.24), which differed (P less than .01). Umbilical blood flows of Charolais (3.78) were greater (P less than .01) than those of Brahman (2.29) fetuses. Rate of placental D2O clearance as well as net fetal uptake of oxygen, glucose, and alpha-amino N, gravid uterine uptake of alpha-amino N, and uteroplacental uptake of glucose and release of estrone sulfate were greater with Charolais than with Brahman fetuses. Gravid uterine oxygen uptake and estrone sulfate release and gravid uterine and uteroplacental lactate output were influenced by the interaction between cow and fetal breed. It is suggested that fetal growth may be limited by uterine blood flow and by function of the uteroplacenta, particularly in late gestation.     

Effect of chronic infusion of placental lactogen on ovine fetal growth in late gestation

To test the hypothesis that placental lactogen (PL) is a Immoral regulator of fetal growth, six singleton sheep fetuses received a continuous intravenous fusion of 1.2 mg/d of purified ovine PL (oPL) for 14 d, beginning on Day 122 of gestation. The plasma concentration of oPL was approximately four-fold higher in infused fetuses than in six control fetuses that received a continuous infusion of saline. The circulating insulin-like growth factor 1 (IGF-1) concentration was also significantly elevated in PL-infused fetuses (43.1 ± 1.7 vs. 31.9 ± 4.l ng/ml; P < 0.05). Animals were slaughtered on Day 136, and the placenta and all major fetal tissues were dissected, weighed, and subsampled for chemical analysis. Fetal weight and crown-rump length were not significantly affected by treatment; however, the aggregate weight of the brain, liver, lungs, and heart tended to be larger (85.3 ± 2.1 vs. 79.9 ± 1.5 g/kg fetus; mean ± SE, P = 0.07) and the thyroid gland was smaller (0.18 ± 0.l vs. 0.26 ± 0.02 g/kg fetus; P < 0.05) in the PL-infused fetuses. The livers of the PL-infused fetuses had also accumulated additional glycogen (13.1 ± l.7 vs. 8.4 ± 0.7 g; P < 0.05). In late gestation, PL within the fetal compartment increases fetal plasma IGF-1 concentration and hepatic glycogen deposition and may affect the growth of several vital organs.     

Bovine fetal infection with Mycobacterium paratuberculosis

In utero transmission of Mycobacterium paratuberculosis, the causative agent of paratuberculosis in cattle, has been suggested. Tissue specimens were obtained at a packing plant from pregnant dairy cows and their fetuses and from cows with clinical signs of paratuberculosis and from their fetuses. Specimens were processed according to methods described for isolating M paratuberculosis from bovine tissues and were incubated on Herrold egg yolk medium for 16 weeks. Presumed positive specimens were confirmed to be M paratuberculosis, using acid-fast staining and subculturing. Of 407 lymph nodes from cows, 34 (8.4%) were culture positive for M paratuberculosis; 9 of 34 (26.4%) of these culture-positive cows had fetuses from which specimens were also culture positive. The results estimated the risk of fetal infection with M paratuberculosis to be 26.4% (95% confidence interval between 11.3 and 40.7%).