Sustainable Management of Dairy Cows in Semi-Arid Summers: Additional Early Nighttime Sprinkler Cooling for Heat Stress Mitigation
1
Department of Livestock Management, University of Veterinary and Animal Sciences, Lahore 54000, Pakistan
2
Department of Animal Science, Njala University, Freetown, Sierra Leone
3
Department of Animal Nutrition, University of Veterinary and Animal Sciences, Lahore 54000, Pakistan
*
Author to whom correspondence should be addressed.
Sustainability 2023, 15(15), 11665; https://doi.org/10.3390/su151511665
Submission received: 15 May 2023
/
Revised: 26 July 2023
/
Accepted: 27 July 2023
/
Published: 28 July 2023
(This article belongs to the Special Issue Animal Science and Sustainable Agriculture)
Abstract
:This study aimed to evaluate the effect of different cooling sessions on the performance and welfare of Holstein Friesian cows during the semi-arid summer in Pakistan. Sixteen lactating cows were randomly assigned to two treatment groups: (1) five cooling sessions per day (5CS) and (2) eight cooling sessions (8CS), with two sessions during early nighttime and one in the early morning. Each sprinkler cooling session lasted 1 hour. The trial was conducted over a period of 8 weeks during August and September of 2021. The results showed that cows in the 8CS group produced an average of 2.9 kg/d more milk than those in the 5CS group. Additionally, the respiration rate and total feeding time of cows in the 8CS group was significantly lower than that of the 5CS group. Moreover, the core body temperature of cows was not significantly influenced by addition of extra cooling sessions. In conclusion, the results suggest that the addition of cooling sessions in the early nighttime had a positive effect on milk yield and welfare in Holstein cows during the semi-arid summer season. These findings could have significant implications for the management of dairy cows in similar climatic conditions.
1. Introduction
Heat stress is one of the greatest challenges facing livestock production in the 21st century, particularly in hot regions of the world. Climate change is further exacerbating the severity of heat stress due to higher temperature extremes and a greater number of hot days. Dairy animals, including Holstein Friesian cows of temperate origins, are particularly vulnerable to heat stress due to their elevated internal heat loads resulting from high milk production [1] as well as due to their origin in temperate regions. Consequently, these animals require increased resource utilization for heat abatement during hot summer months, including groundwater, energy, and housing infrastructure.
Effective cooling systems are critical strategies for mitigating the negative impacts of heat stress in dairy cows [2]. While sprayed water from sprinklers or soakers has been the most common method of cooling dairy cows during summer [3,4]; this method consumes a significant amount of groundwater [5]. As the declining levels of groundwater due to climate change raise concerns about water footprints and water-use efficiency in cooling dairy animals [6], evaluating different water reduction strategies at dairy farms has become increasingly important. Intermittent cooling sessions have emerged as an effective means of reducing water usage on farms [7,8,9]. In comparison to continuous showering, intermittent cooling sessions significantly reduce water usage without compromising cow performance, particularly during semi-arid summers [9]. However, while it is well-known that cows require cooling during the daytime, it is worth noting that their body temperature is actually highest during the early nighttime hours [10,11]. This finding suggests that cooling measures are equally necessary during this time to ensure optimal animal welfare and productivity. Studies have indicated that cows’ bodies continue to absorb heat even after sunset, resulting in an increase in their head load that can be uncomfortable and detrimental to their health and productivity. Consequently, providing cooling during the early nighttime hours is crucial in ensuring the well-being and performance of dairy cows, particularly in semi-arid summer conditions.
In this context, the present study was conducted with the hypothesis that adding extra cooling sessions during the early nighttime to the previously evaluated cooling sessions would enhance heat abatement in dairy cows. Therefore, the objective of the current study was to evaluate the effect of extra cooling sessions during early nighttime and morning on the physiological and productive responses of Holstein Friesian cows during semi-arid summers in Pakistan. These findings could have significant implications for the sustainable management of dairy cows in similar climatic conditions, as they explore innovative approaches for mitigating heat stress in dairy cows while also addressing water usage concerns.
2. Materials and Methods
The present study was conducted at the Dairy Animals Training and Research Center, University of Veterinary and Animal Sciences (UVAS), Lahore, Ravi Campus, Pattoki, Pakistan (31°03′43.9″ N 73°52′36.1″ E) during a hot humid summer (August to September 2021).
