研究課題
Hot climate has negative effects on productivity in dairy cattle, but the effect varies from breeds to breeds. The present study aims to measure heat stress by evaluating heart rate variability (HRV) in Cambodian dairy cattle.Cambodian crossbred dairy cows (native Zebu x Holstein Friesian) were used. Heart rates were recorded using a Holter-type electrocardiograph with apex-base (A-B) leads. Animals were kept inside the shelter during the first 24-h period beginning from 18:00 (Day 1). On Day 2, all cows were kept in the shelter for 12 h, exposed to direct sunlight for 12 h as a heat-stress treatment and returned to the shelter during last 24-h period (Day 3). Rectal and ambient temperatures were recorded. The HRV were calculated using power spectrum analysis.Rectal temperatures and heart rates increased in all animals under direct sunlight as compared to those in the shelter. The power spectral analysis of HRV revealed that three out of the five cows studied showed a decrease in their parasympathetic nervous activity and a tendency of increase in sympathetic nervous activity under direct sunlight, showing that those three cows are likely to be more heat stressed. The other two cows did not show such increase in sympathetic nervous activity under sunlight exposure by the frequency domain parameters of HRV. The present result suggests that the latter two cows are likely to have higher heat tolerance. Results from the present study demonstrate that the power spectral analysis of the HRV would prove to be a useful tool to evaluate heat tolerance in individual dairy cows.
すべて 2018 2017
すべて 雑誌論文 (1件) (うち査読あり 1件、 オープンアクセス 1件) 学会発表 (1件) (うち国際学会 1件)
The Journal of Veterinary Medical Science
巻: 80 ページ: 181-185
10.1292/jvms.17-0368
