Deep body temperature is usually maintained at a

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1 se 1699 ms 7/9/01 7:31 AM Page 387 BEHAVIOR OF DAIRY COWS IN RESPONSE TO DIFFERENT BARN COOLING SYSTEMS E. Frazzi, L. Calamari, F. Calegari, L. Stefanini ABSTRACT. Forty-two dairy cows were subdivided in three groups of 14 cows each. Each pen of cows was provided with a feeding area, a freestall area, and an external paddock. The study was conducted in an experimental barn located in the Po Valley of Italy. The cows were observed during summer 1995 for milk yield and quality and for their behavior (movements and residence time in the different areas of each pen) under different microclimatic conditions (temperature, relative humidity, light exposure, air speed). The feeding and freestall areas were arranged with: (1) fans in the first pen; (2) fans and misting in the second pen; and 3) the third pen was used as control. During the summer months (from June to September) microclimatic conditions, milk yield, and cow position (monitored with video cameras and automatic still cameras placed in different areas of the barn) were recorded. During the hottest period, lower milk yield reductions were recorded for the cows housed in pens with fans or with fans and misting. This result was consistent with the behavior of the cows inside experimental pens that spent longer periods of resting time in the feeding and freestall areas, and showed overall behavior similar to that observed during a cooler period. Some cows also lay in the wet dirty areas of the pens or crowded in a well-ventilated place. The results of this study confirm the usefulness of cooling systems for cows in a warm climate. Keywords. Animal housing, Dairy barns, Cooling systems, Ventilation. Deep body temperature is usually maintained at a stable level in homeothermic animals. When the ambient temperature rises or falls from optimum, the animal reacts with different physiological and behavioral means to prevent body temperature from diverging more than a small amount from the optimal setpoint. The physiological responses of the cow to heat stress are to (1) increase heat loss through evaporation (sweating and panting), and (2) reduce the heat generated by maintenance (15-20% under heat stressing conditions) and due to production (specifically heat generation linked to digestive activity). The reduction of metabolic processes can lead to typical consequences of heat stress including hormonal changes, lower fertility, and lower milk yield (Johnson, 1987). Some milk characteristics also degrade. In particular, decreases in cheese-making qualities, such as titratable acidity and coagulation properties are observed (Cappa et al., 1989; Vazhapilly et al., 1992). Several behavior modifications in response to heat stressing conditions have been observed in dairy cattle. In freestall barns, cows stay inside during the hottest hours of the day to obtain shelter from intense solar radiation. During the night, cows go outside. During warm summer Article has been reviewed and approved for publication by the Structures & Environment Division of ASAE. The authors are Ermes Frazzi, Associate Professor, Agricultural Engineering Institute, Faculty of Agricultural Sciences, Luigi Calamari, Associate Professor, Institute of Animal Production, and Ferdinando Calegari, Researcher, Agricultural Engineering Institute, Faculty of Agricultural Sciences, Università Cattolica del Sacro Cuore, Piacenza, Italy; and Luigi Stefanini, Research Farm, Vittorio Tadini, Gariga di Podenzano, Piacenza, Italy. Corresponding author: E. Frazzi, Università Cattolica del Sacro Cuore, Istituto di Genio rurale, Via Emilia PSE 84, Piacenza, Italy, phone: , fax: , <genrur@pc.unicatt.it>. weather, cattle tend to abandon freestalls to lie outside the barn (Arave and Albright, 1981), especially at night. During the day, cows often lie down in dark damp passages rather than in the freestalls (Frazzi and Calamari, 1993). Under heat stressing conditions, the cows spend a considerable part of the day standing rather than lying down (Igono et al., 1987). The percentage of cows resting or ruminating in the standing position has been observed to increase linearly as temperature increased (Shultz, 1984). By standing, cows maximize evaporation from body surfaces and benefit from convection due to wind. In hot weather, the percentage of cows drinking water or lingering around the trough