CattleNetwork.com Staff   |   Updated: May 17, 2010

Key #1 - Feed should be mixed twice daily. During the warmer parts of the year, TMR mixes (or silages) should be mixed or fed at least twice daily. Less frequent mixing allows the feeds to heat in the wagon and feedbunk which can result in cows eating less feed. Less feed consumed usually results in lower milk production. Once a day mixing may have been an option during the colder parts of our winters, but is not an option when temperatures start climbing. For those with outside feeding areas, shade cloth over the feedbunk helps keep cows cooler and encourages them to eat during the day.

Key #2 - Cows eat most of their feed overnight when temperatures tend to decrease and cows are able to cool off. With the decreases in overnight temperatures, cows tend to consume more feed during these very early morning hours. The key here is to make sure that quality feed is available when cows want to eat. During the hotter parts of the summer, cows may consume almost 70% of their feed in these overnight/early morning hours. Thus, batch sizes need to be adjusted for this key change in feed intake during different parts of the day.

Key #3 - Use of fans and sprinklers can help cows cool off while in the holding pen, eating areas, and resting areas. Cows are the most comfortable when their environmental temperature is between 40 and 70 F. As the temperature (and humidity) rise, cows undergo heat stress. The bottom line is that heat stress results in cows eating less, reduced fertility, and decreased milk production. Heat stress can be reduced by placing sprinklers (that wet the cow’s coat) and fans in holding pens and over feedbunks. Sprinklers are placed on a timer and run approximately for 2 minutes and off for 10-12 minutes. Fans run continuously. In addition, fans are placed over the freestalls or resting area. Fans should come on automatically when temperatures are greater than 70F.

Key #4 - Rebalance rations with new forages. New forages should be analyzed and these results used to balance rations accordingly. Also, with summertime feeding, mineral balances (e.g. potassium) are shifted slightly to account for not only the nutrient composition of new forages but also the stresses associated with the heat.

Key # 5 - Minimize heat stress on close-up dry cows or those within 3 weeks of calving. Shade and access to fans and sprinklers are the most critical during this close-up to calving time frame. Minimizing stresses on this group of cattle is critical to getting them to milk well during the next lactation. Allowing these cows (and possibility the far-off dry cows) access to the fans and sprinkler systems in the barn or holding pen once daily can help reduce heat stress on these cows. Reducing stress also includes providing shade (that does not result in increased incidence of mastitis from lying on manure accumulated in the shaded area), 30 inches of bunk space per cow, and adequate space for rest.

Key #6 - Make sure that heifers on pasture have adequate forage and plenty of cool, clean water. Cool season grasses are more sensitive to soil water deficiencies and have optimum growth with temperatures are between 65 and 75F. As a result, cool season grasses are often dormant during the summer months. To prevent mastitis in pre-fresh heifers, proper fly control is important. In addition, do not allow heifers to ?swim? in ponds for cooling.

Source: Donna Amaral-Phillips, University of Kentucky College of Agriculture

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