Tora Ephrem, Shrube Mesfin, Kaba Tamirat, Seyoum Wasihun
Arba Minch University, College of Agriculture Sciences, Department of Animal Sciences, P.O. Box 21, Arba Minch, Ethiopia.
Vet Med Int. 2021 Nov 16;2021:6677986. doi: 10.1155/2021/6677986. eCollection 2021.
Calf mortality has been a major cause of economic losses in the dairy industry in Ethiopia. The condition results in a significant drop in the number of replacing heifers and bulls for sustainable dairy business. Reports on calf mortality with a wide range of prevalence are rising in the country; however, a pooled prevalence of this condition has not been established. Thus, this systematic review and meta-analysis aimed to quantitatively estimate the pooled prevalence of calf mortality in Ethiopia.
Meta-analysis was carried out to obtain the pooled prevalence of calf mortality in Ethiopia. A comprehensive literature search was carried out on PubMed, African Journals Online, CAB, Web of Science Direct, and Google Scholar. Eligible studies were selected based on predefined inclusion and exclusion criteria. Moderators such as the study area, breed of calf, study design, agroecology, and year of study article published were used as a milestone of data extraction. The random-effect model was used to estimate pooled prevalence. Publication bias and the variation in prevalence estimates attributed to heterogeneity were also assessed.
Twenty-five original research papers on the prevalence of calf mortality in various parts of Ethiopia were included. The reported prevalence of calf mortality was between 0.9% and 37%. The pooled prevalence of calf mortality in the country was 14.79%, and the pooled calf mortality estimate across studies for the entire period regarding 1991 to 2000, 2001 to 2010, 2011 to 2016, and 2017 to 2020 was 26.54%, 17.03%, 14.21%, and 11.23%, respectively. Analysis of study subgroups and location revealed significant variations in prevalence. High heterogeneity was observed in the pooled estimates and even after the subgroup meta-analysis. The funnel plots and Egger's regression asymmetry coefficient ( = -1.0434) (95% CI = -1.49, -0.59; value of 0.012) did suggest the presence of publication bias. There was also an indication of missing studies that could be incorporated by Duval and Tweedie's trim and fill method where they might fall on a funnel plot and visualize them in an attempt to increase the plot's symmetry. Analyses also suggest that calf breed, sample size, and study location are likely to be moderators of calf mortality prevalence in Ethiopia.
This finding shows that calf mortality is widespread and could result in considerable economic losses for the dairy industry in Ethiopia. Inevitably, a significant reduction in calf mortality prevalence has been observed in recent years since 2010, but the reduction has not yet reached an economically tolerable level. Calf breed susceptibility contributed to the high prevalence. Therefore, interventions for increasing calf health and performance should be focused on minimizing calf mortality on farm and animal levels.
犊牛死亡率一直是埃塞俄比亚乳制品行业经济损失的主要原因。这种情况导致用于可持续乳制品业务的后备小母牛和公牛数量大幅下降。该国关于犊牛死亡率且患病率范围广泛的报告不断增加；然而，尚未确定这种情况的合并患病率。因此，本系统评价和荟萃分析旨在定量估计埃塞俄比亚犊牛死亡率的合并患病率。
进行荟萃分析以获得埃塞俄比亚犊牛死亡率的合并患病率。在PubMed、非洲期刊在线、CAB、科学网直接数据库和谷歌学术上进行了全面的文献检索。根据预先定义的纳入和排除标准选择符合条件的研究。研究区域、犊牛品种、研究设计、农业生态和研究文章发表年份等调节因素被用作数据提取的里程碑。采用随机效应模型估计合并患病率。还评估了发表偏倚以及归因于异质性的患病率估计值的变化。
纳入了25篇关于埃塞俄比亚不同地区犊牛死亡率患病率的原创研究论文。报告的犊牛死亡率患病率在0.9%至37%之间。该国犊牛死亡率的合并患病率为14.79%，1991年至2000年、2001年至2010年、2011年至2016年以及2017年至2020年期间各研究的犊牛死亡率合并估计值分别为26.54%、17.03%、14.21%和11.23%。研究亚组和地点分析显示患病率存在显著差异。在合并估计值中以及亚组荟萃分析后均观察到高度异质性。漏斗图和埃格回归不对称系数（=-1.0434）（95%CI=-1.49，-0.59；P值=0.012）确实表明存在发表偏倚。也有迹象表明存在缺失的研究，这些研究可以通过杜瓦尔和特威迪的修剪和填充方法纳入，在漏斗图上可能会显示出来并尝试使其对称。分析还表明，犊牛品种、样本量和研究地点可能是埃塞俄比亚犊牛死亡率患病率的调节因素。
这一发现表明犊牛死亡率普遍存在，可能给埃塞俄比亚的乳制品行业带来相当大的经济损失。不可避免的是，自2010年以来，近年来犊牛死亡率患病率已显著降低，但降幅尚未达到经济上可承受的水平。犊牛品种易感性导致了高患病率。因此，提高犊牛健康和性能的干预措施应侧重于在农场和动物层面尽量降低犊牛死亡率。
