Letters to the editor

Sir;- Outbreaks of ovine abortions caused by Campylobacter fetus fetus (previously C. fetus intestinalis) occur sporadically in mimy areas of New Zealand. The devastating effects on some flocks have stimulated recent studies of the disease,^(1)(3)(7) and have also led to the commercial production of a single strain vaccine (Campylovexin; Wellcome N.Z. Ltd, Auckland). However, it has been shown that single strain C. Fetus vaccines do not protect against serologically distinct strains.⁽²⁾ Since at least two different serotypes of C. fetus fetus are present in New ZealandY) it is not surprising that the commercially available vaccine is only partially effective in some outbreaks.⁽⁷⁾     

Prolactin assay for fescue toxicity in sheep

Fungal endophyte (Acremonium spp.) toxicity affects sheep and cattle grazing a number of forages, including ryegrasses (Lolium spp.) and tall fescue (Festuca nrundinacea). The endophyte in tall fescue is responsible for ill thrift, as indicated by low weight gains or weight loss⁽¹⁾ and decreased reproductive efficiency⁽²⁾, and is associated with increased body temperatures. Extensive research has been undertaken in the USA to determine ways of reducing the impact of fescue toxicity on the beef industry⁽³⁾, whilst New Zealand research is directed toward both ryegrass and fescue endophyte toxicity and its impact on sheep⁽⁴⁾⁽⁵⁾ and cattle⁽⁶⁾ production. Much of this work involves field evaluations of productive performance in animals fed toxic and non-toxic forage, so that it is important to be sure that treatment effects are due to the endophyte.     

Ineffikacy of ivermectin against Cooperia spp. infection in cattle

Ivermectin, either as an injectable or topical formulation, is used widely to control parasites in New Zealand cattle. These formulations have been well documented as having high efficacy against the major nematode species which infect tattle^(1)(2)(3)(4), although the efficacy against adult Cooperia oncophora is reported to be 95%⁽⁵⁾. This is considered to be one of the doselimiting species. There have been two reports of lower than expected efficacy of the topical formulation against Cooperia spp. in cattle. In a slaughter trial, Bisset et al. ⁽⁶⁾ found that ivermectin applied topically at the recommended dose rate of 500 𝛍g/kg failed to achieve a statistically significant reduction in the burden of Cooperia spp. worms compared with untreated calves. The geometric mean of adult Cooperia spp. worms present in the treated calves was 5788 compared with 7524 present in the untreated calves. This reduced efficacy was not attributed to acquired anthelmintic resistance because ivermectin had not been used on the farm previously. In Australia, Eagleson and Allertonc⁽⁷⁾ found in controlled field trials that ivermectin applied topically at 500 𝛍g/kg ranged in efficiency in reducing faecal egg counts from 80.7% to 100% ; four out of 13 trials achieving less than 90% and a further four were in the range of 90–95% reduction. Larvae obtained from the faeces of ivermectin-treated cattle on days 11–14 after treatment were predominantly Cooperia spp.     

Feline leukaemia virus testing

Extract

Sir:- In September 1981 we published the results of leukaemia virus (Felv) testing of cats in New Zealand.⁽²⁾ In addition we detailed recommendations for Felv testing of cats in this country. These recommendations were revised and updated in a second letter to the Journal in 1982.⁽³⁾ Since then a further 465 cats have been tested at Massey University using the leukassay test (ELISA) (Leukassay F, Pitman Moore).     

Correlations between potassium, calcium and magnesium in blood and muscle of standardbred trotters

This study was conducted to investigate the relationships between the concentrations of potassium, sodium, calcium and magnesium of plasma and muscle in horses, as interactions between these ions can be important in the development of muscle cell injury. Blood samples and gluteal muscle biopsies were taken from 20 healthy Standardbreds to determine the potassium concentration in plasma (cK⁺(P)), red blood cells (cK⁺(RBC)), and muscle (cK⁺(M)), and the calcium and magnesium concentrations in plasma and muscle. No correlations were found between cK⁺(P), cK⁺(RBC), and cK⁺(M). Significant positive correlations were found between cK⁺(M) and muscle magnesium (p<0.01); and cK⁺(P) and plasma calcium (p<0.005). Significant negative correlations were found between cK⁺(M) and the percentage of muscle water (p<0.005); and the muscle magnesium and calcium concentrations (p<0.02).     

Ryegrass Staggers: Isolation of Potent Neurotoxins Lolitrem a and Lolitrem B From Staggers-Producing Pastures

Sir, — We wish to report the isolation of two potent neurotoxins from herbage collected from pastures on which the disease of livestock known as ldryegrass staggers rd^(8)(11) occurred. These neurotoxins have been partially characterised by their mass spectral properties (see below) and appear to be new compounds not previously reported. We propose the general name lolitrems for the neurotoxins, based on their association with ryegrass (Lolium perenne L.) and on their ability to produce tremors in animals, and name the isolated compounds lolitrem A and lolitrem B.     

Can sheep become infected by grazing pasture contaminated by cattle with Johne's disease?

