Perceptions of veterinarians and producers concerning Johne’s disease prevalence and control in US beef cow-calf operations

BACKGROUND: Efforts to educate producers and veterinarians in the United States regarding the management, prevention and control of Mycobacterium avium subspecies paratuberculosis (MAP) infection have increased over recent years. While nationwide awareness about MAP infection is improving, current level of awareness among beef producers and veterinarians is largely unknown. This study compares the perceptions of beef producers and veterinarians on the burden of MAP infection in cow-calf herds and on measures to control new infections. Questionnaires were mailed to 989 US beef producers through state Designated Johne’s Coordinators and to 1080 bovine veterinarians belonging to a US nationwide professional association. RESULTS: Twenty-two percent (34/155) of producers reported having infected animals in their herds. The mean (minimum, median, maximum) prevalence reported by producers was 0.8% (0, 0, 10). Twenty-seven percent (27/100) of producers had at least one clinical animal during the previous year. Compared to the small herds (<50 head), the mean test-positive percentages and estimated prevalences were higher in medium (50–149) and highest in large (≥150) herds. Seedstock herds had a lower prevalence and these producers were more likely to enroll in Johne’s disease (JD) control programs and test their herds. Veterinarians reported a mean overall animal level prevalence in their client herds of 5% (0, 2, 60). Similarly, 26% (0, 10, 100) of client herds had at least one infected animal. Mean percentage of infected cows within infected herds was 9% (0.01, 5, 80). Producers generally performed activities to control MAP transmission more frequently than perceived by veterinarians. Compared to veterinarians’ opinions, producers were less likely to cull cows with signs consistent with JD (P < 0.01), but more likely to test purchased additions (P < 0.01). Testing recommendations by veterinarians (n = 277) for beef cow-calf herds were bacterial culture of feces (3%), PCR (14%), ELISA (35%) and a combination of these tests (47%). Seventy-nine percent of veterinarians recommended a 12-month interval between testing. CONCLUSIONS: Seedstock producers who had had JD risk assessments performed on their farms were more supportive of JD control programs and had a correspondingly lower prevalence. It is important to increase educational activities to provide relevant information to veterinarians and producers for better management and control of JD. Educational programs should target larger herds to maximize the impact

Comparison of calf weaning weight and associated economic variables between beef cows with and without serum antibodies against or isolation from feces of Mycobacterium avium subsp paratuberculosis

OBJECTIVE—To compare calf weaning weight and associated economic variables for beef cows with serum antibodies against Mycobacterium avium subsp paratuberculosis (MAP) or from which MAP was isolated from feces with those for cows that were seronegative for antibodies against or culture negative for MAP. DESIGN—Retrospective study. ANIMALS—4,842 beef cows from 3 herds enrolled in the USDA National Johne’s Disease Demonstration Herd Project. PROCEDURES—Individual cow ELISA and culture results were obtained from the project database. During each parity evaluated for each cow, the 205-day adjusted weaning weight (AWW) of its calf was calculated. The AWW was compared between test-positive and testnegative cows by use of multilevel mixed-effect models. The median value for feeder calves from 2007 to 2011 was used to estimate the economic losses associated with MAP test– positive cows. RESULTS—The AWW of calves from cows with strongly positive ELISA results was 21.48 kg (47.26 lb) less than that of calves from cows with negative ELISA results. The AWW of calves from cows classified as heavy or moderate MAP shedders was 58.51 kg (128.72 lb) and 40.81 kg (89.78 lb) less, respectively, than that of calves from MAP culture–negative cows. Associated economic losses were estimated as $57.49/calf for cows with strongly positive ELISA results and$156.60/calf and $109.23/calf for cows classified as heavy and moderate MAP shedders, respectively. CONCLUSIONS AND CLINICAL RELEVANCE—Calves from cows with MAP-positive test results had significantly lower AWWs than did calves from cows with MAP-negative test results, which translated into economic losses for MAP-infected beef herds. (J Am Vet Med Assoc 2013;243:1609–1615)http://avmajournals.avma.org/loi/javmaam2014ab201

Perceptions of veterinarians in bovine practice and producers with beef cow-calf operations enrolled in the US voluntary bovine Johne's disease control program concerning economic losses associated with Johne's disease

