A study of naturally occurring cases of ovine foot abscess in New Zealand

A study was made of various aspects of 53 naturally occurring cases of foot abscess in sheep in New Zealand. Radiographic techniques were used to follow the progress of the lesion and from this it was concluded that foot abscess could be defined as an infection of the distal interphalangeal joint. The term “foot abscess” was considered preferable to the term “infective bulbar necrosis”.

The attack rate of foot abscess was reported to be higher for rams than for ewes and the condition was less prevalent during summer.

Once infection was established in the distal interphalangeal joint a relatively uniform and thus predictable series of events took place that inevitably resulted in some permanent damage and deformity to the digit. If rupture of the axial collateral ligaments occurred, the joint became unstable and the de- gree of permanent deformity was greater. Treatment with antibiotics did not appear to markedly affect the progress of the lesion or the outcome, once infection had become established in the joint.

Although the prognosis for complete recovery was poor, in most cases the foot healed sufficiently after a period of about two months to allow the animal to walk normally.     

Salmonellosis in sheep and zinc oxide dosing–a reply from massey university

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Madam:– We are surprised that Messrs Smith and Towers misinterpreted our letter on salmonellosis in ram hoggets following prophylactic zinc dosing as a criticism of their actions or of their research and publication record. In fact, they echo our caution in stating that the results of drenching sheep with a fortnight's accumulated dose of zinc oxide have been presented and discussed as preliminary and that "no final recommendations will be made until optional dose rates and safety factors have been assessed."     

Multiple resistance in Trichostrongylus and Teladorsagia (Ostertagia) in goats to oxfendazole,levamisole and moxidectin,and ineffi cacy of trichlorphon

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We wish to report the identification, from a flock of commercially-traded goats, of nematode worms that we have been unable to kill using the anthelmintic groups currently registered for use in sheep in New Zealand.     

The impact of highly concentrated Mo and Cu dietary supplements,fed as a bolus,on the efficacy of chelated versus inorganic Cu in cattle on a low-Cu diet

AIM: To compare the efficacy of chelated versus inorganic forms of dietary Cu supplements, fed as a bolus, when challenged by a daily bolus of dietary Mo in cattle on a low-Cu diet.

METHODS: Forty non-lactating, Friesian dairy cows of adequate Cu status were assigned to four groups and fed a basal diet of baled silage containing 5.3 mg Cu and 0.4 mg Mo/kg DM. The experimental design was a factorial of two chemical forms of supplemental Cu and two levels of Mo intake, provided as pelleted grain supplements made from crushed barley/molasses plus Cu and Mo. The supplements contained 140 mg Cu/kg as Cu sulphate pentahydrate (CS), 140 mg Cu/kg as Cu glycinate (CG), CS plus 38 mg Mo/kg as sodium molybdate (CS+Mo), or CG plus 38 mg Mo/kg (CG+Mo). Commencing on Day 0, supplements were fed once daily (offered 1–1.2 kg/cow) and were completely consumed within 5–10 minutes, which constitutes a bolus type of administration. Liver samples were collected by biopsy at Days ?24, 13, 41 or 47, and 69 for Cu determinations.

RESULTS: The diets fed to the Cu+Mo groups were roughly equivalent to 25 mg Cu and 5.7 mg Mo/kg DM. Mean initial concentration of Cu in liver for all groups was 516 (SE 54) μmol Cu/kg fresh tissue. In cows supplemented with CS and CG, the final (Day 69) concentrations increased (p<0.01) to 939 (SE 166) and 853 (SE 163) μmol Cu/kg, respectively. These values were not different (p=0.72). For groups CS+Mo and CG+Mo, the final concentrations of 535 (SE 122) and 453 (SE 102) μmol Cu/kg were not different from initial values or from each other (p>0.25). The rate of accumulation of Cu in liver following bolus Cu and Mo intake was highly variable but was not affected by initial concentration of Cu in liver (p>0.9) or by the form of Cu (p>0.6). Mean rates of accumulation of Cu in liver were 4.0 (SD 3.8) and 0.65 (SD 2.0) μmol Cu/kg fresh tissue/day for the Cu-only treatments and the Cu+Mo treatments, respectively.

CONCLUSIONS: When fed together as a bolus, high Mo intake negated the effect of supplemental Cu but it did not reduce liver Cu stores. There was no difference in the reaction of dietary Mo with chelated Cu (as glycinate) versus inorganic Cu (as sulphate) dietary supplements.     

The response of vaccinated rams to experimental challenge using Brucella ovis

One hundred and thirty eight rams were allocated to four experimental groups. An inactivated Br. ovis vaccine was administered either once by the intraperitoneal route (1 i/p), twice by the intraperitoneal route (2 i/p), or twice by the subcutaneous route (2 s/c), and the last group was left unvaccinated. They were then challenged by the intravenous inoculation of between 123 and 1.23 × 10⁸ live Br. ovis bacteria. The number of rams that succumbed to infection within the four groups was 4/35 (11%) for the 2 s/c, 7/33 (21%) for the 2 i/p, 9/35 (26%) for the 1 i/p and 18/35 (51%) for the unvaccinated rams. Vaccination reduced the number of rams that succumbed to experimental challenge and although there were differences between the vaccinated groups, these were not statistically significant.