without drinking was observed to be greater for unshaded animals than for shaded animals (Shultz, 1984). Cows under heat stressing conditions reduce dry matter intake and decrease the frequency of eating activity during the day and increase such activities during the evening, nighttime, and early morning hours (Schneider et al., 1988). Another very important point concerns cows behavior changes when the surroundings undergo a change. To know how animals react in these circumstances is quite important in order to correctly design and operate both the barn and the ventilation and cooling systems. Research on dairy barn environmental modification under heat stress conditions has demonstrated the positive effect on cow performance of microclimatic interventions such as forced ventilation (Calamari et al., 1994; Frazzi et al., 1997), ventilation with misting and ventilation with sprinkling (Bucklin et al., 1991; Lin et al., 1998; Turner, 1998), and cooling (Frazzi et al., 1998a). However, none of these studies investigated animal behavior to show animal preferences. To answer these questions of cow behavior, a trial was carried out to evaluate the behavior of dairy cows in summer in relation to the environmental conditioning system (fans with or Transactions of the ASAE VOL. 43(2): American Society of Agricultural Engineers / 00 /

2 se 1699 ms 7/9/01 7:31 AM Page 388 without misting), physiological parameters, milk yield, and milk traits. MATERIAL AND METHODS A study was carried out with 42 Italian Friesian cows raised in an experimental freestall barn located in the Po Valley (10 km south of Piacenza, lat N, long E). The barn had freestalls in the rest area and the building was partially open. The largest side (exposed to the west) was completely open to an unshaded paddock, while the other was half closed by a masonry wall. The barn housed a total of 100 lactating cows. The 42 cows used for the trial were in an intermediate phase of lactation. Average days in milk were 145 with an Figure 1 Barn layout. 388 TRANSACTIONS OF THE ASAE

3 se 1699 ms 7/9/01 7:31 AM Page 389 average milk yield of 34 kg/cow/day at the beginning of the trial. The animals were divided into three groups of 14 cows each. Cow selection was based on days in lactation, calving number, and milk yield. The three groups were housed in three pens with different environmental conditioning systems (fans or fans with misting). The first group was used as a control (C), the second group was placed in a pen with fans (V), and the third group was placed in the pen with fans plus misting (VS). The V and VS areas were equipped with axial flow fans (0.735 kw; 125 cm diameter; m 3 /h maximum airflow rate) installed in the east side along the feed passage (fig. 1). The fans were spaced 3 m apart on either side of the drive-through feed alley and positioned to provide airflow in the direction of the prevailing winds. The fans were mounted at a height of approximately 2.5 m and angled downward at about 10 from vertical. The variable speed fans were thermostatically controlled and were switched on at 25 C and reached maximum flow rate at 28 C. A set of two misters (VS) was mounted on each fan. Each mister had a delivery rate of 18 L/h at 750 kpa. The misters were placed in front of each fan (1 m and 6 m from the fan) at a height of approximately 2.5 m. The misters operated on an 8-min cycle activated at 27 C (6 min of misting and ventilation followed by 2 min of ventilation alone). The study was started at the beginning of June and was concluded at the beginning of September. The environmental conditioning system was switched on at the end of June and was switched off at the beginning of August. During the trial, data were collected dealing with: Microclimatic parameters (temperature, relative humidity, and air speed) inside and outside the barn. The microclimatic parameters inside the barn were measured with electronic probes located at cow height in different areas within the three pens and connected to a data logger programmed to record every 10 min. Cow behavior with use of video cameras and automatic photo cameras placed in different areas of the barn such as feeding areas, resting areas, and external paddocks. Observations were made during four days before the hottest period and eight days during the hottest period. Physiological parameters (rectal temperature and breathing rate) were measured weekly in the afternoon (1630 h). Milk yield and some milk traits, from the afternoon milking, after physiological measurements were recorded. A representative sample was collected from the afternoon milking (1400 h) and analyzed within 1 h for ph, titratable acidity, and rheological Figure 2 Maximum daily air temperature and minimum relative humidity for the control group. Figure 3 Hourly average temperatures measured inside the barn during hotter period (21-27 July 1995). VOL. 43(2):

