If control of Neospora caninum infection is technically feasible does it make economic sense?

Recent work on Neospora caninum, a protozoan parasite that causes abortions in dairy cattle has focused on a number of different control options. Modelling has suggested the most effective options for control but the present paper argues that the most effective option might not necessarily be optimal from an economic point of view. Decision trees, using published quantitative data, were constructed to choose between four different control strategies. The costs of these interventions, such as 'test and cull', therapeutic treatment with a pharmaceutical, vaccination or "doing nothing" were compared, and modelled, in the first instance, on the New Zealand and Australian dairy situation. It is argued however, that the relative costs in other countries might be similar and that only the availability of a registered vaccine will change the decision tree outcomes, as does the within-herd prevalence of N. caninum infection. To "do nothing" emerged as the optimal economic choice for N. caninum infections/abortions up to a within-herd prevalence of 18%, when viewed over a 1-year horizon, or 21% when costs were calculated over a 5 years horizon. For a higher (>or=21%) within-herd prevalence of N. caninum infection vaccination provided the best (i.e. most economic) strategy. Despite being the most efficacious solutions, 'test and cull' or therapeutic treatment never provided a viable economic alternative to vaccination or "doing nothing". Decision tree analysis thus provided clear outcomes in terms of economically optimal strategies. The same approach is likely to be applicable to other countries and the beef industry, with only minor changes expected in the relationships of decisions versus within-herd prevalence of N. caninum infection.     

The genome of black cottonwood, Populus trichocarpa (Torr. & Gray)

We report the draft genome of the black cottonwood tree, Populus trichocarpa. Integration of shotgun sequence assembly with genetic mapping enabled chromosome-scale reconstruction of the genome. More than 45,000 putative protein-coding genes were identified. Analysis of the assembled genome revealed a whole-genome duplication event; about 8000 pairs of duplicated genes from that event survived in the Populus genome. A second, older duplication event is indistinguishably coincident with the divergence of the Populus and Arabidopsis lineages. Nucleotide substitution, tandem gene duplication, and gross chromosomal rearrangement appear to proceed substantially more slowly in Populus than in Arabidopsis. Populus has more protein-coding genes than Arabidopsis, ranging on average from 1.4 to 1.6 putative Populus homologs for each Arabidopsis gene. However, the relative frequency of protein domains in the two genomes is similar. Overrepresented exceptions in Populus include genes associated with lignocellulosic wall biosynthesis, meristem development, disease resistance, and metabolite transport.     

Helminth parasites of gemsbok (Oryx gazella) in the Klein Karoo

The number and species of helminth parasites from three gemsbok (Oryx gazella) were recorded, and their faecal nematode egg counts and the level of pasture contamination determined. Six nematode genera were recovered and four species identified, of which Trichostrongylus rugatus was the most prevalent. Other nematode species recovered were Cooperia sp., Agriostomum sp., Haemonchus contortus, Nematodirus spathiger and Ostertagia ostertagi. None of the worms were present in all animals studied, and no new host associations were found. Cysticerci were recovered from the mesenteries of one gemsbok and a further two unidentifiable helminths were recovered from the abomasum and the kidney fat layer of another antelope.     

Fin erosion on rainbow trout on commercial trout farms in the United Kingdom

Fish weighing less than 30 g and more than 100 g were sampled from 38 rearing units on 10 commercial farms growing rainbow trout for the table market. A fin index was calculated for each of the eight rayed fins on 949 trout by dividing their length by the standard length of the fish. There was a large range in the indices of all eight fins. The fin indices of the small and large fish were compared, controlling for farm effect. With the exception of the dorsal fin, all the indices were larger for the small fish than for the large fish, but the magnitude of the difference was greater for some fins than others. In comparison with the fins of wild fish, the pectoral and dorsal fins appeared to be most eroded and the damage to these fins was evident even in the small fish. The erosion of the caudal, anal and ventral (or pelvic) fins was more prominent in the larger fish. Variations in the fin indices of the caudal, anal and ventral fins suggested that there was little variation between rearing units on the same farm, but that there was significant variation between individual fish in the same rearing units, and between fish on different farms.     

