Heated Drinking Water for Dairy Cows?

Transcription

1 Agrartechnische Forschung 6 (2000) Heft 4, S. E 97-E 101 E97 Heated Drinking Water for Dairy Cows? Jürgen Beck 1, Daniela Katzschke 1 and Herbert Steingaß 2 1 Universität Hohenheim, Institut für Agrartechnik, Stuttgart 2 Universität Hohenheim, Institut für Tierernährung, Stuttgart Recently, dairy farmers and manufacturers repeatedly claimed that heated drinking water could improve feed intake, milk yield, and animal health, especially in high yielding dairy. This was the reason for an examination (4 trial periods) which was carried out at the Experimental Station for Livestock Biology and Ecological Farming of the University of Hohenheim. The influence of heated drinking water (24 C, 17 C, 24 C) was compared with the effect of cold water with a constant temperature of 3 C using feed- and water intake, milk yield, milk constituents, and drinking behaviour as examination parameters. The trials yielded the following results: - daily intake of roughage and concentrate feed - not influenced; - daily water intake - significant influence in some cases (more cold water was drunk); - total daily drinking duration - significantly longer for cold water, slower intake; - daily milk yield (FPCM) - insignificant tendency towards higher milk yield with cold water; - milk fat content - insignificant tendency towards higher values with cold water; - live body mass - not influenced; - selection trial: 94.4% of the daily water intake in the form of warm water - reduced excess heat of the high yielding dairy cow with cold water. Therefore, heating the drinking water for dairy to 17 C or 24 C in order to increase the milk yield does not make sense. Furthermore, heating to 24 C must be expected to require a converted 2.4 kwh/cow*day. This corresponds to daily electricity costs of approximately DM 0.54/cow*day, which could be compensated for through a yield increase of about one litre per day, which, however, was impossible to realize. If the only goal is to guarantee frost-free water supply, more cost-efficient solutions certainly offer themselves. Keywords Drinking water, warming, dairy cattle, feed intake, milk yield, milk fat content, behaviour, economic feasibility The Problem Lately, farmers and drinker manufacturers have repeatedly expressed the opinion that heating the drinking water for high yielding dairy leads to higher feed intake and positive effects on the milk yield and animal health. Numerous studies were already conducted in the past (from 1951 until 1990) to examine the effects of different drinking water temperatures on the performance of ruminants [1,2,3,4,5,6,7,8,9,10].However,some of the results were rather contradictory. With the aid of precise methods of measurement value registration, this current question was therefore addressed in four periods of trials conducted at the Experimental Station for Livestock Biology and Ecological Farming of the University of Hohenheim in cooperation with the Institute of Animal Nutrition in Hohenheim. During these trials, the influence of heated drinking water was examined in comparison with constantly cold water using feed- and water intake, milk yield, and drinking behaviour as parameters. Trial Animals and Methods In three trials (V1, V2, V3), the test group was offered warm water (24 C, 17 C, 24 C), and the data were compared with those of the control group, which was always given 3 C cold water. The trials were carried out in the form of an alternating trial lasting 2 x 4 weeks. The fourth trial was conducted as a three-week free choice trial (V4) where the animals were able to choose freely between a water temperature of 3 C and 24 C. The error probability in the statistical evaluation was always = All trials were carried out at the Experimental Station for Livestock Biology and Ecological Farming of the University of Hohenheim ( Meiereihof ). A maximum of 20 dairy of the race German Holstein-Friesian (Black Pied) with an average milk yield of more than 25 kg took part in the trials. The animals were kept in an outdoor climate stall (cubicle House with free stalla without bedding, equipped with matresses, slatted floor), milked twice a day in a 2x3 auto-tandem milking parlour, and fed an enhanced roughage mixture plus additional concentrate feed at 2 automatic feed dispensers. Important components of the roughage mixture included maize silage, grass silage, haylage, second-cut hay, supplementary feed, and soy bean meal. The dry