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.

Comparative mammalian choline metabolism with emphasis on the high-yielding dairy cow

“…1978(Neill at al. , 1979Dawson et al 1981;Kennedy et al 1995). Xue & Snoswell, 1986a;Mato et al 1994;Armentano,1994).…”

Effect of Choline in All-Concentrate Diets of Feedlot Steers and on Ruminal Acidosis

“…Contribution bv the gut is challenged by studies (Dawson et al 1981;Neill et al 1978Neill et al ,1979) that show choline is rapidly metabolized in the rumen of sheep fed hay diets with little being absorbed from the gut and some incorporation into protozoa as phosphotidylcholine. Goodson and Tuznik (1971) reported a reduction in bacterial counts but an increase in protozoal counts in choline-supplemented sheep fed a corn-cob-based diet.…”

“…Effect (Bremer and Greenberg 1961;Neill et al 1979). Contribution bv the gut is challenged by studies (Dawson et al 1981;Neill et al 1978Neill et al ,1979 …”

Fotossensibilização em cordeiros recriados e suplementados em pastagem de Brachiaria brizantha cv. Marandu

“…Consequentemente, os ovinos têm um grande aporte endógeno de colina com uma taxa de rotatividade lenta, e uma necessidade mínima de colina exógena (DAWSON et al, 1981) A formação de colina endógena ocorre pela metilação sequencial de fosfatidiletanolamina, os grupos metil que são fornecidos por S-adenosil-L-metionina (ZEISEL, 2000). Grupos metil podem ser derivados a partir de fontes exógenas tais como Metionina, betaína e também colina, mas pode ocorrer também como tetrahidrofolato, onde a vitamina B 12 também está envolvida.…”

“…Uma situação bastante frequente em ovinos é a toxemia da gestação, na qual também ocorre balanço energético negativo. Talvez a colina possa contribuir de maneira mais efetiva nestes casos, ressaltando a grande capacidade de produção e reciclagem da colina pelos ovinos (ROBINSON et al, 1984;ROBINSON et al, 1987;DAWSON et al, 1981).…”