Changes In Heart Rate Variability Of Dairy Cows Under Different Stress Level

Heart rate variability was a precise, sensitive and no-harm indicator of the sympathetic nervoussystem and parasympathetic nervous system. The aim of this study was to investigate the changes in the parameters related to characteristics of autonomic nervous system in different milk yield,temperature,age and gestation periods, check up the tension and balance between the sympathetic nervous system and parasympathetic nervous system, and proving by dairy cow physiology,hormone indicator, in order to improve dairy cow animal welfare.Part 1:The aim of this study was to measured the difference between high and low milk yield group on Action(ACT), Heart rate variability(time domain and frequency domain), urine cortisol and urine insulin, in order to analyse the characteristic and to investigate the pressure of high milk yield cow autonomic nervous system. Select 16 healthy similar parity cows in 108 Holstein dairy cows randomly, and allotted into high milk yield group(45.75±6.02 kg/d) and low milk yield group(10.75±1.50 kg/d) respectively, every group have 8 cows. Use Actiheart-4 record HRV date for 24 hours, record respiration rate, rectal temperature and collect urine in7:00,13:00,18:00 every day. The result shows that 1)high milk yield group ACT, SD, LF, RMSSD and urine insulin were significant lower than low milk yield group, and the urine cortisol was significant higher than low milk yield group(P<0.05); 2)BPM, IBI, HF, LF/HF, rectal temperature and respiratory rate of each group don’t have a significant difference with low milk yield group; 3)BPM, IBI, urine insulin have a significant difference in different times(P<0.05). The results shows that HRV of high milk yield group was significant decreased. Parasympathetic tone of high milk yield group was significant lower than lowmilk yield group, and high milk yield cows have more stress than lowmilk yieldcows.Part 2:The aim of this study was to investigate the effects of different gestation periods on heart rate variability of holstein cow, and analysis the characteristic of automatic nervous system. Select 12 healthy same age holstein dairy cows randomly, and allotted into early gestation, mid-gestation and latter gestation, every group have 4 cows. Use Actiheart-4 record HRV date for 24 hours, record respiration rate, rectal temperature in7:00,13:00,18:00 every day, and collect urine in 13:00 every day. The result shows that 1)ACT, urine cortisol, urine insulin in latter gestation was significantly lower than early, middle gestation; SD HF in middle gestation were significantly lower than early and latter gestation; RMSSD and LF in different gestation period were significantly different; BPM in early gestation was significantly lower than middle and latter gestation, and IBI was higher; 2) BPM in afternoon was significantly higher than in morning and noon, and IBI was lower; LF/HF in afternoon was significantly higher than morning and noon; record respiration rate and rectal temperature didn’t have a significantly difference. The results indicated that HRV was significant decreased in the middle gestation, it shows thatparasympathetic tone was decreased and sympathetic tone was increased in the mid-gestation, people should concern not only the latter gestation but also the mid-gestation in cow milk yield.Part 3:The aim of this study was to compare the difference of heart rate variability between high milk yield and low milk yield under the summer heat stress, analyse the tension and balance of the autonomic nervous system, and proving by dairy cow physiology endocrine indicator. In summer select 22 healthy similar parity cows in Holstein dairy cows randomly, and allotted into high milk yield group and low milk yield group respectively, every group have 11 cows. Use Actiheart-4 record HRV date from 12:00-14:00, record respiration rate, rectal temperature and collect urine in13:00. The result shows that 1)BPM,IBI,SD, LF, HF, LF/HF of high milk yield group don’t have a significantly difference with low milk yield; high milk yield group RMSSD was significantly higher than low milk yield group(P<0.05); 2) HF, LF/HF of different action group don’t have a significantly difference; BPM, IBI have tendency to perform a significantly difference(0.05<P<0.1), dairy cow SD, RMSSD, LF under different action have a significantly difference, and became higher when action was higher; 3) record respiration rate, rectal temperature urine cortisol and urine insulin of dairy cow don’t have a significantly difference under heat stress. It shows that there was no difference of autonomic nervous system between high milk yield group and low milk yield group under heat stress, and parasympathetic tone was increased when action was higher.