The intensity of resistance by mature Merino ewes against Haemonchus contortus and Tichostrongylus colubriformis in single-species and combined-species infection

Three-year-old, non-lactating and non-pregnant Merino ewes, raised on pasture under a program of strategic treatment with anthelmintic and found to be extremely resistant to "trickle" infection with Haemonchus contortus, were given single-dose infections with either H. contortus or Trichostrongylus colubriformis or both species together. The purpose was to ascertain the intensity of protective immunity against the 2 parasites in sheep with immunity acquired from a presumably slight exposure to infection. To provide a criterion, some infected ewes were immunosuppressed with corticosteroid, dexamethasone. Untreated ewes were extremely resistant to challenge infection with either 15,000 or 150,000 H. contortus or 15,000 T. colubriformis. Surprisingly, when mixed infection was given, egg counts for H. contortus were significantly elevated compared with infection by that species alone. Antibody to antigens from infective larval and adult H. contortus was measured in serum by enzyme-linked-immunosorbent assay (ELISA) during the course of infection. Serum titres against larval antigens were significantly depressed when infections with either H. contortus or T. colubriformis were permitted by immunosuppression with dexamethasone, whereas those against adult antigen were depressed when infection with T. colubriformis was permitted.     

The effects of duration and concentration of plasma progesterone on the fertility of post-partum cows treated with pregnant mare serum gonadotrophin and intravaginal progesterone

The effects of duration of insertion of progesterone releasing devices (PRIDs) on the concentrations of plasma progesterone (plasma P4) and the relationship of these with fertility were examined respectively in ovariectomised and intact Bos taurus cattle. In experiment 1, ovariectomised cows (n = 14) were treated with PRIDs to produce high and low plasma P4 for 7 or 14 days giving 4 treatment groups designated H7, H14, L7 or L14. Mean plasma P4 in the H14 and L14 groups were 6.6 and 6.0 ng/ml respectively, during the first week and 5.4 and 3.8 ng/ml respectively, during the second. Mean plasma P4 of 6.3 and 4.2 ng/ml were observed in H7 and L7. In experiment 2, suckled cows (n = 171) received the same PRID treatments as cows in experiment 1, plus either 375 or 750 iu pregnant mare serum gonadotrophin, and subsequent calving rates were recorded. These were significantly lower after L7 than the other treatments (12% v 38%, P less than 0.025). These results showed that fertility after oestrus was closely related to plasma P4 observed before oestrus and indicated that treatment with progesterone for as little as 1 week can produce normal fertility providing plasma P4 attain a critical threshold during treatment.     

Isolation of <Emphasis Type="Italic">Penicillium hirsutum</Emphasis> from spoiled,packaged asparagus spears in Japan

During storage studies on asparagus spears packed in plastic film and held at 15°C, a Penicillium fungus was associated with subsequent spoilage. On the basis of colony characteristics, the isolate was identified as Penicillium hirsutum Diercks. This report is the first of Penicillium hirsutum causing spoilage of asparagus spears in Japan. Inoculation tests showed that among all the Penicillium species tested in this study only the identified fungus was able to infect asparagus spears.     

Differentiation of Toxocara canis and T. cati eggs by light and scanning electron microscopy

In this study, we investigated the morphological identification of Toxocara canis and T. cati eggs on the basis of light and scanning electron microscopic (SEM) observations. T. canis and T. cati eggs used in this study were recovered from the uteri of respective gravid female worms. Measurement of egg size was not helpful in the differentiation of these species, because approximately 90% of eggs measured were of similar size. Using SEM, we were able to differentiate T. canis eggs from T. cati eggs based on their respective characteristic surface structures. Both species have subspherical eggs with markedly pitted surfaces like those of a golf ball, but the surface pitting in T. canis is more coarse than that in T. cati. In this study, however, these differences were not absolute, as 16% of T. canis and 29% of T. cati eggs showed surface pitting that was uncharacteristic of their species. Of the 16% of T. canis eggs that could not be differentiated by surface structure, 3% had pitting resembling T. cati, and the remaining 13% showed intermediate type surface pitting. Similarly, 5% of T. cati eggs resembled T. canis, and 25% of these were of intermediate type. Light microscopic observation yielded results similar to those of SEM, indicating that light microscopy is also a useful tool for the identification of Toxocara eggs.     

