Established method of chondroitin sulphate extraction from buffalo (Bubalus bubalis) cartilages and its identification by FTIR.

A study was conducted for extraction of chondroitin sulphate (CS) from buffalo tracheal, nasal and joint cartilages. CS was extracted from cartilages using 0.25% papain digestion, dialyzed, precipitated with 10% TCA and finally lyophilized to dry powder. Dimethylmethylene blue assay was performed to estimate the quantity of CS extracted. Identification of extracted CS was performed with SDS-PAGE and Fourier transforms infrared spectroscopy (FTIR). SDS-PAGE analysis of extracted CS revealed similar electrophoretic pattern to that of standard and the molecular weight ranged from 5 to 20 kDa. FTIR spectra of extracted CS revealed presence of characteristic peaks of -CONH vibration of amide group, coupling of C-O stretching vibration, S=O stretching vibrations and -C-O-S molecules confirms the CS moiety. It can be concluded that extraction method adopted could efficiently be utilized for the extraction of CS from buffalo by-products like tracheal, nasal and joint cartilages.

Epigenetic change in IGF2R is associated with fetal overgrowth after sheep embryo culture.

Manipulation or non-physiological embryo culture environments can lead to defective fetal programming in livestock. Our demonstration of reduced fetal methylation and expression of ovine IGF2R suggests pre-implantation embryo procedures may be vulnerable to epigenetic alterations in imprinted genes. This highlights the potential benefits of epigenetic diagnostic screening in developing embryo procedures.

Radioactivity measurements of former military personnel exposed to weapon debris.

Sixteen former military personnel who were present at the "Smoky" atmospheric nuclear weapon test have been investigated for internal deposits of radioactivity. Whole-body and thorax gamma-ray measurements, thorax and skeletal actinide measurements, and urinalyses for plutonium-239 and strontium-90 indicated no evidence of radioactivity in excess of that found in the general population.

Ovine fetal development is more sensitive to perturbation by the presence of serum in embryo culture before rather than after compaction.

The effects on subsequent fetal development of the presence or absence of serum at different times during IVC of ovine zygotes were studied. Zygotes, recovered from superovulated ewes 36h after intrauterine AI using semen from a single sire, were cultured for 5 days in synthetic oviductal fluid (SOF) media supplemented with either BSA and amino acids (SOF-) or with 10% (v/v) steer serum (SOF+). Serum was present or absent during the first two and last 2 days of IVC giving four treatments (SOF-/SOF-; SOF-/SOF+;SOF+/SOF- and SOF+/SOF+). In total, 224 embryos, including 26 in vivo controls, were transferred singly at day 6 post-AI to synchronous recipients and the products of conception recovered at day 125 of gestation. Presence of serum during IVC had a biphasic effect on embryo development. The inclusion of serum during the first 2 days of IVC retarded early embryo development while the inclusion of serum during the last 2 days of IVC produced more blastocysts by day 6. These effects were independent of each other. The presence of serum during the first 2 days of IVC resulted in increased weights of gravid uterus, placenta, fetus, fetal heart and liver. The incidence of fetuses whose total or organ weights were greater than three standard deviations above the corresponding mean weights of control fetuses was also greater when serum was present during the first 2 days of IVC. However, even when serum was absent throughout IVC there was still an infrequent incidence of fetal weights greater than three standard deviations above the mean for control fetuses. These observations provide evidence that it is the early pre-compaction stages of embryo development that are particularly sensitive to perturbations leading to abnormal fetal development.

Investigation of the Booroola (FecB) and Inverdale (FecX(I)) mutations in 21 prolific breeds and strains of sheep sampled in 13 countries.

