Heat stress reduces milk production and modulates milking behaviour in Girolando cow managed in a pasture-based automated milking system under tropical conditions

Effect of season and temperature before and after calving on the future milk production of born heifers

Submitted 2020-07-03 | Accepted 2020-09-09 | Available 2020-12-01 https://doi.org/10.15414/afz.2020.23.mi-fpap.167-173 Global warming is already affecting several areas and a further increase of 1.5°C is expected by 2050. Dairy cattle are particularly sensitive to high temperature. So, the aim of this study was to examine the effect of temperature-humidity index (THI) on milk traits, considering changes of climatic parameters in the different seasons from 2010 to 2018. The study was conducted in 3 farms located in a hilly-mountainous area of Tuscany, the Mugello, situated from 220 to 450 m above sea level. Data on average daily milk yield and composition were monthly collected in the 3 farms from 2010 to 2018, while climatic parameters were recorded by a climatic station located in the area of the farms. As regards the climatic parameters, no significant variations have been observed in the last decade. The THI calculated thanks to the recording of temperature and humidity of the weather station, during the warmest months, was high enough to cause heat stress. The milk quality traits declined when THI increased. In conclusion, there was not any evidence that global warming has been affecting Mugello, but, despite its altitude, high THI usually reached during spring and summer seasons are already high enough to cause heat stress and a further increase could worsen farm productivity. Keywords: climate change, milk quality, heat stress, dairy cow References Amamou, H. et al. (2019). Thermotolerance indicators related to production and physiological responses to heat stress of Holstein cows. Journal of Thermal Biology, 82, 90–98. https://doi.org/10.1016/j.jtherbio.2019.03.016 André, G. et al. (2011). Quantifying the effect of heat stress on daily milk yield and monitoring dynamic changes using an adaptive dynamic model. 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Temperature humidity index (THI) is widely used to assess the effect of temperature and relative humidity on performance in animals. In summer the THI was between 74 – 89 with average value of 81.18. in winter months THI ranged between 49 -70 with the average of 60. The results showed a significant effect of heat stress on daily milk yield and milk composition. In the present study the daily milk yield decreases from 4.46 to 3.65kg, heat stress reduced milk yield by 18.2%. There was a significant effect of heat stress on milk composition. Heat stress significantly reduced milk fat content from 8.3% during the winter to 7.19% during the summer. Milk protein percentage significantly decreased as a result of summer heat stress (3.08 vs.2.9 %, respectively for the winter and summer). In the present study the SNF decreases from 9.08 to 9.05 %, heat stress reduced SNF % as the THI value went from ≤ 74 to ≥ 83 in summer. Results showed that milk production is a function of THI. The negative slope of regression line indicates that milk production fat%, protein% and SNF% decreases as THI increases. This regression indicates that in general for each point increase in THI value. There was decrease in milk yield of 0.028kg per buffalo per day. Heat stress environments have been associated with depression in milk fat%, protein% and SNF%. There was decrease in milk fat of 0.046% per buffalo per day. There was also decrease in milk protein of 0.00014 % per buffalo per day. The decrease in milk SNF of 0.0047 % per buffalo per day.

