|The Israeli dairy herd consists of 120000 cows, in about 1100 farms. All the dairy cows in Israel are Holsteins. 2002 average production reached 24000 lib/cow/year, 3.5% and 3.1% fat and protein respectively.
Israel’s climate is “Mediterranean – Subtropical”. Summer months (June – October) are hot and humid. In dairy farms not using any cooling, summer average daily milk production reaches only 85% of winter level. In this season, milk protein and fat are reduced, while somatic cells count is increased, creating a significant drop in milk quality. Israeli “Herd-book” data from these herds shows that peak lactation of summer calving cows is 8 – 12 lib/day lower than those calving in winter (those lactations starting in July are 2000 lib/year lower compared to those starting in December). Lactation persistency is also lower in summer, compared to winter months. Conception Rate of cows inseminated in these herds in summer is less than half of that of winter months (20% and 50% respectively). Both direct decline in milk production and in the flow of calving creates a significant seasonality in milk supplied by these herds to the market.
Most of the dairies in Israel are concerned with the necessity and make the efforts to cool their cows during summer, although only few of them are practicing it properly and get the expected results. In the successful dairies, cooling is mainly done by a combination of wetting and forced ventilation. This treatment effectively increases evaporation from cows and prevents them from becoming “heat-stressed” during summer. Cooling makes use of low-pressure sprinklers (large size droplets) combined with high potential fans. For efficiently cooling, cows are “treated” in the holding area before and between milking and in the feeding strip, between milking and during feeding time.
The following article describes the development of cooling method in Israelalong the last 30 years and the achievements obtained during this period.
The effect of cooling dairy cows was first studied by a large- scale survey realized during four years (1998 –2001), including 11 farms located in the coastal part of Israel. Cows subjected to an intensive cooling (six farms) were cooled in the holding and feeding area for a total of 10 cooling periods and 7.5 cumulative hours per day. Cooling combined sprinklers (100 l/h) and high- speed fans. Cows in five other farms not using any cooling, served as a controls. Summer (July-September) milk production reached 98.5% of winter (December-February) level in the cooled cows, and only 90.7% in the non- cooled ones. Conception-rates (first insemination) during winter were 46.6% and 43.5% in cooled and not-cooled cows respectively, While during summer, conception-rates in the same groups where 33.8% and 16.7% respectively.
Recently, an intensive cooling system was developed in Israel, based on wetting and ventilating the cows. The “CowKool” system (Polak Bros. Inc. Tel Aviv, Israel) make use of special and high-potential fans with 4 units of low-pressure foggers (7 L/h/) each, installed in front of each fan. The “CowKool” system was installed in the holding-pen and the feeding area of the dairy farm. The main advantage by using the “CowKool” system is in the ability to intensively cool the cows without wetting the feeding-strip floor.
The effect of “cowkool” system on dairy cows was evaluated in Israel during 2001 and 2002 summers. In summer 2001, “CowKool” system was installed in on side of a dairy barn and compared to a conventional cooling system using sprinklers and fans (as described above in this article in the 4 years survey), installed in the other side of the dairy barn.
Average daily Temperature Humidity Index (THI) during the evaluation period (July-October), ranged between 70 and 76, and was above critical level most of the days. Cows in both groups maintained normal rectal temperatures during hot hours of the day (101.8°F and 108.5°F), for cows cooled by sprinklers or “CowKool” respectively. Production and Conception rate did not differ between treatments and are presented in table 1.
Table 1 – Milk production (Lib/d) and Conception Rate (CR) (%), for cows cooled in summer by a conventional cooling (sprinklers) or “CowKool” system.
During summer 2002 “CowKool” system installed in a dairy farm in the south of Israel. Milk production during summer months was compared to that of 3 neighbor farms not using cooling system. Results are presented in table 2.
Table 2 – Summer milk production (lib/d) of cows cooled by “CowKool” system and non-cooled cows.
Conclusions – Intensive cooling of cows in summer, based on wetting force ventilation reduced great part of summer decline in milk production and fertility. Replacing sprinklers by low-pressure “CowKool” system reduced amount of water used and wetting of the feeding strip floor without affecting cows’ performance. During summer 2003 “CowKool” system was widely installed in dairy farms all over Israel. We are in a process of evaluating its results in large-scale survey. First results looks very promising.