Objective-To determine the diversity of Salmonella serotypes isolated from a large population of cull (market) dairy cows at slaughter.Design-Cross-sectional study.Sample Population-Salmonella organisms isolated from the cecal-colon contents of 5,087 market dairy cows,Procedure-During winter and summer 1996, cecal-colon contents of cull dairy cows at slaughter were obtained from 5 US slaughter establishments. Specimens were subjected to microbiologic culturing for Salmonella spp at 1 laboratory. Identified isolates were compared with Salmonella isolation lists published by the Centers for Disease Control and Prevention (CDC) and the National Veterinary Services Laboratory (NVSL) for approximately the same period. The Simpson diversity index was used to calculate the likelihood that Salmonella isolates selected randomly by establishment were different.Results-Of 58 Salmonella serotypes identified, Salmonella ser. Montevideo was the most prevalent. Two of the top 10 CDC serotypes identified from humans in 1996, Salmonella ser. Typhimurium and S Montevideo, appeared on our top 10 list; 8 of the top 10 were found on NVSL listings. Thirty-one of 59 S Typhimurium isolates were identified as DT104 and found at a west slaughter establishment, 30 during the winter and 1 during the summer. The greatest diversity of serotypes was at a southeast establishment during the summer; the least diversity was at a central establishment in the winter.Conclusions and Clinical Relevance-58 Salmonella serotypes were isolated from market dairy cows at slaughter and could pose a threat for food-borne illness. Salmonella Montevideo was the most frequently isolated serotype and may contribute substantially to salmonellosis in dairy cattle.

OBJECTIVETo determine the prevalence of Salmonella spp in the cecal-colon contents of cull (market) dairy cows at slaughter because of potential public health ramifications.DESIGNSurvey study.SAMPLE POPULATIONCecal-colon contents collected from 5,087 cull (market) dairy cows at slaughter at 5 slaughter establishments across the United States.PROCEDUREDuring 2 periods of the year, winter (January and February) and summer (July through September), 5 cull (market) cow slaughter establishments in the United States--west (WE), southeast (SEE), central (CE), north central (NCE), and south central (SCE)--establishments were visited, and cecal-colon contents of cull dairy cows were obtained at the time of slaughter. Samples were examined by microbiologic culture at a single laboratory for Salmonella spp.RESULTSSalmonella spp were detected in 23.1% of cecal-colon content samples from cull dairy cows across the 5 slaughter establishments. The highest site prevalence (54.5%) was detected at the WE during the summer period, whereas the lowest was found at the CE during the summer (4.3%) and at the NCE during the winter (4.5%). Considerable variation in the daily prevalence of Salmonella spp was found, particularly at the WE and the SCE. Salmonella spp were isolated from 93% of cecal-colon contents collected on a summer day at the WE.CONCLUSIONS AND CLINICAL RELEVANCEResults strongly suggest that there is a high prevalence of Salmonella spp in cull dairy cows at slaughter, which could burden Hazard Analysis Critical Control Point programs implemented in slaughter establishments. Procedures to reduce Salmonella load at the dairy farm and during transport to slaughter could reduce the risk of spread during the slaughter process.

The authors provide an overview of the circumstances associated with culling of dairy cattle in the United States of America (USA) and focus on the possible significant microbiological hazards associated with meat from cull dairy cows. Cull dairy cows are an important source of food in the USA, accounting for at least approximately 17% of ground beef. The potential microbiological hazards for foodborne illness from cull dairy cows discussed here include Salmonella (with special attention to S. Typhimurium DT104), Escherichia coli O157:H7, Campylobacter jejuni, Listeria monocytogenes, Clostridium perfringens and Staphylococcus aureus. Possible sources and means of contamination are pointed out, as are the potential foodborne risks from Bacillus cereus and Aeromonas spp. In conclusion, widespread microbiological studies are needed to determine the prevalence and risk of foodborne pathogens in cull dairy cattle.

In response to a dairy operator's request for help in evaluating heifer replacement costs, a worksheet was developed (using Lotus 1-2-3tm) to assess the cost of raising calves. Specific categories relating to calf raising were compiled and measures for calculations were established to determine variable and fixed costs. Testing and implementation of the spreadsheet were carried out on several large-scale dairies, with the individual dairy operators providing cost and population information pertaining to each of the categories. The worksheet provides a way to calculate fixed and variable calf-raising costs for calves of varying age-groups and weights.

Abomasal mechanical and myoelectric activity were measured in two adult Holstein cows. Hypocalcaemia was induced using a constant infusion of disodium EDTA and serum total and diffusible calcium concentrations were measured. Abomasal motility remained normal in the face of declining calcium concentrations until a threshold value was reached (1.2 +/- 0.2 mmol litre-1) below which all mechanical and electrical activity was absent. A similar threshold effect was observed when calcium concentrations were allowed to rise. These data do not support hypocalcaemia as being a clinically important cause of abomasal atony.

