Performance of lactating dairy cattle housed in two-row freestall barns equipped with three different cooling systems

摘要

One hundred fifty-nine Holstein cows (66primiparous and 93 multiparous) were assignedto each of three different coolingsystems installed in two-row freestall barnson a northeast Kansas dairy. One barn wasequipped with a row of five 48-inch fansmounted every 40 ft over the freestalls and arow of 10 36-inch fans mounted every 20 ftover the cow feed line. Another barn wasequipped with five 48-inch fans mounted overthe freestalls. Both of these barns were alsoequipped with identical sprinkler systemsmounted over the feed line. The third barnwas equipped with a row of five 48-inch fansmounted over the freestalls. In addition tothe sprinklers over the feed line, additionalsprinklers were mounted on the back alley ofthe third barn. Data were collected for an 85-day period to evaluate the three systemsunder heat stress during the summer of 1999.Cows cooled with these three systems producedsimilar amounts of milk and consumednearly equal amounts of feed. Summer heatstress generally reduces milk production20%, if cooling systems are not installed.Based on this estimated loss, these systemsreturned over $10,000/pen/year above ownershipand operational cost. These resultsindicated that effective cooling in a two-rowfreestall barn includes a sprinkler system onthe feed line and properly sized and spacedfans over the freestalls.