Bovine leukemia virus infection in cattle of China: Association with reduced milk production and increased somatic cell score

Yang, Yi; Fan, Wei; Mao, Yongjiang; Yang, Zhen; Lu, Guangyu; Zhang, R.; Zhang, H.; Szeto, Christopher; Wang, C.

doi:10.3168/jds.2015-10580

Cited by 94 publications

(82 citation statements)

References 21 publications

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“…In the US, where there is no control program for BLV, the animal-level prevalence in the dairy cattle population has increased steadily from approximately 10% at that time to over 40% today [5–12]. Other major dairy producing countries that have not implemented large-scale eradication programs, including Canada, Argentina, Japan, and China, have also reported BLV prevalence in their dairy herds of 30-50% [11, 13–21]. In contrast, 19 member states of the European Union, the United Kingdom, New Zealand, and Australia have completely eradicated BLV from their dairy cow populations, and control programs are underway in the remaining member states of the EU resulting in an overall herd prevalence in the EU of less than one percent [11, 22, 23].…”

Section: Introductionmentioning

confidence: 99%

“…While some previous studies do not show significant negative effects of BLV infection on production and longevity or survival [13, 24, 25], the majority of recent studies have reported a negative association between BLV infection and both milk production and cow longevity [21, 22, 26–32]. Between 2010 and 2012, our research group conducted studies of BLV in 113 Michigan dairy herds using milk ELISA1 testing of a sample of 40 cows in each herd to estimate within-herd AP, which ranged from 0% to 80.6% with an average of 32.8% [9, 33–36].…”

Section: Introductionmentioning

confidence: 99%

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Prevalence of Bovine Leukemia Virus Antibodies in US Dairy Cattle

LaDronka

Ainsworth

Wilkins

et al. 2018

Veterinary Medicine International

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Objective To estimate current US herd-level and animal-level prevalence of bovine leukemia virus (BLV) in dairy cows and characterize epidemiologic features. Design Cross-sectional observational study design and survey. Animals 4120 dairy cows from 103 commercial dairy herds in 11 states across the US. Procedures Milk samples were collected from dairy cows through routine commercial sampling and tested for anti-BLV antibodies by antibody capture ELISA. Based on the ELISA results of a sample of an average of 40 cows per herd, within-herd apparent prevalence (AP) was estimated by a directly standardized method and by a lactation-weighted method for each herd. Within-herd AP estimates were summarized to give estimates of US herd-level and animal-level AP. Differences in AP by lactation, region, state, breed, and herd size were examined to characterize basic epidemiologic features of BLV infection. Results 94.2% of herds had at least one BLV antibody positive cow detected. The average within-herd standardized AP was 46.5%. Lactation-specific AP increased with increasing lactation number, from 29.7% in first lactation cows to 58.9% in 4th and greater lactation cows. Significant differences were not observed based on region, state, breed, or herd size. Conclusions and Clinical Relevance These results are consistent with a historical trend of increasing prevalence of BLV among US dairy cattle. Given the findings of other studies on the negative impacts of BLV infection on milk production and cow longevity, these findings are clinically relevant for veterinarians counseling dairy clients on the risks of BLV to their herds.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Prevalence of Bovine Leukemia Virus Antibodies in US Dairy Cattle

LaDronka

Ainsworth

Wilkins

et al. 2018

Veterinary Medicine International

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“…62 This increase of SCC may indicate that BLV-infected cattle could present higher incidence of mastitis than BLV-free animals. A high SCC in milk is undesirable for the dairy industry because it increases the acidity of milk and decreases the quality of cheese.…”

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confidence: 99%

“…BLV-infected cows with ≥4 parities in their early and middle lactation stage had 13.2% and 14.9% reduction rate, respectively, compared with noninfected cows. 62 Another study analyzed the lactation history and BLV infection status of 4,052 cows from 348 herds and showed that infected cows in their 2nd and 3rd lactations had significantly lower life milk production compared with their negative counterparts with the same number of lactations. No significant differences were found between infected and noninfected cows with >3 lactations.…”

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confidence: 99%

Bovine leukemia virus: current perspectives

Juliarena¹,

Barrios²,

Lützelschwab³

et al. 2017

VAAT

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Enzootic bovine leukosis, caused by bovine leukemia virus (BLV), is the most common neoplasm of dairy cattle. Although beef and dairy cattle are susceptible to BLV infection and BLV-associated lymphosarcoma, the disease is more commonly detected in dairy herds, mostly because of the management practices in dairy farms. The pathogenicity of BLV in its natural host, the bovine, depends mainly on the resistance/susceptibility genetics of the animal. The majority of infected cattle are asymptomatic, promoting the extremely high dissemination rate of BLV in many bovine populations. The important productive losses caused by the BLV, added to the health risk of maintaining populations with a high prevalence of infection with a retrovirus, generates the need to implement control measures. Different strategies to control the virus have been attempted. The most effective approach is to identify and cull the totality of infected cattle in the herd. However, this approach is not suitable for herds with high prevalence of infection. At present, no treatment or vaccine has proven effective for the control of BLV. Thus far, the genetic selection of resistant animals emerges as a natural strategy for the containment of the BLV dissemination. In natural conditions, most of the infected, resistant cattle can control the infection, and therefore do not pass the virus to other animals, gradually decreasing the prevalence of the herd.

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“…The BLV FRET-PCR was performed as described previously [3] in a LightCycler 480 II real-time PCR platform to detect BLV. In brief, the gag gene sequences of representative BLV isolates were obtained from GenBank and the Clustal multiple alignment algorithm was used to identify a highly conserved region of the proviral polymerase DNA gene common to all the above BLV gene sequences.…”

Section: Methodsmentioning

confidence: 99%

First Molecular Characterization of Bovine Leukemia Virus Infections in the Caribbean

et al. 2016

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Bovine leukemia virus (BLV) is a retrovirus that causes enzootic bovine leucosis. To investigate the presence and genetic variability of BLV in the Caribbean for the first time, we preformed fluorescence resonance energy transfer (FRET)-PCR for the pol of BLV on DNA from whole blood of cattle from Dominica, Montserrat, Nevis and St. Kitts. Standard PCRs with primers for the env were used for phylogenetic analysis of BLV in positive animals. We found FRET-PCR positive cattle (12.6%, 41/325) on Dominica (5.2%; 4/77) and St. Kitts (19.2%; 37/193) but not on Montserrat (0%, 0/12) or Nevis (0%, 0/43). Positive animals were cows on farms where animals were raised intensively. Phylogenetic analysis using the neighbor-joining (NJ) method on partial and full-length env sequences obtained for strains from Dominica (n = 2) and St. Kitts (n = 5) and those available in GenBank (n = 90) (genotypes 1–10) revealed the Caribbean strains belonged to genotype 1 (98–100% sequence homology). Ours is the first molecular characterization of BLV infections in the Caribbean and the first description of genotype 1 in the region.

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Bovine leukemia virus infection in cattle of China: Association with reduced milk production and increased somatic cell score

Cited by 94 publications

References 21 publications

Prevalence of Bovine Leukemia Virus Antibodies in US Dairy Cattle

Prevalence of Bovine Leukemia Virus Antibodies in US Dairy Cattle

Bovine leukemia virus: current perspectives

First Molecular Characterization of Bovine Leukemia Virus Infections in the Caribbean

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