The present trial evaluated the effect of crossbred composition and Temperature and Humidity Index (THI) on vaginal temperature (VT) of Girolando dairy cows maintained under tropical pasture during warm seasons. The VT was monitored along 41 to 96 h in 615 Girolando cows with different Holstein (H) × Gir genetic composition (1/2 H = 284, 3/4 H = 248, and 7/8 H = 83) from six Brazilian farms in the summer of 2016 and 2017. VT of each cow at each hour of the day and the respective THI were averaged per hour across all monitoring days to generate an averaged value for VT and THI during 24 h. A linear mixed model with repeated measures using restricted maximum likelihood (REML) method for (co)variance components estimation procedure was employed. The final model adjusted the VT for the effects of cow, time, THI, farm, year, pregnancy status, body condition score (BCS), milk yield, genetic composition, and genetic composition*time interaction. Fixed effects were evaluated by ANOVA and tested with Tukey test in R software version 3.6.1 (R Core Team, 2019). Overall mean of VT, air temperature (AT), and THI were 39.06 ± 0.52 °C, 25.63 ± 0.40 °C, and 75.06 ± 3.96, respectively. VT had moderate positive correlation with THI (r² = 0.45, P < 0.001) and AT (r² = 0.46, P < 0.001). The VT had estimated linear increase of 0.05 °C for each THI unit increase (P < 0.001). Least square mean of VT varied among the farms (P < 0.001), pregnancy status (P < 0.001), and BCS (P < 0.05) but not for Milk yield (P > 0.05). The daily average VT was affected by genetic composition (P < 0.001) with highest temperature for 3/4 H (39.08 ± 0.06 °C a) and 7/8 H (39.09 ± 0.06 °C a) and lowest temperature for 1/2 H (38.95 ± 0.06 °C b). The difference of VT among the three crossbred groups varied in function of the time of the day, from 12:00 to 20:00 h (P < 0.001), with 3/4 Holstein and 7/8 Holstein cows reaching similar VT, above to the upper limit 39.1 °C and higher than 1/2 Holstein cows during all this period. In conclusion, Girolando cows are sensitive to heat stress in tropical condition during warm seasons. Moreover, Girolando cows with genetic composition higher than 3/4 Holstein display reduced thermoregulatory efficiency. Therefore, Girolando cows in tropical dairy farms require strategies to mitigate heat stress according to their genetic composition.

Milk production may be reduced before dry-off to decrease the risk of cows developing intramammary infections during the dry period. Such reductions in milk may be possible in automated milking systems (AMS) where milking frequency and feed allocation at the AMS can be controlled at the cow level. This study investigated the effect of dry-off management of cows milked in AMS on milk yield, milking behavior, and somatic cell count (SCC). Using a 2 × 2 factorial arrangement of treatments, applied from d 14 to 1 before dry-off, 445 cows from 5 commercial dairy farms in Quebec, Canada, were assigned within farm to either (1) reduced feed [RF; allowed a maximum of 0.75 kg/d of AMS pellet for the first week (14 to 8 d before dry-off) of treatment, and 0.50 kg/d for the second week (7 to 1 d before dry-off) of treatment], or (2) nonreduced feed (NF; allowed up to 2 kg/d of AMS pellet), and either (1) reduced milking (RM; reduced to 2 milkings/d or as many times as required to yield 17 kg/milking), or (2) nonreduced milking (NM; allowed up to 6 AMS milkings/d) and no maximum production. Feed and milking behavior data, as well as milk yield and SCC were collected from the AMS software. The RF cows had lower AMS feed delivered during the treatment period, as per the experimental design. Across the treatment period, the NF-NM cows had the highest milking frequency (2.7 times/d), followed by the RF-NM cows (2.4 times/d), and then both of the RM groups (1.8 times/d), which did not differ from each other. All cows, except the NF-NM cows, were gradually milked less frequently as dry-off approached. Across the entire 2-wk treatment period before dry-off, cows with RM allowance experienced a higher reduction in milk yield compared with the cows with no milking allowance restrictions (-4.8 vs. -3.6 kg). Similarly, cows with a RF allocation tended to have a higher reduction in milk yield than cows with NF (-4.6 vs. -3.7 kg). As result, those cows with both reduced milking permissions and feed allocation at the AMS experienced the greatest drop in milk production before dry-off. There were no differences between treatments for milking frequency or yield in the next lactation. Somatic cell score (calculated from SCC) was not different between treatments in the 2-wk or day before dry-off, nor in the first month after calving. Overall, these data suggest that reducing both milking frequency and feed quantity in the AMS is the most efficient method to decrease milk yield before dry-off, without negatively influencing milking frequency or yield in the next lactation, as well as without affecting milk quality.

