Can farm animals help to study endocrine disruption?

The phenomenon of endocrine disruption can be regarded as part of the disciplines of toxicology and environmental toxicology. These two disciplines have generated guideline protocols on how various effects of chemicals should be tested as a basis for regulatory decisions. These protocols almost exclusively involve laboratory rodents and the data obtained are then used for human risk assessment. Would it be justifiable, then, to introduce or promote the use of other species in these test protocols? There are, at any rate rationales for studying effects in species other than laboratory rodents: (1) other species may better mimic the human system; (2) they may in some cases be more useful for studying a certain mechanism or phenomenon; (3) they may highlight the diversity of effects or sensitivity between species. However, there are at least two basic criteria that must be met for a species before it can be introduced in this context: (a) we must have a good understanding of the physiological system to be studied; and (b) we must have a number of tools to study effects on this system. When it comes to the reproductive system – regarding which most endocrine disruption has been reported – farm animals are second only, or in some respects superior, to laboratory rodents with respect to these criteria. This review gives examples of how farm animals can be of use in the study of endocrine disruption with a focus on the author's own data from studies in the pig.     

Major long‐term changes in the ecology of the Ythan estuary,Aberdeenshire, Scotland; how important are physical factors?

1. Long‐term data sets on macro‐algae, sediment invertebrates, shorebirds and physical parameters are explored for the Ythan estuary, Scotland. 2. Coverage by macro‐algal mats has increased over the last 40 years with significant impacts on the distribution and abundance of benthic invertebrates and their shorebird consumers. Areas of the estuary worst affected by the mats now support fewer Corophium volutator, whilst the abundance of this and other species has increased in areas less affected by mats, possibly through enrichment by non‐local macro‐algal detritus. 3. Shorebird abundance increased between the early 1960s and the 1980s, possibly in response to enhanced invertebrate abundance in unaffected areas, but has declined since, as algal mats continue to spread. 4. The cause of the increased biomass of macro‐algae is contentious, but the present analysis shows that the increase is unlikely to be related to changes in the physical characteristics of the estuary, which appear to have remained fairly constant over at least the last 30 years. Copyright © 1999 John Wiley & Sons, Ltd.     

A recent growth increase of European beech (Fagus sylvatica L.) at its Mediterranean distribution limit contradicts drought stress

Future changes in tree growth, associated with a warmer and drier climate, are predicted for many species and locations across the European Mediterranean Basin. However, quantification of the intensity and severity of related consequences for forest ecosystem functioning and productivity remains challenging. Species-specific distribution limits that are particularly sensitive to small changes in the ambient climate may provide an ideal test bed to assess the nature of past growth trends and extremes and their responsible controls. Here, we seek to understand how twentieth century climate change affected the growth of European beech (Fagus sylvatica L.) nearby its south-eastern distribution limit in Albania and Macedonia on the Balkan Peninsula. We sampled 93 living trees from undisturbed mixed forest stands at ~1,450 m a.s.l. and 29 timbers from nearby historical buildings. Application of different tree-ring detrending techniques allowed robust composite chronologies with varying degrees of high- to low-frequency variability to be developed back to 1648 ad. Comparison with local meteorological station measurements and continental grid-box climate indices revealed spatiotemporal instability in growth–climate response patterns. Nevertheless, year-to-year and decadal-long fluctuations in radial beech growth were significantly (P < 0.001) negatively correlated at ?0.61 with June–September temperature over the 1951–1995 period. This (inverse) relationship between increased beech growth and decreased summer temperature is somewhat indicative for the importance of plant-available soil moisture, which likely controls ring width formation near the species-specific south-eastern distribution limit. Significant positive correlations between beech growth and drought (scPDSI; r = 0.57) confirm metabolistic drought constraints. However, an unexpected late twentieth century growth increase not only contradicts the previously observed growth dependency to summer soil moisture, but also denies any putative drought-induced forest ecosystem suppression in this part of the Mediterranean Basin.     

Is tree growth in boreal coniferous stands on mineral soils affected by the addition of wood ash?

Increasing use of forest fuels for energy production is generating greater quantities of wood ash. In Sweden, it is recommended that this ash should be returned to the forest to counter soil acidification and avoid potential future nutrient deficiencies, but the effects on tree growth require clarification. Thus, 10 field experiments were established in Sweden in 1990–2006 to study the effects of adding wood ash of various origins, doses and combinations of both ash and nitrogen on stem growth in Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L. Karst.) stands on mineral soil. Observations after 5–15 years show that growth responses were strongest when N was added, either alone or with wood ash. Growth responses to additions of wood ash without N were small and variable and statistically insignificant at all study sites. However, there were indications that adding wood ash may increase stem-wood growth at fertile sites and decrease it at less fertile sites. Hence, at fertile sites, it may compensate for the growth reductions that normally follow whole-tree harvests, at least temporarily, presumably due to its effects on soil N turnover. At less fertile sites, adding N is probably essential to counteract these growth reductions.     

