الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
This study was carried out in two private dairy farms in Dakhlia governorate during the period from June 2009 till end of November 2011 to investigate the occurrence and risk indicators of mastitis and to propose a new approach for prevention and control of mastitis in dairy herds. The milking cows were examined clinically and by California mastitis test (CMT) for detection of sub clinically mastitic quarters then individual quarter milk samples were taken separately from each cows for isolation and identification of mastitis causing bacteria. The in vitro sensitivity of bacterial isolates to some antibiotics and antiseptics were done and a control program for mastitis in dairy farms was proposed. Results revealed that the percentage of mastitis at cow’s & quarters levels were 44.6 & 32.8 %, respectively in farm I and 34.7& 27.2 % in farm II, respectively. Moreover, the percentages of subclinical mastitis were higher at both levels as compared to those had clinical mastitis in both farms. CMT is accurate and economically feasible test for early detection of new intramammary infection. Coagulase Negative Staphylococci (CNS) was the predominant causative agents of mastitis as it isolated in highest percentage from milk samples followed by Staph. aureus & E. coli then Strept. agalactiae & Strept. uberis. Dairy cows at age (>8 years), parities (>4), at late stage of lactation and those with high milk yield (over 18 kg/day) had a great risk of developing mastitis than dairy cows had other evaluated criteria. The in vitro sensitivities of bacterial isolates from mastitic quarters against certain antibiotics and antiseptics indicated that Enroflxacin followed by Cloxacillin were the antibiotics of choice to use for treatment of clinically mastitic cows and dry cow therapy, respectively meanwhile, Iodine was the antiseptic of choice for teat dipping. A control program based early detection and treatment of clinically mastitic cows, dry cow therapy and sound husbandry practices particularly milking time hygiene accompanied by post milking teat dips for all milking cows significantly reduce the extent and severity of mastitis in dairy herds, besides mitigation the rates of new intramammary infection and eliminate existing infection in both treated groups.