The effect of cold exposure of sheep on digestion, rumen turnover time and efficiency of microbial synthesis

Abstract

1. Six closely shorn sheep were given brome grass (Bromus inermis) pellets at 1 h intervals and maintained at ambient temperatures of −1 to 1° and 18–21° for 28 d. Measurements of digestion were made during the last 10 d of temperature exposure.2. Cold exposure resulted in a reduction in apparent dry matter (DM) digestibility from 0·482 to 0·450, and of apparent digestibility of organic matter (OM) from 0·511 to 0·477. Neither apparent digestibility nor retention of nitrogen was affected.3. Apparent digestibility of OM in the rumen decreased from 0·300 to 0·242 with cold exposure, and was highly correlated with turnover time in the rumen of 108Ru, which was used as a particulate marker.4. The efficiency of microbial synthesis (g N incorporated into microbial cells/kg OM apparently digested) was correlated with the dilution rate of the solute marker (51Cr) and with the turnover time of the particulate marker (103Ru) in the rumen.5. Digestion in the intestine of DM and OM accounted for significantly more of apparent digestion in the whole gastrointestinal tract for sheep kept in the cold than for sheep kept in the warm. The apparent digestibilities of DM and OM entering the intestines were similar in sheep on both treatments, but significantly more non-ammonia-N was digested in the intestines of cold-exposed sheep.6. The influence of dilution rate of rumen fluid on the efficiency of synthesis of microbial cells in the rumen is discussed.

Effects of Chinese herbal medicine and cold exposure on plasma glucose, leucine and energy metabolism in sheep

“…Therefore, the higher N digestibility as well as the higher numerical values of urinary N excretion for the CHM-diet indicated a higher amount of synthesised microbial protein, which suggested that the bioactive components of Chinese herbal medicine might play a role in enhancing microbial activities in the rumen. Kennedy, Christopherson, and Milligan (1976) Nakamura, Kobayashi, Takahashi, and Terashima (1995) also observed an unchanged CP digestibility in sheep exposed to cold for 18 days.…”

Effects of outdoor winter housing and feeding level on performance and blood metabolites of suckler cows fed whole-crop barley silage

“…Roughly speaking they seem to be fairly parallel during the winter which means that the highest values were in the treatment AU, then in the AT and RT treatments, with the lowest values in cows in the harshest conditions, in the AS and RS treatments. As mentioned earlier, cold exposure has been reported to increase reticulorumen motility (Kennedy et al, 1976(Kennedy et al, , 1977Gonyou et al, 1979) and reduce digestive efficiency (Young, 1981). Butyrate is metabolized to β-HB in the rumen epithelium and surplus ammonia from the rumen and intestine is a source for urea synthesis in the liver.…”

“…Experiments (e.g. Kennedy et al, 1976Kennedy et al, , 1977Gonyou et al, 1979) have shown that when ruminants are exposed to cold, there is also an increase in rumination activity, reticulorumen motility and rate of passage of digesta as well as a reduction in the volume of the reticulorumen. A consequence of these changes is a reduction in digestion in the reticulorumen, particularly with roughages and associated with an increased rate of passage of digesta which results in reduced digestive efficiency (Young, 1981).…”

Physical constraints on voluntary intake of forages by ruminants.

“…Regulation of Flow by the Animal. Fractional passage rate from the reticulorumen increases as DMI increases (Riewe and Lippke, 1970) and during cold stress (Kennedy et al, 1976). Stanley et al (1993) found that as VDMI increased for Hereford × Angus cows consuming chopped alfalfa hay from 61 to 6 d before calving, fill in the reticulorumen decreased, and fractional passage rate of indigestible ADF increased by 87%.…”