Abstract
The current study aims to investigate the causes of high mortality rate in suckling calves due to bacterial and viral infection in relation to locality, seasons and age as well as through a high light on the histopathological effect of isolated organisms on tissues of dead suckling calves using both light and electron microscope. This work was performed on a total number of 144(25.1%) dead calves from total reported diseased 573 suckling calves. Samples collected from Al Sharquia, Al Behaira and Al Giza Governorates of Egypt during May 2016 to February, 2017. The mortality rate recorded in Al Sharquia, Al Behaira and Al Giza in percentage of 31.2%, 22.4% and 18.6 % respectively. Mortality rate was more prevalence in winter 69.4% than summer 30.6%. Enteritis cases were reported in 13.2 %, Pneumonia represented 21.5% while pneumoentritis was 65.3%. Isolated bacteria and viruses from out of 144 suckling dead calves suffering from enteritis were Escherichia coli (E. coli) 2.08 %, Salmonella typhimurium (S. typhimurium) 2.7% mixed infection of BVDV with E. coli 4.1%, and mixed of Rota virus with S. typhimurium in 4.1 % of cases. In Pneumonic Calves, the most prevalence isolates were Pasteurella multocida (P. multocida) 6.9% followed by Bovine Viral Diarrhea virus (BVDV), as a single infection, 6.2%, meanwhile mixed infection of both microorganesms were 15.2%. On the other hand, mixed isolates, bacteria and viruses, from 144 suckling dead calves suffering from pnemoentritis wererepresented in 84(58.4%) cases of dead examined calf, Isolated organisms were mixed infection of BVDV with S. typhimurium and E. coli 13.8 %, other cases showed mixed infection of BVD with S. typhimurium 13.8 %, other cases showed mixed of P.multocida with S. typhimurium 13.1 % finally cases of mixed infection of BVD with E.coli and P.multocida 18.7%. Pathological examination of Pneumonic calves revealed marked changes represented by two types of pneumonia which observed as Acute fibrinosuppurative bronchopneumonia (6.9%), and Interstitial pleuropneumonia (21.5%),entric calves revealed Hemorrhagic enteritis (13.2) %. In addition, in pneumoentric calves which represented 58.4%of dead calves andshowed, Fibrino-necrotizing bronchopneumonia, Necrotizing ulcerative enteritis, lymphocytic hepatitis with congestive cirrhosis, Interstitial nephritis, Acute hemorrhagic myocarditis and Splenic lymphoid depletion.
Highlights
Produce mild to severe clinical signs and death within 24 to 36 hours or may cause permanent lung damage
Pneumonia is often referred to bovine respiratory disease Complex (BRDC) which caused by stress, virus, and bacterial agents, that often as fibrosis, adhesions and death (Zaher et al, 2014 and Voiriot et al, 2016)
Bovine viral diarrhea virus (BVDV), P. multocida and other bacteria are considered the most BRDC of bovine that associated with respiratory infection with severe
Summary
Produce mild to severe clinical signs and death within 24 to 36 hours or may cause permanent lung damage. It has been estimated that 75% of early calf mortality in dairy herds is caused by acute diarrhea in the pre-weaning period, and still a major cause of economic loss to cattle producers. Various infectious agents such as viruses and bacteria are involved in calf diarrhea (Bartels et al, 2010 and Muktar et al, 2015). The most common pathogenic agents of neonatal enteritis complex that leading to high mortality are rotavirus, BVDV, S. typhimurium, E. coli and P. multocida which are responsible for more than 50% of all neonatal diarrheas during the first week. The current study designed to investigate the causes of high mortality rate in suckling calves due to bacterial and viral infection in relation to the season it spots some light on the micro morphological and ultrastructural changes induced by the isolated organisms on tissues of dead suckling calves using both light and electron microscope
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