Extract

Madam:- Transmission of Johne's disease (JD) under natural conditions from sheep to cattle has been demonstrated in iceland⁽²⁾ but not in New Zealand.⁽¹⁾ The reverse, sheep becoming infected with Mycobacterium paratuberculosis of bovine origin, has been shown experimentally with large inocula (c. 5 × 10⁹organisms/lamb),⁽³⁾ but not under natural conditions. It could be important in New Zealand where sheep may be used to “clean up” pasture grazed by paratuberculous cattle.     

Production of dairy cows fed whole-crop cereals or ryegrass silages supplemented with a fixed amount of concentrate

Abstract

Feed intake and milk production responses to whole-crop cereal silages and ryegrass silage (RGS) supplemented with a fixed amount of concentrate were measured in three 4×4 Latin square-designed experiment with three 17-day periods using 12 Holstein cows. Diets consisted of a fixed amount of concentrate (10 kg) and one of the following silages offered ad libitum: RGS, Mondego wheat silage (MWS), Alva wheat silage (AWS), and triticale silage (TS). Silage dry matter intake and milk yield were significantly higher for RGS. Milk composition was not affected by silage treatment. The whole-crop cereal silages tended to show higher milk concentrations of anteiso C15:0, iso C15:0, C16:1 and C18:1 and lower concentrations of C18:2 and C18:3. This study suggests better response of dairy cows to a single cut RGS than to whole-crop cereal silages harvested in an early stage of maturity.     

XX/XY mosaicism in lymphocyte cultures from a pig with freemartin characteristics

Sir. — Cultural confirmation of venereal campylobacteriosis in cattle can only be achieved if samples arc cultured on the day of collection or a suitable transport medium is used. Clark et al.⁽³⁾ have developed a selective enrichment medium for Campylobacter fetus venerealis which is also an effective transport medium ⁽⁸⁾. However, this transport medium is very cumbersome to prepare in that it requires a special gas mixture and large quantities of fresh bovine serum. This letter reports on the evaluation of Clark’s ⁽⁸⁾, cooked meat medium with antibiotics (CMMA), Weybridge ⁽⁴⁾, modified EMJH ⁽⁵⁾, Stuart’s (Oxford) and Cairy Blair (Oxoid) media, as transport media for C. fetus veneralis.     

Neospora abortion epidemic in a dairy herd

Neospora caninrm is a protozoan closely related to Toxoplasma gonclii. It was discovered only a few years ago, but it is now recognised as one of the most common and important causes of abortion in cattle. Brain lesions characteristic of Neospora infection have been found in about 25% of aborted foetuses submitted to diagnostic laboratories in New Zealand and overseas⁽¹⁾⁽²⁾. Average abortion rates due to Neospora on New Zealand farms have been estimated at 7% of pregnancies compared with 4% due to other causes⁽¹⁾. The upper range of abortion rates for Neospora was 17–30% compared to only 7–10% for other causes, showing that the economic effects of Neospora abortions on the more severely affected farms can be devastating.     

Anthelmintic resistance in cattle nematodes in New Zealand: Is it increasing?

Extract

In contrast to the situation in sheep, anthelmintic resistance in cattle nematodes in New Zealand appears to be relatively uncommon. A brief review in 1991 indicated that only six confirmed cases had been reported(l). All related to resistance to benzimidazole anthelmintics and involved infections of Cooperia and, to a lesser extent, Ostertugia and Trichostrongylus. Since then, however, a further 13 cases of benzimidazole resistance in cattle have been identified by faecal egg count reduction tests conducted on submissions to the Batchelar and Ruakura Animal Health Laboratories (Table I). In addition, another two cases have recently been detected by similar means by ethers ⁽²⁾⁽³⁾. In the latter two instances, these not only involved resistance to benzimidazole drenches but to milbemycin/ avermectin type anthelmintics as well. Like those listed in Table I, the main parasite genus implicated on both of these occasions was Cooperia.     

Prevention of Ryegrass Staggers

Extract

Sir:- We recently obtained some interesting results in significantly reducing ryegrass staggers (RGS) in young Friesian calves by preventative drenching with Nutrimol (liquid seaweed animal health aid).     

Characteristics of Two Saprolegnia Species Isolated from Coho Salmon with Saprolegniosis

Abstract

Several fungi have been isolated from the lesions of coho salmon Oncorhynchus kisutch that have saprolegniosis. Of these fungi, one that occurred frequently was identified as Saprolegnia parasitica strain H2 (=S. diclina type 1). A much rarer fungus was identified as S. diclina strain H3 (=S. diclina type 3). This article describes the pathogenicity of the isolates to coho salmon and the relationship of pathogenicity to the lengths of the isolates, hooked hairs.     

