title: On the insensitivity of sheep to the almost complete microbial destruction of dietary choline before alimentary-tract absorption.
abstract: 1. Injection of [Me-14C]choline into sheep indicated that the small amount of phosphatidylcholine present in abomasal digesta was largely (69%) of non-dietary or ruminal origin. 2. Long-term feeding of [Me-3H]choline to sheep produced insignificant labelling of plasma phosphatidylcholine, indicating that more than 99% of the choline body pool was of non-dietary origin. 3. In contrast, when rats were fed with [Me-3H]choline for similar periods, 18-54% of the tissue phosphatidylcholine was derived from dietary choline. 4. The loss of [14C]choline and 32P from the plasma phosphatidylcholine after a single injection of these isotopes indicated a markedly slower turnover of choline in the sheep compared with the rat. This observation, coupled with a lack of liver glycerophosphocholine diesterase, provides an explanation for the insensitivity of the sheep to an almost complete microbial destruction of dietary choline before alimentary-tract absorption.
mesh_terms: D000018:Abomasum / Q000378:metabolism*; D000818:Animals; D002794:Choline / Q000378:metabolism*; D004032:Diet; D050356:Lipid Metabolism; D008297:Male; D010713:Phosphatidylcholines / Q000097:blood / Q000378:metabolism; D051381:Rats; D012756:Sheep / Q000097:blood / Q000378:metabolism*; D013279:Stomach, Ruminant / Q000378:metabolism
chemical_list: D010713:Phosphatidylcholines; D002794:Choline