The use of aminoglycosides, colistin and beta-lactam antibiotics as animal feed drugs for pigs in Schleswig-Holstein

An evaluation of production orders for medicated feedingstuffs for pigs given in 1998 in Schleswig-Holstein showed aminoglycosides, colistin and beta-lactam antibiotics as regularly used antibiotical ingredients. The presented study analyses the production orders which include these antibiotics more in detail particularly with regard to the prescribed dosages. In part, there were deviations to the rules of good clinical practise for the use of anitbiotics. The applied dosage of spectinomycin and apramycin was often lower than suggested in the literature. The low oral bioavailability of amoxicillin was not considered when using amoxicillin in medicated feedingstuffs.     

Principles of treatment for mast cell tumors

Mast cell tumors (MCT) are the most common malignant cutaneous tumors that occur in dogs. They are most commonly found on the trunk, accounting for approximately 50% to 60% of all sites. MCTs associated with the limbs account for approximately 25% of all sites. Cutaneous MCTs have a wide variety of clinical appearances. Histologic grade is the most consistent prognostic factor available for dogs. MCTs located at 'nail bed' (subungual), inguinal/preputial area, and any mucocutaneous area like perineum or oral cavity carry a guarded prognosis and tend to metastasize. MCTs usually exfoliate well and are cytologically distinct. The extent of staging procedures following fine-needle aspirate cytologic diagnosis is based on the presence or absence of negative prognostic indicators. Surgery is the treatment of choice for solitary MCTs with no evidence of metastasis. Reponses rates to chemotherapy, (partial response) as high as 78% have been reported, and preliminary evidence suggests that multiagent (prednisone and vinblastine) protocols may confer a higher response rate than single-agent therapy. MCTs are the second most common cutaneous tumor in the cat. There are two distinct forms of cutaneous MCTs in the cat. The more common form is the mastocytic form, and the less common is the histiocytic form. Unlike in the dog, the head and neck are the most common sites for MCTs in the cat followed by the trunk and limbs. Cats with disseminated forms of MCT often present with systemic signs of illness, which include depression, anorexia, weight loss, and vomiting. The diagnosis and staging of MCTs in cats is similar to that in the dog. As with dogs with cutaneous MCTs, surgery is the treatment of choice. Little is known about the effectiveness of adjunctive chemotherapy options for cutaneous MCTs. Adjunctive chemotherapy does not appear to increase survival times.     

Consequences of specialized breeding in the Swedish Warmblood horse population

In many European warmblood studbooks, clear specialization toward either jumping or dressage horses is evident. The Swedish Warmblood (SWB) is also undergoing such specialization, creating a possible need for separate breeding programs and a discipline-specific Young Horse Test (YHT). This study investigated how far specialization of the SWB breed has proceeded and the potential consequences. Individuals in a population of 122,054 SWB horses born between 1980 and 2020 were categorized according to pedigree as jumping (J), dressage (D), allround (AR), or thoroughbred (Th). Data on 8,713 J horses and 6,477 D horses assessed for eight traits in YHT 1999–2020 were used to estimate genetic parameters within and between J and D horses and between different periods. Future scenarios in which young horses are assessed for either jumping or dressage traits at YHT were also analyzed. More than 80% of horses born in 1980–1985 were found to be AR horses, while 92% of horses born in 2016–2020 belonged to a specialized category. The average relationship within J or D category was found to increase during the past decade, whereas the relationship between these categories decreased. Heritability estimates for gait traits were 0.42–0.56 for D horses and 0.25–0.38 for J horses. For jumping traits, heritability estimates were 0.17–0.26 for J horses and 0.10–0.18 for D horses. Genetic correlations between corresponding traits assessed in J and D horses were within the range 0.48–0.81, with a tendency to be lower in the late study period. In the future scenarios, heritability and genetic variance both decreased for traits that were not assessed in all horses, indicating that estimation of breeding value and genetic progress for these traits could be affected by a specialized YHT. However, ranking of sires based on estimated breeding values (EBVs) and accuracy of EBVs was only slightly altered for discipline-specific traits. With continued specialization in SWB, specialization of the YHT should thus be considered.     

