Author/Authors :
Alameen ، A. O. نويسنده Department of Physiology, Faculty of Veterinary Medicine, University of Khartoum, Sudan. , , Abdelatif ، A. M. نويسنده Department of Physiology, Faculty of Veterinary Medicine, University of Khartoum, P.O.Box 32, Khartoum North, Sudan. , , Elnageeb ، M. E. نويسنده Department of Physiology, Faculty of Veterinary Medicine, University of Khartoum, Sudan. ,
Abstract :
Physiological processes in cattle generally reveal a pattern of diurnal rhythmicity that could be influenced by various intrinsic and extrinsic factors. The objective of this study was to monitor the daily rhythms in thermoregulation and blood constituents and endocrine responses in crossbred cows (Butana x Friesian) in a tropical environment. Also it was intended to explore the effect of level of milk production of cows on the pattern of diurnal responses. The cows used in the investigations were six relatively high producing cows (14.30 kg/day) and six low producing cows (7.10 kg/day) during late lactation. The nycthemeral changes in physiological parameters were monitored at 6 hrs intervals for 48 hrs. The rectal temperature (Tr) and respiratory rate (RR) increased in the afternoon (12:00 PM) in both groups and high producing cows maintained higher values during the course of the study. The packed cell volume (PCV) and Hb concentration were higher in high producing cows compared to low producing cows. Serum levels of glucose, cholesterol and triglycerides showed a significant diurnal variation in both groups of cows. Serum urea concentration showed relative stability in both experimental groups. Serum levels of glucose, cholesterol, triglycerides and urea were lower in high producing cows than in low producing cows. Serum enzymes AST and ALT showed irregular diurnal variation in both high and low producing cows and high producing cows maintained lower aminotransferase enzyme activity. Serum cortisol level was higher at 12:00 PM and 6:00 PM compared to values measured in the morning (6:00 AM) and night (12:00 PM) and cortisol level was higher in high producing cows. Serum insulin level did not reveal significant diurnal variation in both groups of cows and insulin level was higher in high producing cows. The findings may be utilized in diagnosis of metabolic diseases and monitoring the production of dairy cows.