Mycobiota and mycotoxins contamination in raw materials and finished feed intended for fattening pigs production in eastern Argentina

The aim of the present study was to determine the mycobiota and natural levels of mycotoxins such as zearalenone, fumonisin B₁, aflatoxin B₁ and ochratoxin A present in raw materials and finished fattening pig feed. Samples were examined for total fungi and genera distribution. Zearalenone, FB₁, AFB₁ and OTA contamination were determined using high pressure liquid chromatography and thin layer chromatography. Milled maize and finished feed samples showed fungal contamination over than 1 × 10⁴ CFU/g. All samples contained at least one of the main mycotoxigenic genera Aspergillus, Fusarium and Penicillium. A. flavus and F. verticillioides were the most prevalent species. Only some Aspergillus section Nigri strains from suckling pig to growing pig samples were able to produce OTA. A. flavus strains from milled maize, wheat bran, suckling pig to growing pig samples were able to produce AFB₁. All samples were positive for FB₁. Sucking pig, piglet, growing and boar feed samples showed ZEA natural contamination. AFB₁ and OTA contamination were not detected. There was a 100% correlation between FB₁ and ZEA contamination in sucking pig, piglet, growing and boar feed samples; 50% piglet samples and 67% suckling pig samples showed ZEA levels over the recommended limits. The present study has shown the occurrence of two mycotoxins, FB₁ and ZEA in feed intended for fattening pig consumption. In animal production, the simultaneous presence of toxicogenic fungi and low dietary levels of mycotoxins in field conditions can cause possible health impacts and lost performance in pigs from feeding spoiled feeds.     

Sensible heat transfer from the fowl: Boundary‐layer resistance of a model fowl

1. The sensible heat transfer from a physical model of an adult fowl was investigated for the range of air speeds encountered in poultry houses in the United Kingdom, 0.09 to 2.7 m/s, equivalent to Reynolds numbers (Re) from 10³ to 3 × 10⁴. The Grashof number (Gr) range studied was from 6 x 10⁶ to 10⁷.

2. The pooled results were analysed to give a relationship between the Nusselt number (Nu) and Re in the mixed convective regime of: A combination of Nu, Re and Gr did not produce a better fit to the results.

3. Enhancement of heat transfer observed when Re was close to 10³ was probably caused by an interaction between the forced and natural air currents.     

Tuberculosis in a rabbit: A case revisited

Extract

There has been only one reported case of tuberculosis caused by Mycobacterium bovis in a free-living wild rabbit, Oryctolagus cuniculus cuniculus ⁽¹⁾. Because of continued interest in that case, the common classification of rabbits and hares in the family Leporidae and a current report of a case in a hare⁽²⁾, this opportunity is taken to re-record the case in the rabbit in greater detail.     

Prevalence of Yeasts and Mycelial Fungi in Bovine Parasitic Otitis in the State of Minas Gerais,Brazil

Infestations by rhabditiform nematodes and acarids of the genus Raillietia are considered the primary causes of external otitis in cattle in tropical regions. Recently, yeasts of the genus Malassezia have been associated with a relatively high percentage of otitis cases, but the occurrence of other yeasts and mycelial fungi has not yet been reported in the literature. This work studied the presence of fungi in the ear canal of 45 cattle with external parasitic otitis. The results were positive for yeasts of the genus Malassezia in 31 (68.9 %) of the 45 cultures in Mycosel medium supplemented with olive oil. The 45 cultures in Sabouraud dextrose medium revealed the growth of seven (15.5 %) yeasts of the genus Candida, five (11.1 %) Rhodotorulamucilaginosa, two (4.4 %) fungi of the genus Aspergillus and eight ‘Micelia sterilia’. Future studies may confirm and elucidate the importance of these agents in the aetiology of bovine otitis.     

Inducible pine rosin defense mediates interactions between an invasive insect–fungal complex and newly acquired sympatric fungal associates

Mutualism between insects and fungi drives insect evolutionary diversification and niche expansion; for invasive insects, however, mechanisms by which they maintain mutualistic relationships with beneficial fungi have not been clearly explored. Here, we report that an invasive herbivorous insect, the red turpentine beetle (RTB), with its co‐invasive mutualistic fungus, Leptographium procerum, has newly acquired a set of sympatric fungi during invasion, which could potentially outcompete the RTB mutualistic fungus. Host pine Pinus tabuliformis exhibited more rosin‐based responses to the sympatric fungi than to RTB mutualistic fungus and, in return, the rapidly induced rosin suppressed the sympatric fungi more significantly than L. procerum. In addition, from direct fungal pairing competitions, we found that the antagonistic effects of sympatric fungi on L. procerum were drastically reduced under induced rosin defense. Our results together with previous findings imply that pine oleoresin defense (turpentine and rosin) might have been exploited by the invasive mutualistic fungus L. procerum, which helps to explain its invasion success and, by extension, its mutualistic partner RTB in China.     

Distribution of Rhodococcus equi in animals,birds and from the environment

Extract

Madam:— As well as causing sporadic infections in animals, Rhodococcus (Corynebacterium) equi has been isolated from the gastro-intestinal tract of healthy grazing animals and from the environment. ^{(1 )(5)(6)(8)(11)} R. equi has been isolated in this laboratory from cattle and pigs in association with tuberculosis- like lesions and from lungs and abscesses from horses and deer.