Characteristics of Cowsheds in Vietnamese Smallholder Dairy Farms and Their Associations with Microclimate—A Preliminary Study

Abstract

In smallholder dairy farms (SDFs), farmers often build cowsheds using local materials and based on self-accumulated experience without due consideration to reducing the risk of heat stress. This study aimed to characterise the heat stress abatement strategies and microclimate within SDF cowsheds from four typical dairy regions of Vietnam (south lowland, south highland, north lowland and north highland) and identify the housing parameters most associated with the microclimate. The study was conducted on 32 SDFs (eight SDFs per region) in autumn 2017. Twelve housing management variables, illustrating cowshed design and heat stress abatement methods of each SDF, were collected. Six microclimate parameters, collected within the cowshed, were temperature (AT), humidity, air speed (AS), heat load index (HLI), Temperature-humidity index (THI) and accumulated heat load units (AHLU) during a day (06:00 h to 18:00 h). Factor analysis and cluster analysis was applied to group cowsheds of SDFs into clusters where SDFs in the cluster had the same cowshed characteristics. Multivariable linear models were applied to define the parameters most likely to inform future research into heat stress mitigation on SDF. Averaged from 08:00 h to 18:00 h, microclimate inside the cowsheds was considered hot (HLI > 79) in the highland and very hot (HLI > 86) in the lowland regions. Cows in the lowland regions accumulated high heat load (AHLU > 50) by 18:00 h. Cowsheds of SDFs varied widely and grouped into seven cowshed types, but no type was more effective than others in reducing heat stress conditions within cowsheds. Using roof soakers together with fans decreased AT and HLI by 1.3 °C and 3.2 units, respectively, at 14:00 h compared to 11:00 h. Each 100 m increase in altitude was associated with decreases of 0.4 °C in AT, 1.3 units in HLI and 0.8 units in THI (p < 0.001). Each meter increase in the eave height of the cowshed roof was associated with decreases of 0.87 °C in AT, 3.31 units in HLI and 1.42 units in THI, and an increase of 0.14 m/s in AS (p < 0.05). The cowshed parameters that should be prioritised for future research into the amelioration of heat stress in SDF cows include using the roof soakers together with fans, increasing altitude, eave roof height and floor area per cow.

Impacts of heat stress on global cattle production during the 21st century: a modelling study

“…30 Several relatively low-cost relief strategies are effective and profitable in reducing heat stress impacts, including the use of simple sheds that are well-designed for providing shade, bathing animals several times each day, and installing electric fans in sheds. 31 Different arrangements of shade trees in treelivestock systems can be highly effective in reducing heat stress. 32 For more intensive cattle production systems in which animals are confined or confined seasonally, there are many alternative cooling, ventilation, and buildingdesign options.…”

Increases in extreme heat stress in domesticated livestock species during the twenty‐first century

“…In lower input livestock systems, various lower cost adaptation strategies may be effective in reducing the impacts of heat stress in smallholder systems. These include the use of simple sheds to provide shade, animal baths, roof soaking, and installing fans in sheds, for example (Bang et al, 2021 ; York et al, 2017 ). Certain arrangements of shade trees in silvopastoral livestock production systems, particularly in Latin America, have been shown to be an effective means of reducing heat stress (Cuartas Cardona et al, 2014 ; Ibrahim et al, 2006 ; Pezzopane et al, 2019 ).…”

Multivariate analysis identifying the main factors associated with cow productivity and welfare in tropical smallholder dairy farms in Vietnam

“…Finally, eight SDFs per region were randomly selected from the SDFs in that economic survey who agreed to continued involvement in further studies. More details about the process to select the SDFs for the current study can be found in our previous studies (Bang et al, 2021c , 2021b , 2021a, 2021d).…”

“…Microclimate data from 0600 to 1800 h within the cowshed of each SDF was measured by a Kestrel 5400 Heat Stress Tracker (NIELSEN-KELLERMAN, USA). Means (± SD) of ambient temperature, humidity, and temperature-humidity index (THI) in South Lowland were 29.5 ± 1.1°C, 81.8 ± 3.8%, and 82.5 ± 1.3 units, respectively; in South Highland, 25.4 ± 1.3°C, 80.5 ± 4.9%, and 75.5 ± 1.6 units; in North Lowland, 29.7 ± 1.5°C, 82.0 ± 6.0%, and 82.9 ± 2.0 units; and in North Highland, 26.0 ± 1.1°C; 80.6 ± 4.1%, and 76.7 ± 1.3 units (Bang et al, 2021c ).…”

“…In this study, we focused on the multidimensionality of Vietnamese SDFs. The aim was to combine the data from the different themes of previous studies by the same authors (Bang et al, 2021b , 2021a , 2021c , 2021d ) to build multivariate explanatory models to enable the identification and ranking of potential factors affecting the productivity and welfare of dairy cows in SDFs. The factors include milk yield and quality, body weight and body condition score, heat stress level, fertility, and udder health of the cows.…”