Changes in placental development have been associated with foetal abnormalities after in vitro embryo manipulations. This study was designed to investigate bovine conceptus development and substrate levels in plasma and fluids in in vivo-and in vitro-produced (IVP) concepti and neonates. In vivo-produced and IVP embryos were derived by established embryo production procedures. Pregnant animals from both groups were slaughtered on days 90 or 180 of gestation, or allowed to go to term. Conceptus and neonatal physical traits were recorded; foetal, maternal and neonatal blood, and foetal fluids were collected for the determination of blood and fluid chemistry, and glucose, fructose and lactate concentrations. Placental transcripts for specific glucose transporters were determined by quantitative RT-PCR. No significant differences in uterine and conceptus traits were observed between groups on day 90. On day 180, larger uterine, placental and foetal weights, and an increase in placental gross surface area (SA) in IVP pregnancies were associated with increased glucose and fructose accumulation in foetal plasma and associated fluids, with no differences in the expression of components of the glucose transporter system. Therefore, the enlarged placental SA in IVP pregnancies suggests an increase in substrate uptake and transport capacity. Newborn IVP calves displayed higher birth weights and plasma fructose concentrations soon after birth, findings which appeared to be associated with clinical and metabolic distress. Our results indicated larger concepti and increased placental fructogenic capacity in mid-to late IVP pregnancies, features which appeared to be associated with an enhanced substrate supply, potentially glucose, to the conceptus.

A cooperative research study involving members of a regional committee (North Central Regional Committee on Swine Nutrition [NCR-42]) was conducted to assess the variability in nutrient composition (DM, CP, Ca, P, Se, and amino acids) of corn and soybean meal from 16 sources (15 states, mostly in the Midwest) and to assess the analytical variability in nutrient assays among 22 laboratories (labs; 16 experiment station labs and six commercial labs). Corn samples were obtained from each participating station's feed mill during a 3-yr period (1989, 1990, and 1992), as were soybean meal samples during a 2-yr period (1989 and 1990). Both regular soybean meal (with hulls) and dehulled soybean meal were represented in the study. Samples were analyzed for DM and CP by all 22 labs, for Ca and P by 15 labs, for amino acids by 10 labs, and for Se by 6 labs. Each lab used its own analytical procedures. Samples of corn and soybean meal varied in their nutrient composition depending on the area of origin. The greatest variation among sources was in Se concentration, ranging from .02 to .29 mg/kg in corn and .08 to .95 mg/kg in soybean meal. Crude protein and lysine in corn were positively correlated, but the regression coefficient was low (r2 = .49). The relationship between CP and lysine for the two soybean meals combined was considerably stronger (r2 = .81). Lysine in corn increased by .018 percentage point and lysine in soybean meal (regular and dehulled combined) increased by .063 percentage point for each 1 percentage point increase in CP. Except for CP and Se, the analytical variability among labs was as great as, and in some cases greater than, the variability in nutrient composition among sources of corn and soybean meal. Within-lab analytical variability tended to be less than among-lab variability. Some labs performed certain analyses with considerably less variability and more accuracy than others.

A cooperative study using 215 sows during two parities (349 litters) was conducted at six stations to determine the effect of raw soybeans in gestation and lactation diets on sow and litter performance. Sows were bred and allotted to fortified corn diets containing either soybean meal (control) or raw soybeans. A corn-soybean meal-soybean oil diet, isocaloric to the raw soybean diet, was included as a third treatment at three stations. All diets contained 14% CP. These diets were fed during both gestation and lactation through two parities. The daily gestation feed intake ranged from 1.8 to 2.3 kg/sow, depending on station. During lactation, the sows were allowed ad libitum access to their respective diets. Gestational weight gain was not influenced by diet, but sows fed raw soybeans consumed less (P less than .01) feed during lactation and had greater (P less than .01) lactational weight loss and their pigs were lighter in weight (P less than .05) both at 21 d and at weaning (varied between 3 and 5 wk of age). Sows fed the diet with supplemental oil had reproductive and lactational performance similar to those fed the control diet. Milk obtained at d 10 to 14 of lactation from sows fed raw soybeans had lower (P less than .05) protein content than milk from sows fed the other two diets, but fat content of the milk tended to be increased by raw soybeans or by added soybean oil. Return to estrus was not affected by diet.(ABSTRACT TRUNCATED AT 250 WORDS)

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A substantial portion of placental function is committed to the regulation of nutrient transfer from the dam to the fetus, with glucose being the major substrate for conceptus metabolism. Due to its homomorphism with glucose, xylose can be used as tracer for the assessment of placental nutrient transfer capacity. This study was designed to evaluate transplacental permeability to xylose in bovine pregnancies on Days 90 and 180 of gestation. In Experiment 1, pregnant and nonpregnant females were infused into the jugular vein or into the allantoic sac with a 10% xylose solution to evaluate the maternal plasma xylose disappearance and the existence of feto-maternal xylose transfer, respectively. Glucose and xylose concentrations were determined in venous blood samples collected at 0,15,30, 60, 90, 120, 150, and 180 min. A materno-fetal but not a feto-maternal xylose transport was observed in both gestational periods. In Experiment 2, pregnant animals were slaughtered on Days 90 or 180 of gestation. A 10% xylose solution was infused intravenously into each female 60 min before slaughter to measure the materno-fetal transfer of xylose. Fetal and maternal blood samples and amniotic and allantoic fluids were collected for the determination of glucose and xylose concentrations. An increase in xylose accumulation in the uterine subcompartments was observed toward the end of the second trimester of pregnancy, demonstrating an increase in materno-fetal placental sugar transport as pregnancy advances. In conclusion, xylose can be a valid tracer for studies on transplacental transport with potential implications to conceptus growth in cattle. RESUMOUma porção importante da função placentária é dedicada à regulação da transferência de nutrientes da mãe ao feto, com a glicose sendo o substrato mais expressivo para o concepto. Devido ao homomorfismo com a glicose, a xilose pode ser usada como um marcador para a avaliação da capacidade de tranferência de nutrientes pela placenta. Este estudo visou a avaliação da permeabilidade transplacentária à xilose em fêmeas bovinas nos dias 90 e 180 de gestação. No Experimento 1, fêmeas vazias e prenhes receberam uma infusão de uma solução de 10% de xilose na veia jugular para a avaliação do desaparecimento da xilose no plasma materno, ou no saco alantóico para a avaliação da existência da transferência fetomaterna de xilose. As concentrações de glicose e xilose foram determinadas em amostras de sangue venoso coletadas aos 0, 15, 30, 60, 90, 120, 150 e 180 min. Foi observada a existência de um transporte materno-fetal, mas não feto-materna, de xilose para ambos períodos gestacionais. No Experimento 2, fêmeas prenhes foram abatidas nos Dias 90 ou 180 de gestação. Antes do abate (60 min), as fêmeas receberam uma solução de 10% de xilose por via intravenosa para a mensuração da transferência materno-fetal à xilose. Amostras de sangue materno e fetal, e dos fluídos amniótico e alantóide, foram coletadas após o abate para a determinação das concentrações de glicose e xilose. Foi observado um aumen...