scholarly journals Effect of Mixed-Flow Fans with a Newly Shaped Diffuser on Heat Stress of Dairy Cows Based on CFD

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4315 ◽  
Author(s):  
Yao ◽  
Shi ◽  
Zhao ◽  
Ding
Keyword(s):  
Energy Efficiency ◽  
Heat Stress ◽  
Dairy Cows ◽  
Cfd Simulation ◽  
Elevation Angle ◽  
Maximum Flow ◽  
Dynamics Simulation ◽  
Mixed Flow ◽  
Wind Speeds ◽  
Flow Flux

Mixed-flow fans (MFF) are widely used to reduce the heat stress in dairy cows in summer. Our research team developed MFFs with a newly shaped diffuser with the length of 250 mm and the circumferential angle of 150°, which have better performance in terms of maximum flow flux and energy efficiency. However, how the elevation angle of the diffuser influences the performance of MFFs and how the optimal fan perform in the field experiment has not been studied yet. In this paper, the diffuser was optimized by CFD (Computational Fluid Dynamics) simulation of the fan and a laboratory prototype test. An orthogonal test showed no interaction among length, circumferential angle, and elevation angle. The diffuser with an elevation angle of 10° performed better than that with an elevation angle of 0°, showing increased jet lengths, flow flux, and energy efficiency by 0.5 m, 0.69%, and 1.39%, respectively, and attaining greater axial wind speeds and better non-uniformity coefficients at the dairy cattle height. Then, through on-site controlled trials, we found that the 10°/150°/250 mm diffusers increased the overall average wind speeds by 9.4% with respect to the MFFs without a diffuser. MFFs with the newly shaped diffuser were used for field tests, and their effectiveness in alleviating heat stress in dairy cows was evaluated by testing environmental parameters and dairy cows’ physiological indicators. Although the temperature–humidity indexes (THIs) in the experimental barn with the optimized fan at different times were lower than those in the controlled barn, the environmental conditions corresponded to moderate heat stress. However, this was not consistent with cow's respiratory rate and rectal temperature. Finally, on the basis of the CFD simulation of a dairy cow barn, the equivalent temperature of cattle (ETIC), which takes into account the effect of air velocity, showed that the environment caused moderate heat stress only at 13:00, but not at other times of the day. This shows that ETIC is more accurate to evaluate heat stress.

Optimization of Diffuser Parameters for Mixing Fans in Agricultural Buildings

2018 ◽  
Vol 34 (2) ◽  
pp. 437-444 ◽  
Author(s):  
Tao Ding ◽  
Lumeng Fang ◽  
Ji-Qin Ni ◽  
Zhengxiang Shi ◽  
Baoxi Sun ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Energy Efficiency ◽  
Optimal Design ◽  
Field Test ◽  
Cfd Simulation ◽  
Maximum Flow ◽  
Uniformity Coefficient ◽  
Wind Speeds ◽  
Average Wind ◽  
Flow Flux

Abstract. Mixing fans (MFFs) are widely used in ventilation of agricultural buildings to improve the uniformity of the air supply, thereby improving the ventilation efficiency. In order to improve the ventilation performance of MFFs, a new visor-shaped diffuser was designed and installed on a MFF. The angle and the length of the diffuser were crucial parameters that affected the performance of the MFFs with the diffusers. Thereby, in this study numerical simulation with 42 diffusers of different angles (ranged from 90-270°) and different lengths (ranged from 150-650 mm) with the MFF were studied with Computational Fluid Dynamics (CFD) simulation to acquire the optimal design of diffusers. The numerical simulation results show that the diffusers of 90°/450 mm, 120°/350 mm, and 150°/250 mm with jet lengths of up to 5.85, 5.90, and 5.85 m, respectively, had better performances among all the diffusers. The optimal prototype diffusers of 90°/450 mm, 120°/350 mm, and 150°/250 mm of MFFs were tested by laboratory study and field test. The test was conducted in wind speed distributions at distances of 0.5 to 1.0 m from the axial of MFFs. During the test, we evaluated the MFFs performance such as maximum flow flux, maximum energy efficiency, and non-uniformity coefficient. The diffuser of 150°/250 mm showed the best performance, increasing the flow flux and energy efficiency by 3.8% and 11%, respectively, and obtain higher axial wind speeds and larger non-uniformity coefficients. Finally, the diffusers of 150°/250 mm were tested in a free-stall dairy barn. The field test result shows that the diffusers of 150°/250 mm increased overall average wind speeds by 7.4% and local average wind speeds at bedding 1 and bedding 2 by 31.0% and 27.7%, respectively, which agreed with our numerical simulation and laboratory test. This optimal design of mixing fans could be applied to improve the air mixing in agricultural buildings. Keywords: Agricultural buildings, Diffuser, Mixing fan, Numerical simulation, Optimization.

