Ogundeji Abiodun A, Lakew Hermela, Tesfuhuney Weldemichael, Lombard Willem
Department of Agricultural Economics, University of the Free State, Bloemfontein, South Africa.
Department of Soil, Crop and Climate Sciences, University of the Free State, Bloemfontein, South Africa.
Heliyon. 2021 Feb 13;7(2):e06202. doi: 10.1016/j.heliyon.2021.e06202. eCollection 2021 Feb.
Heat stress affects dairy cows' feed intake, reproductive system and milk production. This study analysed the financial implications of heat stress for small scale milk producers. The semi-arid regions of the Free State - Bloemfontein, Bothaville, and Bethlehem were selected for the study. To estimate the impact of heat stress on milk production, baseline (1950-1999) and mid-century (2040-2070) climate data and Temperature Humidity Index thresholds (THI) of 70 and 65 were used. Mid-century data with no adaptation strategy resulted in a doubled loss, while moderate heat-mitigation strategies (wetting and forced ventilation) resulted in positive improvements in milk production and income of farmers. Results show strong polynomial correlations (R of 0.73-0.79) between the T and milk-production losses where above T of 25°C, milk-production loss increased sharply. The combined average loss of milk production during the hot summer was estimated at 0.35 liters per cow in a day, which is equivalent to ZAR1.27 per cow per day. With changing climate, the highest revenue loss was recorded in the MPI_ESM_MR future climate scenario. Moreover, results from the questionnaires show that heat stress reduces farmers' milk production significantly in the summertime, and for most of the respondents, measures that should be taken are too costly to apply. Exhaustive analysis of the economic impacts of heat stress on milk production is recommended for future studies, as it is an important sector in alleviating household food insecurity in South Africa.
热应激会影响奶牛的采食量、生殖系统和产奶量。本研究分析了热应激对小规模奶农的财务影响。研究选取了自由邦的半干旱地区——布隆方丹、博塔维尔和伯利恒。为了估算热应激对产奶量的影响，使用了基线（1950 - 1999年）和世纪中叶（2040 - 2070年）的气候数据以及70和65的温度湿度指数阈值（THI）。世纪中叶的数据在没有适应策略的情况下损失翻倍，而适度的热缓解策略（洒水和强制通风）使奶产量和农民收入得到了积极改善。结果表明，当温度高于25°C时，温度与产奶量损失之间存在很强的多项式相关性（R为0.73 - 0.79），产奶量损失急剧增加。炎热夏季奶牛每天的产奶量平均综合损失估计为0.35升/头，相当于每头奶牛每天1.27南非兰特。随着气候的变化，在MPI_ESM_MR未来气候情景中记录到了最高的收入损失。此外，问卷调查结果显示，热应激在夏季显著降低了奶农的产奶量，而且对于大多数受访者来说，应采取的措施实施成本过高。建议未来的研究对热应激对产奶量的经济影响进行详尽分析，因为这是缓解南非家庭粮食不安全问题的一个重要领域。
