ObjectiveA cross-sectional study was conducted from November 2015 to March 2016 to estimate the prevalence, to assess the risk factors and to isolate the major etiological agent of subclinical mastitis in Bishoftu town. The study was conducted on 262 cross breed lactating cows selected from 12 intensively managed dairy farms. California mastitis test (CMT) and bacteriological culture methods were used as diagnostic tools.ResultFrom 262 cows examined, 105 (40.1%) and from 1048 quarters examined, 170 (16.1%) were positive for sub-clinical mastitis using CMT. All CMT positive samples were cultured for etiological agent identification. From 170 samples cultured, 153 were positive for known subclinical mastitis pathogens. The dominant bacteria isolated were Staphylococcus species from these Staphylococcus aureus (44.9%) was the major one followed by Streptococcus spp. (25.3%) and other gram negative enteric bacteria, Escherichia coli (8.8%). Age, body condition score, milk yield, and number of parity were considered as potential risk factors; among these, age and number of parity have statistically significance association with the occurrence of subclinical mastitis (P < 0.05) both in the CMT and the bacteriological tests.

A study was conducted at five locations to determine the survival rate of calves and to estimate the performance level of improved dairy cows under commercialized farming systems in Ethiopia. Seven hundred and one calves born from 1997 to 1999, and 797 cows were included in the study. Cumulative calf/heifer survival at 360, 540 and 720 days was 80%, 76% and 70%, respectively. Number of services per conception averaged 2 while mean age at first service and days open were 850+/-18 and 192+/-11 days, respectively. Calf survival, days open and age at first service were significantly affected by breed and management factors (p <0.05), whereas parity significantly affected the number of services per conception and days open. There was a tendency towards improved performance over the years. This was especially so for calf survival and days open. Clearly, all the traits measured varied among study farms, indicating that substantial improvement can be achieved through better management. This paper describes these individual traits of improved dairy breeds under commercialized farming systems in Ethiopia.