Post-natal growth and development of Simmental calves derived from in vivo or in vitro embryos

Large fetuses arising from embryos produced in vitro have been shown to exhibit altered organ development in utero, but it is not known whether this persists post natally. Post-natal growth and development was examined in 18 Simmental bulls derived from in vivo frozen-thawed (n = 6), in vitro frozen-thawed (n = 6) or in vitro fresh (n = 6) embryos and reared together post weaning on an ad libitum diet until slaughter at approximately 13 months old. Calves weighing less than 60 kg at birth (n = 11) were classified as normal, and heavier calves (n = 7; all from in vitro embryos) as oversize. Lifetime growth rates and slaughter weights apparently were unaffected by embryo source or birthweight. Mean (+/- s.e.m.) post mortem liver and kidney weights were unaffected by embryo source, but hearts of bulls from in vitro frozen embryos were heavier than those of bulls from in vivo frozen embryos (2.7 +/- 0.04 v 2.3 +/- 0.07 kg, P<0.025). Heart weight per kilogram body weight at slaughter for the 7 perinatally oversize males (4.01 +/- 0.08 g) exceeded that of the other 5 bulls from in vitro embryos (3.60 +/- 0.10 g kg(-1); P<0.04) and the 6 in vivo males (3.56 +/- 0.12 g kg(-1); P<0.02). Overall, one-third of the variation in heart weight at slaughter (r2 = 0.35; P = 0.01) was due to variation in birthweight. This is the first study to demonstrate birthweight-related developmental effects on post-natal organ weight following the transfer of embryos produced in vitro.     

Transfer of plutonium to rat embryos in vivo and in vitro.

The 239Pu distribution in the 12.5-day-old rat conceptus was compared between in vivo and in vitro experimental systems to establish a possible mechanism of cross-placental transfer of this radionuclide. In the in vivo study, plutonium citrate solution was injected intravenously to pregnant Wistar rats. In the in vitro study, either plutonium citrate or plutonium hydroxide colloid was administered, as a solution of Eagle MEM and FCS containing 239Pu at the concentration used in the maternal serum in the in vivo experiments, to rat conceptuses maintained by the whole-embryo culture method. The concentration of 239Pu in the yolk sac (239Pu activity per gram wet weight) were much higher than in the embryo in both the in vivo and in vitro experiments, suggesting that the yolk sac may be an effective barrier against the transfer of plutonium to the embryos. The ratios of the 239Pu concentration in the yolk sac to that in the embryo were relatively constant with time after administration in the in vitro system; 18-27 for plutonium citrate and 67-84 for plutonium hydroxide. In the in vivo experiment, these ratios changed with time after injection; 15 at 5 min and 62 and 60 min after injection. This suggests that in the in vivo system, the chemical form of 239Pu changed with time after injection, probably to a macromolecular form such as the hydroxide colloid or plutonium-protein complex although 239Pu was injected to the maternal blood as citrate.     

Net utilization of roughage and concentrate diets by sheep.

1. Two diets, an all-roughage diet and a high-concentrate diet, were fed at two levels, a low level of estimated 1-5 times maintenance energy requirement and a higher level of estimated two times maintenance energy requirement, to South African Mutton Merino castrated male sheep, aged 13 months and in fairly lean condition at the start of the 93 d experimental period. 2. Body composition and energy retention were determined using the comparative slaughter technique and two series of digestibility and balance studies were done during the course of the experiment. Metabolizability of each diet was estimated and corrected for fermentation heat using the fermentation balance approach. 3. Although there were significantly different rates of energy gain on different diets and feeding levels, fat energy gained (% total energy gained) was similar for the four groups, i.e. 78-80. 4. Regression of energy gain v. corrected metabolizable energy (ME) intake indicated that the maintenance energy requirements of sheep used in this experiment were 310-2 and 302-3 kJ ME/kg body-weight0-75 per d and the values for net utilization of ME for body energy gain were 0-411 and 0-479 with the roughage and concentrate diets respectively. 5. It was concluded that the estimated maintenance energy requirements of sheep obtained in this study are realistic values and that the efficiency of utilization of surplus ME for the two diets did not differ significantly.     

