A randomized intervention study was conducted to determine if discontinuing use of calf milk replacer medicated with oxytetracycline results in increased tetracycline susceptibility in Salmonella and Campylobacter spp. and Escherichia coli in dairy calves over a 12-month period. Dairy herds with enteric bacteria with known low tetracycline susceptibility were enrolled for the study. Fecal sampl...

A recent dairy survey conducted in 1996 by the National Animal Health Monitoring System suggests between 20 and 40% of dairy herds in the United States have some level of Johne's disease. This figure will continue to increase unless producers implement management regimes that will help control the spread of this disease within their herds. The neonatal calf is the target for infection with Myco...

faecal samples from 291 dairy calves from 10 dairy herds in kerman were examined to investigate theprevalence of cryptosporidium infection. cryptosporidium spp. oocysts were identified by using themodified ziehl-neelsen staining technique in 63 (21.65%) calves. calves were grouped according to theirage as follows:

Shiga toxin-producing Escherichia coli (STEC) are pathogens of significant public health concern. Several studies have confirmed that cattle are the main reservoir of STEC in Argentina and other countries. Although Shiga toxins represent the primary virulence factors of STEC, the adherence and colonization of the gut are also important in the pathogenesis of the bacteria. The aim of this study ...

Professional heifer growers and dairy producers are faced with the challenge of raising healthy calves, while still paying close attention to rearing costs and profit. Factors that may be considered in selecting a liquid feeding program may include the number of calves fed, economics and cash flow, nutritional characteristics, calf performance targets, resource availability (e.g. consistent sup...

A challenge experiment was performed to investigate whether administration of Mycobacterium avium subsp. paratuberculosis (MAP) via the respiratory route leads to MAP infection in calves. Eighteen calves from test negative dams were randomly allocated to four groups. Six calves were challenged with MAP nasally and six calves were challenged by transtracheal injection; three orally challenged ca...