Effectiveness of fan and feedline sprinklers in cooling dairy cattle housed in 2- or 4-row freestall buildings

摘要

Two studies were conducted to evaluate the effectiveness of fan and feedline sprinkler systems in reducing summer heat stress of dairy cattle housed in 2- and 4-row dairy freestall barns equipped with head-to-head stalls. In the 2-row study, 159 Holstein cows were assigned to one of three cooling systems. Treatment one (F+S) was a row of five 122 cm fans mounted every 12 m over the freestalls and a row of ten 91 cm fans mounted every 6 m over the feedline. Treatment two (S) was a row of five 122 cmfans mounted every 12 m over the freestalls. In addition, both treatments (F&S and F) utilized identical feedline sprinkler systems. Treatment three (S+) was a row of five 122 cm fans mounted every 12 m over the freestalls with a feedline sprinkler andan additional sprinkler on the rear alley of the building. In the 4-row study, 93 multiparous Holstein cows were assigned to one of three cooling treatments in a 4-row freestall building. Treatments were 1) a double row of 91 cm fans spaced at 7.3 m intervals over the freestalls (2S), 2) a single row of 91 cm fans spaced at 7.3 m intervals over the freestalls and feedline (F&S) or 3) a double row of 91 cm fans spaced at 7.3 m intervals over the freestalls and a row of 91 cm fans over the feedline (F&2S). All 4-row treatments had a similar feedline sprinkler system. Milk production was measured and recorded for a 24 h period every 14 d throughout the study. Respiration rates were determined on four different d during heat stress at 07:00 and 15:00 hours. In the 2-row study, cows and heifers produced similar (P>.05) amounts of milk with each treatment. Respiration rates were also similar (P>.05) for all systems during the morning and afternoon periods. In the 4-row study, cows treated with the F&S cooling system produced more (P<,05) milk than those treated with the 2S treatment (44.8 vs 42.6 kg/c/d). The F&2S treatment (43.8 kg/c/d) was intermediate (P>.05) to the other two treatments. Respiration rates were elevated (F<.05) for the 2S treatment as compared to F&2S and F&S. Based on the data collected and analyzed, an effective cooling system for a 2-row freestall barn included a feedline sprinkler and fans over the freestalls. In the case of the 4-row freestall barn, fans should be located over thefeedline and over the freestalls in addition to a feedline sprinkler.