Effects of pesticides and fertilizer on invertebrate populations of grass and wheat plots in Kent in relation to productivity and yield

At a site in Kent, perennial ryegrass (Lolium perenne) variety S24 and Italian ryegrass (L. multiflorum) variety RVP, wheat varieties Armada and Norman, and the original mixed grass ley were grown in small plots during 1982–84. Two toxic pesticides (phorate and aldicarb) were applied to half the total number of plots three times each year to eliminate soil invertebrate populations. Fertilizer was also applied to most plots. The yields of the crops, grown with and without pesticide, and the effects of the fertilizer were compared. Grass herbage yield was measured on three occasions during the summers of 1983 and 1984. Wheat grain yields were also determined in 1983. During the first year significant differences were not apparent in grass dry matter yield between pesticide-treated and non-treated plots, but significant differences were found in the second year. The perennial ryegrass was more susceptible to pest damage than the Italian ryegrass or the grass ley. Grass yields varied between cuts and in relation to variety and pesticide treatment, yields tending to be greater in untreated plots. Fertilizer treatment greatly increased grass dry matter yields, particularly with the Italian ryegrass. The effects of pesticide treatment on both wheat varieties varied although some yield enhancement was evident. Invertebrate animal populations in pesticide and fertilizer-treated plots were also assessed in autumn 1982, spring and autumn 1983 and spring 1984. In contrast to pesticide treatment, fertilizer treatment had little effect on soil invertebrate populations. Nematode populations were reduced at each sampling occasion by the pesticide treatment. Slug populations were initially unaffected but were subsequently reduced. Leatherjackets, by far the most abundant pest in both grass and wheat plots, were markedly affected by pesticides on all sampling occasions. Generally, fewer soil-dwelling dipterous larvae were recovered in spring than in autumn. Stem-boring dipterous larvae were virtually absent.     

欧盟对动物促生长剂的措施及其对畜牧业的影响

欧盟专员 Ｆｒａｎｚ Ｆｉｓｃｈｌｅｒ于 １９９５年 １１月 ２９～３０日和１２月１日在布鲁塞尔组织了关于肉类生产中使用生长促进剂的科学研讨会。此后有关抗生素作为饲料添加剂的一场新的争论又开始了。同时对同化激素和生长激素类促生长剂的应用前景也展开了争论。禁用生长激素的理由，是否有科学的依据？对于中国畜牧业会有什么潜在的影响？本文将就欧盟禁用动物促生长剂产品的科学依据以及对中国畜牧业有什么影响作一探讨。１同化激素和生长激素是否有应用前景 让我们首先回顾一下同化激素（促合成代谢剂ａｎａｂｏｌｉｃ ｏｇｅｎ…     

Rotavirus infection in calves in Bangladesh

Faecal samples from 434 calves under 1 year of age (307 diarrhoeal and 127 normal) were collected from three dairy farms and one village in selected areas of Bangladesh. The samples were tested by an enzyme-linked immunosorbent assay (ELISA) to detect the presence of rotavirus antigen. Of 402 dairy calves tested, 28 (7.0%) were positive, of which 21 (7.2%) were from diarrhoeic calves and 7 (6.3%) from non-diarrhoeic calves. Rotavirus infection varied from farm to farm (2.7–9.2%) and there was no positive response from any of the 32 village calves. Rotavirus was most commonly found in calves of 1 week of age or less (up to 22.2% in one group) but was not found in any calves later than 6 months of age. More than 80% of rotavirus-positive samples from diarrhoeic calves exhibited a titre of 128 or more (geometric mean 345±4.5), whereas non-diarrhoeal calves had titres less than or equal to 128 (geometric mean=29±1.9), suggesting that rotavirus infection in calves in Bangladesh was mostly associated with diarrhoea.     

Individual antigens of cattle. Bovine CD2 (BoCD2).

The data obtained in the workshop provide further evidence that CH128A and IL-A26 and the 12 new mAbs that form a cluster recognise the bovine orthologue of CD2. The mAbs inhibit rosetting with SRBC, stain cells in primary and secondary lymphoid organs in patterns consistent with those obtained in humans with anti-CD2 mAbs, and the 11 IgG mAbs all immunoprecipitate a peptide with a Mr of 58-62 kDa. It is not clear from the studies whether the epitopes defined by the mAbs correspond with the region I and II epitopes present on CD2. None of the data suggest that any of the mAbs recognise the region III (CDD2R) epitope (Peterson and Seed, 1987; Knapp et al., 1989). Further studies are now needed to define the physical and functional relation of the epitopes and establish whether antibody-mediated activation corresponds with that noted in humans. Data reported in one study (Baldwin et al., 1988) with IL-A26 suggest possible differences in the requirements for activation. In addition, further studies are needed to demonstrate how many cell types express BoCD2. In mice, evidence has been presented which shows the mouse orthologue is expressed on some B cells (Yagitta et al., 1989). Studies in cattle have clearly shown CD2 is present on the majority of CD4+ and CD8+ T-cells and a small population of CD4-/CD8- cells (Baldwin et al., 1988; Davis, unpublished observations). Evidence presented in this workshop has shown that some CD2+ cells express a WC2 molecule (Sopp et al., 1991).(ABSTRACT TRUNCATED AT 250 WORDS)     

The failure of selenium supplementation to prevent copper-induced liver damage in Fischer 344 rats.

This study evaluates the ability of selenium (Se) supplementation to prevent experimental copper (Cu)-induced hepatocellular damage. Weanling male Fischer 344 rats were randomly assigned to groups of 15, 3 groups (A,B,C) were fed Cu-loaded diets (containing 2000 microg/g copper, added as CuSO4) and different levels of Se (added as Na2SeO3 x 5H2O) as follows: A) Cu-loaded/Se adequate diet (0.4 microg/g Se, fed basis); B) Cu-loaded/Se-supplemented diet (2 microg/g Se); and C) Cu-loaded/Se-deficient diet (< 0.2 microg/g). Three additional groups (D,E,F) were fed diets containing adequate levels of Cu (14 microg/g Cu, fed basis) and different levels of Se as follows: D) Cu-adequate/Se-adequate diet; E) Cu-adequate/Se-supplemented diet (2 microg/g Se); and F) Cu-adequate/Se-deficient (< 0.2 microg/g) diet. After 4, 8, and 12 weeks on the experimental diets, liver samples were processed for histology, histochemistry, metal analysis, glutathione peroxidase (GSH-Px) measurement, and quantification of malondialdehyde (MDA). Morphologic changes characteristic of Cu-associated hepatitis, without an increase in hepatic MDA levels, were seen in all Cu-loaded rats in each sampling. Similar changes occurred in rats fed Se-adequate, Se-supplemented and Se-deficient diets. This study demonstrates that Fischer 344 rats fed 2000 microg/g Cu develop morphologic changes due to Cu toxicity without evidence of lipid peroxidation. Furthermore, Se supplementation does not result in protection against Cu-induced liver injury.