Effects of spraying cooling on open beef cattle barn in Southern China

Abstract: To evaluate the cooling effect of spraying combined with fan on the performance of beef cattle. Two breedings of beef cattle were tested in this study (Simmental Crossbred and Jinjiang Yellow Cattle ) and they were housed in open beeflot barn in Southern China. Fans and spraying were operated during 8:00-24:00 and 10:00-19:00, respectively. Spraying ran intermittently with 5 min on and 10 min off, and fans ran continuously. Data of evaluation index such as environmental factors, rectal temperature (Tr), respiration rate (RR) and daily weight gain (DG) were collected. Temperature-humidity-velocity index (THVI), heat load index (HLI) and accumulated heat load (AHL) were calculated to estimate the effects of climatic variable and heat accumulation. The results showed that, compared with the control barn, the average air temperature was lower by 2.1℃(P<0.01) , the THVI was lower by 3.2℃ (P<0.01) and the HLI was lower by 4.3 (P<0.05) in treatment barn during spraying running period, while the relative humidity was higher by 5.8% (P<0.01). For the Simmental Crossbred, cooling by fans combined with spraying can reduce its rectal temperature and respiration rate during 10:00-18:00 by 0.5℃ (P<0.01) and 11 breaths per minute (P<0.01), respectively. Also, its accumulated heat load were relieved while there was no significant effect on its daily weight gain. For Jinjiang Yellow Cattle, the applying of cooling system reduced its respiration rate by 14 breaths per minute (P<0.01) and increased its daily weight gain by 27.5% at 0.19 kg per day (P<0.05). The effects on heat accumulation for Jinjiang Yellow Cattle was not clear because there were no heat accumulation both in treatment and control barns.