4 se 1699 ms 7/9/01 7:31 AM Page 390 parameters. Milk yield from the morning milking (0230 h) was also measured. The physiological parameters, milk yield, and milk characteristics results were statistically analyzed with the GLM (General Linear Model) procedure of SAS (1988) using covariance analysis with the preliminary period values as covariates. The factors used were environmental conditions, period, cows within environmental conditions and the interaction between environmental conditions and period. There were three levels, natural ventilation (C), fans (V), fans and misting (VS), of environmental conditions. The three levels of the period factor were: preliminary period (B) before 1 July, with ventilation and cooling systems switched off; experimental period (D), in the period of maximum heat stress (21 and 27 July) with the environmental conditioning system switched on; and Figure 4 Hourly average relative humidities measured inside the barn during hotter period (21-27 July 1995). Figure 5 Standing cows in the paddock during hotter period in summer TRANSACTIONS OF THE ASAE

5 se 1699 ms 7/9/01 7:31 AM Page 391 post-experimental period (A after 15 August with ventilation and cooling system switched off). The results relative to cow behavior were analyzed with a chi square analysis. RESULTS Air speed values measured at a height of 2.5 m in the pen with fans and in the pen with fans and misting (fig. 1) ranged from 0.5 to 2.5 m/s with a mean value of 1.7 m/s. At cow level, the air speed dropped to a mean value near 0.8 m/s with values higher than 1 m/s in the feeding area and in the freestalls near to the feeding area. Our previous trials indicated that significant reduction of heat stress was obtained with air speeds of 0.8 to 1.0 m/s that are obtainable with relatively simple and inexpensive ventilation equipment (Frazzi et al., 1998b). Beyond this limit there were further improvements, but the cooling effect was reduced (Frazzi et al., 1998b). The behavior of maximum temperature and minimum humidity inside the barn for the control group (fig. 2), measured on the days when cow physiological parameters were measured and milk samples were collected, indicated that the microclimatic conditions during the summer season studied were not extremely hot. The last 10 days of July was the hottest period. During this period (from 21 July to 27 July), mean daily maximum temperature reached at 1700 h, was 31.5 C and the daily minimum temperature Figure 6 Standing cows as a percentage of total cows in rest area during hotter (top) and cooler period (bottom) in summer VOL. 43(2):

6 se 1699 ms 7/9/01 7:31 AM Page 392 reached at 0600 h was 22.2 C (fig. 3). The behavior of microclimatic conditions during this hottest period was similar in all the pens except for the pen equipped with fans and misters which showed a lower increase of temperature during the day (maximum value of 30.9 with respect to 31.7 C for other two pens). Small differences were also observed for relative humidity during this hottest period (fig. 4). The minimum value, reached at 1700 h, was 57% in the pen with fans and misters with respect to 54% for the control. In all pens, the relative humidity reached values above 90% at 0600 h, when the temperature reached minimum values. The results from observations of cow behavior confirmed that the cows in all treatments stayed inside the barn during the hours of the day when solar radiation was high. The temperature was lower in the barn, but the humidity was higher and the air movement was very low in the pen without fans. It seemed that the solar radiation load dominated as compared to other microclimatic parameters. Our results showed that if solar radiation exceeded 500 W/m 2 the cows preferred to stay inside the barn both in the morning and in the afternoon. In the afternoon, a small percentage of animals preferred to stay outside the barn for a period of time (fig. 5). This was probably due to a less favorable microclimate in the