The nature of bacterial lipids in the rumen of hay‐fed sheep

Abstract

The lipids extracted from the mixed ' free ' rumen micro-flora of two hay-fed sheep consisted of 39.2% of phospholipids, 38.2% o€ neutral fat, 12.4% of lower fatty acids (probably rumen fermentation products), 10.1 yo of unsaponifiable matter and 0.1 yo of steam-volatile, neutral solid. The ' true ' lipids amounted to 9 % of the dry weight of the bacteria. The neutral fat was noteworthy for the relatively high mean molecular weight (312.0) of its component acids. No linoleic or linolenic acid was detected in the neutral fat or phospholipids. The significance of this with respect to the host animal is discussed. The ?$ : 1 ' ratio of the phospholipids indicated the presence of mono-and di-aminophosphatides. The unsaponifiable matter contained carotenoid pigments (probably xanthophylls) and 16.1 yo of a steroid-like substance, possibly CZ7H4802, m.p. r3o-r3z0, precipitable by digitonin, but not identical with the hydrated form of cholesterol.

The nutritive value of rumen micro-organisms in ruminants

“…The lipid content of fraction 2 + 3 was 92.1 g/kg DM. This value is very similar to those reported in the literature (Garton & Oxford, 1955;Czerkawski, 1976;Kurilov et al 1976).…”

The lipolysis and hydrogenation of lipids in the digestive tract of the sheep

“…fraction in the lipid of both ruminal and duodenal diegsta: of particular note was the considerable content (up to 20 %) of C 18 unsaturated acids. Cunningham & Loosli (1954) were unable to demonstrate the synthesis in vitro of polyethenoid C 18 fatty acids by bovine ruminal bacteria and Garton & Oxford (1955) could not detect linoleic or linolenic acid in the fatty acids of the glyceride or phospholipid of ruminal bacteria from sheep receiving hay. The presence of C 18 unsaturated acids has recently been reported, however, by Keeney et at.…”

The Rumen Microbial Ecosystem

“…By this approach, Garton and Oxford (1955) determined that lipid accounted for 9% of the dry weight of rumen bacteria and consisted of phospholipids (39%), neutral lipids (38%), steam-volatile fatty acids (12%) and non-saponifiable material (10%). By this approach, Garton and Oxford (1955) determined that lipid accounted for 9% of the dry weight of rumen bacteria and consisted of phospholipids (39%), neutral lipids (38%), steam-volatile fatty acids (12%) and non-saponifiable material (10%).…”