2.1. Study Animals, Housing, and Management
Sixteen Holstein Friesian cows with average daily milk yield 15.5 ± 5.2 kg (±SD), days in milk 257 ± 93, and parity 2.3 ± 1.4 were enrolled for the study. The cows were housed in a naturally ventilated freestall barn. The barn was 50 m long (east–west) and 30 m wide, with a central feeding alley having two pens (north and south), each 13.5 m wide. Each pen had the adjacent outdoor loafing area with dirt floor as a resting surface. The ridge and eve height of the barn were 12 and 6.7 m, respectively. A polyvinyl water pipe (5.08 cm diameter) was installed along the feed bunk. The sprinkler nozzles on the pipe were at 2 m apart having 180-degree radius and angled to spray water towards the back of the cows standing at the feed bunk. Cows were given total mixed ration ad libitum twice a day and had free access to water. Milking was done twice daily in the 6 × 6 herringbone milking parlor (GEA Farm Technologies, Bönen, Germany) at 05:00 and 17:00 h.
2.2. Experimental Design and Study Groups
The enrolled cows were randomly divided into two treatment groups of 8 cows each: (1) cows receiving five cooling sessions of 1 h each (5CS); and (2) cows receiving eight cooling sessions (8CS). The cooling sessions in the 5CS group were held at 07:00, 10:00, 12:00, 14:00, and 16:00 h daily, while the additional cooling sessions in the 8CS group were held at 04:00, 19:00, and 22:00 h. In each cooling session, the sprinkler cycle was 6 min long with 3 min of water on and 3 min off, and a flow rate of 1.25 L/min. The 5CS group was housed in the north pen, and the 8CS group was housed in the south pen of the shed. The pen selection was randomized.
Four industrial fans (Model FS-75, Bilal Electronics, Lahore, Pakistan; blade length 60 cm, width 15 cm) were available to each treatment group, with two over the feed bunk, and two positioned on the freestalls (one for each row), all located approximately 3 m above the ground level. All the fans were blowing in the east–west direction towards the back of the cows. A rubber mat was placed along the feed bunk for cows to promote comfort while feeding and showering. The trial lasted for 9 weeks from August to September 2021.
2.3. Climate Measures
A portable weather meter (Kestrel 5400 Cattle Heat Stress Tracker: 0854AGLVCHVG) was used to measure the weather conditions during the study. The weather meter was placed 20 m away from the shed in an open area and was set up to take readings every 10 min. The meter recorded various meteorological measures, including atmospheric air temperature (°C), relative humidity (RH%), temperature humidity index, wind speed, heat load index, and black globe temperature (°C).
2.4. Production, Physiological, and Behavioral Measures
Milk yield was recorded twice daily at 05:00 and 17:00 h by inline milk meters in the milking parlor. Milk samples were collected from each of the lactating cows three days per week and analyzed to determine the milk components. The milk was analyzed for protein, fat, lactose, total solid, and solid not fat using a portable milk analyzer (Lactoscan Standard, Milktronic Ltd., Nova Zagora, Bulgaria). Feed intake data were recorded as group data and were reported as dry matter intake (DMI) per group of eight cows.
The core body temperature (CBT) of the cows was monitored continuously for 24 h, three days per week, by recording readings every 20 min using intravaginal data loggers (Thermochron iButton: model DS1921H-F5, iButtonLink, Llc., Whitewater, CA, USA) administered with an inert controlled internal drug release insert (Zoetis, Auckland, New Zealand). The cows’ respiration rate was recorded twice daily at 04:00 and 14:00 h. This was done by counting the number of flank movements of a cow over a period of 30 s using a stopwatch, which was then converted to breaths per minute.
The Nedap CowControlTM system (NEDAP, Groenlo, The Netherlands) was utilized to measure behavioral data on lying time, eating time, and standing times. Neck collars were affixed around the neck of cows to record the eating time, while leg data loggers were fastened with straps on left hind legs to estimate standing and lying times. These parameters were monitored continuously for 24 h, three days per week.