Following challenge, unvaccinated rams were the first to excrete Br. ovis in their semen; three weeks following inoculation. Next, those vaccinated by either one or two doses by the intraperitoneal technique began to excrete the organism (five weeks) and then finally those rams vaccinated twice by the subcutaneous route (seven weeks).     

Anthelmintic resistance and management of nematode parasites on beef cattle-rearing farms in the North Island of New Zealand

AIM: To provide information on current farmers’ opinions and farming practices thought to be related to anthelmintic resistance, and to test for associations between the presence of anthelmintic resistance and management practices on beef cattle- rearing farms in the North Island of New Zealand.

METHODS: A study using an interview-based questionnaire about management of internal parasites was conducted on 62 beef cattle-rearing farms in the North Island of New Zealand, using case-control analyses to test for associations between management practices and the presence or absence of resistance to ivermectin or albendazole. Resistance was inferred from faecal nematode egg count (FEC) reduction (FECR) tests (FECRTs) when there was <90% reduction in FEC 7-10 days after treatment of calves <12 months of age.

RESULTS: Of the 59 farmers who completed the questionnaire, most (n=40) ranked parasites highly, and at about the same level as quality and quantity of feed, as important production-limiting factors for their enterprises. In contrast, anthelmintic resistance was not perceived to be a problem on 13 farms, and its importance was rated low on 24, moderate on 15, and high on only six farms. Despite all farms having planned parasite control programmes, there was heavy reliance on clinical signs of parasitism to determine frequency of treatments. About one in three farmers with beef breeder cows routinely treated their calves at marking, one in five treated mixed-age cows, and almost half treated rising 2-year-old cows before calving. One in four farmers used anthelmintics on calves on 8–12 occasions in their first year of life. Co-grazing with other species was rare, but follow-on grazing within 3 months after older cattle or sheep was common. On most farms, grazing cattle was restricted to part of the farm, a finding with implications for parasite control and persistence of larvae in refugia. Macrocyclic lactone (ML) anthelmintics or their combinations with other action families were currently, and for the past 5 years, used more frequently than benzimidazoles and levamisole, and benzimidazole-levami- sole combinations. The prevalence of resistance to ivermectin was high (82%) and no plausible model of associations could be constructed from the data. The prevalence of resistance to albendazole was 60%, and the risk of resistance increased as the number of rising 1-year-old cattle present mid-winter increased, and decreased as the number of breeding cows >2 years old present mid-winter increased.

CONCLUSION: It is clear that in practice anthelmintic resistance is a secondary consideration to obtaining productivity advantages from the use of anthelmintics in beef cattle. Farmers’ opinions were divided on many issues and the overall impres- sion was of confused and diverse thinking regarding the principles of the use of anthelmintics. The overall outlook regarding anthelmintic resistance in cattle is bleak unless the need for integrated and long-term research activities is acted upon soon.     

A case of "watery mouth" in a New Zealand Romney lamb

Watery mouth was diagnosed as the cause of illness and subsequent death in a 3-day-old Romney lamb which had not received early colostrum. The history, clinical signs and post-mortem findings were typical of the disease as seen in other countries, including Great Britain. The diagnosis was based on the clinical signs and was supported by an absence of post-mortem findings of other specific neonatal diseases. The potential importance of watery mouth under conditions of intensive husbandry in New Zealand is discussed.     

The effect of breeding ewe lambs on subsequent two-year-old ewe performance

This study was undertaken to determine if breeding ewe lambs (hoggets) would influence subsequent two-year-old (two-tooth) ewe liveweight and reproductive performance and their lamb's performance to weaning. Two-tooth Romney ewes that had been bred and lambed as a hogget (n = 505) were compared with those of 196 ewes that were bred as a hogget but did not lamb and 235 ewes that were not presented for breeding as a hogget. Hogget lambing resulted in reduced (P < 0.05) two-tooth liveweight and body condition score at breeding although still present this liveweight difference was reduced by two-tooth lamb weaning. Two-tooth ewes that had previously lambed as a hogget had greater (P < 0.05) returns to service rates and lower (P < 0.05) fecundity (multiple-bearing/two-tooth bred) than those that were bred for the first time. Two-tooth lamb liveweights were unaffected by hogget lambing. These results show that hogget lambing had a small negative effect on subsequent two-tooth reproductive performance. This was most likely caused by reduced liveweight at two-tooth breeding and indicates that farmers need to ensure management practices are in place to reduce the impact of hogget lambing on two-tooth liveweight.