Review and update of a Nutrient Transfer model used for estimating nitrous oxide emissions from complex grazed landscapes, and implications for nationwide accounting.

In New Zealand, nitrous oxide emissions from grazed hill pastures are estimated using different emission factors for urine and dung deposited on different slope classes. Allocation of urine and dung to each slope class needs to consider the distribution of slope classes within a landscape and animal behavior. The Nutrient Transfer (NT) model has recently been incorporated into the New Zealand Agricultural GHG Inventory Model to account for the allocation of excretal nitrogen (N) to each slope class.

Transcriptional profiling of equine endometrium before, during and after capsule disintegration during normal pregnancy and after oxytocin-induced luteostasis in non-pregnant mares.

The current study used RNA sequencing to determine transcriptional profiles of equine endometrium collected 14, 22, and 28 days after ovulation from pregnant mares. In addition, the transcriptomes of endometrial samples obtained 20 days after ovulation from pregnant mares, and from non-pregnant mares which displayed and failed to display extended luteal function following the administration of oxytocin, were determined and compared in order to delineate genes whose expressions depend on the presence of the conceptus as opposed to elevated progesterone alone. A mere fifty-five transcripts were differentially expressed between samples collected from mares at Day 22 and Day 28 of pregnancy.

Patterns of conceptus development and of progesterone concentrations in maternal blood preceding spontaneous early pregnancy failure in mares.

Sixteen cases of spontaneous pregnancy loss (11 of singletons and five of pairs of twins) are described. The losses occurred between gestation Days 13 and 25 in 12 mares being monitored almost daily by transrectal ultrasonography (for measurement of conceptus growth) and blood sampling (for determination of maternal plasma progesterone concentrations as evidence of luteolysis) in experimental studies of early pregnancy. In 10 of the 16 cases the uterus was flushed and eight conceptuses were recovered for morphological assessment.

5Alpha-Reduced Steroids Are Major Metabolites in the Early Equine Embryo Proper and Its Membranes.

Steroid production and metabolism by early conceptuses are very important for the establishment and maintenance of pregnancy in horses. Our earlier work suggested the possible formation of 5alpha-reduced steroids in equine conceptuses. We have now demonstrated the formation of 5alpha-reduced metabolites of androstenedione, testosterone, and progesterone by the embryo and its membranes.

Salt as a mitigation option for decreasing nitrogen leaching losses from grazed pastures.

Background: The main source of nitrogen (N) leaching from grazed pastures is animal urine with a high N deposition rate (i.e. per urine patch), particularly between late summer and early winter.

Constraints on Mammalian forelimb development: insights from developmental disparity.

Tetrapod limb development has been studied extensively for decades, yet the strength and role of developmental constraints in this process remains unresolved. Mammals exhibit a particularly wide array of limb morphologies associated with various locomotion modes and behaviors, providing a useful system for identifying periods of developmental constraint and conserved developmental mechanisms or morphologies. In this study, landmark-based geometric morphometrics are used to investigate levels and patterns of morphological diversity (disparity) among the developing forelimbs of four mammals with diverse limb morphologies: mice, opossums, horses, and pigs.

Therio-ontology: a personal view of 40 years of farm animal embryo form and function.

The main purpose of this autobiographical reminiscence of 40 years of embryo research is to provide young theriogenologists with a firsthand account of how career development can depend strongly on early influences that become modified by changing circumstances. With no intention of being didactic, I hope that my experience of coping with enormous changes in techniques and attitudes may be of use to some of those embarking on a further 40 years of change of at least equal enormity.

Morphology of twin and triplet equine conceptuses during weeks 3 and 4 of pregnancy.

Twin ovulations are common in horses, but twin pregnancies are rarely carried to term. Theories of how one or both twins is/are naturally eliminated in early pregnancy, termed 'embryo reduction', have been based on ultrasonographic, not morphological, studies. Here we describe conceptuses recovered transcervically between Days 15 and 28 from 31 twin and two triplet pregnancies.

Biosynthesis of oestrogen by the early equine embryo proper.

The embryo proper in early equine pregnancy has recently been shown to have a remarkable capacity for metabolism of oestrogens. High concentrations of oestrogens in yolk-sac fluid could provide substrate for local metabolism in tissues of the embryo proper and this activity could have significance for early development. Due to the high level of oestrogen metabolism in the embryo proper we examined the possibility that it could also biosynthesise oestrogens.

Relationship between the timing of prostaglandin-induced luteolysis and effects on the conceptus during early pregnancy in mares.