This study compares the perceptions of producers and veterinarians on the economicimpacts of Mycobacterium avium subspecies paratuberculosis (MAP) infection in cow-calfherds. Questionnaires were mailed to beef producers through the Designated Johne’sCoordinators and to veterinarians belonging to a nationwide professional organization.Important components of losses associated with MAP infected cows were used to estimatetotal loss per infected cow-year using an iterative approach based on collected survey data.Veterinarians were more likely to perceive a lower calving percentage in MAP infectedcows compared to producers (P = 0.02). Income lost due to the presence of Johne’s disease(JD) in an infected cattle herd was perceived to be higher by veterinarians (P < 0.01). Com-pared to veterinarians without JD certification, seedstock producers were more likely toperceive genetic losses due to culling cows positive for MAP (P < 0.01). There were mixedopinions regarding the magnitude of lowered weaning weight in calves from infected cowsand perceived differences in risk of other diseases or conditions in infected cows. An annualloss of $235 (95$89–$457) for each infected animal was estimated based on infor-mation from the producer survey. The analogous estimate using information inputs fromveterinarians was$250 ($82–$486). Mean annual loss due to JD in a 100 cow herd with a7% true prevalence was $1644 ($625–$3250) based on information provided by producers.Similarly, mean annual loss based on information collected from veterinarians was$1747($575–$3375).Program for the Study of Johne’s Disease in Texas and by a cooperative agreement with USDA-APHIS-VS.http://ww w.elsevier.com/locate/prevetmedhb2014ab201

Evolution of the Bovine TLR Gene Family and Member Associations with Mycobacterium avium Subspecies paratuberculosis Infection

Members of the Toll-like receptor (TLR) gene family occupy key roles in the mammalian innate immune system by functioning as sentries for the detection of invading pathogens, thereafter provoking host innate immune responses. We utilized a custom next-generation sequencing approach and allele-specific genotyping assays to detect and validate 280 biallelic variants across all 10 bovine TLR genes, including 71 nonsynonymous single nucleotide polymorphisms (SNPs) and one putative nonsense SNP. Bayesian haplotype reconstructions and median joining networks revealed haplotype sharing between Bos taurus taurus and Bos taurus indicus breeds at every locus, and specialized beef and dairy breeds could not be differentiated despite an average polymorphism density of 1 marker/158 bp. Collectively, 160 tagSNPs and two tag insertion-deletion mutations (indels) were sufficient to predict 100% of the variation at 280 variable sites for both Bos subspecies and their hybrids, whereas 118 tagSNPs and 1 tagIndel predictively captured 100% of the variation at 235 variable sites for B. t. taurus. Polyphen and SIFT analyses of amino acid (AA) replacements encoded by bovine TLR SNPs indicated that up to 32% of the AA substitutions were expected to impact protein function. Classical and newly developed tests of diversity provide strong support for balancing selection operating on TLR3 and TLR8, and purifying selection acting on TLR10. An investigation of the persistence and continuity of linkage disequilibrium (r2≥0.50) between adjacent variable sites also supported the presence of selection acting on TLR3 and TLR8. A case-control study employing validated variants from bovine TLR genes recognizing bacterial ligands revealed six SNPs potentially eliciting small effects on susceptibility to Mycobacterium avium spp paratuberculosis infection in dairy cattle. The results of this study will broadly impact domestic cattle research by providing the necessary foundation to explore several avenues of bovine translational genomics, and the potential for marker-assisted vaccination

Microbial Fuel Cells and Microbial Ecology: Applications in Ruminant Health and Production Research

Microbial fuel cell (MFC) systems employ the catalytic activity of microbes to produce electricity from the oxidation of organic, and in some cases inorganic, substrates. MFC systems have been primarily explored for their use in bioremediation and bioenergy applications; however, these systems also offer a unique strategy for the cultivation of synergistic microbial communities. It has been hypothesized that the mechanism(s) of microbial electron transfer that enable electricity production in MFCs may be a cooperative strategy within mixed microbial consortia that is associated with, or is an alternative to, interspecies hydrogen (H2) transfer. Microbial fermentation processes and methanogenesis in ruminant animals are highly dependent on the consumption and production of H2in the rumen. Given the crucial role that H2 plays in ruminant digestion, it is desirable to understand the microbial relationships that control H2 partial pressures within the rumen; MFCs may serve as unique tools for studying this complex ecological system. Further, MFC systems offer a novel approach to studying biofilms that form under different redox conditions and may be applied to achieve a greater understanding of how microbial biofilms impact animal health. Here, we present a brief summary of the efforts made towards understanding rumen microbial ecology, microbial biofilms related to animal health, and how MFCs may be further applied in ruminant research