Twenty-one of the world's prolific sheep breeds and strains were tested for the presence of the FecB mutation of BMPR1B and the FecX(I) mutation of BMP15. The breeds studied were Romanov (2 strains), Finn (2 strains), East Friesian, Teeswater, Blueface Leicester, Hu, Han, D'Man, Chios, Mountain Sheep (three breeds), German Whiteheaded Mutton, Lleyn, Loa, Galician, Barbados Blackbelly (pure and crossbred) and St. Croix. The FecB mutation was found in two breeds, Hu and Han from China, but not in any of the other breeds. The 12 Hu sheep sampled were all homozygous carriers of FecB (FecB(B)/FecB(B)) whereas the sample of 12 Han sheep included all three genotypes (FecB(B)/FecB(B), FecB(B)/FecB+, FecB+/FecB+) at frequencies of 0.33, 0.58 and 0.08, respectively. There was no evidence of FecX(I) in any of the breeds sampled.

Zygote donor nitrogen metabolism and in vitro embryo culture perturbs in utero development and IGF2R expression in ovine fetal tissues.

Tests were made of the effects of altering nitrogen metabolism in zygote donor ewes on fetal development and expression of the gene encoding the type II insulin-like growth factor receptor (IGF2R) following the transfer of ovine embryos cultured from these zygotes, either in the absence or presence of serum. Zygotes, recovered from superovulated ewes (32 on a urea supplemented (30 g urea/kg) diet (high N) and 32 on a control diet (low N)) 36 h after intrauterine AI using semen from a single sire, were cultured for 5 days in synthetic oviductal fluid (SOF) media either with BSA and amino acids (SOF-) or with 10% (v/v) steer serum (SOF+). In total, 166 embryos, including 30 in vivo controls, were transferred singly at day 6 post-AI to synchronous recipients and the products of conception recovered at day 125 of gestation. Elevated plasma urea concentrations in zygote donors were associated with accelerated early embryo development, low pregnancy rates (16%) for embryos from the high N, SOF+ treatment, and significantly influenced fetal development and the expression of IGF2R in the fetal heart at day 125 of gestation. Importantly, the culture of sheep zygotes under serum-free conditions led to a high incidence of aberrant conceptus development and IGF2R expression. Consequently, maternal nitrogen metabolism prior to zygote recovery and in vitro culture can influence fetal development and the expression of an imprinted gene following embryo transfer, and these data support the notion that environmental effects on the follicle-enclosed oocyte may contribute to the etiology of the Large Offspring Syndrome.

Utilization of carrageenan, citric acid and cinnamon oil as an edible coating of chicken fillets to prolong its shelf life under refrigeration conditions.

AIM: The present study was conducted to determine efficacy of edible coating of carrageenan and cinnamon oil to enhance the shelf life of chicken meat stored under refrigeration conditions. MATERIALS AND METHODS: Chicken breast was coated with carrageenan and cinnamon oil by three methods of application viz., spraying brushing and dipping. The coated meat was evaluated for drip loss, pH, thiobarbituric acid number (TBA), tyrosine value (TV), extract release volume (ERV), Warner-Bratzler shear force value (WBSFV), instrumental color, microbiological, and sensory qualities as per standard procedures. RESULTS: There was a significant difference observed for physicochemical parameters (pH, TBA, TV, ERV, drip loss and WBSFV) and microbiological analysis between storage periods in all the samples and between the control and treatments throughout the storage period but samples did not differed significantly for hunter color scores. However, there was no significant difference among three methods of application throughout the storage period though dipping had a lower rate of increase. A progressive decline in mean sensory scores was recorded along with the increase in storage time. CONCLUSION: The carrageenan and cinnamon edible coating was found to be a good alternative to enhance the shelf life of chicken meat under refrigeration conditions. It was also observed from study that dipping method of the application had comparatively higher shelf life than other methods of application.

Electro-olfactogram and multiunit olfactory receptor responses to binary and trinary mixtures of amino acids in the channel catfish, Ictalurus punctatus.

