Influence of different schedules of feeding on daily rhythms of blood urea and ammonia concentration in cows

Abstract

Many physiological processes of domestic animals exhibit daily rhythmicity. The goal of the present study was to investigate, in cows, the influence of different schedules of feeding on daily rhythms of blood urea and ammonia concentrations. Fifteen Italian Brown cows, from the same farm, clinically healthy and placed at the same environmental temperature and photoperiod, were used for this study. Thirty days before the experiment, all the subjects were divided into three homogeneous groups of five cows: A group was fed at 08.00, B group was fed at 16.00, both having access to food for two hours (A group 08.00 -10.00; B group 16.00 -18.00) and C group was fed ad libitum. Blood samples were collected at four hour intervals for 72 consecutive hours starting at 08.00 of the first day and finishing at 04.00 of the third day via intravenous cannula inserted into the jugular vein. On each serum, blood urea and ammonia concentrations were assayed. Data analysis was conducted by one-way repeated measures analysis of variance (ANOVA) and by the single cosinor method. ANOVA showed a significant effect of time on all parameters studied, in either day, with P 5 0.0002 for ammonia in A group and P 5 0.0001 for ammonia and P 5 0.0005 for urea in B group. Cosinor analysis identified the periodic parameters and their acrophases (expressed in hours) during the three days of monitoring: urea showed nocturnal acrophases in B group, ammonia showed diurnal acrophases both in A and B groups. Our results suggest the influence of external stimuli, such as feeding time, on the rhythmic pattern of the metabolites involved in liver function and the hypothetic interaction between circadian clocks placed in the liver and the mean circadian system.

Daily rhythm of salivary and serum urea concentration in sheep

“…Other investigations clearly showed a circadian rhythm of urea with diurnal peaks in cows [14] and documented the effect of different feeding schedules on daily rhythms of serum urea and ammonia concentration [6,15]. Monogastric animals also showed a daily rhythm of plasma urea concentration with diurnal acrophases [13].…”

“…Few studies were carried out on the rhythmicity of liver function in farm animals. Serum concentration of urea was evaluated in cows during different feeding schedules [6] and in goats maintained under various schedules of lighting and feeding [7] in order to understand the mechanisms of entrainment of liver function. Ruminants, such as sheep and cattle, secrete a large amount of saliva from the salivary glands into the rumen (≥100 litre/day in cattle and ≥10 litre/day in sheep).…”

Seasonal change of daily motor activity rhythms in Capra hircus

“…The data logger was placed 2 m above the floor and recorded data every hour, which were downloaded every 15 d. Both temperature and humidity varied during the year (vernal equinox: 178C, 128C, 70%; summer solstice: 288C, 238C, 68.5%; autumn equinox: 24.08C, 218C, 71%; winter solstice: 15.58C, 10.58C, 73%; maximum and minimum temperatures and mean humidity, respectively). Actiwatch-Mini † (Cambridge Neurotechnology Ltd., UK), actigraphy-based data loggers that record a digitally integrated measure of motor activity were placed on each goat by means of collars that were accepted without any obvious disturbance (Berger 1993;Piccione et al 2007b). …”

Daily rhythm of creatinine in dog: clinical and diagnostic significance

“…The effect of different feeding schedules on daily rhythms has been documented in cows about serum urea and ammonia concentration (Cai et al 1994;Piccione et al 2007). A daily rhythm of serum urea concentration with diurnal acrophases was also found in a monogastric animal, the horse (Piccione et al 2005a).…”