building. The presence of fans, with or without evaporative cooling, modified cow behavior from that observed in the control group with increased animal presence in the paddock during the hotter hours of the day (fig. 5) when fans were used. Around 10 to 15% of cows in the paddock were observed in the area with misters during the hotter hours from 1000 h to 1900 h. Cows left the barn and stayed in the paddock for a few minutes (maximum min) and then returned inside the barn. The fact that the cows, after being wetted, went out in the paddock to dry in the sun could have negative implications, because water evaporation from the skin, instead of removing body heat, occurs using solar energy. This phenomenon, that for this study was limited, was much more evident in a previous test conducted during the summer 1994; one of the three sections was treated only with showers without forced ventilation. The number of animals present in the paddock during the day was larger, and performances were not improved. In these examples, the paddock s presence could counteract the results obtained inside the barn. This point must be attentively considered. Cows with white-colored coats stayed in the paddock longer. Other studies (Goodwin et al., 1997) have shown a preference by white-coated cows for unshaded areas compared to areas below an iron roof. The cows that were cooled by fans only stayed inside the barn in the morning until the first hours of the afternoon and then crowded in the paddock in the late afternoon. Ventilation without misting when air temperature and humidity were high was avoided by the animals and they preferred outside conditions in the late afternoon. It is known that cows under heat stressing conditions spend a considerable part of the day standing rather than lying down. The data shown in figure 6 confirm this, with a higher number of cows in standing position during the hotter period as compared to the cooler period. Animals in the feeding area were not included in the count of standing cows. These results indicate that the higher percentage of standing animals is due to thermal stress (fig. 6). The different behavior of cows in the areas with different environmental conditioning systems was interesting. The differences, often statistically significant, indicated a higher number (especially in the afternoon) of standing animals in the pen without fans with respect to those in conditioned pens (table 1). In the pen with fans and misting, the number of standing animals was lower with respect to the other areas. The higher time spent standing for C group s cows can be explained by the cows greater difficulty of maintaining body temperature. In this group, during the hotter period mean rectal temperature in the afternoon was 39.5 C compared to values lower than 39 C (P < 0.05) of the other two groups (table 2) and mean breathing rate was 94/min with respect to 78/min of V group and 70/min of VS group (P < 0.05). Similar results were found from the data concerning the cows lying in the freestalls (fig. 7). The presence of cows in the freestalls was lower in control group with respect to the others, both in the cooler and hotter period (table 1). In the hotter period, a reduction of lying cows in the freestalls was observed in VS and V group. In the C group, the Table 1. Standing cows in rest area and lying cows in freestalls during cooler period (Pre) and hotter period (Hot); cows raised in pen without (C) or with fans (V) in control group (C), or fans and misters (VS) Hour of the Day Pre Hot Pre Hot Pre Hot Pre Hot Cows lying V AB A 54 * 26 A A A in freestalls VS 51 * 36 A B 61 * 41 B B 49 * 31 B (%) C 35 * 49 B AB AB AB AB Standing in V B AB AC AB B A Rest area VS AB 32 * 14 A B (%) C A 13 * 24 B A 14 * A 29 B AB A A 9 * 21 B * = P < 0.05: differences between Pre and Hot. AB = P < 0.05: differences between groups. Table 2. Least squares means (covariance analysis) of selected physiological and milk parameters of dairy cows belonging to the control (C), fans (V), and fans plus misting (VS) group, in the preliminary (Pre), hotter (Hot), and after hotter (Post) periods* Parameter Period C V VS MSE Rectal temperature ( C) Pre A A Hot B c B b 38.6 a Post A A Breathing rate (n/min) Pre B 59 B 54 B Hot C 94 c C 78 b C 70 a Post A 37 A 37 A 42 Milk yield (kg/d) Pre B 34.1 B 33.8 B Hot A 29.0 A 29.6 A 29.4 Post A 28.1 A 29.8 A 28.7 Milk acidity ( SH/50mL) Pre Hot Post Milk rheologycal parameters Clotting time (min) Pre A 19.4 B 19.0 A Hot B 24.1 B 22.7 B 21.9 Post A 19.2 A19.0 A 20.6 Curd firmness (mm) Pre B 21.1 B 22.2 B Hot A 10.4 A 14.4 A 15.0 Post B 22.1 B 23.3 B 21.6 * Measurements were performed in the afternoon. The means on the rows without common superscripts (right) are significantly different for P < The means on the columns with common superscripts (left) are significantly different for P < TRANSACTIONS OF THE ASAE