substance- and energy content (in the dry matter (dm)) of the ration was 47.1% and 5.7 MJ NEL in the first trial, 46.2% and 5.6 MJ NEL in the second trial, 41.6% and 5.6 MJ NEL in the third trial, and 42.7% and 5.5 MJ NEL in the free choice trial. The concentrate feed contained 8.3 MJ NEL/kg of dry matter (dm). The food was dispensed individually depending on the milk yield. Roughage performance was assumed to be 9 kg of milk. The feeding places were designed as single troughs with a computer-controlled trough flap, which rested on precise weighing bars (+/- 10 g) and were equipped with transmitter-receiver units for the collar responders (figure 1). This allowed the feed intake data of each individual animal to be registered. Individual drinking water intake was esta-

2 E98 blished in the same way. Due to the computer-controlled individual access permission for a certain drinker, a spatial separation of the trial- and the control group was not necessary. The water in the storage drinkers (capacity: approximately 130 l) was warmed up with a heating element (3 kw) or cooled with a submerged milk cooler. In addition to the feed- and water intake, the live body mass of the animals and the milk yield were registered automatically every day. The milk constituents were analyzed once a week. Furthermore, the electricity consumption of the warm water drinker was registered. Weather data were provided by the Institute of Physics and Meteorology of the University of Hohenheim. J. Beck, D. Katzschke and H. Steingaß (V2) showed that more cold than warm water was drunk (67.04 l vs l and l vs l). In the third trial (V3) (figure 2), however, the difference was significant: l of cold water vs l of warm water. The number of drinking processes per cow and per day ranged between 7.50 and In all trials, the daily drinking duration per animal was significantly higher if the water was cold: vs min. (V1), vs min. (V2), and vs min. (V3). Except for the third trial (V3), the amount of water taken in per drinking process was not significantly different even though more cold water was drunk (8.57 vs l in V1, 9.21 vs l in V2, and vs 8.16 l in V3). Hence, cold water was drunk significantly more slowly than warm water. In the three trials, the drinking speed varied between 3.53 and 4.01 l/min of cold water and 4.53 and 5.35 l/min of warm water. With regard to the milk yield, no significant differences were established at the different water temperatures in all trials. This is shown in figure 3 using the comparison between 3 C and 17 C as an example. However, the milk yield tended to be higher when the water was cold than when it was heated. The milk fat content also showed an increasing tendency if the water was cold, in contrast to warm water (table 1 and figure 4). The milk protein content, however, remained uninfluenced. The live mass of the animals was not influenced by the drinking water temperature in the individual trials. The mean minimal/maximal temperatures of the outside air amounted to 3.7 C /12.2 C in V1, 10.5 C/20.4 C in V2, and -0.9 C/5.0 C in V3. The free choice trial (V4) clearly showed that if the were given free choice of the drinker and, hence, of the water temperature, they exhibited a statistically significant preference for the heated drinking water. They covered 94.4% of their water requirement with 24 C warm water. Figure 1: Integration of the heated storage drinker into the weighing system and the data aquisition of the experimental unit for the registration of roughage intake (experimental station for livestock biology and ecological farming "Meiereihof") Wasseraufnahme water intake [l/d] C 24 C Figure 2: Water intake per cow and day at 3 C and 24 C (whole herd, V3) 29 Results In none of the three trials were significant differences ( = 0.05) in roughage and/or concentrate feed intake established between the two water temperatures. During an average of 46 eating periods per day, to kg dm of roughage per cow was taken in, which took between 2.98 and 3.55 h. During one eating period, one cow ate between 0.27 and 0.32 kg dm. Depending on the milk yield, 6.3 to 7.6 kg dm/d*animal of concentrate feed were eaten. Only in some cases was the water intake significantly influenced by the water temperature. As a tendency, trial 1 (V1) and 2 Tägliche Milchleistung daily milk yield [kg FECM/d] C 17 C Figure 3: Daily milk yield at 3 C and 17 C (whole herd, n = 18, V2)