In vivo electrophysiological recordings from populations of olfactory receptor neurons in the channel catfish, Ictalurus punctatus, clearly showed that responses to binary and trinary mixtures of amino acids were predictable with knowledge obtained from previous cross-adaptation studies of the relative independence of the respective binding sites of the component stimuli. All component stimuli, from which equal aliquots were drawn to form the mixtures, were adjusted in concentration to provide for approximately equal response magnitudes. The magnitude of the response to a mixture whose component amino acids showed significant cross-reactivity was equivalent to the response to any single component used to form that mixture. A mixture whose component amino acids showed minimal cross-adaptation produced a significantly larger relative response than a mixture whose components exhibited considerable cross-reactivity. This larger response approached the sum of the responses to the individual component amino acids tested at the resulting concentrations in the mixture, even though olfactory receptor dose-response functions for amino acids in this species are characterized by extreme sensory compression (i.e., successive concentration increments produce progressively smaller physiological responses). Thus, the present study indicates that the response to sensory stimulation of olfactory receptor sites is more enhanced by the activation of different receptor site types than by stimulus interaction at a single site type.

Chemical composition of solar dried blood and the ruminal content and its effect on performance of Japanese quails.

AIM: The aim was to determine the chemical composition of solar dried blood and rumen content (DBRC) and further ascertain the concentration at which DBRC could be included in Japanese quail diets without any adverse effect on its performance. MATERIALS AND METHODS: Feeding trial on the effect of DBRC on performance of Japanese quails was studied up to 5 weeks. 252 numbers of day old (Nandanam Type III breed) Japanese quails were purchased from Poultry Research Station, Madhavaram and divided into 7 batches (control+ six treatments) each consisting of 36 birds. The DBRC was included at 0%, 5%, 10%, 15%, 20%, 25% and 30% in diets as control, treatment-1 (T1), treatment-2 (T2), treatment-3 (T3), treatment-4 (T4), treatment-5 (T5) and treatment-6 (T6) respectively in a completely randomized design to replace soybean meal in Japanese quail feed. The birds were provided with ad-labidum feed and drinking water ad-libitum during the entire experimental period. RESULTS: The crude protein (CP), crude fiber (CF), ether extract (EE) and ash contents of DBRC were 35.87%, 17.40%, 3.6% and 12.6%, respectively. The amount of essential amino acids and non-essential amino acid content were found to be 12.98 and 4.87 (g/100 g of feed) respectively in DBRC feed. Result showed that all birds fed DBRC diets performed better than the control group. Mortality was unaffected by dietary treatments. There was a significant difference (p<0.01) observed in weight gain in treatment groups compared to the control. CONCLUSION: Up to 30% DBRC could be incorporated in the diets of Japanese quails without any adverse effects on its performance.

Identification of a component of the sea urchin hyaline layer, HLC-175, which undergoes proteolytic processing during development.

To define the role(s) played by the sea urchin extraembryonic matrix, the hyaline layer, we have previously purified and characterized a number of the protein components of this structure. We are currently studying the timing and significance of the proteolytic processing of these species. The localization of HLC-175 in the egg and 1-hr-old embryo was determined by indirect immunofluorescence analysis. The relationship between HLC-175 and the 109- and 81 kDa species was determined by a combination of native gel electrophoresis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under non-reducing conditions and protein gel blot analyses using the anti-175, -109 and 81 kDa antisera. Using gel exclusion chromatography we have fractionated a mixture of proteins extracted from the surface of 1-hr-old sea urchin embryos. A set of fractions eluting from the column contained three species of apparent molecular masses 175-, 109- and 81 K. These species comigrated on analysis by either non-reducing SDS-PAGE or native gel electrophoresis. Inclusion of the reducing agent, dithiothreitol, in the solubilizing solutions abolished comigration of these polypeptides. When polyclonal antisera were prepared against each of these antigens cross-reactivity between the 175- and 109 kDa species and between the 175- and 81 kDa species was detected. Developmental protein gel blot analyses revealed a precursor-product relationship between the 175- and the 109- and 81 kDa polypeptides. Indirect immunofluorescence analysis confirmed the localization of HLC-175 to the hyaline layer. The results reported here clearly identify HLC-175 as a component of the hyaline layer.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of melatonin on the peripheral concentrations of LH and progesterone after oestrus, and on conception rate in ewes.

