Submit Manuscript | http://medcraveonline.com Background Rearing calves and heifers as replacement milkers, is a serious business and the replacement stock are one aspect of dairying no dairy farmer can afford to overlook. In brief, while it is true that the milking herd generates the income, calves and heifers are just as valuable to the dairy’s future as the current milking herd. Traditionally heifers, as calves and as primiparae, have been thought of as a group as free of mastitis since without appreciable lacteal secretion, there is reduced nutrient fuid available to support growth of intramammary pathogens. 3 However, mastitis during development of the mammary gland and in early lactation is hypothesized to adversely affect their milk production and udder health, leading to considerable economic losses for dairy farms. 4 Heifers (2yrold primiparous cattle) have a high incidence of clinical mastitis (CM) in the peripartum period relative to older animals in herds. Studies reported a high incidence of CM and IMI in frst-calving heifers immediately following calving. 5 Most studies of intramammary infections (IMI) in heifers have been performed as single surveys to determine the prevalence of IMI at, or close to, parturition or have compared IMI several months before parturition with IMI at parturition. 2 The prevalence of intramammary infections (IMI) in non-lactating and freshly calved heifers has been the focus of study in many countries. 6 Antimicrobials are used frequently for treatment and prevention of mastitis. To successfully control mastitis and to avoid potential problems associated with bacterial resistance and treatment failure, it is important to be aware of antimicrobial resistance characteristics of mastitis pathogens. 7 Although many farmers and veterinarians in the study area have observed heifers calving with nonfunctional quarters, clinical mastitis, or elevated somatic cell counts. No investigation on udder health of dairy heifers and the risk factors for heifers mastitis was carried out in the study area. However, there is only one study from Ethiopia by Siraj et al. 8 that has been published with regard to bacterial pathogens and udder infection dynamics during the early lactation period in primiparous cows. Hence, large scale risk factor J Dairy Vet Anim Res. 2017;5(5):169‒176. 169 © 2017 Wubshet et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and build upon your work non-commercially. Incidence of heifer mastitis and identifcation of major associated pathogens in dairy farms at wolaita soddo town, southern Ethiopia Volume 5 Issue 5 - 2017 Ashenaf Kiros Wubshet, 1 Tesfaye Sisay Tesema, 2 Muuz Gebru sahile, 3 Biniam Tadesse Derib, 1 Aklilku Feleke Haile, 4 Hagos Asgedom Wedeabyezgi 1 1 National Animal Health Diagnostic and Investigation Centre, Ethiopia 2 Addis Ababa University, Institute of Biotechnology 3 Mekelle University, College of Veterinary Medicine, Ethiopia 4 Addis Ababa University, College of Veterinary Medicine and Agriculture, Ethiopia Correspondence: Ashenaf Kiros wubshet, National Animal Health Diagnostic and Investigation Centre, Sebeta, Ethiopia, Tel +251910017931, Email nafkw@gmail.com Received: November 27, 2016 | Published: July 27, 2017 Abstract The replacement stock is one of the vital parts of dairying no dairy farmer can afford to overlook. Although heifers, as calves and as primiparae, have been thought of as a group as free of mastitis, many studies indicated that clinical mastitis (CM) was even higher in heifers during calving than multifarious cows. The present longitudinal study was conducted to assess the incidence of heifer mastitis, to isolate and identify the causative pathogens and their susceptibility profile against some antimicrobials. By using convenience sampling method a total of 28 heifers from two sampling point (large scale dairy farms1 and small holders’ cooperative dairy farms2 were followed and sampled throughout study period. Physical examinations of udder and milk and California mastitis Test (CMT) was applied detect clinical and subclinical mastitis, respectively. Accordingly, a total of 112 quarters were examined. The incidence of mastitis per gland at risk was 60.7% and the spontaneous cure rate of infected quarters was 24.18%. Incidence of heifers intramammary infections (IMI) in the study area was highest at calving (35.7%). Infection per quarter revealed that 43/112 (38.3%) of which 9/43 (20.9%) quarters were clinical and 34/43 (79.0%) quarters were sub clinical type of mastitis. However, 5(4.5%) of the total quarters examined were blind. Incidence of mastitis in rear quarters was significantly higher than front quarters (p<0.05). The result revealed that high milk producing heifers (HF and jersey) were significantly susceptible to mastitis (p<0.05). The univariate logistic regression showed that breed, age, practice of milking mastitic cow last, housing nature, hand wash before and in between milking and udder hygiene had significant effect on the prevalence of subclinical mastitis. Staphylococcus aureus (30.3%), Coagulase negative Staphylococci (CNS) [15.2%] and Streptococcus agalactiae (15.2%) were the predominant bacteria. Relatively most of the isolates are susceptible to chloramphenicol, gentamycin, ciprofloxacin and kanamycin but resistant to penicillin. High incidence of heifer mastitis especially occurs as a subclinical type and in high milk producing breeds and older age groups in this area. Serious attention should be given to heifers prepartum udder health because it is most essential for control and prevention of heifer mastitis.. Keywords: antimicrobials susceptibility, bacterial pathogens, dairy farms, heifer mastitis, longitudinal, risk factors Journal of Dairy, Veterinary & Animal Research Research Article Open Access