Effects of suckling on oestradiol benzoate induced LH release in post-partum, ovariectomised cows

Twelve suckling and 12 non-lactating post-partum cows were treated with a progesterone-releasing pessary for 7 or 14 d followed by an injection of 500 micrograms oestradiol benzoate (ODB) 24 h after pessary removal or no injection. Suckling had no significant effect on plasma progesterone concentrations (plasma P4) or plasma luteinising hormone concentrations (plasma LH) during pessary insertion. After pessary removal plasma LH rose in response to ODB. The extent of the rise was similar in suckling and non-lactating cows treated with progesterone for 14 d but was significantly lower in non-lactating than suckling cows (P less than 0.025) treated for 7 d. These findings indicate that suckling increases the responsiveness of plasma LH in post-partum cows following progesterone and oestrogen treatment compared to non-lactating cows and that extended treatment with progesterone can remove this difference.     

Antimicrobial activity of Memecylon malabaricum leaves

The petroleum ether, chloroform and methanol extracts of Memecylon malabaricum leaves were tested for antimicrobial activity. Only methanol extract has shown activity against bacteria both Gram (+) and Gram (-), and fungi.     

Seasonal dynamics of mineral N pools and N-mineralization in soils under homegarden trees in South Andaman,India

Agroforestry trees are now well known to play a central role in the build up of nutrients pools and their transformations similar to that of forest ecosystem, however, information on the potential of homegarden trees accumulating and releasing nitrogen (mineralization) is lacking. The present study reports seasonal variations in pool sizes of mineral N (NH₄⁺-N and NO₃⁻-N), and net N-mineralization rate in relation to rainfall and temperature under coconut (Cocos nucifera L.), clove (Eugenia caryophyllata Thunb) and nutmeg (Myristica fragrans Houtt. Nees) trees in a coconut-spice trees plantation for two annual cycles in the equatorial humid climate of South Andaman Island of India. Concentration of NH₄⁺-N was the highest during wet season (May–October) and the lowest during post-wet season (November–January) under all the tree species. On the contrary, concentration of NO₃⁻-N was the lowest in the wet season and the highest during the post-wet season. However, concentrations of the mineral N were the highest under the nutmeg and the lowest under the coconut trees. Like the pool sizes, mean annual mineralization was the highest under the nutmeg (561 mg kg⁻¹ yr⁻¹) and the lowest under the coconut trees (393 mg kg⁻¹ yr⁻¹). Rate of mineralization was the highest during the post-wet season and the lowest during the dry season (February–April) under all the tree species. High rainfall during the wet season, however, reduced the rate of nitrification under all the tree species. The mean annual mineralization was logarithmically related with rainfall amount and mean monthly temperature.     

Large cardamom (Amomum subulatum Roxb.) plantation — An age old agroforestry system in Eastern Himalayas

Large cardamom (Amomum subulatum Roxb.) is a shade loving plant grown in the Indian hill states of Sikkim and Dargeeling district of West Bengal. About 30 important tree species are used to provide shade to the cardamom plants. Alnus nepalensis, a deciduous, nitrogen fixing and fast growing tree, is the species most commonly underplanted with cardamom. In addition to providing shade, it is also used for fuelwood. The old trees are cut and young plants coming up are allowed to grow in cyclic order. The quick decomposing leaf litter of A. nepalensis also fertilises the cardamom plants. The nitrogen added to the soil in this way has been found to be as high as 249 kg/ha. Large cardamom thrives well in a moist soil, which is maintained by water diverted from seasonal springs on the upper slopes. The system is well suited to conserving soil, water and tree cover of the characteristically steep slopes of the region. Moreover, the management inputs required for growing cardamom are low but the crop gives a higher financial return than rice or maize. The shade trees used in the system are also a major source of fuel, fodder and timber, especially as access to state owned forests is restricted by legislation. However, increasing incidence of viral chirkey and foorkey disease, panicle rot and capsule borer are reducing the cardamom productivity. It has been observed that integrating dairying and apiculture will further augment profitability from large cardamom agroforestry system.     

Animal health monitoring and surveillance in Switzerland

Switzerland has traditionally used a passive disease reporting system for all notifiable diseases. This type of system is not suitable for the documentation of very low prevalences (freedom from disease), sub-clinical cases and non-notifiable diseases. In order to meet the high international standards for animal health surveillance and to fulfil the general need for sound animal health data, Switzerland has evaluated the feasibility of modern monitoring and surveillance concepts. In general, the principle of active surveillance has been acquired and is now being applied whenever possible. In this paper, several examples of Swiss surveillance systems are presented and discussed. They include systematic testing of random population samples, carcase screening at abattoirs and sentinel herd monitoring.