This article is written at the end of July, the hottest part of the year here in Israel, when every return home from abroad is first accompanied by going to the fridge to drink a lot of cold water. I decided that this is the right time to write about the importance of water in the dairy farm, especially for those located in warm regions. The issue of water in the dairy farm is an essential element in achieving milk yield, production efficiency and high profitability, especially in the warm regions of the world. However, even though water is a relatively cheap ingredient, the issue of its use is still not adequately addressed, compared to the other food topic. In this article, I intend to bring to the attention of those involved in the dairy industry in warm regions, the importance of water for achieving high milk yields and good profitability, this in all regards to drinking water, as well as water used to cool the cows.
Let’s start with the fact that in most of the farms, dry matter consumption per cow is monitored daily (on a herd basis and sometimes on a group basis). How many dairy farms monitor cows’ water consumption like this? There is no doubt that such monitoring may help detect malfunctions in the feeding and management practices, and taking practical steps to ensure that water consumption does not limit cows’ comfort and health, and does not harm cows’ milk production and fertility. This is true for all the farms, but especially for those located in warm regions. Under conditions of thermal comfort, about 70% of the water consumed by the cow is drinking water and the rest is consumed through food. In warm climates, where cows suffer heat stress, of course, the share of drinking water increases from the cows’ normal daily water consumption, a fact that should be taken into account when planning the water supply to the farm.
Heat stress affects the performance of cows, due to impairment of food consumption. Feed efficiency is also affected, following the diversion of part of the energy consumed by the cow to activate the heat relief mechanisms, “at the expense” of milk production. When exposed to heat stress conditions, there is an increase of 30% or more in cows’ water consumption. This increase is due to the fact that heat relief mechanisms includes, among other things, increased evaporation from the cow’s body surface through the skin, the respiratory system through panting and from the urine. Water has an extremely high “heat capacity” which makes it an ideal mean for internal and external cooling of cows. Sufficient access to water and its quality will influence cow’s ability dissipate heat and maintain important biological functions. In order to maintain her “water balance” the cow will reduce the concentration of water in the feces by 25%, will reduce the volume of urine, and correspondingly, will use a significant part of the additional water consumed to increase by 60%, the loss of water in evaporation from the skin and the respiratory system. High yielding cows (40 kg per day and more), consume 115 liters of water per day in temperate climate conditions, and 150 liters per day or more in warm conditions, while increasing the frequency and duration of drinking events along the day.
The recommendation that exists today by the professionals is to provide “water trough space” of 10 cm per cow. In a recent survey conducted in dozens of dairy farms in US and Mexico, including farms located in particularly warm regions, it was found that in most of these farms, “water trough space” per cow was lower than recommended. In large herds and in intensive milk production conditions we often observe aggressive behaviors of dominant cows, including around water troughs. In these conditions, “inferior” and young cows may be harmed, in such a way that their water consumption will be lower than needed, harming their performance. Cow’s stay for long time in sites where there is no access to drinking water, such as the milking center, treatment and insemination sheds, and farm walkways, as well as long “locking” time in the feed line, may worsen the problem. In order to prevent such situations, it is recommended in large dairy farms located in warm regions to add water troughs, installing them also in the waiting yard, treatment yards and on the walkways to the milking parlor. It is recommended that this water troughs space will be in addition to the 10 cm that are generally recommended, and as a general rule, the water trough space should not be less than 15 cm per cow. Needless to say that these water troughs should be shaded and with easy access. Studies shown that dairy cows spend only 20 to 30 minutes a day drinking water, with most of the water consumed after milking and eating time. It is well known that “dominant” cows prefer drinking immediately when leaving the milking parlor, in the water troughs that are located in the walkways. Installing water troughs in this area will reduce the pressure on the water troughs inside the sheds and allow easy access to them as well for the “inferior” cows. Larger water trough space can help ease the bottleneck in accessing water at preferred drinking times and especially under heat stress conditions, where, as mentioned, the demand for water is greater. In order to achieve maximum water consumption in these conditions, consideration must be given, in addition to the water trough space, also to the depth of the water trough and its filling rate, in such a way that the volume of water during peak drinking times does not decrease. Metal frames must be installed to prevent cows from entering the water trough or secreting into it, and these must be installed in a way that does not limit cow’s access to drinking water.