3 Agrartechnische Forschung 6 (2000) Heft 4, S. E 97-E 101 E99 Out of a total average of l/d, only 3.85 l were drunk from the cold drinker. When evaluating the drinking behaviour over the course of the day, two main drinking periods after milking were determined. Between 12 a.m. and 6 a.m., the number of drinker visits per hour diminished continuously. During the two main visiting periods (6 h altogether), the herd drank 41.57% of the total daily water quantity. During the visit peak in the afternoon, more water was drunk than during the morning peak. During the free choice trial, the mean maximal temperature of the outside air amounted to 21.8 C, and the mean minimal temperature was 12.2 C. Discussion In all three trials, the amount of daily feed intake proved not to be influenced by the water temperature (table 2). The differences can rather be explained with the different milk yield: the rounded average daily milk yield amounted to 25 kg (V2), 27 kg (V1), and 29 kg (V3). If the roughage intake is considered, values prove to be relatively constant. Concentrate feed was dispensed depending on the milk yield. Therefore, the quantity taken in during the three trials differed. The higher total feed intake in trial 1, which exceeded feed intake during trial 2 by approximately 0.7 kg dm/d, is mainly caused by the higher concentrate feed intake because the animals ate about 7% more concentrate feed and only approximately 2.5% more roughage. Trial 3 (V3) is an example of roughage replacement. Total feed intake during V3 is about the same as during V1, but roughage intake is approximately 0.8 kg dm lower. It is well known that the thermoneutral range of dairy shifts downwards as the milk yield increases. Due to the high metabolic turnover, a large amount of excess heat is generated, which must be dissipated. This puts strain on the animal and affects the energy budget, especially since certain mechanisms of heat dissipation also consume energy (e.g. panting, increase of blood circulation). Water has high heat capacity and is therefore very appropriate for heat dissipation or the cooling of a body. The heat quantity absorbed by the water can be calculated as follows: Water quantity/d in [l] * T * = heat quantity/d absorbed by the water in [kj] (1). In this equation, T is the difference between the body temperature (which is assumed to be 39 C) and the drinking water temperature. Milchfettgehalt milkfatcontent[%] 4 3,95 3,9 3,85 3,8 3,75 3,7 3,65 3,6 3, C 24 C Table 1: Milk yield and fat content depending on the drinking water temperature Trial (drinking water temperature) Number of FPCM (kg) In the following Table 3, the values for the three trials were established. It becomes clear that the cold water absorbs twice as much heat per day as the warm water. Depending on the milk yield, the daily heat release of a dairy cow can roughly be calculated using the following formula according to [11]: H=Me m +ME 1 -NEL 1*milk yield [kg/d] (2) Cold water Milk fat content (%) Figure 4: Development of the milk fat content at 3 C and 24 C (whole herd, n = 20, V1) FPCM (kg) Warm water Milk fat content (%) V1 (3 / 24 C) V2 (3 / 17 C) V3 (3 / 24 C) Table 2: Influence of water temperature on roughage and concentrate intake with different milk yield for all of the three trials Trial 1 Trial 2 Trial 3 Water temperature 3 C 24 C 3 C 24 C 3 C 24 C Milk yield [kg/d] Roughage [kg TS/d] Concentrate feed [kg TS/d] Roughage + conc. feed [kg TS/d] where: H = daily heat generation in MJ/d Me m = energy requirements for preservation from convertible energy (ME): 0.48 MJ/W 0.75 ME 1 = energy requirements for milk production: 5.3 MJ/kg FPCM NEL 1 = energy content of the milk: 3.17 MJ/kg FPCM. Heat release will be calculated using the first trial as an example. On average, the animals weighed approximately 620 kg. Table 3: Heat capacity of the daily incorporated drinking water and absorbed heat (cooling effect) Body temperatur Water temperatur Daily water intake Heat capacity Absorbed heat [ C] [ C] [l/d] [kj/l] [kj] V V V V V V