It has previously been shown that administration of the indoleamine melatonin to advance the breeding season of ewes is also associated with an increase in ovulation rate and subsequent litter size. Experiment 1 assessed whether, in ewes receiving melatonin to advance the breeding season, the indoleamine acts directly on the corpus luteum to enhance progesterone secretion or indirectly through increased activity of the hypothalamic pulse generator. Six ewes received 3 mg melatonin orally at 15.00 h daily from 22 March onwards, six were induced to ovulate during mid-anoestrus following withdrawal of a progestagen pessary and injection of exogenous gonadotrophin and six acted as naturally ovulating controls. First overt oestrus occurred between 17 May and 8 July in melatonin-treated ewes, between 21 October and 3 January in control ewes and on 8 July in all induced ewes. On days 2 and 10 after the first overt oestrus, melatonin-treated ewes had pulsatile LH activity characteristic of that measured in control ewes ovulating naturally during the breeding season. There was an absence of any pulsatile LH activity in the induced ewes. Progesterone concentrations between days 7 and 12 following oestrus were significantly higher in melatonin-treated than in control and induced ewes, suggesting a luteotrophic role for melatonin. Experiment 2 was carried out to determine whether administration of melatonin commencing after induced ovulation and insemination would alter the endocrine status of the ewe and thereby influence the establishment of pregnancy and embryo survival.(ABSTRACT TRUNCATED AT 250 WORDS)

Stimulation of reactive oxidant production in neutrophils by soluble and insoluble immune complexes occurs via different receptors/signal transduction systems.

Cell-free synovial fluid from patients with rheumatoid arthritis contains soluble and insoluble IgG-containing immune complexes which activate reactive oxidant production in human neutrophils. In this report we have measured the effects of inhibitors of signal transduction pathways on neutrophil activation by these complexes and also following activation by synthetic soluble and insoluble immune complexes made from human serum albumin (HSA) and anti-(HSA) antibodies. In all aspects studied, the soluble rheumatoid complexes and the soluble synthetic complexes were indistinguishable in the ways in which they activated neutrophils. Activation of reactive oxidant production in response to these soluble complexes was completely inhibited by pertussis toxin (indicating G-protein coupling of receptor occupancy), completely insensitive to staurosporine (indicating that oxidant production did not require protein kinase C activity), only marginally (< 30%) inhibited by butanol (indicating that dependence upon activity of phospholipase D was minimal), and completely inhibited by chloracysine, an inhibitor of phospholipase A2. In contrast, activation of reactive oxidant production in response to the insoluble rheumatoid or insoluble synthetic immune complexes was largely pertussis toxin insensitive, inhibited by > 50% by staurosporine, inhibited by > 50% by butanol, and completely inhibited by chloracysine. These results show that the receptor-mediated signal transduction systems activated by the soluble and insoluble immune complexes are different. Because the soluble complexes activate a transient burst of reactive oxidant secretion from primed neutrophils, the mechanisms regulating either the release or the intracellular production of oxidants within rheumatoid joints are distinct and hence may be pharmacologically modified independently of each other.

Proto-oncogene homologous sequences in the sea urchin genome.

Using probes specific for several oncogenes/proto-oncogenes we have performed gel blot hybridization analyses of genomic DNA isolated from the sea urchin Strongylocentrotus droebachiensis. Probes prepared from v-erbB, v-myc, c-myb and v-fps were found to hybridize with discrete fragments of HindIII digested genomic DNA. In contrast, probes prepared from v-abl, v-fos, v-sis, v-src, and v-mos either hybridized with multiple fragments, indicating non-specific binding, or failed to hybridize at all above background levels. These results clearly demonstrate the presence of proto-oncogene homologous sequences in the sea urchin genome.

Neutrophil function in whole blood and after purification: changes in receptor expression, oxidase activity and responsiveness to cytokines.

