Testate amoebae as predators of nematodes

Testacea were observed ingesting nematodes in the litter horizons of native forests in New Zealand. Nematodes were most commonly attacked from the tail end but some specimens were attacked at mid-body. Nematodes with damaged tails were recovered in greatest numbers from the highest, wettest site sampled. Nebela (Apodera) vas (Certes, 1989) and Difflugia sp. (possibly lanceolata Penard, 1890) were the predators; both species were redescribed using light and scanning electron microscopy and morphometry. Most damaged nematodes were Ironus sp. but Clarkus, Tobrilus, Iotonchus, Cobbonchus, Dorylaimus and Plectus were also attacked. Literature on testacean feeding strategies was reviewed briefly.     

Response of the fauna of a grassland soil to doubling of atmospheric carbon dioxide concentration

The effects of elevated CO₂ on rhizosphere processes, including the response of soil faunal populations and community structure, have so far received little attention. We report on significant responses in the soil fauna of ryegrass/white clover swards to both increasing CO₂ from 350 to 750 μl · l^–1 and, to a period of 60 days when some of the turves were subject to drought, in a controlled climate growth room experiment. The nematodes which increased were predominantly Enoplia, including dorylaimids, alaimids and trichodorids. This accords with both the doubling of Alaimus under elevated CO₂ conditions reported in a similar experiment and with the common association of Enoplia with less disturbed habitats. The most marked decrease was in the bacterial-feeding Rhabditis (Secernentea). The increase in omnivorous and predacious nematodes may have been responsible for the decrease in populations of bacterial-feeding nematodes. However, in contrast to their standing crops, the turnover rate of bacterial-feeding nematodes and soil microbial biomass probably increased as a result of increased grazing by these omnivorous and predacious nematodes. Increases in earthworm and enchytraeid populations were related to increased below-ground productivity reported for the same trial. Received: 30 September 1996     

Effect of fertilizers with the new nitrification inhibitor DMPP (3,4-dimethylpyrazole phosphate) on yield and quality of agricultural and horticultural crops

In 1997-1999, 136 field trials were conducted under various soil-climatic conditions in western and southern Europe in order to assess the effects of N fertilizers with the new nitrification inhibitor (NI) 3,4-dimethylpyrazole phosphate (DMPP) on the yield and quality of various agricultural and horticultural crops. Results show that DMPP may increase the mean crop yield (grain yield, winter wheat +0.25 t ha^-1, wetland rice +0.29 t ha^-1, grain maize +0.24 t ha^-1; tuber yield, potatoes +1.9 t ha^-1; corrected sugar yield, sugar beets +0.24 t ha^-1; biomass, carrots +4.9 t ha^-1, lambs' lettuce +1.9 t ha^-1, onions +0.5 t ha^-1, radish +4.6 t ha^-1, lettuce +1.4 t ha^-1, cauliflower +5.2 t ha^-1, leek +1.7 t ha^-1, celeriac +2.2 t ha^-1) and/or improve crop quality (e.g. reduced NO₃^- concentration in leafy vegetables). In some crops, the same yield level as obtained with the control (fertilizer without DMPP) was achieved with one fewer applications of N, or with a reduced N application rate. The positive effect of DMPP on crop yield was especially pronounced at sites with a high precipitation rate or intensive irrigation, and/or light sandy soil. DMPP had a negative effect on the crude protein concentration of winter wheat and on the biomass yield of spring-grown spinach.     

Use of the caudolateral curvilinear osteophyte as an early marker for future development of osteoarthritis associated with hip dysplasia in dogs

OBJECTIVE: To determine the relationship between the caudolateral curvilinear osteophyte (CCO) and osteoarthritis associated with hip dysplasia in dogs. DESIGN: Longitudinal cohort study. ANIMALS: 48 Labrador Retrievers from 7 litters. PROCEDURE: In each of 24 sex- and size-matched pairs fed the same diet, a restricted-fed dog was fed 25% less than a control dog for life. The dogs' hips were evaluated in the standard ventrodorsal hip-extended radiographic projection at 16, 30, and 52 weeks of age and then yearly for life. Histologic examination of hip joint tissues was performed on 45 dogs. RESULTS: Median age at death was 11.2 years. Adjusting for feeding group, dogs with a CCO were 3.7 times as likely to develop radiographic signs of osteoarthritis than those without a CCO. Stratified by diet, 100% of the control dogs with a CCO developed radiographic signs of osteoarthritis and 55% of restricted-fed dogs with a CCO developed radiographic signs of osteoarthritis. The CCO was the first radiographic change seen in 22 of 29 (76%) dogs with osteoarthritis. Overall, 35 of 37 (95%) dogs with a CCO had histopathologic lesions of osteoarthritis. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate a relationship between a CCO on the femoral neck and subsequent development of radiographic signs of osteoarthritis in Labrador Retrievers evaluated over their life span. A CCO is an important early radiographic indication of osteoarthritis associated with canine hip dysplasia.     

