Meta-analysis of reproductive performance of improved dairy cattle under Ethiopian environmental conditions

Abstract Dairy cattle production plays a great role in food security and generates income, draught power, and manure input for crop production. The present review focuses on major reproductive performance indicators; age at first service (AFS), age at first calving (AFC), calving interval (CI), days open (DO), and number of services pre conception (NSPC) of improved dairy cattle in Ethiopia. The overall mean values of AFS, AFC, CI, DO, and NSPC were 27.8 ± 5, 37 ± 4.9, 442.7 ± 80.5, 126 ± 40.27 days and 1.57 ± 0.23 numbers, respectively. The review showed the AFS of exotic dairy cattle breeds as 30.5 ± 2.6 for pure exotic, 26.8 ± 3.8 for 75–100%, 25.04 ± 4.5 for 50–75%, 26.7 ± 7 for 50% and 28.1 ± 5.7 days for <50% exotic blood levels; for AFC, it was 38.5 ± 5.5, 38.4 ± 4.1, 37.9 ± 5, 37.7 ± 4.2 and 35.2 ± 5.1 days of 50%, pure exotic (100%), 50–75, 75–100, and <50% exotic blood levels, respectively. In descending order, the average CI was found 460.2 ± 40.73, 450 ± 57.27, 446.8 ± 38.56, 445.3 ± 32.86, and 434.1 ± 118.02 days for 50–75%, pure exotic (100%), 75–100, 50, and <50% exotic blood levels, respectively. Exotic blood levels of <50 and 50% were the highest and lowest in both DO and NSPC, and recorded at 155.1 ± 48.36 and 98 ± 23.04 days; 1.7 ± 0.2 and1.2 numbers, respectively. Holstein Friesian (HF) cross Barka breed in AFS; Jersey cross Arsi breed in AFC and CI; HF cross Fogora breed in DO, HF cross Borena and HF cross Barka breed in NSPC were comparatively performing better in mean values. To improve the reproduction performance of improved dairy cattle, access to quality feed, veterinary service, heat detection, and artificial insemination skills should be improved.