Neutrophil function and plasma membrane receptor expression was measured in cell suspensions isolated by two separate procedures and in unfractionated whole blood. When cells were prepared by a combined dextran/ficoll procedure, their ability to generate reactive oxidants in response to fMet-Leu-Phe was greater than in corresponding cells isolated by a one-step procedure on Mono-Poly Resolving Medium (M-PRM). Cells prepared by both methods could be primed in vitro by rGM-CSF, but the priming ratio was greater in cells prepared by the latter method. The ability of neutrophils in whole blood to generate reactive oxidants in response to fMet-Leu-Phe was extremely low, but this was increased by more than 10 fold if the blood was pre-incubated with rGM-CSF. Similarly, expression of CD 11b and CD 16 was very low (or undetectable) in neutrophils in whole blood, but this was rapidly increased upon priming. Activation by PMA resulted in a down regulation of CD 16 expression as the receptor was shed from the cell surface. Neutrophils isolated by either the dextran/ficoll or the M-PRM method showed increased expression of receptors compared with those in whole blood, although this expression was lower in cells isolated by the latter method. These data indicate that the isolation procedures used to obtain purified neutrophils prime both receptor expression and oxidase function, although these effects are minimalised in isolation procedures using M-PRM. Furthermore, as CD 16 expression on neutrophils in whole blood is rapidly up-regulated during priming, it seems likely that, as for complement receptors, rapidly-mobilisable intracellular stores of this receptor exist.

Phospholipase D-dependent and -independent activation of the neutrophil NADPH oxidase.

Stimulation of the respiratory burst of human neutrophils by fMet-Leu-Phe (in the absence of cytochalasin B) is largely unaffected when the activities of protein kinase C and phospholipase D are inhibited. This has been confirmed using three separate assays to measure the respiratory burst. However, whilst these enzymes are not required for the initiation or maximal rate of oxidant generation, they are required to sustain oxidase activity. In contrast, in the presence of cytochalasin B, fMet-Leu-Phe stimulated oxidase activity is much more dependent on phospholipase D activity. It is proposed that (in the absence of cytochalasin B) activation of the NADPH oxidase utilises cytochrome b molecules that are already present on the plasma membrane and activation occurs independently of phospholipase D and protein kinase C. Once these complexes are inactivated, then new cytochrome b molecules must be recruited from sub-cellular stores. This translocation and/or activation of these molecules is phospholipase D dependent. Some support for this model comes from the finding that the translocation of CD11b (which co-localises with cytochrome b) onto the cell surface is phospholipase D dependent.

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.

Fetal growth and development following temporary exposure of day 3 ovine embryos to an advanced uterine environment.

The effect of exposing Day 3 ovine embryos to an advanced uterine environment for a period of 3 days on subsequent fetal growth and development between Day 35 and Day 135 of gestation was studied. Day 3 embryos were recovered from superovulated donor ewes and transferred to synchronous final or asynchronous temporary recipients for 3 days. Embryos were recovered from these temporary recipients and transferred to Day 6 final recipients. Gravid uteri were recovered, weighed and dissected on Days 35, 45, 60, 90, 110, 125 and 135 of gestation. Fetal weight and length data were analysed by fitting non-linear Gompertz models of the form log(e) y = a - be(-ct), where y is fetal size and t is time from conception. Various terms including treatment, gestational age, embryo stage at transfer and fetal sex were fitted to this model. Fetal development was assessed by relating organ weight to fetal bodyweight using the linear allometric equation log(e) y = log(e) a + b log(e) x, where y is organ weight and x is fetal weight. Temporary exposure of Day 3 embryos to an advanced uterine environment did not increase the rate of embryo development and had no effect on fetal growth and development between Days 35 and 135 of gestation in this study. A single Gompertz model (log(e) y = 10.134 - 17.047e(-0.1733t)) explained 99.8% of the variation in fetal weight. Of terms fitted to this model only gestational age and fetal sex influenced fetal weight, with male fetuses being 5% heavier (P<0.05) than female fetuses. Fetal development was also unaffected by experimental treatment in this study. Allometric coefficients established for various fetal components agreed well with those from previously published studies.

Comparative biochemical analysis of sea urchin peristome and rat tail tendon collagen.

