The benefits of cooling cows in the summer

Milk production losses in summer months are generally related to the negative impact of heat stress on cows in lactation and late gestation stages. In the last 4 decades, several studies have been carried out in different parts of the world to mitigate heat through the implementation of cooling systems. In recently published articles, the different benefits achieved by properly implementing these means were presented. Among these benefits can be seen those related to the environment (reducing the negative impact of milk production on the liberation of Methane into the atmosphere), the impact on the welfare of the cows (reducing the time that the cows are stressed and not comfortable) and, finally, the economic benefits (increasing milk production which increases production efficiency and reduces production cost, leaving an additional income for the producer, and perhaps reducing the price for the consumer). This article will present the negative impact of heat stress on the environment, on animal welfare and on farm economic benefits from intensively implementing cooling systems in the summer.

Cooling cows in summer is a common practice used by dairy farmers in Israel for decades and has lately been widely adopted by dairy farmers around the world, especially in hot regions. The increase in cows’ need for cooling is related to both global warming and the increase in cow productivity, leading to an increase in cow heat production and the need for its dissipation. The most common cooling practice in dairies worldwide is based on a combination of wetting and forced ventilation of the cows, usually in the holding pen, before and between milking sessions, and along the feed line. During the summer months, Israeli cows are intensely cooled, receiving a 30-60 minute “cooling treatment” almost every 3 hours, and a total of 6 cumulative hours throughout the day.

A large-scale survey based on data from the “Israel Herdbook” showed that high-yielding cows, properly cooled in the summer, achieved 98.5% of the milk produced by their herdmates in winter, while non-cooled cows reached only 88% of winter production (summer averages are 0.6 and 3.6 kg/day less than winter production averages, in cooled and uncooled cows, respectively). While winter conception rates were similar across farms (~45%), summer conception rates for cooled cows were nearly double compared to non-cooled cows (34% and 16%, respectively). In general, annual milk production from cooled cows in Israel tended to be 5% to 10% higher, compared to non-cooled cows.

Recently, great attention is being paid all over the world to the relationship between the milk production process and the environment. The milk production process in many countries is being examined these days, not only in economic parameters, but also in its emission of greenhouse gases and its contribution to global warming. In this article, the “greenhouse gas emission balance” was calculated for the use of cow cooling practices in Israeli dairy farms, we assume that the same data can fit with many other dairy sectors in the world. In our study, we relate the increase in CO2 emissions to the atmosphere, due to the use of electricity to operate the fans in the cooling process, to the expected reduction in CO2 emissions to the atmosphere, due to the reduction in the number of cows and their emission of methane (CH4), for maintenance. Based on the parameters taken into account in the study, we discovered that by improving production efficiency, related to cooling, and reducing the size of the herd by 5%, to produce the same amount of milk, it will reduce the emission of CO2 in 320 kg / cow / year. This is double what is emitted in the process of operating the fans to activate the cooling system, “saving” an emission of 160 kg of CO2 per cow/year. Should annual production increase by 10% (a common result in many dairy sectors in hot regions), the reduction in CO2 emission will reach 4 times the amount emitted during the cooling process, and the emission to be “saved” will; be of 480 kg of CO2 per cow/year.

In recent publications, we described the high cost-effectiveness of intensively cooling cows in the summer to mitigate heat stress. There is no doubt that cows need intensive cooling in the summer, but does this process and the need to move the cows frequently and have them stay more hours a day to cool down negatively affect their welfare? The “moving” of the cows to the cooling site and the long periods that they remain standing on this site, led Israeli researchers (Honig et al., JDS 2012) to investigate whether such a helping procedure deprives the cows of the required rest. Forty-two high-performance adult cows were divided into two cooling treatment groups, both cooled by a combination of 30 seconds of wetting every 5 minutes and forced ventilation, for 45 minutes per treatment period. One group was cooled 5 times, and a total of 3.75 cumulative hours per day (5T), while the other group were cooled 8 times per day and a total of 6 cumulative hours per day (8T). Through sophisticated equipment, connected to the milking system, milk production, feed consumption, body temperature, as well as resting and rumination time were monitored. The results are described in Tables 1 and 2.

Table 1. Effect of cooling time on the resting and rumination time of the cow.

As expected, increasing cooling time increased feed intake by 2.1 kg DM/d (8.5%) and daily milk production by 3.4 kg/d (9.3%). Body temperature and respiration rate were significantly lower in 8T cows, as compared to 5T cows (0.8 C and 30 less breaths per minute, respectively). Unexpectedly, cows that were severely cooled and forced to stand longer in the “cooling site” lay down for longer time per day. If we exclude the “mandatory waiting time” in cows with longer cooling periods, they were found to lie down almost 10% more during the 24 hours, compared to those with shorter cooling time. Rumination time was also increased by 6% in cows in the longest cooling time group (445 and 415 minutes per day, for 8T and 5T cows, respectively). What we can learn from these results is that intensely cooling high-yielding cows in summer not only improves their productivity, but also improves their welfare. Heat-stressed cows often tend to stand crowded and panting, while cooling cows more often on extremely hot summer days allows them to stay in normal thermal conditions for more hours per day, rest longer and likely, feel more comfortable. In conclusion, dairy farmers need to know that by cooling their cows, they are not only improving the profitability of their farm, but at the same time, improving their welfare. Farmers don’t need to fear from obliging cows to stand more time to be cooled, as this is beneficial for both.