2.5. Blood Metabolites
Blood samples were obtained from the jugular vein of each cow once a week between 02:00 and 03:00 h. The samples were drawn into sterile vacutainer tubes containing anticoagulant, immediately placed in a cold storage system, and transported to the laboratory. In the laboratory, the samples were centrifuged to separate the serum, which was then stored at a temperature of −20 °C until further analysis. The serum was analyzed for glucose (using the Glucose GOD FS kit from DiaSys Diagnostic Systems GmbH, Holzheim, Germany), blood urea nitrogen (using the Randox Urea Kinetic kit from Randox Laboratories Ltd., Crumlin, UK), and cortisol (using the Cortisol Elisa kit from Calbiotech, CA, USA). A spectrophotometer (Epoch2, Bio-Tek, Winooski, VT, USA) was utilized to measure the levels of these biomarkers in the serum samples.
2.6. Statistical Analysis
All the statistical analyses were performed using SAS (SAS for Academics: SAS Institute Inc., Cary, NC, USA). Normality of the study data was assessed using the Shapiro–Wilk test. Weekly means of core body temperature (CBT), respiration rate (RR), milk yield, and behavioral data were calculated and were subjected to repeated-measures analysis of variance (ANOVA) with the mixed procedure of SAS. The least square means were separated using Tukey’s adjusted p-values for the comparisons. Significance was considered at p ≤ 0.05 and tendencies at p < 0.10.
3. Results
3.1. Climate Measures
The 24-h averages of temperature (T), relative humidity (RH), and temperature–humidity index (THI) are presented in Table 1. The mean T and RH were 35 °C and 60%, respectively, indicating a hot and humid environment. The THI was 84, indicating a moderate to severe heat stress for the cows. The average black globe temperature, which measures the radiant heat load, was 40.1 °C.
Mean hourly values indicated that all climate measures were higher during the daytime, except for humidity, which was lower during the day (Figure 1).
3.2. Production, Physiological, and Behavioral Measures
The results showed that the cooling sessions had a significant effect on the daily milk yield of the cows. Specifically, cows in the 8CS group produced an average of 2.9 kg/d more milk compared to those in the 5CS group (17.8 vs. 14.9 kg/d, respectively; SEM = 0.68, p = 0.04; Table 2). However, there was no significant difference in the percentage composition of fat, proteins, and lactose in the milk between the two groups (Table 2). The group DMI data showed that the cows in the 8CS group had 9.3 kg/8 cows more DMI than the 5CS group (p = 0.039; Table 2).
There was no significant effect of different cooling sessions on the core body temperature (CBT) of the cows (Figure 2). Both the 5CS and 8CS groups had similar CBT values (40.23 ± 0.19 vs. 40.21 ± 0.23 °C; Mean ± SE) during the daytime period. However, numerically, the CBT of cows in the 8CS group was lower than in the 5CS group during the nighttime (from 20:00 to 04:00 h) and early morning hours (from 04:00 to 08:00 h). The cows in both groups exhibited the lowest CBT during the early morning hours (05:00 to 07:00 h), while the highest CBT values were observed from 17:00 to 22:00 h.
The RR was also lower in the 8CS group during both morning and afternoon hours, and in both groups, the RR was higher during the afternoon than the morning (Figure 3). These results suggest that adding cooling sessions during the early morning hours can effectively reduce the physiological responses of cows and improve their comfort during heat stress.
Cooling sessions had a significant effect on total feeding time and feeding bout duration (Table 3). Cows in the 8CS group spent more time feeding than those in the 5CS group (5.7 vs. 4.8 h/d; SEM = 0.33). Similarly, cows in the 8CS group had longer feeding bouts than those in the 5CS group (14 vs. 11 min; SEM = 0.61; p = 0.001; Table 3). However, the number of feeding bouts was similar between the treatment groups (26 vs. 26).
Cooling sessions did not affect the total lying time, number of lying bouts, or the duration of lying bouts (Table 3). The lying time of cows averaged 10.2 h/d in this study. The number of lying bouts and the duration of each lying bout averaged 11 bouts/d and 55 min/bout, respectively. Likewise, the total standing time, standing bouts, and total step counts per day were similar between the treatment groups. The total standing time of cows averaged 13.9 h/d.
3.3. Blood Metabolites
Blood metabolite analysis showed no significant differences in glucose and cortisol levels between the treatment groups (Table 4). The average glucose and cortisol levels of cows in both treatment groups were 46.8 mg/dL and 1.9 mg/dL, respectively. However, the blood urea nitrogen (BUN) levels in the 5CS group were significantly higher than in the 8CS group (17.3 vs. 15.0 mg/dL, respectively; p = 0.039).
