| Calf diarrhea, which always occurred in the 1-month-old calves, is a symptom due to the intestinal bacteria, viruses, parasites and other pathogens or nutritional factors, environmental factors cause calf immune-compromised. The bacterial infection is one of the major reasons. As the cattle industry has been expanding, the calf diarrhea becomes rising. High mortality rate seriously affects the growth of calves. It may lead to economic losses in the cattle industry, so the calf diarrhea research has great scientific and practical significance. In this study, we investigated a calf diarrhea incidence in a dairy farm at Xianyang and diagnosis and integrated control the calf diarrhea. The farm had appeared several calves of high fever, diarrhea, sallow sparse muck with bloody discharge. In detail, two calves were joint swelling, lameness, one diarrheic calves died. Necropsy dead calf found that many organs had different degrees of bleeding: splenic was atrophy bleeding and dark, liver was bleeding, had a point of white necrosis; lung was squeezed with pus; gastrointestinal was bleeding with mucosa swelling. Based on clinical symptom, we initially suspected that it was Salmonella diarrhea. Collecting disease incidence and mortality calf feed, through laboratory diagnosis, we have identified that it was Salmonella. Based on antibiotic susceptibility of clinical trials, we have picked out the bacteria highly sensitive antibiotic. The test results are as follows:1. The isolated bacteria, which came from the aseptic token dead calf liver, spleen and feces, were inoculated on agar plates or Mac-conkey agar plates in a humidified atmosphere at 37 oC for 24 h. Stool was re-inoculated in bright green bile- four sulfur sodium broth in a humidified atmosphere at 37 oC for 12-24 h. 11 suspected strain bacteria were isolated from the dead calf. All of them were Gram-negative(G-) bacilli, specially, 5 of them, on agar plate, were round, uplift, neat edges, smooth, moist, translucent white small colonies; 6 of them, on Mac-conkey agar plate, were gray white round and small colonies.2. Biochemical test of bacteria with sugar fermentation test. 5 of the isolated bacteria can ferment glucose, maltose, does not ferment sucrose, lactose; indole test, VP test was negative; MR test, citric acid test positive; triple sugar iron negative slant, bottom produce acid and gas, and produces H2 S, so the bacteria is Salmonella. The other 6 can ferment glucose, maltose, sucrose and lactose produce acid and gas, indole test, MR test was positive; VP test, citric acid test positive; triple sugar iron negative slant, bottom produce acid and gas, and don not produces H2 S, so the bacteria is Escherichia coli.3. Pathogenicity test: 16 mouse were tested, 6 of them, which were intraperitoneally injected with 0.4 mL Salmonella or Escherichia coli, another 6 of them, which were intraperitoneally injected with 0.2 mL Salmonella or Escherichia coli. 3 mouse, which were intraperitoneally injected with 0.4 mL Salmonella, died in 12 h; another three, which were intraperitoneally injected with 0.2 mL bacteria isolates, died in 18 h. The mouse, which intraperitoneally injected with Escherichia coli, were all healthy. The last four mouse, which intraperitoneally injected with common broth, were all healthy. The result illustrated that the isolates pathogenic could cause the mice illness.4. Antibiotic susceptibility tests showed that this Salmonella was highly sensitive with ceftriaxone, pioneer will, ceftiofur; moderately sensitive with fortum, gentamicin; resistant to ciprofloxacin, norfloxacin.5. We used the sensitive antibiotics for diarrhea calves symptomatic treatment, which had good treatments. In detail, we have applied ceftiofur injection, according to the weight of 2 mg dose intramuscular injection, once a day, once every 3~5 days treatment, and with the comprehensive treatment measures. |
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