To advance the understanding of early pregnancy and pregnancy failure in horses, this study determined how luteolysis induced by cloprostenol (an analogue of prostaglandin F2α) affects conceptus development. Mares were injected on Days 12, 14, 16 or 18 of pregnancy with either cloprostenol (treatment groups, total n=83 pregnancies) or saline (controls, n=81), and growth of the conceptuses was monitored and compared by daily ultrasonography until they were collected transcervically on Days 15-22, 1-4 days after the injections. The comparisons were extended in the recovered conceptuses by counting somites, measuring the volume and osmolality of yolk-sac fluid and its concentrations of proteins, estrone sulfate and progesterone, and by assessing the morphology of the capsule and vascular system.

Estrogen metabolism by the equine embryo proper during the fourth week of pregnancy.

Estrogen production by the trophoblast is considered important in early equine pregnancy and leads to high concentrations in yolk-sac (Y-S) fluid. The embryo proper is a potential site for their action. We examined estrogen metabolism in the embryo proper because some actions of estrogens are derived from locally formed metabolites.

Electrolyte distribution and yolk sac morphology in frozen hydrated equine conceptuses during the second week of pregnancy.

To investigate how equine conceptuses expand rapidly despite the hypo-osmolality of their yolk sac fluid, 18 conceptuses, aged 8-12 days and 0.8-10.0 mm in diameter, were examined by cryoscanning electron microscopy and energy dispersive X-ray microanalysis to determine the distribution of Na, Cl and K in their fluids.

Desialylation of core type 1 O-glycan in the equine embryonic capsule coincides with immobilization of the conceptus in the uterus.

During the second and third weeks of pregnancy, the equine conceptus expands rapidly while it is enclosed within a glycan capsule. Around day 16 of gestation, the conceptus loses its mobility in the uterus by a process termed 'fixation', coinciding with various changes in the capsule. Here, we compared the structure of the carbohydrate moieties expressed by the capsule during pre- and post-fixation periods.

Farm animal embryo technologies: achievements and perspectives.

Progress and changes in embryo technology in farm animals are briefly reviewed in terms of how well embryos can be made and used and what the subject has taught us about the maintenance of pregnancy and reproduction in general. Generalizations are made about the need to not accept dogma, how initially complex techniques always become simplified and thereby more applicable, and the need for the support of long-term and basic research. Personal views are offered on how best to prepare and motivate the next generation of scientists in the field, and the need for scientists to engage in the debate of how embryo technologies should be used responsibly in countering global inequalities.

Improved method for extraction and LC-MS analysis of pyrrolizidine alkaloids and their N-oxides in honey: application to Echium vulgare honeys.

A method for analyzing honey samples was developed that enabled the simultaneous detection and identification of pyrrolizidine alkaloids and their N-oxides. Honey samples were treated with methanol or dilute sulfuric acid and then centrifuged to remove insoluble material. Subsequent strong cation exchange, solid-phase extraction of the supernatant provided a fraction that was analyzed for the presence of pyrrolizidine alkaloids and their N-oxides using high-pressure liquid chromatography coupled to electrospray ionization mass spectrometry.

Solid-phase extraction and LC-MS analysis of pyrrolizidine alkaloids in honeys.

Strong-cation-exchange, solid-phase extraction of pyrrolizidine alkaloids and their N-oxides from honey samples was followed by reduction of the N-oxides and subsequent analysis of total pyrrolizidine alkaloids using high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry. A limited survey of 63 preprocessing samples of honey, purposefully biased toward honeys attributed to floral sources known to produce pyrrolizidine alkaloids, demonstrated levels of pyrrolizidine alkaloids up to approximately 2000 parts per billion (ppb) in a sample attributed to Echium plantagineum. Up to 800 ppb pyrrolizidine alkaloids was detected in some honeys not attributed by the collector to any pyrrolizidine alkaloid-producing floral source.

Estrogen metabolism in the equine conceptus and endometrium during early pregnancy in relation to estrogen concentrations in yolk-sac fluid.

Because estradiol (E(2)) production by the early equine conceptus is considered crucial to the establishment of pregnancy, the amounts of E(2), estrone (E(1)), and their sulfates (E(2)S, E(1)S) were measured by RIA in yolk-sac fluid of 63 conceptuses collected by transcervical lavage over the period of 11-26 days after ovulation. Amounts increased significantly with age of conceptus, especially for E(1)S. Then, the metabolism of E(2), which may be highly relevant for its action, was examined in the conceptus and endometrium over the period when the conceptus ceases to migrate within the uterus.

A history of farm animal embryo transfer and some associated techniques.

Events over the last 125 years that have been particularly important to the development of embryo transfer in farm animals are reviewed, arguing that an appreciation of the history of a discipline helps shape its future. Special attention is paid to how the motivations of the scientists involved have changed over time, and how these changes have influenced the practical application of embryo transfer to animal breeding.