Dry cows are negatively affected when subjected to heat stress conditions. These losses are mainly related to lower milk and milk solids production in late lactation, as well as fertility traits in the early stages of lactation. Heat-stressed dry cows also suffer from a higher incidence of diseases and metabolic disorders after calving (primarily due to reduced cow immune function). All of these changes take place after calving and in the early stages of next lactation, although they do occur in the fall and early winter when heat stress is over. The list of research on dry cow heat stress mitigation is outlined in the table below. As can be seen, in most studies, the positive effect of cooling dry cows on their production in next lactation is compared to cows with only shade.

The benefit of cooling lactating cows will be done through presenting results of a project recently carried out in Mexico. In summer of 2015, we began cooling in a format that combines cooling in the “waiting yard” and in “special cooling yards” of five dairy. By using cooling yards, cows could receive a one-hour “cooling treatment” around each milking session, as well as one hour of cooling, approximately four hours from the end of each milking session. In total, the cows received 6 cumulative hours of cooling per day, combining cycles of wetting and forced ventilation, once every 4 hours, day and night. In this article, I have chosen to present the results obtained 5 years after the beginning of this project, data from the “La Cantabra” dairy farm, where the “cooling principles” described above have been optimally applied, while La Cantabra farm persisted in collecting data until date. In this farm, four adjacent “cooling tunnels” were built in 2015 and have fans of about 2 meters in diameter and wetting system, activated alternately. In two of these tunnels the cows remained before and after each milking session, which allowed the cows to cool (along with what was given in the waiting yard), for an hour at a time. The other two tunnels were used to cool the cows for an hour at a time, and the cows were brought into them between milking sessions. The cows in this farm were cooled for a total of 6 hours a day, and in order to transport the cows to the cooling yards, an additional 6 workers were hired who did it in three shifts, 24 hours a day, all day long. To examine the extent of the effect of cooling the cows on their performance in the summer, we monitored the average conception rate of all inseminations and the average daily production of the cows in different months, for the four years prior to beginning of the project (2011-2014), and comparing them with the six years since the project started (2015 - 2020). The results are shown in figure 1, for conception rate, and figure 3, for milk production, with figure 2, showing the herd’s average “days in milk” in the different months, for the year 2014 (the year before project started) and 2020.

Figure 1. Average conception rate, of all inseminations given in the different months of the years 2011-2014 (before the cooling project started, and in the years 2015-2020, in which it was activated.

In the presented in Figure 1, a significant improvement in conception rate can be seen in the summer months after the implementation of intensive cooling. In the years prior to the beginning of the project, the conception rate began to decline as early as April and returned to its normal level only in December. The conception rate during this period decreased from 40% in winter, to approximately 15% in summer. In contrast, during the period when intensive cooling was implemented, a conception rate of 30% or more was maintained throughout the summer months.

Figure 2. Average “days in milk” in different months of the years 2011-2014 (before the cooling project started) and in 2020, after 5 years of implementation.

As can be seen in Figure 2, the improvement in the conception rate in the five years since the beginning of the project contributed to the reduction in the average number of “days in milk” in the summer months, a significant factor in the improvement of the mean annual yield per cow, as shown below.

From what is presented in figure 2, a significant reduction in the number of “days in milk” can be seen, after five years of intensive activation of cooling in the summer, as a result of the improvement of summer fertility.

Figure 3. The average daily production per cow (liters), in the different months, in 2011-2014 (before the start of the cooling project) and in the years 2015-2020, in which intensive cooling was implemented in summer

From the presented in Figure 3, a significant reduction in the degree of summer decline in average milk production per cow is seen, between the period prior to the implementation of intensive cooling in the farm and the period in which it was properly operated. The difference in production between winter and summer, and the relationship between production between summer and winter (liters/day), in 2014, before implementing cooling, and 2020, five years after its implementation, are presented in Fig 3 and Table 1.

Table 1. The difference in production and the relationship between summer and winter in 2014, before implementing cooling, and in 2020, five years after implementation.

From the presented in table 1, it is clearly seen the reduction in the decrease in daily milk production, between winter and summer, due to the implementation of intensive cooling in the La Cantabra dairy farm. The La Cantabra farm had about 2,000 cows at the beginning of the project and the average annual milk production per cow in 2014 was 10,600 liters. Milk yield per cow reached 12,100 by the end of 2020, an addition of 1,500 liters to annual yield per cow, an average increase of 250 liters per cow each year, and 10-15% in annual production per cow, post-op of intensive cooling. Factors that contributed to achieving the results included intensive maintenance of forced ventilation and “wetting quality”, as recommended, giving cows sufficient space per cow in the cooling sites, which prevented overcrowding, giving the cows enough “cooling time” during the day (six cumulative hours, once every 4 hours), even at night, and distribution of fresh feed, freely, 24 hours a day.

The implementation of cooling implies a high financial investment for the installation and operation of the cooling system. Based on current data in Mexico, we believe that the investment for the construction and installation of cooling equipment in cooling tunnels, similar to those existing in La Cantabra, can reach about 400,000 USD (approximately 200 USD per cow). The cost of operating the cooling system during the summer is expected to be 45 USD per cow for electricity, additional manpower, and equipment maintenance. Using special computer software developed together with an economist, we examined the economic benefit from investing in cooling the cows. For this calculation, we took the actual results obtained in La Cantabra (an expected increase of 10% in the annual production of each cow, and assuming a 5% improvement in “feed efficiency” during the summer months.

The study did not take into account the expected economic benefits arising from improving cow health and fertility in the summer. Based on the results described, we found an increase in annual income per cow of 235 USD, and 470,000 USD in annual income for a dairy farm with 2,000 cow’s farm.

The results described in this article show that the investment in cooling the cows can be paid for at the end of the first year of operation and from then on the annual income of the farm can be increased by more than 200 USD per cow, each year, making the investment in cow cooling one of the best investments a dairy farmer living in warm regions can do.