The effects of heat stress on milk production of dairy ewes have been very little studied, especially under Mediterranean conditions. For this reason, such effects were studied in ten Sarda dairy sheep farms associated to the Sardinian Breeders Association, located throughout Sardinia. They had whole farm milk yield records registered every 48 hours from April 1st until July 15th, in the years 2003 and 2004. Meteorological data were obtained from data collected by meteorological stations of the Weather Forecast Service of Sardinia located near each farm. To determine the effects of meteorological conditions on milk yield, analysis of variance using the SAS (SAS Institute Inc., Cary, NC, USA) mixed procedure was performed. The results showed that Sarda dairy sheep were highly sensitive to high temperatures, especially when they persisted for long periods. All analysed meteorological factors, except for wind speed, significantly influenced milk yield. Milk yield was more influenced by minimum air temperatures than by any other meteorological parameter. Increases in minimum temperatures from the optimal range of 9-12 °C up to 27-30 °C caused on average a decrease in milk yield of 36% (0.35 kg/d per head). The highest milk yields were observed at maximum air temperatures ranging from 24 to 30 °C and at mean temperatures varying from 15 to 18 °C, with progressive decreases, up to 20% (about 0.22 kg/d per head), at higher temperatures. The effects of duration of temperatures higher than some threshold values on milk yield were also relevant. Optimal air relative humidity for milk production was between 65 and 75%, in accordance with values reported in the literature. Rainfall negatively influenced milk yield, probably because it disturbs grazing, with decreases up to 23% (0.20 kg/d per head) under conditions of 6 mm-cumulative rainfall in two days. Milk production was also influenced by Temperature Humidity Index (THI), with a decrement of 25% (0.23 kg/d per head) as THI increased from 60-65 to 72-75. Wind influenced milk yield only when associated with other meteorological factors; it alleviated the negative effects of heat stress on milk yield at higher speed values. In conclusion, despite of their small body size, which should favour heat exchange and thermoregulation, milk yield of Sarda ewes was markedly reduced by heat stress.

Modeling variability of the lactation curves of cows in automated milking systems

Automated feeding robots (AFR) are increasingly being used on North American dairy farms to reduce dependency on human labor for feeding. These systems mix, deliver, and push up feed to cows at any frequency or interval desired, allowing for more frequent feed delivery than conventional feeding systems (CFS). This observational study investigated differences in ration consistency, milk components, milk fatty acid profile, and cow behavior between herds using AFR and those using CFS. Sixteen commercial dairies with automated milking systems (AMS) in the upper Midwest United States were paired based on herd size and location into eight blocks each consisting of one CFS and one AFR herd. Feed bunk samples were collected at four equally spaced time points for 3 consecutive d and analyzed for coefficient of variation (CV) of nutrient composition and particle size distribution. Bulk tank milk samples were collected 1 ×/d for 3 d and analyzed for fat, protein, milk urea nitrogen (MUN), lactose, and milk fatty acid (FA) profile. Daily AMS visit intervals, milk yield and composition, and rumination time data were collected from AMS software. A linear mixed model tested fixed effects of feeding system, block, and the random effect of day nested within block. The CV of feed bunk DM, ADF, NDF, and lignin was lower in AFR. Bulk tank milk fat, protein, and MUN were not different between AFR or CFS. AFR had a greater proportion of de novo synthesized FA, but no difference in preformed or mixed FA. Herds with AFR had a shorter AMS visit interval with more AMS refusals per day than CFS. Results imply that AFR may be associated with lower daily variation in fiber concentration at the feed bunk, increased mammary de novo fatty acid synthesis, and increased frequency of cow visits to the AMS compared to conventional PMR feeding.

ویژگی‌های محیطی یکی از عوامل مؤثر بر عملکرد گاوهای شیری می‏باشد. برای برآورد میزان تأثیر این عوامل از شاخص دما-رطوبت (THI) استفاده می‏شود. در این حوزه اطلاعات نسبتا کمی در دسترس می‌باشد. به همین منظور تأثیر تنش دما-رطوبت بر تولید شیر یک گاوداری صنعتی شهر مشهد طی هفت سال با استفاده از معادلات مربوطه مورد مطالعه قرار گرفت. همبستگی معنی‌داری بین داده‌های روزانه تولید شیر و معادلات مختلف برآورد THI در سری زمانی سالانه و فصلی (بهار، پاییز و زمستان) وجود نداشت و فقط در فصل تابستان همبستگی معنی‌دار و منفی بین تولید روزانه شیر و شاخص دما-رطوبت وجود داشت، همچنین از بین هشت معادله موجود، معادله THI4 که از روی دمای خشک و دمای نقطه شبنم به دست می‌آید، همبستگی بیشتری با داده‌های تولید شیر نشان داد. بررسی نوسانات تولید شیر و شاخص منتخب THI نشان داد حد شروع تأثیر گذاری تنش دما-رطوبت بر گاوهای این گاوداری 75 بود که به اندازه 5 واحد بیشتر از عدد ارائه شده بر اساس معیارهای جهانی است. در طی 7 سال دوره آماری مورد بررسی در مجموع نسبت به حالت بدون تنش حدودا 401 تن کاهش تولید شیر برای این گاوداری برآورد گردید که بیشترین مقدار مربوط به سال 1392 و کمترین مقدار مربوط به سال 1387 بود. افزایش درجه حرارت و رطوبت در فصل تابستان از علل اصلی ایجاد این تنش است و خروج از شرایط بهینه محیطی تنها در این فصل در حیوان تنش ایجاد کرده و باعث کاهش تولید شیر شده است.