7 se 1699 ms 7/9/01 7:31 AM Page 393 Figure 7 Lying cows in freestall as a percentage of total cows during hotter (top) and cooler period (bottom) in summer values were unchanged in the afternoon, but during the morning an increase of cows lying in the freestalls was observed. This behavior could be due to the higher time spent during the hottest hours of the day standing rather than lying down for C group s cows. This also indicates that during the morning, after feed distribution, the cows of C group left the feed area quicker and stayed in the freestalls. This behavior can reduce dry matter intake which lowers metabolic heat production but has negative effects on the satisfaction of cows requirements for maintenance and production and on milk yield and quality. During the hottest period, the smallest milk yield reduction and the best milk characteristics were recorded for the cows housed in the pens with fans and with fans and misting (table 2). In particular, the cheesemaking properties were positively influenced. Clotting time (lower values indicate better characteristics) and especially curd firmness (higher values indicate better characteristics) worsened to a lesser extent during hottest period in V and VS with respect to C group. These results are similar to previous trials (Calamari et al., 1994; Frazzi et al., 1997). The results are consistent with observations of cow behavior. Cows spent longer periods of resting time in the feeding area and in the freestalls, and showed overall behavior similar to that of cooler periods (table 3). Some cows also lay in the wet dirty areas of the pens or crowded in the well-ventilated portion of the areas. Our results confirm the usefulness of VOL. 43(2):

8 se 1699 ms 7/9/01 7:31 AM Page 394 Table 3. Presence of dairy cows in different areas (percentage) for control (C), fans (V), and fans plus misting (VS) group in the afternoon hours (from 12 pm to 18 pm) during hottest period Parameter (%) C V VS Cows in the freestalls 40 ab* 37 a 46 b Cows in the passage areas Cows in the paddock 17 a 26 b 17 a Cows feeding * a, b = P < 0.15: differences between groups. using an adequate environmental modification system when constructing barns in a warm climate. CONCLUSIONS The data on the behavior of milking cows under heat stressing conditions demonstrated a correspondence between performance and behavior of cows in areas of a barn with different environmental conditioning systems. The presence of misting induced the animals to use a paddock in the daytime, despite a strong solar radiation load. This reduced the concentration of animals inside the barn with an improvement of the microclimatic conditions. The best results (rectal temperature, breathing rate, milk yield, and milk characteristics) were observed in the hottest period for cows housed in pens with environmental conditioning systems (fans with or without misting). These results were consistent with the behavior of the cows in experimental pens. Cows spent longer periods of resting time in the feeding and freestall areas and showed overall behavior similar to that observed during cooler periods. Our results confirm the usefulness of installing adequate equipment for environmental modification in barns in a warm climate. ACKNOWLEDGMENT. This research was supported by a grant from the Italian M.U.R.S.T. 40% and from Emilia- Romagna Region (with the operational coordination of C.R.P.A.) REFERENCES Arave, C. W., and J. L. Albright Cattle behavior. J. Dairy Sci. 64(6): Bucklin, R. A., L. W. Turner, D. K. Beede, D. R. Bray, and R. W. Hemken Methods to relieve heat stress for dairy cows in hot humid climates. 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Vazhapilly, P., L. Calamari, E. Frazzi, A. Azzoni, and V. Cappa Effect of heat stress on cheese making quality of milk from dairy cows raised in Po valley. In Proc. CIGR Environmental and Energy Aspects of Livestock Housing, Polanica (Wroclaw), Poland, Polanica, Poland: CIGR. 394 TRANSACTIONS OF THE ASAE