Hordofa Debele, Abunna Fufa, Megersa Bekele, Abebe Rahmeto
Ministry of Agriculture, Livestock Resource Sector, Addis Ababa, Ethiopia.
College of Veterinary Medicine and Agriculture, Addis Ababa University, P.O. Box 34, Bishoftu, Ethiopia.
Heliyon. 2021 Dec 6;7(12):e08546. doi: 10.1016/j.heliyon.2021.e08546. eCollection 2021 Dec.
Calf morbidity and mortality are major causes of economic losses on dairy farms worldwide, with a far greater impact in developing countries such as Ethiopia. A prospective longitudinal study on dairy farms in the city of Hawassa was conducted between August 2018 and July 2019, to estimate the cumulative incidence of calf morbidity and mortality and to identify the associated risk factors. For this purpose, 221 calves from 20 farms were examined every 15 days from birth to the age of six months. We used the Kaplan Meier (K-M) method, log rank test, and Cox proportional hazards regression to analyze the data. Of the calves examined, 48.4% (n = 107) had various clinically visible health problems, while 19.5% (n = 43) died from various causes. Using the K-M method, the cumulative incidence of all-cause morbidity at the end of the sixth month of life was 50.12% (95% CI: 43.58%-57.05%), while the cumulative incidence of all-cause mortality was 20.04% (95% CI: 12.56%-26.06%). The most commonly diagnosed disease syndrome was diarrhea (64.5%), followed by pneumonia (15%), septicemia (6.5%), joint disease (4.7%), conjunctivitis (3.7%), umbilical infections (2, 8%) and other unknown causes (11.2%). Diarrhea was also the leading cause of death (46.5%). The other causes of calf mortality were pneumonia (16.3%), septicemia (7%), and unknown diseases (30.2%). In the K-M hazard analysis, the greatest risk of calf morbidity and mortality was observed during the first month of life and then the risk decreased significantly as the calves grew. Of the 21 potential risk factors studied, the multivariable Cox proportional hazards regression model showed that time calves ingested their first colostrum, calving difficulty, and calving season were the three predictors that were significantly associated with a higher risk of morbidity and mortality. A higher risk of morbidity was observed in calves that had ingested their first colostrum six hours after birth (HR = 1.9; P = 0.003), had calving difficulties (HR = 2.96; P < 0.001) and were born in the rainy season (HR = 1.64; P = 0.017) compared to calves that had consumed colostrum immediately after birth, had no difficulties at birth and were born in the dry season. The same three factors have been identified to influence calf mortality. The mortality risk was 2.73 (P = 0.002), 4.62 (P < 0.001) and 2.74 (P = 0.002) times higher in calves that had difficulty calving, ingested their first colostrum meal six hours after birth and were born in the rainy season, respectively. In general, the calf morbidity and mortality rates identified in this study were beyond economically justifiable limits and calls for educating farmers to raise awareness of some easy-to-fix issues such as colostrum feeding.
犊牛发病和死亡是全球奶牛场经济损失的主要原因，在埃塞俄比亚等发展中国家影响更为严重。2018年8月至2019年7月，在哈瓦萨市的奶牛场进行了一项前瞻性纵向研究，以估计犊牛发病和死亡的累积发病率，并确定相关风险因素。为此，从20个农场选取了221头犊牛，从出生到6个月龄每15天检查一次。我们使用Kaplan Meier（K-M）法、对数秩检验和Cox比例风险回归分析数据。在检查的犊牛中，48.4%（n = 107）有各种临床可见的健康问题，而19.5%（n = 43）死于各种原因。使用K-M法，生命第六个月末全因发病的累积发病率为50.12%（95%CI：43.58%-57.05%），而全因死亡的累积发病率为20.04%（95%CI：12.56%-26.06%）。最常诊断的疾病综合征是腹泻（64.5%），其次是肺炎（15%）、败血症（6.5%）、关节疾病（4.7%）、结膜炎（3.7%）、脐部感染（2.8%）和其他不明原因（11.2%）。腹泻也是主要死因（46.5%）。犊牛死亡的其他原因是肺炎（16.3%）、败血症（7%）和不明疾病（30.2%）。在K-M风险分析中，犊牛发病和死亡的最大风险在出生后第一个月观察到，然后随着犊牛生长风险显著降低。在所研究的21个潜在风险因素中，多变量Cox比例风险回归模型显示，犊牛首次摄入初乳的时间、产犊困难和产犊季节是与发病和死亡风险较高显著相关的三个预测因素。与出生后立即摄入初乳、出生时无困难且出生在旱季的犊牛相比，出生后6小时才摄入初乳的犊牛发病风险更高（HR = 1.9；P = 0.003），产犊困难的犊牛发病风险更高（HR = 2.96；P < 0.001），出生在雨季的犊牛发病风险更高（HR = 1.64；P = 0.017）。同样这三个因素也被确定会影响犊牛死亡率。产犊困难、出生后6小时才摄入初乳且出生在雨季的犊牛，其死亡风险分别高出2.73倍（P = 0.002）、4.62倍（P < 0.001）和2.74倍（P = 0.002）。总体而言，本研究确定的犊牛发病率和死亡率超出了经济上合理的限度，需要对农民进行教育，以提高他们对一些易于解决的问题（如初乳喂养）的认识。