4. Discussion
The current findings demonstrate that increasing the frequency of cooling sessions is an effective strategy for improving milk yield in dairy cows. Specifically, cows in the 8CS group produced more milk than those in the other groups, likely due to the more sustained relief from heat stress provided by the additional cooling sessions, especially during the early nighttime. This is supported by the lower core body temperatures (CBT) observed during these periods in the 8CS group compared to the 5CS group. These findings align with those of other studies [7,8,9] that have shown that additional cooling sessions can increase milk yield. Additionally, the 8CS group had reduced maintenance requirements, as evidenced by their lower respiration rate, indicating that they had more energy available for milk production. The similar milk component yields in the 5CS and 8CS groups is consistent with the findings of previous studies by [7,9]. These studies also reported similar responses of different cooling sessions on milk components. However, the 8CS group in our study produced more milk, resulting in a slightly higher quantity of milk components. Although the findings of the current study did not reveal a significant effect of cooling sessions on the CBT, the slightly lower values indicate a positive impact of cooling cows during the early nighttime period. It is possible that a larger sample size of cows could have resulted in a significant difference. The hourly patterns of CBT observed in this study were consistent with those reported in a previous study [11]. They reported that CBT was lower during the early morning hours due to the lower environmental temperature, while it increased steadily throughout the day due to the heat load on the animals. The lack of additional cooling sessions during the early nighttime for the 5CS group, combined with the emission of thermal radiation stored in the floor and farm structures, may have contributed to the higher CBT observed in these cows during the early nighttime hours. The significantly lower average RR in the 8CS group as compared to the 5CS group, both in the morning (6 breaths/min) and afternoon (10 breaths/min), could be attributed to the three extra cooling sessions in the 8CS group. The additional cooling sessions decreased the overall heat load of cows in the 8CS group. This finding is in line with the results of Honig et al. [7], who affirmed that the respiration rate was lower in the 8CS than in the 5CS cows in the morning (49.1 and 54.6, respectively) as well as in the afternoon (50.0 and 83.0 breaths/min, respectively). The highest average RR (77 breaths/min) was recorded in the 5CS group. This also agrees with the findings of previous literature [7,9]. Likewise, Tresoldi et al. [4] also stated that spraying cows more often reduced RR (but not CBT) with a difference of about <10 breaths/min. Overall, the results suggest that the additional cooling sessions provided more consistent and sustained relief from heat stress, leading to improved health and productivity of cows. The low ambient temperature and THI in the morning hours, as opposed to the high values of these parameters in the afternoon, may be responsible for the low RR in the morning and high in the afternoon for both the 5CS (63 vs. 77 breaths/min) and 8CS (57 vs. 67) groups.
The results of this study showed that cows in the 8CS group spent almost an hour (54 min) more at the feed bunk than cows in the 5CS group. The additional three cooling sessions in the 8CS group may have reduced the heat load and provided better comfort for the cows compared to those in the 5CS group. Although the cows in both treatment groups visited the feed bunk equally, cows in the 8CS group had an average of 3 min longer feeding duration per visit due to more effective heat load reduction via additional cooling sessions. The total average lying time in both the 8CS and 5CS groups (10.4 vs. 9.9 h/d, respectively) was shorter than that reported by Ruud and Boe [12]; 13.7 h/d), but longer than the average lying time of both groups (~8 h/24 h) reported by Honig et al. [7]. This difference may be due to climatic conditions and the effectiveness of the cooling strategy employed. Regardless of the similar number of lying bouts in both groups, cows in the 8CS group had better comfort as indicated by their relatively longer lying bout durations compared to cows in the 5CS group. The cows in the 5CS group had a higher heat load, resulting in a numerically higher standing time compared to cows in the 8CS group. The additional 2.08% total average standing time of the 5CS group may have been due to their efforts to reduce heat increment by conduction and increase heat loss by convection. Nevertheless, the effects of cooling sessions and the magnitude of ambient thermal conditions may have contributed to the similar standing bout frequency in both treatment groups.