Teat conformation characteristics, udder height, total milking yield, 2-min yield, 2-min yield adjusted for the linear and quadratic effects of total milking yield, and 305-day milk and fat yields were recorded on 377 Holstein-Friesian cows in 18 herds. Simple relationships of teat conformation measures and udder height to milk flow rate and production traits which were significant (P &lt; 0.05) were as follows. Mean 2-min, total milking, and 305-day milk yields were lower for plumb front teats than for front teats that were not plumb. Cows with plumb rear teats also had lower total milking yields. Cows with cylindrical teats, both front and rear, had lower total milking yields than cows with funnel teats. Teat length was positively correlated with total milking, 305-day milk and 305-day fat yields. Teat diameter measures taken at proximal, medial and distal locations of the teat were positively correlated with all production traits, and rear teat diameter measures were positively correlated with 2-min yield. Udder height was positively correlated with adjusted 2-min yield and negatively correlated with total milking, 305-day milk and 305-day fat yields. Least squares analyses, which corrected for the effects of herd, age of cow at calving, and stage of lactation, were conducted, and significant (P &lt; 0.05) effects were as follows. Cows with cylindrical teats produced 0.7–0.8 kg less total milk at milking than cows with funnel teats. Rear teat diameter was more highly related to milk production than front teat diameter. Proximal and distal diameter of the rear teat was positively associated with all three production traits, and medial rear teat diameter was positively associated with total milking and 305-day milk yields. Also, proximal diameter of the rear teat had a positive relationship with 2-min yield. Total milking yield was positively influenced by front teat proximal and medial diameters, but medial diameter had a negative effect on adjusted 2-min yield. Udder height influenced all traits. High udders had relatively higher milk flow rates but lower milk and fat production. Each centimetre increase in udder height was associated with a 46-kg decrease in 305-day milk. Heritabilities of 2-min yield, adjusted 2-min yield, 305-day milk yield and 305-day fat yield were 0.17, 0.27, 0.18, and 0.50, respectively.

It has been known that, weather condition has a great effect on living being. Now a days the study of the effect of weather conditions on plant, animals and all living being is considered as an interdisciplinary science, which has a great effect on the quality and quantity of living being productions. In order to survive and maintain their physiological activities, warm-blooded animals’ body temperature should be in a specific rang. Therefor in warm days, in order to restrain their body temperature in an optimized rage, their transpiration, breathing and heart beat will raise, while the feeding rate decrease. In these situation if the relative humidity was high too, these cooling reaction cannot response well and therefore animals’ body temperature will raise, and it has been said that animals are under the heat stress. As a consequence of that feeding rate and animal production reduce, reproductive problems accrues, and the rate of getting sick raise. In this regard, researches show that air temperature and environmental humidity are two parameters which has a great effect on cows’ heat stress. In order to evaluate and assess the heat stress, most of the researchers use Temperature Humidity Index (THI). There are numbers of equation to obtain THI, and also their coefficient must be calibrated for every different regions, therefore using them, are sometimes, confusing. Therefore the aim of this study is determining the best THI equation for dairy industry in Mashhad, and also finding the reduction in milk production during the heat stress period. The meteorological data (daily wet and dry bulb and relative humidity records) were obtained from Iran meteorological organization. Then by using 8 common equations, temperature humidity index (THI) were calculated for 7 year period (2007-2013). The daily milk production data was also obtained from improvement center of milk production in Karaj. Then the relationship between daily milk production and 8 obtained THI were calculated for annual and seasonal time scale. At that point by using the correlation coefficients and P-value the best equation to determine THI was chosen. Finding the best THI equation for the study area, led to find a warning heat stress point. As a final point, daily milk production during the heat stress calculated and reduced milk production was estimated during the heat stress time. The results show that there are no significant correlation between annually milk production and obtained THI. Also the relationship between THI and milk production in seasonal scale (spring, fall and winter) were not significant to. Nevertheless, only daily milk production in summer has a significant relationship with temperature-humidity index, which was negative. Which means that daily milk production decreases with increasing THI. Among from 8 investigative equation, the forth equation (which calculate THI by using dry bulb and dew point temperature) has the best correlation coefficient and P-value with daily milk production. By definition the break point in summer daily THI and milk production, the heat stress warning point for Mashhad dairy industry was found. The results show that when temperature-humidity index raise above 75, the milk production significantly decrease. In order to calculate the amount of milk reduction as a result of THI increasing, the relationship between milk production and THIs’ more than 75 was estimated. Then by subtracting the calculated THI from average milk production in a non-stress day, the loss of milk production were calculated for each cow. Then by multiplying one cow milk lost, by the number of cows, the final milk production loss were calculated for each year. The results show in 2013, the temperature humidity stress had a greatest effect on milk production, so that during a summer time, each cow averagely produce 138.8 lit milk less than usual. This amount is also equal to 1.5 lit milk per a day. During 7 years period investigation, the total milk loss was calculated 401 ton. In conclusion, raising air temperature can cause a heat stress and a reduced milk reduction. When the heat comes with high relative humidity, these effects highlighted and cows were under enormous stress therefore their body temperature transpiration, breathing and heart beat raise, while the feeding rate decrease, and as a result of that milk production reduced which can cause a great damage in diary industry

