Bovine Mastitis Epidemiology; Practical Approaches and Applications

Epidemiological study was carried out in two private dairy farms of totally 350 lactating cows of different breeds, ages and distributed in Beni-Suef governorate during the period from April, 2009 till the end of November, 2011 through field screening survey by using of California mastitis test (CMT) for each quarter milk samples followed by Somatic cell count (SCC) and bacteriological examination to identify the major causative agents of intramammary infection (IMI), determining the prevalence of mastitis and related risk indicators, evaluation the in vitro sensitivity of bacterial isolates to certain antibiotics and antiseptics commonly used in veterinary practices and finally establishing a new practical approach for prevention and control of mastitis in dairy herds. Results revealed that the highest percentage of subclinical and clinical mastitis at cow level was 41.88% and 13.67% in farm (I) compared with 33.05% and 9.87% in farm (II) respectively based on bacteriological results. It was found that the most frequently major causative agents isolated were Coagulase negative staphylococci (CNS) was the prevalent organisms isolated from individual milk samples 32.21% followed by Staph.aureus 26.84% , E. coli (o157&o103) 21.48% , Strept.agalactiae 12.75% , Strept.uberis 3.35% and Klepsiella spp. 3.35% respectively .in relation to score (-) ; CNS was represented the highest percentage (83.33%) followed by Strept.agalactiae (16.67%). Meanwhile in farm (II), Staph.aureus was the second predominant isolates (26.27%) next to CNS (36.86%) compared to others (E. coli 19.49%, Strept.agalactiae 11.0%, Klepsiella spp. 3.4% and Strept.uberis 2.97%). The sensitivity of CMT was high in farm II (98.9%) compared to (98.0%) in farm II. Meanwhile specificity of test was nearly similar in both farms (98.1%) in relation to causative agent. There was a significant different (P<0.001) amongst mean SCC in all studied groups in both examined farms. when studying the seasons of year, age, lactation stage and parity factor, it was found that the highest percentage of subclinical and clinical mastitis was occurred in summer in both farms at 44 (36.06%) &18 (14.75%) in farm (I) while in farm (II) was 66 (27.5%) &21 (8.75%) . in relation to age susceptibility, younger cows (3-5 years) were more affected by mastitis in both farm than adults (6-8 years ) and older cows (>9 years) .Moreover in lactation stage, occurrence of mastitis was higher in early lactation stage in farm (I&II) 60.68% and 45.5% respectively; occurrence of mastitis in farm (I) was high in cows with parities (>4) 65.79% compared with farm (II) the highest occurrence of mastitis at cows with parities (2-4) 17.78 % respectively. Enrofloxacin was the most effective antibiotic where 96.3 % of all isolates were susceptible except Strept.dysgalactiae was intermediate. Prevention and control mastitis Program was concluded that dry cow therapy , hygienic milking procedure and post milking teat dipping have an important role in eliminating the existing and decrease new intra mammary infection from 17 (42.5 %) to 5 (12.5%) and from 19 (47.5) to 9 (22.5) in both treated groups.