A critical evaluation of serum methylmalonic acid and vitamin B12 for the assessment of cobalt deficiency of growing lambs in New Zealand

AIM: To derive reference ranges for serum methylmalonic acid (MMA) for the diagnosis of cobalt/vitamin B₁₂-responsiveness in lambs and critique existing serum vitamin B₁₂ reference ranges.

METHODS: Individual animal data from earlier supplementation trials, involving 225 ewes, 106 suckling lambs, 301 lambs during the suckling and post-weaning periods and 414 weaned lambs, for which weight gain to supplementation was observed, were used to derive relationships between serum vitamin B₁₂ and MMA, and liveweight gain.

RESULTS: Serum MMA concentrations were rarely elevated above the norm of <2 µmol/L when serum vitamin B₁₂ concentrations were >375 pmol/L, and not elevated into the range where a liveweight response to supplementation occurred (>10 µmol/L) unless serum vitamin B₁₂ concentrations were below 200 pmol/L. Suckling lambs were able to maintain high growth rates despite elevated serum MMA concentrations (>20 µmol/L).

CONCLUSIONS: The current reference ranges used in New Zealand for serum vitamin B₁₂ are set conservatively high. Serum MMA concentrations appear to allow better differentiation of a responsive condition than vitamin B₁₂ concentrations. Serum MMA concentrations <13 µmol/L indicate responsiveness to supplementation whilst concentrations <7 µmol/L indicate unresponsiveness. In the range 7–13 µmol/L, variation in response was observed and predictability of response is less certain, but supplementation is advisable.

CLINICAL RELEVANCE: The current reference ranges for vitamin B₁₂ responsiveness are conservatively high and lead to over-diagnosis of vitamin B₁₂ deficiency in ill-thriftiness of sheep.     

The effect of ivermectin treatment of late pregnant dairy cows in south-west Victoria on subsequent milk production and reproductive performance

SUMMARY A total of 498 dairy cows in 5 predominantly pasture-fed herds were allocated to pairs. One cow in each pair was treated with a single dose of ivermectin during the dry period. Treated and untreated cows were managed as a single group throughout the trial. Most cows calved between 45 and 115 days after treatment. When data from all herds were pooled, treated cows produced an extra 74 L of milk over the first 100 days of the subsequent lactation (95% confidence interval 20 to 128). Means were greater among treated groups relative to untreated groups in all 5 herds. However, when analysed individually, differences were statistically significant (P < 0.05) in 1 herd only. Over the complete lactation, mean milk volume for treated cows was 86 L greater than for untreated cows (95% confidence interval of difference -57 to 229; P = 0.24). Untreated cows produced 2473 L and 5883 L for the first 100 days of lactation and for the complete lactation, respectively. Milk production responses to treatment did not vary significantly with parity, body condition score, previous production index, calving date category or with plasma pepsinogen concentration or faecal egg count at the time of treatment. Faecal egg counts and plasma pepsinogen concentrations were low at the start of the study. The interval from calving to conception was 4.8 days less in treated cows (95% confidence interval 1.2 to 8.2) relative to untreated cows when data from all 5 herds were pooled. Differences within individual herds were not statistically significant.     

Muscle enzymes in the diagnosis of ovine weaner nutritional myopathy

SUMMARY The diagnostic performance of plasma tests for muscle enzymes was measured in sheep from flocks affected by clinical and sub-clinical nutritional myopathy. Parallel combinations of tests for creatine kinase (CK), alanine amino transferase (ALT), aspartate amino transferase (AST) and lactate dehydrogenase had higher diagnostic sensitivity than CK alone. The enzymes ALT and AST showed the highest correlation with the degree of muscle damage. A parallel combination of tests for plasma CK and ALT as well as tests for plasma α-tocopherol and red cell glutathione peroxidase are recommended for the diagnosis of nutritional myopathy and a decision on the appropriate treatment. The number of false negative results based on a diagnosis from the microscopic examination of single muscles was higher than for the parallel combination of tests. The number of false negatives was highest for the vastus intermedius and lowest for the tensor fascia lata. Diagnosis using a panel of blood tests has the advantages of overcoming problems of inadequate muscle sampling, a larger number of sheep in the flock can be tested and a more rapid diagnosis can be obtained.     

