The effects of 48 hours fasting on cardio- respiratory patterns and rectal temperature in dairy cattle.

Abstract

Objective This research was executed to examine what is happening with heart rhythm, heart rate, rectal temperature and respiration rate in dairy cattle who are fasting for 48 hours. This is one of two papers wrote about this research. The other paper gives some more information about the acid- bace balance and the electrolytes.

Method Five healthy Holstein Frisian dairy cows (mean age 2, 9 years and mean days in lactation 274, 2) were followed for one week. Monday was adaptation day, on Tuesday the normal values were measured and on Wednesday and Thursday the cows were fasting. At Friday, the cows were eating again. Five times every day clinical examination was done: heart rate, respiration rate and rectal temperature were measured. One time a day urine was taken and also one time a day an ECG was made. The ECG was made to detect cardiac dysrhythmia’s. In urine was measured: pH, net acid excretion, S.G., creatinine and potassium. Three times a day blood was taken. In blood was measured: blood- gas values, electrolytes, hematocrit, total protein, BHBZ, creatinine and NEFA’s.

Results Heart rate and respiration rate were significantly decreased during fasting. This returns very quickly to normal when the cows were eating again. Rectal temperature decreases also somewhat but this was not significant. At the ECG a prolonged ST segment, a prolonged TQ interval and a prolonged TP interval were seen.

Conclusion The decreased heart rate was due to the increased influence of the parasymphatetic nervous system. And the increase of the parasymphatetic nervous system can have many reasons which are not become clear in this study. The abnormalities on the ECG’s were possibly due to a hypokalemia and/or a dysfunction of the potassium channels. The decrease in respiration rate was possibly due to a decrease in stomach filling.