We report here a biochemical comparison between type 1 rat tail tendon collagen and collagen isolated from sea urchin peristome tissue. The sea urchin collagen consisted of two species of apparent mol masses, 140 and 116 kDa. Amino acid compositional analysis of the 140 and 116 kDa species revealed the presence of hydroxyproline and hydroxylysine as well as a glycine content of 28.1 mol.%. In solubility experiments the rat tail tendon collagen was found to precipitate at sodium chloride concentrations between 1 and 2 M while peristome collagen remained soluble at salt concentrations as high as 4 M. Incubation of the peristome and rat tail tendon collagen preparations with a sea urchin collagenase/gelatinase resulted in cleavage of the former but not the latter collagen. Upon heat denaturation at 60 degrees C, however, the rat tail tendon collagen served as a substrate for the gelatinase. Cyanogen bromide cleavage of rat tail and peristome collagens generated largely unique peptide maps. Collectively, these results suggest that structural differences exist between echinoderm and vertebrate type 1 collagens.

Asymmetric septal hypertrophy in autopsies in men.

Asymmetric septal hypertrophy (ASH) was not identified in the 2,790 autopsies performed in a Veterans Administration hospital since 1958. Recent reports consider ASH to be a common cardiac disease in the diffuse form that has extensive myofiber disorientation. A retrospective study of 419 autopsies was undertaken to see if that diagnosis had been overlooked; but, in 100 autopsies with detailed photographic records of ventricular and septal size, ASH was not found. There were slight average increases in the posterior portions of the septum and right ventricle, and an average septal-left ventricular ratio of 1.1. Since neither staff pathologists nor consultants who reviewed entire hearts with cardiomyopathy noted features of ASH, we consider it to be a rare disease in elderly veterans.

Dietary excesses of urea influence the viability and metabolism of preimplantation sheep embryos and may affect fetal growth among survivors.

In the first of two experiments investigating the effect of dietary urea on the survival and metabolism of ovine embryos, 30 Border Leicester x Scottish Blackface ewes received a maintenance diet (milled hay, molasses, minerals, vitamins) with no urea (control, C; n = 10) or with added urea at 15 g (low urea, LU; n = 10) or 30 g (high urea, HU; n = 10) kg-1 feed for a 12 week period. The degraded nitrogen (N) status relative to estimated rumen microbial N requirements was -2, +9 and +20 g per day, respectively. One week after allocation to diets, progesterone priming (12 days) commenced. Ewes received 800 IU of equine chorionic gonadotrophin at progesterone withdrawal, were inseminated 52 h later (Day 0) and embryos were collected from five ewes per group at Day 4 and from five ewes at Day 11. If available, one embryo was returned to each ewe; the rest were cultured in vitro. There was no effect of treatment on progesterone, luteinizing hormone (LH), or time of oestrus onset C, LU and HU plasma urea (P < 0.001) and ammonia levels (C vs. HU, P < 0.01; LU vs. HU, P < 0.05) differed. Day 4 HU embryos were retarded relative to C and LU embryos. After 3 days of culture, 70%, 66% and 0% of C, LU and HU embryos, respectively, were viable. Mid-term pregnancy rates following transfer were 63%, 43% and 33%. Only one HU lamb (male) was born following embryo transfer, its birthweight (10.1 kg) exceeded that of its C (n = 3; 7.0, 7.0, 7.5 kg) and LU (n = 2; 7.3, 8.2 kg) counterparts (P < 0.025). In the second experiment, C2 (2.5 g urea kg-1; n = 5) and HU2 (30 g kg-1; n = 7) diets which provided similar intakes of degraded N relative to microbial requirements as those for C and HU ewes in Experiment 1 were fed to Border Leicester x Scottish Blackface ewes superovulated with 16 mg of porcine follicle-stimulating hormone. Urea and ammonia levels in utero-oviductal samples were elevated in HU2 ewes (P < 0.05). At collection (Day 3), HU2 embryos used more glucose (P < 0.01) and, following culture, some exhibited up to a 2.8-fold increase in metabolism. In conclusion, excess rumen degradable N in ewe diets elevates urea and ammonia in plasma and in utero, with an associated increase in embryo mortality. Nevertheless, metabolism appears to be up-regulated in some embryos and, among those that survive, fetal growth appears to be enhanced.