Expression of adhesion molecules on milk and blood lymphocytes from periparturient dairy cattle with Johne's disease

Twelve dairy cows infected with Mycobacterium avium subsp. paratuberculosis were monitored for lymphocyte subsets and expression of adhesion molecules on cells in blood and milk at parturition and at intervals up to 21 days post-partum. Using fluorescent antibody labeling of cells and analysis by flow cytometry, we determined percentages of T cell subsets (CD4+, CD8+, gammadelta+) and expression of adhesion molecules (CD62L, LFA-1, LPAM-1, and CD44) on cells from blood and milk of these cows. Significantly higher percentages of CD8+ cells were found in milk than in blood at all time points; there were no significant differences in percentages of CD4+ or gammadelta+ cells. CD62L, LFA-1, and LPAM-1 were expressed on a significantly higher percentage of all T cell subsets in milk than in blood at various times after parturition. No differences were seen in expression of CD44. Increased percentages of T lymphocytes expressing adhesion molecules in milk compared to blood suggest that a migratory population of cells is being selectively recruited to the mammary gland from the circulation.     

中药免疫佐剂的研究进展

中药免疫佐剂的开发，扩大了中药的应用领域，同时能够取得很好的经济效益。从中药佐剂开发的必要性出发，综述了中药理论和免疫理论的相关性研究及中药免疫佐剂的开发现状。     

Identification of Chlamydia gallinacea in a parrot and in free‐range chickens in Australia

Chlamydia gallinacea is a recently described bacterial species in a genus known to infect and cause disease in animals and humans. Our report describes the identification of C. gallinacea infection in free‐range laying chickens (Gallus gallus) in Australia, and the identification of C. gallinacea infection in a parrot, a wild Australian galah (Eolophus roseicapillus). There is currently little knowledge of the effects of C. gallinacea infection on avian hosts, but it has been linked to respiratory disease in humans and could potentially cause similar disease in other species. Our report highlights the need for further study and surveillance of Chlamydia species in both wild and domestic hosts in Australia.     

禽用活疫苗SPF化现状及对兽用生物制品企业的影响

目前,禽病防疫仍以疫苗免疫接种为主,疫苗安全性直接影响疫病防控效果,优质疫苗能预防疾病,提高家禽的生产性能,创造经济效益。相反,劣质疫苗可能对动物造成伤害,对环境造成污染,乃至威胁人类的健康。因此,选择安全高效的优质疫苗是做好家禽疫病防疫的关键。为保证疫苗质量安全,实行禽用活疫苗SPF化已经势在必行。     

Skin disease affecting the conservation of the western swamp tortoise (Pseudemydura umbrina)

Objective To review the present position of the western swamp tortoise ( Pseudemydura umbrina ) as an endangered species and significant health issues affecting efforts to save it from extinction.
Procedure A retrospective analysis of the husbandry, hospital and pathology records of the western swamp tortoise captive breeding program at Perth Zoo.
Results In 1987 a captive breeding project was developed to prevent the extinction of the western swamp tortoise but an outbreak of a necrotising dermatitis in 1989 threatened the survival of the captive bred hatchlings. Less severe outbreaks occurred in 1990 and 1993, with isolated cases in between. Of 283 tortoises that were born in captivity or came into captivity from the wild, 37 (13.1%) were affected, comprising 37% of all males, 26% of all females and 13% of animals of unknown gender. Of the affected animals, 70% were less than 2 years of age and 29% were older. Males were 1.6 times more likely to be infected than females but this difference was not statistically significant (P = 0.27). Culture of the lesions consistently yielded unidentified Pseudomonas sp.
Conclusion Improved husbandry, such as strict maintenance of water quality and temperature conditions similar to that of the animal's natural habitat, and monitoring the health of individual tortoises have successfully controlled skin disease in the captive breeding of the western swamp tortoise.