Changes in the composition of the rumen and abomasum lipids of sheep from birth to maturity

Abstract

AbstractThe composition of the lipids of the rumen and abomasum tissues of foetal (at term), 1 month, 2 month and 1‐2‐year old sheep grazed on pasture has been determined.The lipid content of the rumen tissues increased from 2.0% at birth to 3.4% in 1‐2‐year old sheepWhile that of the abomasum tissues increased from 2.6 to 5.7%. The main change in the neutral lipid fraction was a decrease in the hydrocarbon content from 0.13 % in the rumen tissues and 0.08 % in the abomasum tissues at birth to 0.003% and 0.006% respectively in the 1‐2‐year old sheep. The main components of the phospholipid fraction of the rumen and abomasum tissues were 34.9‐ 46.8% phosphatidyl choline; 14.623.5 % phosphatidyl ethanolamine; 14.3‐21.1 % sphingomyelin; with smaller amounts of lysophosphatidyl choline (4 13‐12.6 %), acidic phospholipids (cardiolipin) (4.1‐8 ‐5 %) and phosphatidyl inositol/phosphaticlyl serine (3.0‐5.5 %). No marked changes in phos‐ pholipid composition with age were noted. The amounts of phosphatidyl choline and phosphatidyl ethanolamine tended to be higher in the abomasum than in the rumen whereas the sphingomyelin content of the rumen tissue phospholipids was generally greater than that of the abomasurn tissue phospholipids.From the fatty acid composition of the triglycerides of the rumen and abomasum tissues it appeared that the foetal triglycerides were largely, though not entirely, of endogenous origin. In contrast the phospholipids of the foetal rumen and abomasum tissues contained di‐ and poly‐unsaturated as well as branched‐chain fatty acids in proportions similar to those found in older animals having access to pasture. From these results it is suggested that the phospholipids of the foetus are derived to a considerable extent from the maternal phospholipids.