scholarly journals Characterization of Short-Term Heat Stress in Holstein Dairy Cows Using Altered Indicators of Metabolomics, Blood Parameters, Milk MicroRNA-216 and Characteristics

Animals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 722
Author(s):  
Jang-Hoon Jo ◽  
Jalil Ghassemi Nejad ◽  
Dong-Qiao Peng ◽  
Hye-Ran Kim ◽  
Sang-Ho Kim ◽  
...  
Keyword(s):  
Heat Stress ◽  
Dairy Cows ◽  
Milk Yield ◽  
Milk Fat ◽  
Blood Parameters ◽  
Negative Effects ◽  
Short Term ◽  
Lactating Cows ◽  
Humidity Index ◽  
Holstein Dairy Cows

This study aims to characterize the influence of short-term heat stress (HS; 4 day) in early lactating Holstein dairy cows, in terms of triggering blood metabolomics and parameters, milk yield and composition, and milk microRNA expression. Eight cows (milk yield = 30 ± 1.5 kg/day, parity = 1.09 ± 0.05) were homogeneously housed in environmentally controlled chambers, assigned into two groups with respect to the temperature humidity index (THI) at two distinct levels: approximately ~71 (low-temperature, low-humidity; LTLH) and ~86 (high-temperature, high-humidity; HTHH). Average feed intake (FI) dropped about 10 kg in the HTHH group, compared with the LTLH group (p = 0.001), whereas water intake was only numerically higher (p = 0.183) in the HTHH group than in the LTLH group. Physiological parameters, including rectal temperature (p = 0.001) and heart rate (p = 0.038), were significantly higher in the HTHH group than in the LTLH group. Plasma cortisol and haptoglobin were higher (p < 0.05) in the HTHH group, compared to the LTLH group. Milk yield, milk fat yield, 3.5% fat-corrected milk (FCM), and energy-corrected milk (ECM) were lower (p < 0.05) in the HTHH group than in the LTLH group. Higher relative expression of milk miRNA-216 was observed in the HTHH group (p < 0.05). Valine, isoleucine, methionine, phenylalanine, tyrosine, tryptophan, lactic acid, 3-phenylpropionic acid, 1,5-anhydro-D-sorbitol, myo-inositol, and urea were decreased (p < 0.05). These results suggest that early lactating cows are more vulnerable to short-term (4 day) high THI levels—that is, HTHH conditions—compared with LTLH, considering the enormous negative effects observed in measured blood metabolomics and parameters, milk yield and compositions, and milk miRNA-216 expression.

Effects of dry period length on milk yield and content and metabolic status of high-producing dairy cows under heat stress

2021 ◽  
Vol 53 (2) ◽  
Author(s):  
A. Boustan ◽  
V. Vahedi ◽  
M. Abdi Farab ◽  
H. Karami ◽  
R. Seyedsharifi ◽  
...  
Keyword(s):  
Heat Stress ◽  
Dairy Cows ◽  
Milk Yield ◽  
Period Length ◽  
Metabolic Status ◽  
Dry Period

scholarly journals Recent Advances on Early Detection of Heat Strain in Dairy Cows Using Animal-Based Indicators: A Review