Tolerance of perinidatory primate embryos to RU 486 exposure in vitro and in vivo

Monkey embryos were exposed to RU 486 both in vitro and in vivo (with and without progesterone therapy) in the perinidatory interval. These primate embryos were highly tolerant of RU 486, except when RU 486 alone terminated early pregnancy. There were no indications of teratogenicity in this limited trial when the embryos were exposed to RU 486 either before implantation (10(-7)M in 24-hour cultures) or during the immediate post-implantation interval (50 mg orally/day; days 32 to 39 LMP).     

Estimation of the degradability of dietary protein in the sheep rumen by in vivo and in vitro procedures

Estimates of degradability of nitrogen in the sheep rumen for a basal hay diet and for soya-bean meal (SBM), groundnut meal (GNM) and fish meal (FM), when given together with the hay, were determined from measurements of duodenal N flow, ammonia kinetics and rumen N disappearance from polyester bags and rumen outflow rate. The ability of various in vitro procedures to predict in vivo N degradability was also examined. Four sheep were given a basal hay diet (800 g dry matter (DM) and 19 g N/d) either alone or supplemented with isonitrogenous amounts (15 g N/d) of SBM, GNM or FM. Duodenal non-ammonia-N flow (g/d) was increased more by FM (8.0) than by GNM (5.9) and SBM (5.8), whilst microbial N flow (g/d) was increased more by SBM (3.9) than by GNM (2.3) and FM (1.6). N degradability values calculated from these results were 0.88, 0.76 and 0.57 for the SBM, GNM and FM respectively. The corresponding value for hay was calculated to be 0.76. The irreversible loss of ammonia in the forestomachs (g N/d) was increased more by SBM (11.9) than by GNM (7.2) and FM (5.8), whilst ammonia outflow from the rumen (g N/d) was increased to a similar extent by all supplements (1.1, 0.9 and 0.8 respectively), as was the amount of microbial N (g/d) synthesized from sources other than rumen ammonia (1.8, 2.0 and 1.9 respectively). N degradability values calculated from these results were 0.84, 0.54 and 0.45 for the SBM, GNM and FM respectively. The fractional rate of N disappearance (/h) when the feedstuffs were incubated in polyester bags in the rumen of sheep receiving the basal hay diet (800 g DM/d) was the highest for SBM (0.145) and lowest for FM (0.037), with the hay (0.082) and GNM (0.071) intermediate, whilst the fractional outflow rates from the rumen (/h) of the three supplements were similar (0.034, 0.038 and 0.030 for SBM, GNM and FM respectively). N degradability values calculated from these results were 0.82, 0.67 and 0.60 for the SBM, GNM and FM respectively; the value for the hay was 0.73. Of a number of in vitro procedures tested, only N solubility in sodium hydroxide and ammonia or total non-protein-N (NPN) production during incubation with rumen fluid in the absence of hydrazine sulphate ranked the supplements, although not the hay, in the same order as in the vivo degradability procedures.(ABSTRACT TRUNCATED AT 400 WORDS)     