In order to continuously and systematically monitor cows’ water consumption, it is recommended to install water meters. It is advisable to install these devices in the pipeline that supply water to every group of cows. If this is not possible, it is advisable to, at least install a water meter in the main pipe supplying water to all the farm. Assuming that the amount of water used for cooling and milking is fixed and known, it will be possible to associate any change in the amount of water consumed, to the amount of daily water drank by the cows.
Water quality may have an effect on the amount of water consumed by the cows, especially in warm climate conditions. So, it is recommended to carry out periodic tests of the water in the farm. A high level (above 3,000 ppm) of total dissolved solids (TDS) in the water, may impair the calving performance of the cows. A recently published study showed that cows under heat stress produced more milk, when they consumed water with 900 vs. 3,400 ppm of total dissolved solids. High levels of sulfates and chlorides in drinking water can also impair drinking water and cow performance. High levels of sulfates in drinking water are known to impair the absorption of minerals in cow’s digestive system. Drinking water that is stored in tanks or ponds, the development of algae must be avoided by keeping them in the shade and cleaning them frequently. Different types of algae damage the taste of the water and may reduce its consumption. Frequent cleaning of the water troughs will ensure maximum drinking, a fact that is of course, much more important in warm regions.
And now, let's see the issue of the water to be used to cool the cows in the summer.
Lack of water and its high cost in many parts of the world, lead dairy farmers to avoid incorporating water in cow cooling processes, which is a big mistake that leads to financial loss damage to the environment. The use of fans alone does not allow alleviating the metabolic heat produced by high-yielding cows. A combination of wetting with forced ventilation increases the heat loss from the cows fivefold. It turns out that forced ventilation, which is about 80% of the financial expenditure on cooling (equipment and electricity), contributes to only 20% of the cooling potential that can be obtained from incorporating water in the process. What is particularly frustrating is the fact that avoiding the incorporation of water in the cooling process does not save water for the dairy either. In a study I conducted nearly 40 years ago, as part of my Ph. D thesis, we installed water meters at the entrance to the shed where cooling system was operating, combining wetting and forced ventilation, so, what we measured, was the total water use in this group for drinking and cooling. At the same time, we measured the water consumption in a parallel shed, where the cows of the control group, without cooling treatment were kept, and in which only the amount of water used for drinking was actually measured. At the end of the summer, we found that water consumption was the same in both groups, in other words, the cows in the control group drank the same amount of water that was sprayed on the cows in the “cooling” group, all while the latter ate more and produced more milk.
As shown at the beginning of this article, cows under conditions of heat stress and without cooling may consume between 35 and 50 liters of water more than they should have consumed under conditions of thermal comfort. A recent survey conducted in Italy examined the extent of water use in dairy farms where intensive cooling of cows was applied in the summer, combining wetting and forced ventilation (a cooling procedure similar to that practiced in Israel). The findings of the survey indicated that there is a wide range of the daily use of water for cooling the cows, without this having an effect on the quality of the cooling treatment and the performance of the cows (the summer to winter ratio was similar in farms that used a lot and little water for cooling the cows). The range of water used for cooling in these farms ranges from 20 to 50 liters per cow per day. From the results of this survey, it can be concluded that optimal cooling of cows can be achieved even with wetting to the extent of 20 liters per cow per day, provided that the cooling operation is done intelligently. However, even under conditions where 50 liters of water per cow per day were used, and the use of water for cooling was done with low efficiency, the amount of water sprayed on the cows was less than or equal to the amount of water that the cows would have drunk, if not cooled.
In conclusion, water is a very important factor in the milk production processes, especially when it comes to warm regions. It must be understood that producing milk in warm climate conditions requires the use of larger amount of water, as compared to producing the same amount of milk in temperate climate conditions. Providing sufficient “water trough space” and easy access to water at different farm sites will increase water consumption and contribute to increasing feed consumption and milk production. Evaporating water from cow’s surface through a combination of wetting and forced ventilation is the best and most effective way to cool cows. Evaporation from cow’s surface of the same amount of water that the cows were supposed to drink due to the exposure to heat stress conditions will allow cows produce more milk, with greater production efficiency.