Climatic influences on development and survival of free-living stages of equine strongyles: implications for worm control strategies and managing anthelmintic resistance

Development of resistance to anthelmintic drugs by horse strongyles constitutes a growing threat to equine health because it is unknown when new drug classes can be expected on the market. Consequently, parasite control strategies should attempt to maintain drug efficacy for as long as possible. The proportion of a parasite population that is not exposed to anthelmintic treatment is described as being "in refugia" and although many factors affect the rate at which resistance develops, levels of refugia are considered the most important as these parasites are not selected by treatment and so provide a pool of sensitive genes in the population. Accordingly, treatment should be avoided when pasture refugia are small because such treatments will place significant selection pressure for resistance on worm populations. Given this new paradigm for parasite control, it has become important to identify seasons and circumstances wherein refugia are diminished. Free-living stages of equine strongyles are highly dependent on climatic influences, and this review summarises studies of strongyle development and survival under laboratory and field conditions in Northern (cool) temperate, Southern (warm) temperate and subtropical/tropical climates. In Northern temperate climates, refugia are smallest during the winter. In contrast, refugia are lowest during the summer in warm temperate and subtropical/tropical climates. Although adverse seasonal changes clearly have significant effects on the ability of free living stages of strongyle nematode parasites to survive and develop, available data suggest that climatic influences cannot effectively "clean" pastures from one grazing season to the next.     

Impact of irrigation timing on simulated water-crop production functions

Estimates of the effects of alternative discrete irrigation water scheduling options on consumptive use or evapotranspiration and on crop yield are developed for a northeastern Colorado case study. The analysis proceeds from the premise that farmers, rather than considering irrigation water as a continuously variable input, tend to treat irrigations as discrete events, and make scheduling decisions as choices among numbers of irrigations of approximately equal volume. The van Genuchten-Hanks model is employed to develop a transient-state water-crop production function model. Results for two crops – corn grain and edible dry beans – are presented here. Findings are that the effect of the number of irrigations on evapotranspiration and yield per hectare varies widely, depending upon the timing of applications. When farmers can choose the optimal timing of irrigations, a reduced number of irrigations has a relatively limited adverse effect on crop production until irrigations are reduced to less than four per season. However, there are many situations in which an inability to apply water can result in a very large reduction from potential maximum yield, particularly if water is withheld early in the season and/or during the rapid growth period of the crops. In many contexts of irrigation water management, water policy analysts will wish to consider the more realistic discrete-input simulation model for policy evaluation. Received: 1 November 1996     

Cation treatment and drying‐temperature effects on nonylphenol and phenanthrene sorption to a sandy soil

The objective of this study was to investigate the effects of mono‐ and polyvalent cations on sorption of the two hydrophobic compounds nonylphenol (NP) and phenanthrene (Phe). To this end, exchange sites of a sandy soil were saturated with either Na⁺, Ca²⁺, or Al³⁺ and excess salts were removed by washing. The samples were then sterilized and either stored moist, dried at room temperature, or at 20°C, 60°C, or 105°C in a vented oven. Saturation with Na⁺ led to an increase of dissolved organic C (DOC) concentration in the soil water extracts, whereas the polyvalent cations Ca²⁺ and Al³⁺ decreased it. The ¹H‐NMR relaxometry analyses showed that Al³⁺ restricted the mobility of water molecules that are confined within the SOM structure to a higher extent than Ca²⁺ or Na⁺. According to contact‐angle (CA) analyses, cation treatment did not significantly change the wetting properties of the samples. Batch sorption–desorption experiments showed no clear salt‐treatment effects on the sorption and desorption equilibria or kinetics of NP and Phe. Instead, the sorption coefficients and sorption hysteresis of NP and Phe increased in dry soil. With increasing drying temperature the CA of the soils and the sorption of both xenobiotics increased significantly. We conclude that structural modifications of SOM due to incorporation of polyvalent cations into the interphase structure do not modify the sorption characteristics of the soil for hydrophobic compounds. Instead, increasing hydrophobization of organic soil constituents due to heat treatment significantly increased the accessible sorption sites for nonpolar organic compounds in this soil.     