Glucose metabolism in shorn and unshorn pregnant sheep

1. Whole-body, hind-limb and uterine tissue metabolism of glucose was studied using a combination of isotopic and arterio-venous difference techniques in shorn and unshorn pregnant sheep over the final 4 weeks of pregnancy. This was combined with the measurement of the concentrations of oxygen and carbon dioxide in arterial blood and plasma concentrations of lactate, acetate, non-esterified fatty acids, 3-hydroxybutyrate, glycerol, growth hormone (GH), insulin, glucagon, cortisol, thyroxine and 3,5,3'-triiodothyronine (T3). 2. Glucose entry rate was 28% higher in shorn ewes compared with unshorn controls, even though there was no difference in the arterial plasma concentration of glucose. This effect may have been caused by a decrease in the molar rate, insulin: glucagon (I:G), which was 40% lower in shorn ewes as a result of a significant decrease in the plasma concentration of insulin. There was no difference in the plasma concentration of cortisol or GH. 3. Blood flow across the hind-limb or uterine tissues was not significantly different between shorn and unshorn groups, neither were the net glucose uptake, glucose oxidation rate or contribution of glucose to O2 consumption across these tissues. 4. Insulin-tolerance tests performed on a separate group of shorn and unshorn ewes showed an increased sensitivity to the hypoglycaemic effects of insulin in the shorn group. 5. There was no significant difference between shorn and unshorn animals in the contribution of glucose to CO2 output or in the proportion of glucose entry rate oxidized. CO2 entry rate was 18% higher in shorn ewes compared with unshorn controls which resulted in a 26% higher estimated value for heat production. There was a 47% increase in glucose oxidation rate in shorn ewes but there was no significant difference in the proportion of total heat production which was derived from glucose. The arterial concentrations of O2 and CO2 were significantly higher in shorn ewes, which may be an indication of the higher metabolic rate in these animals. This effect may be mediated via a significant rise in plasma T3 concentration in the shorn group. 6. It is concluded that as a result of long-term cold exposure there is a significant increase in whole-body glucose entry and oxidation rates in the shorn pregnant ewe. The increase in insulin sensitivity at the same time as a decrease in plasma insulin concentration may represent a mechanism to ensure continued glucose supply to insulin-sensitive tissues while the concomitant decrease in plasma I:G stimulates hepatic gluconeogenesis.     

Resistant starch derived from processed legumes: in vitro and in vivo fermentation characteristics

The effect of processing of legumes on resistant starch formation, its rate of fermentation and the production of short chain fatty acids under in vitro and in vivo systems was assessed. The content of resistant starch in pressure-cooked Bengal gram, black gram and red gram was 3.59%, 1.58% and 3.34%, respectively. Fermentation in vitro of resistant starch derived from processed red gram showed higher amount of short chain fatty acids (2.38 mmol), especially butyric acid (2.22 mmol). Under in vivo conditions (in albino rats) all processed legumes showed a higher faecal bulking, and more short chain fatty acids, with a significant increase in the anaerobic bacterial counts. Compared with a processed legume diet, the caecum of animals fed a raw diet showed a preponderance of propionic acid.     

Efficiency of utilization of volatile fatty acids for maintenance and energy retention by sheep.

1. Two experiments were conducted with lambs sustained entirely by intragastric infusion of volatile fatty acids (VFA), protein, minerals and vitamins. 2. In the first experiment to determine the effects of VFA on nitrogen retention four mixtures of VFA (B, C, D and E) were used containing acetic, propionic and butyric acid in the following molar proportions respectively: 45, 45 and 10; 55, 35 and 10; 65, 25 and 10; 75, 15 and 10. The level of infusion was 836 kJ/live weight0.75 per d and the design was a 4 X 4 Latin square with 14 d periods. There were no significant differences in the N balance between the different mixtures of VFA though mixture B tended to give the highest N retention. 3. Thirty-two lambs were used in the second experiment for measurements of heat production in closed-circuit respiration chambers. Six mixtures of VFA were used. These included mixtures B-E from Expt 1 and in addition two mixtures (A and F) containing acetic, propionic and butyric acid in the following molar proportions respectively: 35, 55 and 10; 85, 5 and 10. The heat production was measured both at 450 and 900 kJ/W0.75 per d, except for mixture F, where it was not possible to achieve a rate of infusion in excess of 675 kJ/W0.75 per d. 4. The energy required for maintenance was determined to be 0.45 +/- 0.02 MJ/kg live weight0.75 per d regardless of the mixture used. 5. The efficiency of utilization for fattening (kf) values for the six mixtures were 0.78, 0.64, 0.57, 0.61, 0.61 and 0.59 for mixtures A, B, C, D, E and F respectively. Only mixture A was significantly better utilized than the other mixtures. This mixture also gave the most efficient N utilization. 6. It is concluded from this evidence that differences in kf for diets normally given to ruminants cannot be attributed to differences in utilization of volatile fatty acids.     