Comparison of two radiographic techniques for evaluation of hip joint laxity in 10 breeds of dogs

OBJECTIVE: To evaluate hip joint laxity in 10 breeds of dogs via 2 radiographic techniques. ANIMALS: 500 clinically normal dogs. DESIGN: Prospective study. PROCEDURE: Radiographs obtained via routine hip joint evaluations performed in sedated dogs of 10 popular breeds were randomly selected from a database. Measurements of distraction index (DI) and hip-extended index (HEI) on 1 hip joint radiograph randomly chosen from each dog were made. RESULTS: Mean age of dogs was 20.7 months. Mean HEI was 0.17 (range, 0.0 to 0.72) and mean DI was 0.44 (range, 0.07 to 0.96). Borzois had uniformly tight hip joints as judged by use of both methods and were considered the gold standard by which hip joint laxity was judged (all Borzois had DI < or = 0.32). Overall, DI was significantly greater than HEI. Within each breed, mean DI was always greater than mean HEI. Significant differences were detected among breeds for HEI; however, compared with DI, the magnitude of differences among breeds was less. CONCLUSIONS AND CLINICAL RELEVANCE: Distraction radiography detected the greatest range and magnitude of passive hip laxity in the 10 breeds of dogs. The difference in values between breeds known to have high prevalence of canine hip dysplasia and those in Borzois was greater for DI than for HEI. Breeds must be evaluated individually because of inherent differences in hip joint laxity.     

Maximising canine welfare in veterinary practice and research: a review

This article looks at the existing evidence-base by which veterinary surgeons can make welfare-focused treatment choices. Narrative and structured reviews were conducted. Papers were categorised under headings based on (1) themes in the UK Animal Welfare Act (AWA 2006) - behaviour, environment, nutrition, company and health; (2) iatrogenic harm induced by treatment; (3) decision-making methods, and (4) the subjects' context (e.g. home versus laboratory). There is more information available about 'overt' problems (e.g. acute disease), than 'covert' issues (e.g. chronic pain, lack of company and obesity). Forty of 109 papers covered pain, suffering, injury and disease, compared to 69 across four other themes in the AWA. Twelve papers were identified as focusing on welfare assessment and clinical decision-making. Veterinary surgeons should consider each of the five welfare themes described in the AWA in both veterinary practice and in determining veterinary research priorities.     

C and N turnover of fermented residues from biogas plants in soil in the presence of three different earthworm species (Lumbricus terrestris,Aporrectodea longa,Aporrectodea caliginosa)

A soil microcosm experiment was performed to assess (1) the C- and N- turnover of residues from biogas plants in soils in the presence of three earthworm species (Lumbricus terrestris, Aporrectodea longa and Aporrectodea caliginosa) and (2) the resulting changes in soil chemical and microbiological properties when using these residues as fertilizer in comparison to conventional slurry. Earthworms were exposed in soils, fertilized with an equivalent amount of 120 kg of NH₄-N ha^?1 from: (1) conventional cattle slurry and (2) a fermented residue derived from cattle slurry, grass (silage) and maize. Additional treatments without slurry and earthworms were used as controls.There was considerable evidence that soils fertilized by fermented slurry comprised fewer amounts of readily available nutrients for microbial C and N turnover. We observed significant stimulation of microbial biomass, basal respiration and nitrification in treatments with conventional slurry, especially in the presence of earthworms. However, the stimulation of microbial activity by manure and earthworms were significantly lower in treatments with fermented slurry. Moreover, the results showed clear interactions between different earthworm species and manures. While the biomass of the anecic species (L. terrestris and A. longa) increased in both slurry treatments, the biomass of A. caliginosa (endogeic) decreased, with a significantly stronger biomass decline in treatments with fermented slurry. The metabolic quotients revealed microbial stress metabolism in fermented slurry treatments, predominantly in treatments with A. caliginosa. We conclude that particularly A. caliginosa and soil microorganisms competed for labile C sources in treatments with fermented slurry. An application of these residues as fertilizer might result in a reduction of microbial activity in agricultural soils and in a decline of endogeic earthworms.