Fungal/bacterial ratios in grasslands with contrasting nitrogen management

It is frequently hypothesised that high soil fungal/bacterial ratios are indicative for more sustainable agricultural systems. Increased F/B ratios have been reported in extensively managed grasslands. To determine the shifts in fungal/bacterial biomass ratio as influenced by grassland management and to find relations with nitrogen leaching potential, we sampled a two-year-old field experiment at an organic experimental farm in the eastern part of The Netherlands. The effect of crop (grass and grass-clover), N application rate (0, 40, 80, ) and manure type (no manure, farm yard manure and slurry) on the F/B ratio within three growing seasons was tested, as well as relations with soil and crop characteristics, nitrate leaching and partial N balance. Biomass of fungi and bacteria was calculated after direct counts using epifluorescence microscopy. Fungal and bacterial biomass and the F/B ratio were higher in grass than in grass-clover. The F/B ratio decreased with increasing N application rate and multiple regression analysis revealed a negative relationship with pH. Bacterial activity (measured as incorporation of [³H]thymidine and [¹⁴C]leucine into bacterial DNA and proteins) showed the exact opposite: an increase with N application rate and pH. Leaching increased with N application rate and was higher in grass-clover than in grass. Partial N balance was more positive at a higher N application rate and showed an inverse relationship with fungal biomass and F/B ratio. We conclude that the fungal/bacterial biomass ratio quickly responded to changes in management. Grasslands with higher N input showed lower F/B ratios. Grass-clover had a smaller fungal biomass and higher N leaching than grass. In general, a higher fungal biomass indicated a lower nitrogen leaching and a more negative partial N balance (or smaller N surplus), but more observations are needed to confirm the relationship between F/B ratio and sustainability.     

Development and validation of a SYBR green real-time PCR for the quantification of porcine circovirus type 2 in serum, buffy coat, feces, and multiple tissues

The emergence of multiple genotypes of PCV2, as demonstrated by phylogenetic analysis of whole genome or capsid sequences, makes it necessary to have quantitative diagnostic assays that perform equally well on all strains. The objectives of this study were to develop and validate a novel real-time polymerase chain reaction (PCR) assay targeting the highly conserved rep gene (ORF1) and investigate the effects of diagnostic specimen choice on its performance. The assay was tested in naturally infected conventional pigs, experimentally infected gnotobiotic pigs, and plasmid-spiked negative serum, lung tissue, and feces and found to have a linear detection range of 2.2x10(3) to 2.2x10(10) copies of PCV2 per mL. The assay successfully detected and quantified PCV2 DNA in serum, buffy coat, feces, and multiple lymphoid (bronchial, mesenteric, and superficial inguinal lymph nodes; thymus; tonsil; ileal Peyer's patches; and spleen), and non-lymphoid (myocardium; lung; kidney; liver; and gluteal muscle) tissues from naturally infected pigs. Across all tissues and sera of naturally infected pigs, the mean PCV2 concentration was 3.0logs higher in wasting versus non-wasting pigs. PCV2 concentration measured by tissue culture and immunohistochemical staining in homogenized liver samples of experimentally infected gnotobiotic pigs were compared to the concentrations estimated by quantitative PCR. Similar trends were noted with increasing PCV2 concentration detected in subclinically infected to severely PMWS-affected pigs across all assays. Our diagnostic assay was developed with a conserved target sequence, and performed efficiently in quantification of PCV2 in a variety of tissues from naturally and experimentally infected pigs.     

Effects of Firocoxib and Tepoxalin on Healing in a Canine Gastric Mucosal Injury Model

Background: Little is known about the effect of dual cyclooxygenase (COX) and lipoxygenase inhibition on canine gastric mucosal healing.
Objective: This study compares the effects of putative dual COX and 5-lipoxygenase inhibition with that of COX-2 selective inhibition on gastric mucosal lesion healing in dogs.
Animals: Six normal adult mixed-breed research dogs.
Methods: Gastric body and pyloric lesions were induced by endoscopic biopsy. Dogs were treated with tepoxalin, firocoxib, or placebo for 7 days in a randomized 3-way crossover study design. Healing was evaluated on days 2, 4, and 7 of treatment by endoscopic lesion scoring. Eicosanoid concentrations in plasma and at the lesion margins were determined on days 2, 4, and 7. Repeated measures analyses were performed. All hypothesis tests were 2-sided with P < .05. Multiple comparisons were adjusted using Tukey's test.
Results: Significant treatment differences were noted in the pyloric lesion area measurements. Overall, the firocoxib group had larger lesions than the placebo ( P = .0469) or tepoxalin ( P = .0089) groups. Despite larger pyloric lesions in the firocoxib group, mucosal prostaglandin production did not differ significantly from placebo. In contrast, the tepoxalin group had significantly lower pyloric mucosal prostaglandin production compared with the firocoxib ( P < .0001) or the placebo ( P < .0001) groups but pyloric lesions were not significantly larger than those of the placebo group ( P = .7829).
Conclusion: COX-2 inhibition by firocoxib slowed wound healing by a mechanism independent of prostaglandin synthesis. Suppression of mucosal prostaglandin production by tepoxalin did not alter mucosal lesion healing compared with placebo.