4 E 100 This corresponds to a metabolic live weight W 0.75 of 124 kg. The milk yield was about 26 kg FPCM. If these values are put into equation (2), the resulting daily heat generation amounts to: H H = 0.48 MJ/kg * 124 kg + (5.3 MJ/kg FPCM-3.17 MJ/kg FPCM) * 26 kg FPCM = MJ. In the thermoneutral range, however, only MJ/kg W 0.75 arerequiredtomaintain the body temperature. In this case, this would be approximately 36 MJ/d. The difference between the generated and the required heat quantity is excess heat: 79 MJ/d. In V1, about 12.8% of the excess heat could have been dissipated by the heat quantity of 10.1 MJ/d absorbed at a water temperature of 3 C without the animal having to employ thermoregulation mechanisms. At a water temperature of 24 C, this value would amount to only 5.3%. For the dairy cow, cold drinking water could thus facilitate the dissipation of excess heat and reduce the metabolic load. The animals do not seem to register this rather positive effect of the cold water directly. At least they seem to be aware of the pleasanter feeling when drinking warm water because they clearly (94%) preferred it when given free choice (V4). Water was drunk during two main visiting periods after milking in the morning from 7a.m.until10a.m.andintheevening from 5 p.m. until 8 p.m. It is well known that feed intake also follows a circadian rhythm. The main eating periods coincide with the main drinking periods observed here, which allows the conclusion to be drawn that the drinking periods of cattle are closely linked to feed intake. During the main drinking period, which comprises a total of 6 hours, approximately 42% of the total water requirement of the herd was covered. In addition, the animals showed significant individual differences in drinking water intake. The differences in the daily milk yield between cooled and heated drinking water were not significant in any of the three trials. They are consistent with the results in reference [10]. However, the milk yield tended to be higher if the water was cold. Cold water also resulted in a slightly higher milk fat content than warm water. ANDERSSON (1984), however, established a significantly (p<0.001) higher milk yield if the water was heated to 17 C (26.33 kg FPCM/d) as compared with 3 C cold water (25.39 kg FPCM/d) [1]. At a water temperature of 24 C, the milk yield was kg FPCM/d. The average stall temperature was 15.3 C. She considered the energy budget of the animal to be the J. Beck, D. Katzschke and H. Steingaß reason for the fact that the yield is higher if the water is heated: more energy is required to heat cold water to body temperature than warmer water. At 17 C, the excess heat could have been sufficient for this purpose, while at 3 C additional feed energy could have been necessary which would no longer have been available for milk production. However, the calculation of heat production in the present study shows that considerably more excess heat is generated in the animal than would be required to heat the cold drinking water. It is therefore unlikely that feed energy must be used for this purpose. Instead, it would rather be conceivable that the cold water reduces the strain on the cow s metabolism and that therefore the milk yield tends to be higher than if the water is warm, as the trials presented here indicate. The animals did not eat more, but they gave slightly more milk. This might have been caused by an energy saving effect of the cold water, especially since, as mentioned above, some thermoregulation mechanisms require energy. Milk quantity and, in particular, the milk fat content are decisively influenced by the fermentation conditions in the rumen. Volatile fatty acids are formed there such as acetic acid, butyric acid, and propionic acid. Acetic acid, which is particularly important for milk fat synthesis, is mainly produced by fibrolytic bacteria. Empirical observations have shown that these bacteria are more susceptible to too high temperatures than amylolytic species. Due to the cold drinking water, the average rumen temperature could be slightly lower and thus provide more favourable conditions for fibrolytic bacteria. In addition, the cold water first collects at the bottom of the rumen after drinking. The amylolytic bacteria species, which digest the concentrate feed, are more towards the bottom of the rumen together with the small feed particles and must cope with greater temperature fluctuations due to the cold water. For this reason, their activity could be restricted, while the fibrolytic species, which mainly live in the fibre layer in higher parts of the rumen, could profit from relative advantages at more constant temperatures. These temperature conditions probably contributed to the slightly higher milk fat contents when the water was cooled. Furthermore, it was noticed that during a trial the fat content increased slightly when the drank cold water, while it diminished a little when the water was heated. This points to shifts