The objective of the present study was to evaluate the productive performance and grazing behavior of 25 primiparous and 44 multiparous Holstein cows in a pasture-based automatic milking system (AMS) while experiencing heat stress (defined as a temperature-humidity index [THI] ≥ 68). Productive traits were analyzed according to the THI from days 0, -1, -2, and -3 in relation to the milking day, and grazing behaviors (expressed as the percentage of daily observation time) were related to the average THI only on the day of observation. Milk yield was not associated with the THI on day 0, but a significant linear relationship was found with the THI on the three previous days, decreasing approximately 0.18 kg (primiparous) and 0.40 kg (multiparous) per THI unit increment. In contrast, for multiparous cows only, the milking frequency was positively associated with the THI on the day of evaluation but not on the previous days, increasing 0.01 milking/THI unit increments. Additionally, for each unit of THI increment, cows spent 0.14% more time standing, whereas they exhibited a decrease in grazing, lying, and ruminating behaviors time by 0.30%, 0.04%, and 0.70%, respectively, for both parities. In conclusion, milk loss was related to heat stress conditions from the previous days, but not milking frequency, which increased with the THI of the same milking day. Lower grazing, lying, and ruminating activities and greater standing behavior were observed due to heat stress.

Context Heat stress is an increasing concern for the Australian dairy industry. Aims This study aimed to evaluate the effect of temperature–humidity index (THI) on rumination time (RT), milk yield and quality, and milking frequency in a pasture-based voluntary-movement automatic milking system (AMS). Methods Data were collected from the University of Melbourne Dookie College AMS farm for 3 years (June 2016 to March 2019). Daily RT was collected through the transponder collar (Qwes-HR, Lely). Climatic data (maximum ambient temperature and relative humidity) were obtained from the Dookie Meteorological station to calculate daily maximum THI (THImax). Key results Daily milk yield increased with a rising THImax to 65, then declined after THImax 65. Milking frequency was highest at THImax 90, followed by a steady decline afterwards. Rumination time was maximum at mid-range THImax and declined for high and low values. Conclusions The findings of this study clearly indicated that under pasture-based voluntary-movement AMS, high THI resulted in a drop in the milk yield, milking frequency and RT. Implications With the provision of automation of data collection from AMS, further study with mathematical modelling describing the daily patterns and thresholds in conjunction with the different heat stress levels can be useful for assessing animal welfare and to mitigate heat stress and seek alternative management strategies.