A 25?years experience of group-housed sows–reproduction in animal welfare-friendly systems

Since January 1 2013, group housing of sows has been compulsory within the European Union (EU) in all pig holdings with more than ten sows. Sows and gilts need to be kept in groups from 4 weeks after service to 1 week before the expected time of farrowing (Article 3(4) of Directive 2008/120/EC on the protection of pigs). The legislation regarding group housing was adopted already in 2001 and a long transitional period was allowed to give member states and producers enough time for adaptation. Even so, group housing of sows still seems to be uncommon in the EU, and is also uncommon in commercial pig farming systems in the rest of the world. In this review we share our experience of the Swedish 25 years of animal welfare legislation stipulating that sows must be loose-housed which de facto means group housed. The two most important concerns related to reproductive function among group-housed sows are the occurrence of lactational oestrus when sows are group-housed during lactation, and the stress that is associated with group housing during mating and gestation. Field and clinical observations in non-lactating, group-housed sows in Sweden suggest that by making basic facts known about the pig reproductive physiology related to mating, we might achieve application of efficient batch-wise breeding without pharmacological interventions. Group housing of lactating sows has some production disadvantages and somewhat lower productivity would likely have to be expected. Recordings of behavioural indicators in different housing systems suggest a lower welfare level in stalled animals compared with group-housed ones. However, there are no consistent effects on the reproductive performance associated with different housing systems. Experimental studies suggest that the most sensitive period, regarding disturbance of reproductive functions by external stressors, is the time around oestrus. We conclude that by keeping sows according to the pig welfare-friendly Directive 2008/120/EC, it is possible to combine group-housing of sows with good reproductive performance and productivity. However, substantially increased research and development is needed to optimize these systems.     

Ossification of ungular cartilages in front feet of cold-blooded trotters - a clinical radiographic evaluation of development over time

Background

It has not yet been shown that ossification of ungular cartilages (OUC) is a pathological condition. Beside heredity, factors such as sex, age, repeated concussion, local trauma, hoof and body size have been suggested as contributing factors for OUC development. By comparing radiographs of front hooves from cold-blooded trotters with different age we wanted to evaluate when development of OUC in cold-blooded trotters occurs and if and when it stabilizes in relation to age and workload. Diagnosis and grading of OUC were based on radiological field examinations of 649 Swedish and Norwegian cold-blooded trotters’ front hooves. A hundred and forty-seven of the horses were re-examined 3-13 years (mean age 9, median 8 years) after the first occasion. All radiographs were evaluated blind, using two different grading systems for OUC. Work load, in form of number of races completed, and body size score were collected from official data. Four statistical ordinal regression models were used, compared and evaluated.

Results

We identified a breakpoint at 2.8 ± 0.38 years of age when ossification ends and proposed a simpler grading system with more consistent results. There was no significant correlation between body size and grade of OUC. Comparison of different statistical methods for evaluation of ordinal data revealed a piecewise linear regression model as most suitable.

Conclusions

Individuals with OUC developed this condition during the stage of life when their hooves develop in size. Results from this study can assist equine practitioners when examining and for understanding this condition in their clinical work and is also beneficial for the Scandinavian equine industry when devising breeding programs.     

Human neuroblasts migrate to the olfactory bulb via a lateral ventricular extension

The rostral migratory stream (RMS) is the main pathway by which newly born subventricular zone cells reach the olfactory bulb (OB) in rodents. However, the RMS in the adult human brain has been elusive. We demonstrate the presence of a human RMS, which is unexpectedly organized around a lateral ventricular extension reaching the OB, and illustrate the neuroblasts in it. The RMS ensheathing the lateral olfactory ventricular extension, as seen by magnetic resonance imaging, cell-specific markers, and electron microscopy, contains progenitor cells with migratory characteristics and cells that incorporate 5-bromo-2'-deoxyuridine and become mature neurons in the OB.     

An EMS mutagenesis protocol for sugar beet and isolation of non-bolting mutants

An annual sugar beet line homozygous for the dominant gene for early bolting (B) has been mutagenized with different doses of ethylmeth‐anesulfonate (EMS). Approximately 15 000 M1 seeds were treated with EMS doses between 0.5 and 1% for 4, 6, 8, 12 and 14 h. Among 10 066 M1s, plants with chlorophyll defects and other abnormalities were found. Germination rates ranged between 30 and 100%, whereas the fertility of M1s dropped to 36%. A dose of 1% EMS applied for 8 h was found to yield an acceptable rate of M2 sterility (16%). Exactly 0.5% of the M2 families contained plants with altered bolting behaviour. After selfing these M2 plants, five non‐bolting M3 lines were selected. These plants do not exhibit shoot elongation even after cultivation under long‐day conditions. Thus, they are homozygous for new mutagenized, recessive non‐bolting alleles. Moreover, four M3 lines showed delayed bolting which was clearly different from the early bolting parent. This demonstrates varying activities of the bolting gene due to different mutational events.