A study was conducted to determine the prevalence of mastitis, identify the major bacterial pathogens and test the antimicrobial resistance of milk bacterial isolates in smallholder dairy farms in Selalle area, Ethiopia. A total of 109 smallholder dairy farms comprising 500 crossbred lactating cows were included. The prevalence of clinical mastitis at herd, cow and quarter level was 8.3% (n=9), 1.8% (n=9) and 0.51% (n=10), respectively, while that of sub-clinical mastitis was 54.7%, 22.3% and 10.1%, respectively. The univariate logistic regression showed that among the risk factors considered, presence of teat lesion, stage of lactation and parity number had significant effect on the prevalence of sub-clinical mastitis. However, after multivariate analysis, only presence of teat lesion and stage of lactation had significant effect. The common isolates from the clinical mastitic quarters were St. agalactiae (30%, n=3) and St. dysgalactiae (30%, n=3), while from sub-clinical cases were S. aureus (42.6%, n=83), S. epidermidis (22.1%, n=43), St. agalactiae (12.8%, n=25) and St. uberis (10.3%, n=20). Staphylococcus intermedius and Streptococcus dysgalactiae were the species, which showed high level of susceptibility for most of the antimicrobials tested, while the remaining had varying levels of resistance for almost all the antimicrobials used. Among the antimicrobials employed, erythromycin and sulphonamide showed the lowest proportion of resistant isolates. Considering the possible significant economic losses that could be incurred by both clinical and sub-clinical mastitis, attention should be paid for further detailed investigations including the economic losses and benefits of interventions in the study area.

This study was aimed to generate information on variance components and the resulting genetic parameters (heritability, repeatability, genetic and phenotypic correlations and genetic trends) of some economic traits of Borena and its crosses with Holstein Friesian dairy cattle maintained at Holetta agricultural research center dairy farm. Traits studied were age at first service (AFS), age at first calving (AFC), calving interval (CI), days open (DO) and number of service per conception (NSC). Overall, 11331 dairy cattle reproductive performance records were used for the study. WOMBAT, which is a software package for quantitative genetic analysis of continuous traits, fitting a linear, mixed model; estimates of covariance components and the resulting genetic parameters were employed and obtained. Heritability values of reproductive traits were from very low (0.071, 0.082 and 0.012) for CI, DO and NSC to moderate (0.3 and 0.22) for AFC and AFS traits. Repeatability estimate for CI, DO and NSC were low (0.17, 0.17 and 0.129). Strong and positive genetic correlation (0.98) was appeared between AFS and AFC traits. Negative genetic correlations were observed between AFS and DO (-0.001), AFC and DO (-0.05), AFS and NSC (-0.022), AFC and NSC (-0.29) and CI and NSC (-0.31). AFS were negative phenotypic correlation with CI, DO and NSC. Similarly, AFC was negative phenotypic correlation with CI and DO. Low phenotypic correlation was observed between AFC and NSC, CI and DO, CI and NSC and, DO and NSC. Strong and positive phenotypic correlation was appeared between AFS and AFC. The regression coefficient of mean breeding value for NSC, CI, DO, AFC and AFS on year of birth were -0.0066x+13.25 times/year, -1.19x+2387.4 days/year, -1.23x+2445.6 days/year, 0.2x-410 months/year and 0.48x-980 months/year, respectively.

This study was conducted to evaluate the productive performances of crossbred dairy cattle at Holetta research center dairy farm. A total of 6685 performance records were used and analyzed to determine the effect of period of calving, season of calving, parity and genetic group. The parameters used us indicator of productive performances were Lactation milk yield (LMY), daily milk yield (DMY) and lactation length (LL). The GLM procedure of SAS 2004 software was used for analysis. The overall least square means and standard errors for Lactation milk yield (LMY), daily milk yield (DMY) and lactation length (LL) were ÷ 2204.05 ± 21.12 kg, 6.88 ± 0.05 kg and 326.69 ± 2.03 days, respectively. Result of fixed effect analysis indicated that calving period, genetic group and parity were significantly (p<0.001) influenced all productive traits. LMY, DMY and LL were sensitive to seasonal variation. Comparisons among the crosses revealed a clear-cut difference among the genetic groups. Milk production in the first generation crosses increased more compared to second generations. There were marked decline in performance among 50% F1 (Borena dam x Holstein Friesian sire), F2 (F1 dam x F1 sire) and F3 (F2 dam x F2 sire) from 2203kg of milk to 1697 and 1522 kg, respectively. The 75% first generation was superior LMY compared with other genetic groups and produced about 34.2 %, 74.3%, 94.3% and 45.9% more milk than 50% F1, F2, F3 and 75% second generations, respectively. The higher milk yield of 75% first generation and 50% F1 crosses from other genetic groups could be associated with higher heterosis effect in F1, higher milk gene in 75% and longer lactation length. Based on the productive performances evaluation, the results of LMY, DMY and LL of higher grades (> 50%) in the present study revealed that performances were continued to increase with increasing proportion of exotic genes.

Background: The productivity and profitability of dairy cattle depend largely on reproductive performance. Thus, this study was intended to evaluate the reproductive performance of Jersey cattle raised under semi-intensive management system.Methods: A retrospective analysis consisted of data collected for the last 33 years was conducted. The fixed effects fitted were birth period, calving period, service period, birth season, calving season, service season, parity and genetic group. The general linear model procedure of SAS was used for the statistical analysis of data. Result: The overall least-square means for age at first service (AFS), age at first calving (AFC), calving interval (CI), days open (DO) and the number of services per conception (NSPC) were 22.93±0.22 months, 32.95±0.22 months, 494.16±3.68 days, 221.09±3.73 days and 1.99±0.03, respectively. Year, season and parity had a significant effect on most of the investigated reproductive traits. Imported Jersey cows had an extended CI and DO than farm-bred cows. Besides, the inconsistency of management and variability of climatic variables across year and season seems to have a considerable influence on the reproductive efficiency of cows. Therefore, the improvement in the level of management and selection of parents based on their breeding value would be improve the reproductive performance of Jersey cows.

Performance evaluations for economically important milk production traits are the bases for genetic evaluation, planning breeding program and selection for dairy cows. This study was intended to evaluate milk production traits of pure Jersey dairy cows at Adea-Berga Dairy research center. The data collected from 1986 to 2019 from a herd maintained at Adea-Berga dairy research center was used to estimate milk production traits (lactation milk yield (LMY), daily milk yield (DMY) and lactation length (LL)). A general linear model procedure of the Statistical Analysis System (SAS, version 9.0) was used to analyse the milk performance data. The result of fixed-effect analysis revealed that the influence of year and parity caused significant (p<0.0001) variation in all milk production traits. However, season of calving does not significantly affect milk production traits. Knowledge on the effect of these non-genetic factors for milk production would help in making management decisions for improvement of the herds. The overall least squares mean (LSM±SE) for LMY, DMY and LL were 2166.10±26.71 Litres, 6.37±0.05 Litres and 344.89±3.81 days, respectively. In conclusion, the results of this study suggest that the improvement of milk production traits of the pure Jersey cattle population at Adea-Berga dairy research center is possible through improving the level of feeding, breeding and health management than through genetic selection.