Cows in both treatment groups had similar blood glucose and cortisol levels, which were within the normal range for dairy cows. However, these values were lower than the previously recorded glucose and cortisol concentrations in dairy cows [9]. This could be due to variations in blood sampling timings. In the present study, blood sampling for analysis was done in the early morning hours. If samples were collected in the afternoon, more evident variations would have been observed in response to the different cooling sessions. Nevertheless, the lower levels of glucose and cortisol in the early morning hours could be attributed to the fact that cows were comfortable during this time. The cooler temperatures and more relaxed environment in the early morning provided a break from the heat stress that cows experience during the rest of the day. Moreover, to gain a more comprehensive understanding of the impact of cooling sessions on the metabolic status of dairy cows, future studies should employ comparative blood sampling at various times of the day. During the study period, the climate measures indicated that the cows were exposed to hot and humid summer conditions. The mean 24-h and daytime air temperatures exceeded the recommended comfort limits of −5 to 20 °C for dairy cows [13]. Additionally, the average THI values were significantly higher than the critical threshold of 75, which is known to impact the production performance of cows [14]. Moreover, the maximum THI values recorded during the study (95) suggested that some days were extremely stressful for the cows. The hourly patterns of temperature and relative humidity revealed that although temperatures were relatively lower during the nighttime, the high relative humidity levels maintained elevated THI values, which kept the cows under stress even during the cooler hours of the night.
One of the limitations of the current study was the absence of a control group with continuous showering, which would have allowed for a more robust comparison with intermittent showering. However, previous heat stress management studies conducted in similar environments have indicated that continuous showering results in higher water usage without significant additional benefits on cow performance [9]. Moreover, continuous showering exposes cows to prolonged wet surfaces, increasing the risk of mastitis and hoof issues [15,16].
5. Conclusions
In conclusion, the findings of this study suggest that increasing the number of cooling sessions during the early nighttime can effectively improve milk yield, reduce heat load, and enhance cow comfort. Specifically, the cows in the 8CS treatment group demonstrated higher milk production, lower respiration rate, and longer feeding time. These results underscore the significance of implementing appropriate cooling strategies to mitigate the detrimental impact of heat stress on dairy cows. By doing so, farmers can not only enhance the welfare of their cows but also increase their productivity. The study’s findings can have important implications for farmers who may not be aware of the value of intermittent cooling sessions as a sustainable management practice.
Author Contributions
Conceptualization, M.Q.S. and A.M.; methodology, M.Q.S., A.M. and H.R.; formal analysis, M.Q.S. and M.A.R.; resources M.Q.S. and H.R.; data curation, A.M.; writing—original draft preparation, M.Q.S. and A.M.; writing—review and editing, M.Q.S., H.R. and M.A.R.; supervision, M.Q.S. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by Pakistan Science Foundation, grant number PSF/NSLP/P-UVAS-840 awarded to M.Q.S.
Institutional Review Board Statement
All the experimental procedures were undertaken in compliance with the Institutional Guidelines of the Ethical Review Committee and approved by the Advanced Studies and Research Board of the University of Veterinary and Animal Sciences, Lahore, Pakistan (das/1963 dated 11 November 2021).
Informed Consent Statement
Not applicable.
Data Availability Statement
The data presented in this study are available on request from the corresponding author.
Acknowledgments
The authors are grateful for the support of farm staff at the Dairy Animals Training and Research Center, University of Veterinary and Animal Sciences, Lahore. The authors also thank Israr Hussain for his assistance in data collection.
Conflicts of Interest
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.