Global warming caused by climate change is a challenge for dairy farming, especially in sub-Saharan countries. Under high temperatures and relative humidity, lactating dairy cows suffer from heat stress. The objective of this study was to investigate the effects and relationship of heat stress (HS) measured by the temperature-humidity index (THI) regarding the physiological parameters and milk yield and composition of lactating Holstein Friesian crossbred dairy cows reared in the humid coastal region of Tanzania. A total of 29 lactating Holstein Friesian x Zebu crossbred dairy cows with 50% (HF50) and 75% (HF75) Holstein Friesian gene levels in the second and third months of lactation were used. The breed composition of Holstein Friesians was determined based on the animal recording system used at the Tanzania Livestock Research Institute (TALIRI), Tanga. The data collected included the daily temperature, relative humidity, daily milk yield, and physiological parameters (core body temperature, rectal temperature, respiratory rate, and panting score). THI was calculated using the equation of the National Research Council. The THI values were categorized into three classes, i.e., low THI (76-78), moderate THI (79-81), and high THI (82-84). The effects of THI on the physiological parameters and milk yield and composition were assessed. The effects of the genotype, the parity, the lactation month, and the interaction of these parameters with THI on the milk yield, milk composition, and physiological parameters were also investigated. The results show that THI and its interaction with genotypes, parity, and the lactation month had a highly significant effect on all parameters. THI influenced (p ˂ 0.05) the average daily milk yield and milk fat %, protein %, lactose %, and solids-not-fat %. As the THI increased from moderate to high levels, the average daily milk yield declined from 3.49 ± 0.04 to 3.43 ± 0.05 L/day, while the fat % increased from 2.66 ± 0.05% to 3.04 ± 0.06% and the protein decreased from 3.15 ± 0.02% to 3.13 ± 0.03%. No decline in lactose % was observed, while the solid-not-fat % declined from 8.56 ± 0.08% to 8.55 ± 0.10% as the THI values increased from moderate to high. Also, the THI influenced physiological parameters (p ˂ 0.05). The core body temperature (CBT), rectal temperature (RT), respiratory rate (RR) and panting score (PS) increased from 35.60 ± 0.01 to 36.00 ± 0.01 °C, 38.03 ± 0.02 to 38.30 ± 0.02 °C, 62.53 ± 0.29 to 72.35 ± 0.28 breaths/min, and 1.35 ± 0.01 to 1.47 ± 0.09, respectively, as the THI increased from low to high. The THI showed a weak positive correlation with the average daily milk yield and fat percentage, whereas the protein, lactose, and solids-not-fat percentages showed negative relationships with THI (p ≤ 0.05). CBT, RT, RR, and PS showed positive relationships (p ≤ 0.05) with THI. These negative relationships indicate that there is an antagonistic correlation between sensitivity to HS and the level of production. It is concluded that the THI, the genotype, the parity, and the lactation month, along with their interactions with THI, significantly influenced the milk yield, milk composition, and physiological parameters of lactating Holstein Friesian dairy crosses at THI thresholds ranging from 77 to 84.

Heat stress with measurable effects in dairy cattle is a growing concern in temperate regions. Heat stress in temperate regions differs between environments with different geophysical characteristics. Microclimates specific to each environment were found to greatly impact at what level heat stress occurs and will occur in the future. The landlocked state of Baden-Württemberg, Germany, provides several different environments, hence, a good case-study. Temperature–Humidity Index (THI) from 17 weather stations for the years 2003 to 2022 was calculated and milking yields from 22 farms for the years 2017 to 2022 were collected. The occurrences and evolving patterns of heat stress were analyzed with the use of a THI, and the effect of heat stress on milk yield was analyzed based on milking records from Automated Milking Systems. Daily average THI was calculated using hourly readings of relative humidity and ambient temperature, disregarding solar radiation and wind, as all animals were permanently stabled. Based on studies conducted in Baden-Württemberg and neighboring regions, cited ahead in the section of THI, THI = 60 was the threshold for heat stress occurrence. Findings show that the heat stress period varied between stations from 64 to 120 d with THI ≥ 60 in a year. This aligns with yearly and summer averages, also steadily increasing from May to September. The length of the heat stress period was found to increase 1 extra day every year. Extreme weather events such as heat waves did not increase the heat stress period of that year in length but increased the average THI. Milk yield was found to be significantly (α = 0.05) different between counties grouped into different zones according to heat stress severity and rate of increase in daily average THI. Future attempts at managing heat stress on dairy cattle farms in the temperate regions should account for microclimate, as geographical proximity does not mean that the increase in heat stress severity will be the same in the 2 neighboring areas.