The relationship between rumination appearance, ruminal fermentation and metabolite substance concentrations of blood plasma in sheep

Abstract

The relationship between rumination appearance, ruminal fermentation and metabolite substance concentrations of blood plasma was investigated using four rumen cannulated Suffolk crossbred adult wethers.  The animals were weighing 54 kg on average.  Experimental diet was chopped timothy hay, rolled barley and wheat bran in control treatment (CTL), and chopped timothy hay, starch and casein in experimental treatment (INF), respectively.  In the INF, starch and casein were suspended in buffer solution and infused into the rumen of the four sheep for 4 hours.  The feed was offered to the animal at 9 : 00 and 21 : 00 hours, and the chopped hay and infusate was provided to suffice maintenance requirement of metabolizable energy for each animal.  Seven days of adaptation period was followed by sampling period.  Eating and rumination behavior of the animals was monitored for three consecutive days.  Rumen fluid samples and blood samples were obtained from each sheep at 0, 4, 8 and 12 hours post morning feeding.  Osmotic pressure of rumen fluid and blood plasma and metabolites concentration of blood plasma were determined.  Both of the rumination lag time post prandial and total rumination latency time between the rumination periods were significantly longer for INF than those for CTL.  The number of rumination period of INF was around 50% observed in CTL.  The values of rumen fluid osmolality were significantly higher for INF than for CTL throughout the observations, however, those values did not associated with the differences in blood plasma osmolality between the treatments at each sampling time.  The results in this experiment suggested that a rapid fermentation of the substrates appeared to be associated with the lengthening rumination lag time, which, in turn, might contribute to enhance the absorption rate of fermentation metabolites through the rumen wall of sheep.