Frequencies of PRNP gene polymorphisms in Vietnamese dairy cattle for potential association with BSE.

Summary Since 2004, significant associations between bovine spongiform encephalopathy (BSE) susceptibility in cattle and frequencies of insertion/deletion (ins/del; indel) polymorphisms within the bovine prion protein gene (PRNP) have been reported. In this study, we investigated the frequencies of indel polymorphisms within two variable sites, a 23-bp indel polymorphism in the promoter region (23indel) and a 12-bp indel polymorphism in intron 1 region (12indel), in the PRNP in 206 Vietnamese dairy cattle and seven Japanese BSE-affected cattle. In Vietnamese dairy cattle, the frequency distributions of del allele and del/del genotypic polymorphisms in the 23indel site, which are thought to be associated with BSE susceptibility, were significantly higher, whereas the frequencies of del allelic and del/del genotypic polymorphisms in the 12indel site, which have been reported to confer BSE susceptibility, were significantly lower. We have provided evidence that Vietnamese dairy cattle have a unique genetic background in the PRNP gene in comparison with cattle or sires previously reported in other countries.

Temporal dynamics of dairy health and production in rural smallholder communities in Northern Vietnam.

The objective of this field study was to describe the temporal pattern of dairy cattle health and production and associated risk factors in rural small-holder communities in northern Vietnam, one of the target areas of the government's dairy development programme. A total of 99 dairy farms (11 per commune) were recruited from 9 of 32 communes in Ba Vi District, Ha Tay Province, using random two-stage cluster sampling. All dairy cattle present on the selected farms were included. After the initial questionnaire survey was conducted, farms were visited to collect follow-up information at 3-monthly intervals over a period of one year. The results suggest that offtake as well as mortality are important productivity indices because farmers sell or slaughter dairy cattle that are in poor health at low prices during summer months. Changes in relation to the farming operation suggest that for the farmers adopting dairy production it has become one of the main agricultural activities.

A longitudinal study to identify constraints to dairy cattle health and production in rural smallholder communities in Northern Vietnam.

The objective of the study was to investigate constraints to dairy cattle health and production in rural smallholder communities in northern Vietnam, one of the target areas of the Vietnam government's dairy development programme. A total of 99 dairy farms (11 per commune) were recruited from 9 of 32 communes in Ba Vi District, using random two-stage cluster sampling. After the initial questionnaire interviews were conducted, farms were visited at three monthly intervals over a period of 1 year. Information on several health and production parameters relating to the study cattle was collected. Using multiple indicator modelling, it was found that Fasciola infestation, farmers who had been involved in dairying for longer (not indicative of better management skills), larger herd size, and cattle being kept in a shed were linked to reduced reproductive performances.

An evaluation of tuberculin skin tests used to diagnose tuberculosis in swamp buffaloes (Bubalus bubalis).

Three types of tuberculin tests were evaluated in swamp buffaloes in two herds of known tuberculosis-positive and tuberculosis-negative status, and the results were compared with postmortem records of 73 tuberculous and 12 non-tuberculous buffaloes from a different herd. Of the 73 tuberculous swamp buffaloes, 30 (41%), 46 (63%) and 56 (77%) animals were detected by the caudal-fold skin test, the cervical skin test and the Stormont test, respectively. Of the 12 non-tuberculous buffaloes, 5 (42%), 4 (34%), and 10 (83%) reacted to the above-mentioned three tuberculin tests, respectively. The reaction was more-pronounced in the cervical skin than in the caudal-fold skin when the single intradermal test was used on the same individual. The Stormont test (a form of the double intradermal test) was the most-sensitive but least-specific test. We concluded that the tuberculin tests described showed poor sensitivity and specificity in swamp buffaloes. Another diagnostic procedure should thus be sought for more-accurate diagnosis.