J.J. Vermunt

Inefficacy of moxidectin and doramectin against ivermectin-resistant Cooperia spp. of cattle in New Zealand

Two cases are described in which strains of Cooperia spp. of cattle were found to be resistant to either the oral or the injectable formulations of ivermectin. Injectable moxidectin was not effective against the latter strain and doramectin was not effective against either of the ivermectin-resistant Cooperia isolates. In both cases, the anthelmintic efficacy of oral levamisole was 100%.

Ineffikacy of ivermectin against Cooperia spp. infection in cattle

Abstract 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 u...

Predicting copper status in beef cattle using serum copper concentrations

Abstract Copper deficiency is common in pasture-fed cattle in New Zealand(1). In general, the diagnosis of copper deficiency in a herd of cattle is based on a combination of history, examination of animals, examination of the environment, chemical analysis of blood, liver or pasture, and treatment response trials. The laboratory diagnosis of copper deficiency is currently based on liver and either plasma or serum concentrations of copper. Ellison(2) reviewed the copper reference range for cattle used by the animal health laboratories in New Zealand and concluded that there is strong agreement in the literature that serum copper concentrations greater than 7.9 𝛍mol/l and liver copper concentrations greater than 95 𝛍mol/kg are adequate for young cattle. Furthermore, it has been reported that if copper concentrations in the liver are greater than 150–200 𝛍mol/kg wet weight, there is a negligible increase in serum copper as liver concentrations increase further(2), with individual animal variation accounting ...

Observations on three outbreaks of Leptospira interrogans serovar pomona infection in lambs

Sickness and deaths associated with leptospirosis were reported in three lamb flocks in the Manawatu region. The clinical, pathological and serological features of Leptospiru interrogans serovar pomona infection are described. The mucous membranes of affected animals were pale and jaundiced. Haemoglobinuria, haemoglobinaemia and centrilobular hepatocellular necrosis were also consistent findings. All clinically sick lambs had very high titres in the microscopic agglutination test for L. pomona. Circumstantial evidence of pigs being the source of infection was found in one of the three cases.

The effect of electro-ejaculation on aversive behaviour and plasma cortisol concentration in rams

Electro-ejaculation is used in rams to collect semen for fertility and bacteriological evaluation. Concern has been expressed about animal welfare implications of EE. Two experiments were carried out to compare the aversiveness of electro-ejaculation, part shearing and free movement, and to determine the changes in plasma cortisol concentration produced by electro-ejaculation, shearing and lateral restraint. In the aversion test, transit time was greater (p<0.003) for rams subjected to part shearing than free movement. There were no major differences in the transit time between the rams subjected to electro-ejaculation and those subjected to part shearing or free movement. In addition, there was no significant difference in the effort required to move rams from the three treatment groups into or through the experimental route. These results suggest that electro-ejaculation is no more aversive than part shearing. There were no significant differences in the cortisol response of the rams subjected to electro-ejaculation, shearing or lateral restraint, indicating that there were no significant differences in the distress caused by the three procedures.

Observations on colostral intake in newborn dairy calves

Abstract Extract Neonatal diseases of calves cause a significant loss to the dairy and dairy-beef industries, and the influence of passive immunity derived from colostral transfer on mortality and morbidity is widely recognised(1).

Unusual congenital deformities of the lower limb in two calves

Abstract Congenital deformities of the lower limb were observed in 2 calves from different properties. One was a newborn Holstein-Friesian bull calf with polydactyly and polypodia of the right fore-limb.The other was an 8-month-old Friesian/Jersey crossbred heifer calf, which had a mirror image duplication of the plantar/palmar half of the distal portion of the digits. The abnormalities in the second calf have not previously been described in cattle. This paper presents details of the clinical, radiological and necropsy findings in these 2 calves.

Comparative efficacy of three dry-cow antibiotic formulations in spring-calving New Zealand dairy cows.

Abstract Aim: To evaluate the efficacy of a dry-cow antibiotic preparation containing cloxacillin plus ampicillin in a formulation that gives a 10-week duration of action, in comparison to products containing cephalonium (10-week action) or cloxacillin alone (7-week action). Methods: A total of 493 cows were selected from 6 spring-calving dairy herds in the Manawatu region of New Zealand, according to the criteria of the SAMM plan, to receive intramammary antibiotic therapy at the end of lactation (drying off). Cows were randomly allocated to receive 1 of the 3 dry-cow antibiotic products under investigation. Cows were examined twice during the dry period and twice daily during the first 10 days of their subsequent lactation for the presence of mastitis. Milk samples were collected from individual quarters at the time of drying off and at 7 and 28-35 days after calving, for determination of milk somatic cell counts (SCC). Bacteriology was carried out on milk samples taken from cows that developed mastitis during the first 10 days after calving. Results: No cows developed mastitis during the dry period. Sixteen cows developed clinical mastitis within 10 days of calving; there was no difference in incidence between treatments. Streptococcus uberis was the most commonly isolated organism. Mean SCC on Day 7 were lower (p = 0.019) in cephalonium-treated quarters (189.9 ± 28.4 × 103 cells/ml) than in cloxacillin-treated quarters (388.7 ± 71.2 x 103 cells/ml); values in quarters receiving cloxacillin plus ampicillin were intermediate (252.0 ± 47.0 × 103 cells/ml). SCC were similar between treatment groups on Day 28–35. Conclusions: The use of a combination of cloxacillin plus ampicillin was effective for the prevention of mastitis during the dry- and peri-calving-periods in pastured dairy cattle.

Observations on BVD virus infection in New Zealand beef herds

Abstract Extract Bovine viral diarrhoea (BVD) virus has a worldwide distribution and investigations in various parts of the world have shown that 60%–80% of cattle have neutralising antibodies to the virus(1)(2). Bovine viral diarrhoea virus infection is also common in New Zealand dairy herds(3), and its epidemiology on dairy farms is well understood. It had been considered that the traditional beef cattle population was essentially free from this infection and there was a concern that the rapidly expanding dairy-beef industry may introduce infection into an essentially naive beef cattle population. However, a recent study has shown that BVD virus infection is widespread in beef herds throughout New Zealand(4). To explore the issue further, we have examined the prevalence of BVD virus antibody- positive animals in selected dairy-beef operations and traditional cow-calf herds, and how BVD-virus infection, if present, is maintained within these cattle populations.

Leptospirosis in a lamb.

Abstract Extract Recently, we reported on outbreaks of Leptospira interrogans serovar pomona infection in newly weaned lambs(1). It was suggested that wet environmental conditions played an important role in the pathogenesis of the disease in that class of sheep. This communication presents observations on another case of ovine leptospirosis, one that occurred under different circumstances, i.e. different season, age and environmental conditions.