References
- Chebel, R.C.; Santos, J.E.P.; Reynolds, J.P.; Cerri, R.L.A.; Juchem, S.O.; Overton, M. Factors affecting conception rate after artificial insemination and pregnancy loss in lactating dairy cows. Anim. Reprod. Sci. 2004, 84, 239–255. [Google Scholar] [CrossRef] [PubMed]
- Thornton, P.; Nelson, G.; Mayberry, D.; Herrero, M. Impacts of heat stress on global cattle production during the 21st century: A modelling study. Lancet Planet. Health. 2022, 6, e192–e201. [Google Scholar] [CrossRef]
- Anderson, S.D.; Bradford, B.J.; Harner, J.P.; Tucker, C.B.; Choi, C.Y.; Allen, J.D.; Hall, L.W.; Rungruang, S.; Collier, R.J.; Smith, J.F. Effects of adjustable and stationary fans with misters on core body temperature and lying behavior of lactating dairy cows in a semiarid climate. J. Dairy Sci. 2013, 96, 4738–4750. [Google Scholar] [CrossRef] [PubMed]
- Tresoldi, G.; Schutz, K.E.; Tucker, C.B. Cooling cows with sprinklers: Spray duration affects physiological responses to heat load. J. Dairy Sci. 2018, 101, 4412–4423. [Google Scholar] [CrossRef] [PubMed] [Green Version]
- Bah, M.; Rashid, M.A.; Javed, K.; Pasha, T.N.; Shahid, M.Q. Effects of sprinkler flow rate on physiological, behavioral and production responses of Nili Ravi buffaloes during subtropical summer. Animals 2021, 11, 339. [Google Scholar] [CrossRef] [PubMed]
- Von Keyserlingk, M.A.G.; Martin, N.P.; Kebreab, E.; Knowlton, K.F.; Grant, R.J.; Stephenson, M.; Sniffen, C.J.; Harner Iii, J.P.; Wright, A.D.; Smith, S.I. Invited review: Sustainability of the US dairy industry. J. Dairy Sci. 2013, 96, 5405–5425. [Google Scholar] [CrossRef] [Green Version]
- Honig, H.; Miron, J.; Lehrer, H.; Jackoby, S.; Zachut, M.; Zinou, A.; Portnick, Y.; Moallem, U. Performance and welfare of high-yielding dairy cows subjected to 5 or8 cooling sessions daily under hot and humid climate. J. Dairy Sci. 2012, 95, 3736–3742. [Google Scholar] [CrossRef] [PubMed] [Green Version]
- Bah, M.; Shahid, M.Q.; Pasha, T.N.; Javed, K. Performance and welfare of dairy buffaloes subjected to different cooling strategies during subtropical summer. Trop. Anim. Health Prod. 2022, 54, 51. [Google Scholar] [CrossRef] [PubMed]
- Bah, M.; Javed, K.; Pasha, T.N.; Shahid, M.Q. Performance of Holstein cows subjected to different cooling sessions during subtropical summer. Anim. Biosci. 2022, 35, 1800–1807. [Google Scholar] [CrossRef] [PubMed]
- Tresoldi, G.; Schütz, K.E.; Tucker, C.B. Cooling cows with sprinklers: Effects of soaker flow rate and timing on behavioral and physiological responses to heat load and production. J. Dairy Sci. 2019, 102, 528–538. [Google Scholar] [CrossRef] [PubMed] [Green Version]
- Macavoray, A.; Rashid, M.A.; Rahman, H.; Shahid, M.Q. On-farm water use efficiency: Impact of sprinkler cycle and flow rate to cool Holstein cows during semi-arid summer. Sustainability 2023, 15, 3774. [Google Scholar] [CrossRef]
- Ruud, L.E.; Bøe, K.E. Flexible and fixed partitions in freestalls–Effects on lying behavior and cow preference. J. Dairy Sci. 2011, 94, 4856–4862. [Google Scholar] [CrossRef]
- West, J.W. Effects of heat-stress on production in dairy cattle. J. Dairy Sci. 2003, 86, 2131–2144. [Google Scholar] [CrossRef] [PubMed]
- De Rensis, F.; Garcia-Ispierto, I.; López-Gatius, F. Seasonal heat stress: Clinical implications and hormone treatments for the fertility of dairy cows. Theriogenology 2015, 84, 659–666. [Google Scholar] [CrossRef] [PubMed]
- Bah, M. Optimization of Water Use for Cooling Dairy Animals during Summer. Ph.D. Thesis, University of Veterinary and Animal Sciences, Lahore, Pakistan, 9 July 2021. [Google Scholar]
- Blowey, R. Factors associated with lameness in dairy cattle. Practice 2005, 27, 154–162. [Google Scholar] [CrossRef] [Green Version]
Figure 1.
Hourly patterns of climate measures during the study period: air temperature (AT), relative humidity (%), temperature humidity index (THI), and black globe temperature (BGT).
Figure 1.
Hourly patterns of climate measures during the study period: air temperature (AT), relative humidity (%), temperature humidity index (THI), and black globe temperature (BGT).
Figure 2.