in the microflora and the propagation of fibrolytic bacteria during the trial [12]. In summary, it can be said that heating drinking water for dairy in order to achieve higher yields does not make sense because no statistically significant changes have been established. At an assumed basic milk price of DM 0.55/kg, the yield of a cow would have to grow by approximately 1 kg/d depending on the outside temperature and the desired water temperature just to cover the electricity costs. In the third trial, the average maximal outside temperature was 5 C while the water temperature amounted to 24 C. This led to an electricity consumption of 2.4 kwh per animal and per day. This corresponds to electricity expenses of DM 0.54/animal and day (DM 0.22/kWh). The only reasonable use for a heated drinker is to prevent freezing. However, more favourable solutions to this problem are probably available. According to the results of this study, care should rather be taken to make sure that even under our climatic conditions the drinking water for the animals remains cool and is supplied fresh. Since today the water in the dairy houses usually comes from the tap and rarely from sources that are easier to heat up such as tank wagons or trough drinkers on the pasture, this generally does not pose any problem. Even in the summer, tap water remains cool and fresh at approximately 10 C. Nevertheless, the present results could be an incentive for further studies on the temperature kinetics of the rumen and its effects on the microflora and the heat budget of the dairy cow. In addition, one can draw the conclusion that heatinsulated storage drinkers may also be advantageous in the summer. References Books are indicated by. [1] Andersson, M. (1984) Effects of drinking water temperatures on water intake and milk yield of tied-up dairy In: Drinking water supply to housed dairy Dissertation, Swedish University of Agricultural Sciences, Uppsala, Schweden [2] Baker, C. C., C. E. Coppock, J. K. Lanham, D. H. Nave, J. M. Labore, C. F. Brasington und R. A. Stermer (1988) Chilled drinking water effects on lactating Holstein in summer. Journal of dairy science, 71: [3] Cunningham, M.D., F. A. Martz und C. P. Merilan (1964) Effect of drinking-water temperature upon ruminant digestion, intraruminal temperature and water consumption of nonlactating dairy Journal of dairy science, 47: [4] Himmel, U. (1964) Der Einfluß von temperiertem Tränkwasser auf Milchmenge und Fettgehalt bei Kühen Tierzucht, 18 (3):

5 [5] Ittner, N. R., C. F. Kelly und H. R. Guilbert (1951) Water consumption of Hereford and Brahman cattle and the effect of cooled drinking water in a hot climate Journal of animal science, 10: [6] Lanham, J. K., C. E. Coppock, K. Z. Milam, J. M. Labore, D. H. Nave, R. A. Stermer und C. F. Brasington (1986) Effects of drinking water temperature on physiological responses of lactating Holstein in summer Journal of dairy science, 69: [7] Lofgreen, G. P., R. L. Givens, S. R. Morrison und T. E. Bond (1975) Effect of drinking water temperature on beef cattle performance Journal of animal science, 40 (2): [8] Milam, K. Z., C. E. Coppock, J. W. West, J. K. Lanham, D. H. Nave, J. M. Labore, R. A. Stermer und C. F. Brasington (1986) Effects of drinking water temperature on production responses in lactating Holstein in summer Journal of dairy science, 69: [9] Stermer, R. A., C. F. Brasington, C. E. Coppock, J. K. Lanham und K. Z. Milam (1986) Effect of drinking water temperature on heat stress of dairy Journal of dairy science, 69: [10]Wilks, D. L., C. E. Coppock, J. K. Lanham, K. N. Brooks, C. C. Baker, W. L. Bryson, R. G. Elmore und R. A. Stermer (1990) Responses of lactating Holstein to chilled drinking water in high ambient temperatures Journal of dairy science, 73: [11] Menke, K.-H. (1987) Richtzahlen für die praktische Fütterung In: Tierernährung und Futtermittelkunde, Verlag Eugen Ulmer, Stuttgart, S [12]Theodorou, M.K.; J. France (1993) Microorganisms and their interactions. In: Qantitative Aspects of Ruminant Digestion and Metabolism. J. M. Forbes and J. France, Eds., CAB International, 1993 Agrartechnische Forschung 6 (2000) Heft 4, S. E 97-E 101 E 101 Authors Dr. Jürgen Beck Dipl.-Ing. agr. Daniela Katzschke Universität Hohenheim Institut für Agrartechnik (440) Stuttgart Tel.: +49/(0)711/ Fax: +49/(0)711/ jafbeck@uni-hohenheim.de Dr. Herbert Steingaß Universität Hohenheim Institut für Tierernährung (450) Stuttgart Tel.: +49/(0)711/ steingas@uni-hohenheim.de