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Longitudinal data from 3 commercial dairy herds in the northeast United States, collected from 2004 to 2011, were analyzed to determine the effect of Mycobacterium avium ssp. paratuberculosis (MAP) infection status and progression path on milk production. Disease status, as indicated by MAP test results, was determined through quarterly ELISA serum testing, biannual fecal culture, and culture of tissues and feces at slaughter. Milk production data were collected from the Dairy Herd Information Association. Animals with positive MAP test results were categorized, based on test results over the full course of the study, as high path (at least one high-positive culture) or low path (at least one positive culture or ELISA). The cumulative numbers of positive ELISA and culture results were recorded. The effects of both MAP infection path, status, and number of positive tests on milk production were analyzed using a mixed linear model with an autocorrelation random effect structure. Low- and high-path animals produced more milk before their first positive test than always-negative animals, especially high-path animals. Although mean production decreased after a first positive test, low-path animals were shown to recover some productivity. High-path animals continued to exhibit a decrease in milk production, especially after their first high-positive fecal culture. These results show that not all animals that test positive for MAP will have long-term production losses. Milk production decreased significantly with each additional positive test. Ultimately, production loss appeared to be a function of MAP infection progression.

This report further documents the critical importance of identifying super-shedders, since they contribute billions of MAP CFU daily to the environment, serving to disseminate MAP to susceptible cattle. In many herds, this results in significant numbers of culture-positive fecal samples through passive shedding. The frequency of super-shedders among culture-positive cattle in infected herds is unknown. However, our preliminary investigations have shown that each of three current herds has at least one super-shedder cow, with five super-shedder cows having been identified among the 7.1% ( 41 of 575) of culture-positive cattle in the herds. Our preliminary estimates are that 10% of heavy shedders (or about 2 to 3% of all culture-positive cattle at a single time-point) may be super-shedders, excreting >10 billion CFU MAP per cow per day., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2006

Prevalence of Johne's on US dairy farms is estimated at one-fifth of all herds, and is higher for the population of large herds. Of the animals which test positive for MAP, high levels of bacterial shedding are noted in only a small proportion. Despite this low prevalence of high-shedding animals, elimination of MAP from herds has proven exceptionally challenging, with few published reports of successful eradication of MAP from infected farms. Mathematical modeling may aid us in the understanding of this apparent contradiction., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2005

Traditionally, fecal cultures were either positive or negative for growth of Mycobacterium paratuberculosis (MAP). Nearly all culture-positive cattle were judged to be infected, shedding MAP, thus a threat to spread the disease to susceptible cattle and were culled from the herd as quickly as possible. Over time it was recognized that differences in MAP shedding existed among culture-positive cattle. Cattle were classified as low, moderate or high shedders based on the visible colonies of MAP on the surface of solid media, typically Herrold's egg yolk media (HEYM). Rarely did authors provide the estimated MAP colony forming units (cfu) per gram of manure. Additionally, culture methods were not standardized among diagnostic laboratories in the US, which made it difficult to compare results from one laboratory to another. Laboratories rarely used internal quality control fecal samples. As the infection and disease progressed, the intensity of fecal shedding of MAP increased, culminating in clinical disease which was associated with the greatest numbers of MAP present in manure. Since cattle with clinical signs lose weight and have decreased milk production causing them to be unprofitable, they are soon culled from the herd. If not culled from the herd, they would continue to lose weight and become emaciated with muscle weakness, leading to recumbency requiring euthanasia. The fewest colonies reported is one colony on one of four tubes ofHEYM, which translates into approximately six cfu/gram of feces, assuming the original sample was two grams; 5 ml was transferred from the fecal water tube to the second decontamination tube with HPC. That centrifugation technique was used and the pellet was re-suspended in 1 ml of antibiotic brew, with 200 ul of the re-suspended pellet inoculated onto each of four tubes of HEYM, all with mycobactin J. Low shedders typically had less than 10 colonies on the four tubes ofHEYM. Moderate shedders ranged from 11 to approximately 70 colonies of MAP, while high shedders had more than 70 colonies on any of the four tubes. Calculated on MAP cfu per gram of feces this would be up to 60 cfu for low shedders, 61 to 300 cfu per gram for moderate shedders and more than 300 cfu per gram for heavy shedders. Over the past five years most laboratories in the US report the number of visible MAP colonies on each tube of HEYM, but rarely enumerate above 50 to 70 colonies per tube. Accounting for sample preparation, 50 colonies on each of four tubes represents an estimated 1,050 colony forming units of MAP per gram of manure. The objective of this study was to determine the range of MAP cfu/gram of manure in cattle classified as heavy shedders., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2005