Mean hourly core body temperature of lactating Holstein cows cooled with 5 cooling sessions (5CS: solid line with solid circle) or 8 cooling sessions (8SC: dashed line with open circle) during August and September 2021 (n = 8 animals per treatment, 24 d of recording/animal, 24 h/day). The shaded bars indicate the timing of each 60-min cooling session, which consisted of 10 sprinkler cycles per hour each with 3 min of water on and 3 min off. The bars with solid border indicate the common cooling sessions between the 5CS and 8CS treatment groups. The statistical analysis was performed for each time point, and instead of presenting individual p-values, the SE was reported to represent the variability within each group. The crossing of the error bars indicates a non-significant difference between the groups.
Figure 2.
Mean hourly core body temperature of lactating Holstein cows cooled with 5 cooling sessions (5CS: solid line with solid circle) or 8 cooling sessions (8SC: dashed line with open circle) during August and September 2021 (n = 8 animals per treatment, 24 d of recording/animal, 24 h/day). The shaded bars indicate the timing of each 60-min cooling session, which consisted of 10 sprinkler cycles per hour each with 3 min of water on and 3 min off. The bars with solid border indicate the common cooling sessions between the 5CS and 8CS treatment groups. The statistical analysis was performed for each time point, and instead of presenting individual p-values, the SE was reported to represent the variability within each group. The crossing of the error bars indicates a non-significant difference between the groups.
Figure 3.
Mean respiratory rate (breaths/min) of Holstein cows cooled with 5 cooling sessions (5CS: black bar) or 8 cooling sessions (8CS: gray bar) at two time points during August and September 2021 (n = 8 animals per treatment, 24 days of recording per animal, 3 recording days per week). Error bars indicate the standard error of the mean (SEM; Pooled SEM = 1.33). The interaction between cooling sessions and time of day was significant (p = 0.005).
Figure 3.
Mean respiratory rate (breaths/min) of Holstein cows cooled with 5 cooling sessions (5CS: black bar) or 8 cooling sessions (8CS: gray bar) at two time points during August and September 2021 (n = 8 animals per treatment, 24 days of recording per animal, 3 recording days per week). Error bars indicate the standard error of the mean (SEM; Pooled SEM = 1.33). The interaction between cooling sessions and time of day was significant (p = 0.005).
Table 1.
Summary of daily climate measures on experimental days during August and September 2021.
| 24 h Averages | |||
|---|---|---|---|
| Items | Means ± SE | Minimum | Maximum |
| Air temperature (T, °C) | 35.3 ± 4.6 | 23.3 | 48.0 |
| Temperature humidity index (THI) | 86 ± 4 | 72 | 95 |
| Heat load index (HLI) | 101 ± 11 | 54 | 128 |
| Black globe temperature (BGT, °C) | 40.1 ± 8.7 | 22.6 | 60.1 |
| Relative humidity (RH, %) | 60 ± 15 | 24 | 100 |
| Wind speed (WS, m/s) | 0.3 ± 0.6 | 0 | 5.3 |
| Solar radiation (W/m2) | 110 ± 36 | 80 | 286 |
Table 2.
Comparative milk yield and composition of Holstein cows subjected to various cooling sessions in semi-arid summer: LS Means ± SE.
Table 2.
Comparative milk yield and composition of Holstein cows subjected to various cooling sessions in semi-arid summer: LS Means ± SE.
| Cooling Sessions 1, n/d | ||||
|---|---|---|---|---|
| Items | 5CS | 8CS | SEM | p Value |
| DMI 2, kg/8 cows | 115.9 | 125.2 | 2.7 | 0.039 |
| Milk yield, kg/d | 14.9 | 17.8 | 0.68 | 0.04 |
| Milk components, % | ||||
| Fat | 3.0 | 2.9 | 0.09 | 0.5256 |
| Protein | 3.2 | 3.2 | 0.08 | 0.5958 |
| Lactose | 4.4 | 4.3 | 0.08 | 0.3225 |
| Milk components, g/d | ||||
| Fat | 520.3 | 535.8 | 15.75 | 0.4914 |
| Protein | 513.1 | 539.9 | 48.65 | 0.8310 |
| Lactose | 700.1 | 725.9 | 81.9 | 0.8310 |
1 Cooling sessions treatment groups; 5CS, which involved five cooling sessions of 1 h each; and 8CS, which involved eight cooling sessions. The cooling sessions in the 5CS group were held at 07:00, 10:00, 12:00, 14:00, and 16:00 h daily, while the additional cooling sessions in the 8CS group were held at 04:00, 19:00, and 22:00 h. 2 DMI; daily dry matter intake of a group of 8 cows.