Floc and sediment properties and their environmental distribution from a marine fish farm

Open ocean pen aquacultural operations are leaky systems with potential environmental impacts of metabolic excretions products, feed additives, and anti‐fouling agents. This study analysed the water–sediment interface along a horizontal transect away from a fish farm, noting variations between water, floc, and sediment properties. The properties examined included nitrogen (N), phosphorus (P), carbon (C), sulphur (S), and trace element content, as well as heterotrophic bacteria populations. C, N, labile P, NH₄, Ca, and Zn were elevated in surface sediments at the farm in comparison with sites 100 and 300 m away. The flocs had higher levels of Mg, K, and heterotrophic bacteria than adjacent sediments, indicating the importance of the microbial communities in flocs. The flocs were important in their role as a retention and potential transport mechanism for metals, increasing in concentration of Al, Fe, and Mn with distance from the farm.     

Antibiotic resistances of intestinal lactobacilli isolated from wild boars

Acquired antibiotic resistances have been reported in lactobacilli of various animal and food sources, but there are no data from wild boar. The objective was a preliminary examination of the antibiotic resistance prevalence of intrinsically vancomycin-resistant lactobacilli isolated from wild boar intestines and analysis of the genetic determinants implicated. Out of three wild boars, 121 lactobacilli were recovered and grouped according to their whole cell protein patterns. Initial phenotypic screening revealed that all were susceptible to erythromycin (2 μg/ml), but 30 were resistant to tetracycline (32 μg/ml). Based on Randomly Amplified Polymorphic DNA-PCR clustering, 64 strains were selected as representative genotypes for identification and minimum inhibitory concentration (MIC) determination. Partial 16S rRNA gene sequencing identified four species: (i) L. mucosae (n = 57), (ii) L. reuteri (n = 47), (iii) L. fermentum (n = 12), and (iv) L. murinus (n = 5). Most heterofermentative strains displayed low MICs for ampicillin (AMP), chloramphenicol (CHL), streptomycin (STR), kanamycin (KAN), gentamicin (GEN), erythromycin (ERY), quinupristin/dalfopristin (Q/D), and clindamycin (CLI). Atypical MICs were found mainly in L. mucosae and L. reuteri for TET, KAN, STR, AMP and CHL, but except the TET MICs of L. mucosae mostly at low level. L. murinus strains revealed atypical MICs for aminoglycosides, and/or CHL, AMP, CLI. PCR screening detected tet(W) in 12 and tet(M) in one of heterofermentative strains, as well as the aph(3′)-III kanamycin gene in L. murinus. This is the first report showing acquired antibiotic resistance determinants in intestinal lactobacilli of wild boar origin.     

Short-term evolution of hydration effects on soil organic matter properties and resulting implications for sorption of naphthalene-2-ol

Purpose

Sorption of xenobiotics in soils and especially to soil organic matter (SOM) determines their mobility and bioavailability in ecosystems. However, SOM as the major sorbent may be altered in its physicochemical properties upon changes in boundary conditions such as hydration. Hence, the goal of this study was to determine the influence of soil hydration on physicochemical properties of SOM and the resulting effects on sorption of xenobiotics.

Materials and methods

Samples of a Histosol with 51?% SOM were adjusted to five water contents from 10 to 75?% (w/w based on dry soil mass) and aged for water contact times of 0?weeks to 3?years. The hydrated samples were characterized with respect to thermal properties of SOM and of the incorporated water via differential scanning calorimetry and with respect to hydration-induced swelling via ¹H-NMR relaxometry, and the sessile drop method was applied to determine their soil?Cwater contact angle. Sorption kinetics and isotherms of naphthalene-2-ol in the pre-treated peat samples were determined in batch experiments.

Results and discussion

SOM matrix rigidity varied with the water content and increased with water contact time. An initial minimum in SOM rigidity at ~30?% water content became maximum after ~20?weeks, also resulting in the strongest resistance towards water infiltration. We argue that the anomalies at 30?% water content are related to the critical water content for the formation of freezable water w _crit in the peat samples, which was 26.2?±?0.3?%. Conditions for water-assisted molecular bridging were assumably optimal at 30?% water content. Whereas parameters of naphthalene-2-ol sorption reflecting the sorbed amount were mainly altered by the wetting properties of SOM, sorption linearity and hysteresis were influenced by the anomalies in peat matrix properties at a water content around 30?%.

Conclusions

The study revealed that the interplay of SOM and water led to highly variable and complex changes in SOM physicochemical properties. These properties may serve as a predictor for sorption of xenobiotics in soil at varying hydration conditions enabling a more precise assessment of the environmental fate of xenobiotics.