A case-control study of Potomac Horse Fever (PHF) was carried out on 260 horses on 41 premises in Maryland. Affected horses were compared with two control groups, one consisting of horses on the affected farms, and one of horses on unaffected farms. Variables studied included data gathered from two personal interview questionnaires, feed analysis, microbiological assay of faecal samples, and subsequent retrospective serological assay following the identification of the causative agent. The relative merits of this type of case-control study are discussed. Resultsof multi-variable analysis indicated a lack of association with most of the variables studied, but provided quantitative data on the epidemiology of the disease. They clearly demonstrated that the disease was infectious but not contagious, consistent with the involvement of an arthropod vector. Positive associations were found with a few variables including the previous presence of the disease in a barn and the presence of other livestock. The significance of these results in the light of recent findings is discussed.

Fecal specimens from horses in Montgomery County, Md, and in Fairfax and Loudoun counties, Va, were examined for Clostridium perfringens type A enterotoxin and for C difficile cytotoxin (92 and 108 specimens, respectively). The toxins were found in feces from horses that had experienced an acute diarrhea syndrome and from clinically normal horses. The toxins did not appear to be primary determinants of the diarrhea syndrome, although they may have contributed to the spectrum of clinical entities observed.

A scoring system with 1 to 5 scale was devised to measure body condition of dairy cows at any point during the lactation cycle. Cows were scored on appearance and palpation of back and hind quarters only. Relationships of body weight, frame size measurements, milk production, and characteristics related to the body condition scoring system were determined. During 18 mo, 28 cows in each of 29 dairy herds were used for body measurements and body condition scores. Data were obtained from each herd at 3-mo intervals. Body weight and frame size measurements could not be correlated with body condition score. Dairy cows of greatest efficiency of milk production showed no significant increase in body condition during lactation, had fewer days open, but had lower persistency of lactation. Dairy cows that increased significantly in body condition during lactation were less efficient producers, had a greater number of days open, and had high body condition scores at the end of lactation. The body condition scoring system is a means of accurately determining body condition of dairy cows, independent of body weight and frame size.

This study examined metabolic profiles of commercial dairy herds differing in milk production.Thirty herds were selected with 10 herds averaging more than 7258 kg milk, 10 herds between 6350 and 7258 kg, and 10 herds averaged below 6350 kg.In each herd, 28 cows were selected for blood sampling, which was collected every 3 mo during 12 mo.Cows varied in estimated relative producing ability.Metabolic profiles were established for 19 blood components.Differences among treatment means were significant between high and low producing herds and little between profiles for milking and pregnant nonlactating cows.Metabolic profiles of problem herds remained within normal ranges for all herds except one.Profiles of herds with breeding or mastitis problems remained in the normal range.Metabolic profile testing was of limited value in screening a dairy herd for potential problems or deficiencies.

Practitioners can increase their value to their clients as well as increase the gross veterinary product by developing supplemental expertise in nontraditional disciplines. This can be accomplished through continuing education and the utilization of technical support services such as the professional nutritionist. In addition, contemporary technology such as the electronic moisture tester and the pH meter can be implemented in the acquisition of nutritional diagnostic data. A comprehensive herd health program is precisely the delivery system into which such complimentary expertise can be integrated successfully.

Computerized least-cost rations were simulated for 15 dairy herds from herd-average body weights either reported by Dairy Herd Improvement or by taping heart girths of cows. Differences between simulated rations were predicted for feed costs, intakes of crude protein and net energy, and gain in body weight. Weights reported by Dairy Herd Improvement were 68±37kg per cow less than taped weights. The 360 taped cows averaged 633±39kg body weight. The use of reported mean body weights in the formulation of rations for the milking herd increased predicted intakes of net energy and gains in body weight. The effect upon predicted feed costs and intakes of crude protein was not significant. To compensate for differences in estimations of body weight does not appear to be practical. The error in estimation of body weight is small as compared with other possible errors which affect management decisions.

Thirty Virginia dairy herds were solicited as cooperator herds. The objective was to test in the field the Dairy Cattle Feed Formulation System, a computerized feeding management system. During 12 mo, 13 herds used recommendations of the system regularly, 5 herds were occasional users or made modifications to the recommendations, 11 herds followed other feeding recommendations, and one herd was dropped from the study. Increase in milk production during 12 mo averaged 354, 220, and −39kg per cow for regular, occasional, and no formulation users. Milk fat test, body weight, and body condition were not affected by frequency of using the formulation system. Days open were reduced in herds which were regular users (−13.5, 6.8, and 2.1). The coefficient of variability for milk production within herds was 28%. When herds were divided into two groups of lactating cows or when herds used automatic (magnetic) feeders, daily milk yield averaged 28.1, 17.4, and 33.3kg, for high and low groups or cows with access to automatic feeders. Coefficients of variability were 13, 22, and 10%.