Johne's disease (paratuberculosis) is a chronic, granulomatous infection of the intestinal tract of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP). There is no approved treatment, no known way to eliminate the infection once established, nor is there an effective vaccine for the disease. Johne's disease (JD) has emerged as an important disease of cattle due to the economic impact and the potential link to human Crohn's disease. The recently introduced herd Risk Assessment (RA) and Herd Management Plan (HMP) developed by the National Johne's Working Group (NJWG) have been incorporated into the national program standards by USDA, APHIS. Increased state and federal funding for Johne's disease has increased the focus on ways to control the condition. Methods to control the spread and to reduce within herd transmission of Johne's disease (JD) are being adopted by both dairy and beef herds in many states through implementation of the national Johne's disease program. Implementation of best management practices (BMP) following a herd risk assessment (RA) designed to reduce the risk of transmission of JD remains the focal point of the national effort to reduce the prevalence of JD in cattle herds today. Although a vaccine for JD is available in many states, its use is closely regulated by individual state veterinarians and usage by the profession remains less than 2,000 herds nationally. Test and culling of culture-positive cattle seems a low priority if the infected animals are profitable. Reduction of the herd bioburden of MAP seems a lower priority for many producers. Brumbaugh et al1 demonstrated a reduction in the number of colony forming units (cfu) of MAP from the livers of experimentally MAP-infected mice treated with monensin compared to non-treated controls. More recently he showed monensin reduced the severity of histological lesions in cattle with clinical signs of Johne's disease, including weight loss and diarrhea.2 Initial infection with MAP is generally considered to occur in the neonatal calves. Our laboratory at the University of Pennsylvania, New Bolton Center has successfully induced experimental MAP infection in neonatal calves via oral gavage of MAP on two consecutive days.4 The current experiment was designed to assess the efficacy of monensina to reduce pass-through fecal shedding and to reduce tissue bacterial load (bioburden) of MAP in calves., American Association of Bovine Practitioners Proceedings of the Annual Conference, 2005

A new rapid test for diagnosis of Johne's disease in cattle is described. This unique format Tip-Test™ utilizes the same principles as the Enzyme-linked Immunosorbent Assay (ELISA) test with similar sensitivity and specificity, but can be done in the practitioner's office with the results available in 25 minutes. Two formats of the test are available: a single Tip-Test™ using a tuberculin syringe with disposable supplies provided with the kit, and a 12-sample multi-tip pipetter. The test is designed to detect animals in the later stages of infection and to provide quick laboratory confirmation of clinical cases of Johne's disease., American Association of Bovine Practitioners Proceedings of the Annual Conference, 1999

Johne's disease (paratuberculosis) (JD) is a chronic progressive bacterial enteropathy. Infected animals have generally been exposed to the organism at a very young age. Clinical signs of weight loss and diarrhea are often preceded by a period of months or years during which M. paratuberculosis organisms are shed in feces. The effect of subclinical JD on production and economic parameters has not been well characterized. A study of randomly selected cull dairy cows was conducted at a large plant slaughtering cull cows from throughout the northeastern U.S. Johne's positive cull cows weighed less, produced less milk during their lifetime and less milk during their last lactation than did Johne's negative cull cows., American Association of Bovine Practitioners Proceedings of the Annual Conference, 1990

Botulism in cattle has been associated with the ingestion of contaminated carrion or forages. This report describes the clinical signs and diagnostic approaches in three outbreaks of botulism in cattle where Clostridium botulinum Type B organisms were identified in each herd and specific toxin detected in the forage of one herd. In each of these outbreaks Type B organisms were isolated from the silage which may have been improperly fermented. The key factor may be the lack of adequate fermentation to reach a low pH, thus inhibiting sporulation and toxin production by Clostridium botulinum. Botulinum organisms were also isolated from the rumen contents and feces of affected cattle which help confirm the diagnosis because normal cattle do not have botulinum organisms in the gastrointestinal contents. Mouse toxicity and neutralization testing was performed on a supernatant for the testing of serum. All the mice injected intraperitoneally with botulism toxin containing supernatant died within the 96 hour test period. Those mice receiving a mixture of the trypsinized tissue extract containing the monovalent antitoxin corresponding to the type of toxin present in the tissue survived the 96 hour test period., American Association of Bovine Practitioners Proceedings of the Annual Conference, 1985

An abattoir survey of 1224 culled cows slaughtered at Wyalusing, Pennsylvania (USA) revealed paratuberculosis in 7.2%. The infected cattle came from 13 States., The Bovine Practitioner, No. 21 (1986 November)

The problems of the lower gastrointestinal tract in the cow can be divided into two major categories: (1) diarrhea, and (2) obstruction with lack of adequate fecal output. Less common problems would include bleeding in the intestinal tract, tenesmus or straining, and pain in the abdomen. Diarrhea is the most prominent problem of the gastrointestinal tract facing the large animal practitioner of today. In fact, diarrhea or the complications associated with diarrhea account for 10- 15% of the mortality losses associated with calves born in the United States! Some data indicate this is the major loss to the cattle industry in the United States., American Association of Bovine Practitioners Proceedings of the Annual Conference, 1976

Each of three cows fitted with a rumen cannula were maintained on a constant diet for two weeks prior to the experiment. Each cow was given 4, 8 and 16 mg/ kg cimetidine and probantheline bromide to determine the effects of these drugs on acid secretion. Samples were aspirated every 30 minutes from the abomasum and rumen for one hour prior to receiving the drug and for 5 ½ hours after the treatment. The pH measurements were completed in duplicate on a Model 5 Corning pH Meter. The samples were also analyzed for chloride concentration. Neither probanthelirie nor cimetidine had any significant effect on abomasal pH, suggesting neither drug would be of value in treating abomasal ulcers., American Association of Bovine Practitioners Proceedings of the Annual Conference, 1982

It seems unlikely to cite pregnancy and parturition as direct causes of displacements as displacements have occurred in adult dairy bulls, cows in the middle of lactation, and in heifers (13). Certainly the gravid uterus and parturition must be considered as predisposing factors as nearly 80% of abomasal displacements occur in the first month postpartum (14)., American Association of Bovine Practitioners Proceedings of the Annual Conference, 1971