Table 3.
Comparative behavior of Holstein cows subjected to various cooling sessions in semi-arid summer: LS Means ± SE.
Table 3.
Comparative behavior of Holstein cows subjected to various cooling sessions in semi-arid summer: LS Means ± SE.
| Cooling Sessions 1, n/d | ||||
|---|---|---|---|---|
| Items | 5CS | 8CS | SEM | p Value |
| Feeding behavior | ||||
| Total feeding time, h/d | 4.8 | 5.7 | 0.33 | 0.05 |
| Feeding visits, number/d | 26 | 26 | 1.33 | 0.68 |
| Duration of each visit, min | 11 a | 14 b | 0.61 | 001 |
| Lying behavior | ||||
| Total lying time, h/d | 9.9 | 10.4 | 0.51 | 0.51 |
| Lying bouts, number/d | 11 | 11 | 0.45 | 0.41 |
| Duration of each bout, min | 53 | 57 | 2.16 | 0.17 |
| Standing behavior | ||||
| Total standing time, h/d | 14.1 | 13.6 | 0.51 | 0.51 |
| Standing bouts, number/d | 11 | 11 | 0.53 | 0.87 |
| Step count, ×1000 n/d | 3.5 | 3.7 | 1.74 | 0.48 |
a,b Values with different superscripts in a row are significantly different (p < 0.05). 1 Cooling sessions treatment groups; 5CS, which involved five cooling sessions of 1 h each; and 8CS, which involved eight cooling sessions. The cooling sessions in the 5CS group were held at 07:00, 10:00, 12:00, 14:00, and 16:00 h daily, while the additional cooling sessions in the 8CS group were held at 04:00, 19:00, and 22:00 h.
Table 4.
Blood metabolites of Holstein Friesian cows under different cooling sessions during summer: LS Means ± SE.
Table 4.
Blood metabolites of Holstein Friesian cows under different cooling sessions during summer: LS Means ± SE.
| Cooling Sessions 1, n/d | ||||
|---|---|---|---|---|
| Items | 5CS | 8CS | SEM | p Value |
| Glucose, mg/dL | 48.0 | 45.5 | 2.90 | 0.551 |
| Blood UREA Nitrogen, mg/dL | 17.3 a | 15.0 b | 0.75 | 0.039 |
| Cortisol, µg/dL | 1.94 | 1.86 | 0.11 | 0.615 |
a,b Values with different superscripts in a row are significantly different (p < 0.05). 1 Cooling sessions treatment groups; 5CS, which involved five cooling sessions of 1 h each; and 8CS, which involved eight cooling sessions. The cooling sessions in the 5CS group were held at 07:00, 10:00, 12:00, 14:00, and 16:00 h daily, while the additional cooling sessions in the 8CS group were held at 04:00, 19:00, and 22:00 h.
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |
© 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Share and Cite
MDPI and ACS Style
Macavoray, A.; Rashid, M.A.; Rahman, H.; Shahid, M.Q. Sustainable Management of Dairy Cows in Semi-Arid Summers: Additional Early Nighttime Sprinkler Cooling for Heat Stress Mitigation. Sustainability 2023, 15, 11665. https://doi.org/10.3390/su151511665
AMA Style
Macavoray A, Rashid MA, Rahman H, Shahid MQ. Sustainable Management of Dairy Cows in Semi-Arid Summers: Additional Early Nighttime Sprinkler Cooling for Heat Stress Mitigation. Sustainability. 2023; 15(15):11665. https://doi.org/10.3390/su151511665
Chicago/Turabian StyleMacavoray, Abu, Muhammad Afzal Rashid, Hifzul Rahman, and Muhammad Qamer Shahid. 2023. "Sustainable Management of Dairy Cows in Semi-Arid Summers: Additional Early Nighttime Sprinkler Cooling for Heat Stress Mitigation" Sustainability 15, no. 15: 11665. https://doi.org/10.3390/su151511665
Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.