Animals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 980
Author(s):  
Hang Shu ◽  
Wensheng Wang ◽  
Leifeng Guo ◽  
Jérôme Bindelle
Keyword(s):  
Heat Stress ◽  
Early Detection ◽  
Dairy Cows ◽  
Real Time ◽  
Dairy Farms ◽  
Time Measurement ◽  
Heat Strain ◽  
Detection Methods ◽  
Livestock Farming ◽  
Real Time Measurement

In pursuit of precision livestock farming, the real-time measurement for heat strain-related data has been more and more valued. Efforts have been made recently to use more sensitive physiological indicators with the hope to better inform decision-making in heat abatement in dairy farms. To get an insight into the early detection of heat strain in dairy cows, the present review focuses on the recent efforts developing early detection methods of heat strain in dairy cows based on body temperatures and respiratory dynamics. For every candidate animal-based indicator, state-of-the-art measurement methods and existing thresholds were summarized. Body surface temperature and respiration rate were concluded to be the best early indicators of heat strain due to their high feasibility of measurement and sensitivity to heat stress. Future studies should customize heat strain thresholds according to different internal and external factors that have an impact on the sensitivity to heat stress. Wearable devices are most promising to achieve real-time measurement in practical dairy farms. Combined with internet of things technologies, a comprehensive strategy based on both animal- and environment-based indicators is expected to increase the precision of early detection of heat strain in dairy cows.

scholarly journals Effect of heat stress on milk production and its composition of Holstein Friesian crossbred dairy cows

2016 ◽  
Vol 2 (2) ◽  
pp. 190-195 ◽  
Author(s):  
Mahmud Al Reyad ◽  
Md Abid Hasan Sarker ◽  
Md Elias Uddin ◽  
Raihan Habib ◽  
Md Harun Ur Rashid
Keyword(s):  
Heat Stress ◽  
Dairy Cows ◽  
Milk Yield ◽  
Management Practices ◽  
Management Strategies ◽  
Dairy Farm ◽  
Milk Composition ◽  
Mustard Oil ◽  
Holstein Friesian ◽  
Significant Difference

The aim of this research was to observe the effect of heat stress on milk yield and milk compositions of Holstein Friesian crossbred (HF) dairy cows. To fulfill the objectives, a total of 9 Holstein Friesian crossbred cows were selected for this study. Green grasses (German, Para) were supplied adlibitum and concentrate feeds (mixture of wheat bran, rice polish, mustard oil cake, di-calcium phosphate and salt) were supplied at the rate of 2.0 kg/day/cow. Management practices for all the cows were similar following the BAU Dairy farm practices. Data were collected on milk yield (l/h/d), relative humidity (%) and barn temperature (0C). The obtained temperature humidity index (THI) of July, August, September and October were 84.95, 81.99, 81.40 and 79.57, respectively. The highest THI was found in July which indicated higher heat stress during this month. A significant difference (p<0.05) in milk yield of cows was found among different months of July to October. The highest milk yield (6.10±0.50 l/h/d) was found in October among observed months. The compositions of milk such as total solids (TS), solids-not-fat (SNF), fat, protein, lactose, and ash also differed significantly (p<0.01). The highest values (%) of TS, SNF, fat, protein, lactose and ash content of milk were found in October as 12.63, 8.80, 3.83, 3.69, 4.39 and 0.72, respectively and lowest values (%) were in July as 12.20, 8.50, 3.71, 3.50, 4.30 and 0.69, respectively due to the high THI value. From these results, it is concluded that heat stress has strong effect on milk yield and milk composition of HF cows in Bangladesh. Management strategies are needed to minimize heat stress and attain optimal dairy animal performance.Asian J. Med. Biol. Res. June 2016, 2(2): 190-195

Fertility and hormonal responses to temporary relief of heat stress in lactating dairy cows

1988 ◽  
Vol 29 (5) ◽  
pp. 1027-1035 ◽  
Author(s):  
M.E. Wise ◽  
R.E. Rodriguez ◽  
D.V. Armstrong ◽  
J.T. Huber ◽  
F. Wiersma ◽  
...  
Keyword(s):  
Heat Stress ◽  
Dairy Cows ◽  
Hormonal Responses ◽  
Temporary Relief ◽  
Lactating Dairy Cows
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