Reduction of rotavirus-, coronavirus- and E. coli-associated calf-diarrheas in a large-size dairy herd by means of dam vaccination with a triple-vaccine

Exploratory cohort study to determine if dry cow vaccination with a Salmonella Newport bacterin can protect dairy calves against oral Salmonella challenge

Background

Salmonellosis is a major cause of morbidity and mortality in neonatal calves, often occurring before preventative vaccines can be administered.

Hypothesis/Objective

To evaluate the protective effect on calves of colostrum from cows vaccinated with a commercially available Salmonella Newport bacterin against a Salmonella Typhimurium challenge.

Animals

Twenty Holstein bull calves from a university dairy farm.

Methods

Nonrandomized placebo‐controlled trial in which colostrum was harvested from 30 cows that received 2 doses of either Salmonella bacterin or saline before calving. Colostrum collected from each group was pooled and fed to 2 groups of 10 calves at birth. At approximately 2 weeks of age, calves were challenged with Salmonella Typhimurium. Clinical, hematologic, microbiological, and postmortem findings were compared between the 2 groups.

Results

No differences in mortality, clinical findings, hematology results, blood and fecal cultures, or necropsy findings between the 2 groups were observed. Vaccinated cows had higher colostral titers, and calves fed this colostrum had higher serum titers (mean difference, 0.429; mean [SE], 0.852 [0.02] for vaccinated versus 0.423 [0.02] for control calves).

Conclusions and Clinical Importance

Transfer of colostral immunoglobulins from Salmonella enterica serotype Newport bacterin to neonatal calves was not sufficient to decrease mortality, clinical signs, sepsis, intestinal damage, or fecal shedding when exposed to a highly pathogenic Salmonella isolate. A large‐scale randomized controlled clinical trial is needed to evaluate the efficacy of this bacterin when administered in the dry period for prevention of salmonellosis in neonatal calves.

Coronaviridae, pathogenetic and clinical aspects: an update

A review is given about pathogenetic and clinical aspects of the well-known as well as of recently detected members of the family Coronaviridae. Special attention is paid to coronavirus infections of domestic cattle and pets, whereas avian, murine, rat and human coronaviruses are summarized briefly.

Effect of purified immunoglobulins or pooled colostrum on performance of rearing calves

Fifty Belgian white-blue male calves, purchased from the market at about 10 days of age, were divided into three groups. The basic diet was the same for all calves, and consisted of a restricted amount of commercial milk replacer containing 50 ppm zinc bacitracin and 20 pm virginiamycin, calf starter and grass hay. Weaning occurred when daily starter intake over 7 consecutive days averaged 0.5 kg. Maximum starter intake was restricted to 3 kg day^-1, and grass hay was fed ad libitum. The experiment lasted 20 weeks. Group 1 (control) received the basic diet. Groups 2 and 3 were supplemented with either 2 g purified immunoglobulins (Ig) or 25-ml pooled colostrum (CO) twice daily, via the milk replacer as used in Group 1. Neither Ig nor CO exerted a positive effect on growth rate and feed efficiency. Six calves died: two, one and three in Groups 1, 2 and 3, respectively. Their serum IG content was significantly lower than that of the surviving animals. Mechanisms explaining the lack of any protective effect are discussed. It is supposed that the main reason was due to the gap between the CO feeding at birth and the onset of the administration of Ig or CO at the start of the experiment. At that time, 31 of the 50 calves excreted rota-and/or coronaviruses.