الفهرس 
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Abstract
Bovine Rota virus (BRV) and Bovine Corona virus (BCoV) are the most viral cause of diarrhea in neonatal calf from one day after birth till weaning age. Neonatal calf diarrhea (NCD) considered a destructive disease, affect calves leading to extensive economic losses for the cattle industry, it considers one of the main problems for cattle herd industry development in Egypt, mainly transmitted by fecal oral rout.
So the present study was conducted for a period of one year and four months extending from August 2022 to December 2023 which aimed to study some epidemiological, clinical and diagnostic methods of BRV and BCoV and determine the prevalence of BRV and BCoV in New Valley governorate.
A total of 210 calves of different ages, sexes and breeds from different two localities in New Valley province were clinically examined for the signs of diarrhea. Clinical examination of diseased calves for signs of BRV and BCoV infection revealed that 92 (43.81%) of calves showing watery, yellow diarrhea. 6 (2.85%) had diarrhea contained mucus, 30 (14.28%) had diarrhea with high fever (40-41.5), 24 (11.42%) suffered from loss of appetite, loss of body weight and dehydration accompanying with diarrhea , and 17 (8.09%) exhibit different degree of dehydration, in some cases, calves were seen weakness, unable to stand and depressed. In addition 15 (7.14%) of calves showing mixed enteric and respiratory signs.
Out of 102 fecal samples were collected and screened for detection of BRV and BCoV infection by applying rapid ELISA test, isolation on MDBK cell line. The results of ELISA tests revealed that out of 102 fecal samples 22 of samples (21.56%) were positive for BRV and 24 fecal samples (23.52%) positive for BCoV, there is no mixed infection.
According to age, the highest prevalence of calf infection with BRV was in group I aged from one day to one month and the lowest rate was in group II aged from > One month up to two months but in case of BCoV infection the prevalence of BCoV was highest in group I, group II and group III aged from > Two months up to five months.
Concerning to breeds, the infection rate of BRV was higher only in native breed (24.71%) while the rate of BCoV was higher in Frisian (69.23%) than in native breed (16.85%).
The rate of infection regarding to sex of calves are nearly parallel to each other with percentages of (21.81% in male and 21.27% in female) in BRV, while in case of BCoV were (16.36% in male and 31.91% in female).
Rendering to the effect of seasonal variation in infection rate of both BRV and BCoV, the highest rate of BRV was found in spring followed by winter seasons with a total percentage of (83.33%) and (26.92%), respectively while the lowest rate of BRV was in summer (20%) and autumn season (4.08%). Infection with BCoV was more predominant in winter (30.76%) and autumn (26.53%) seasons but the lowest prevalence of BCoV was been found in spring season (16.66%) and summer season (6.66%).
Concerning to viral growth in cell culture, characteristic CPE was appeared on the second passage and characterized by rounding and enlarged of cells, shrinkage of cell wall together with an increase of granularity forming a bunch of grapes usually rounding.
In recent study RT-PCR test was conducted for genome detection for 5 positive BRV samples which detected by ELISA, the result revealed that, 5 samples was molecularly positive for BRV, the specific band showed at 884 bp after PCR amplification of VP7 gene of BRV and the sequence of positive BRV sample revealed that, the type of BRV was BRV group A.
Conclusion
We can concluded that,
• Bovine Rota virus type A (RVA) and Bovine Corona virus (BCoV) had been occurred in New Valley province in high percent among young cattle calves causing extensive economic losses which requires preventive intervention to reduce infection.
• The most important risk factors that influence the prevalence of BRV and BCoV are age, breed, sex, and season.
• Rapid ELISA test is an accurate, rapid and sensitive assay for detection of BRV and BCoV infection in neonatal calves.
• MDBK cell culture, is an accurate way to identify the characteristic CPE of BRV and BCoV
• RT-PCR and sequencing is more sensitive and specific test for detection of BRV infection than ELISA test.
Recommendation
from our results we can recommended that,
• Infectious neonatal calf diarrhea is one of the most problem in cattle farms in new valley governorate which may be caused by virus infection.
• Other studies must be conducted to investigate other infectious causes of calf diarrhea in New Valley governorate.
• Good management practice for newborn calves
• We advise owners for vaccination of pregnant dams or newly born calves against Bovine Rota and Bovine Corona viruses
• Treatment of calf diarrhea as early as possible to avoid animal dehydration