RU 486 interferes with egg transport and retards the in vivo and in vitro development of mouse embryos

Oral administration of RU 486 at 100 mg/kg BW/day to mice on Days 1 and 2 of pregnancy caused retention of embryos in the oviduct and expulsion of those having entered the uterus. The treatment also retarded the development of embryos. In vitro study showed that RU 486 reduced the percentage of 2-cell mouse embryos developing into blastocysts. Thus, in addition to interfering with egg transport and impairing embryonic development , RU 486 can act directly on the embryo, interfering with preimplantation development .     

Cytogenetic analysis of in vivo and in vitro matured oocytes derived from naturally cycling and stimulated mice

The objective of the study was to analyze the potential role of follicle stimulating hormone (FSH) in cytogenetic changes of in vivo and in vitro matured mouse oocytes and to determine whether the lower developmental potential of immature oocytes is due to a higher incidence of abnormalities in meiotic spindle organization and chromosome alignment as well as aneuploidy. In vivo matured oocytes were collected from naturally ovulated and superovulated (5.0 I U of recombinant follicle-stimulating hormone [rec-FSH] + recombinant human chorionic gonadotropin [rec-HCG]) mice. Immature oocytes were retrieved from naturally cycling mice and from mice primed with rec-FSH for 48 h. The immature oocytes were cultured 18 h for in vitro maturation (IVM). In vivo and in vitro matured oocytes were assessed for the meiotic spindle organization and chromosome alignment as well as aneuploidy. There was no significant difference of meiotic spindle organization, chromosomal alignment and aneuploidy between in vivo and in vitro matured oocytes derived from naturally cycling and stimulated mice. Therefore, the lower developmental potential of immature oocytes does not appear to be directly related to the incidence of abnormal meiotic spindle organization and chromosome alignment or to aneuploidy.     

Undernutrition in sheep. Nitrogen repletion by N-depleted sheep

Wether lambs of 29-44 kg live-weight, totally nourished by the infusion of volatile fatty acids (VFA) into the rumen and casein into the abomasum, were given five treatments in consecutive periods. The treatments were (daily amounts per kg live weight (W)0.75): (a) high-protein for 7 d (2500 mg nitrogen, 650 kJ VFA); (b) low-protein for 7-15 d (525 mg N, 650 kJ VFA); (c) N-free for 7 d (no N, 450 kJ VFA); (d) very-low-protein for 24-28 d (300 mg N, 400 kJ VFA); (e) high-protein for 40 d (2500 mg N, 650 kJ VFA). Nine lambs were subjected to treatments (a), (b) and (c) (Expt 1) and four of the lambs additionally received treatments (d) and (e) (Expt 2). In Expt 1 all nine lambs had a positive N retention on treatment (a) but abrupt change to treatment (b) resulted in substantial negative N balances initially, and a period of approximately 5 d adaptation was required before N equilibrium was re-established. Animals again exhibited negative N balances when the N-free infusion (treatment c) was introduced and during that period there was no evidence of adaptation. Basal urinary N excretion was estimated to be 356 (SE 12) mg N/kg W 0.75. In Expt 2 all four lambs were depleted of N when receiving the very-low-protein treatment (d). The progressively decreasing N losses recorded during days 1 to 12 of the treatment period were slightly greater than those recorded during days 13 to 28 but the difference between the means was not significant (P greater than 0.05). There was no evidence of an adaptation in N retention between days 13 and 28 of the treatment. As assessed during days 13 to 28 of the treatment the efficiency of utilization of infused casein N was 1.0; this compared with a value of 0.66 recorded during treatment (b) in Expt 1. Live weight loss during the period of N depletion was 101 (SE 27) g/d. When lambs were given treatment (e) during the last period of Expt 2, N repletion was rapid and complete within a few days. Ten days after the introduction of the treatment the rate of N retention was estimated to be 1019 (SE 38) mg/kg W 0.75 per d and this value declined at a rate of 9.5 (SE 1.9) mg N/kg W 0.75 per d for the following 30 d.(ABSTRACT TRUNCATED AT 400 WORDS)