[Microorganisms as potential source of fats]. / Mikroorganizmalarin yag üretiminde kullanilmasi.

The production of fat and fatty acids from microorganisms have come up as a problem recently. Since, the fat originated from plants and animals in living world is not enough for the increasing world population. The most important problem was to select the true microorganisms for microbial fat production. Although the fact that bacteria grow fast but due to having small cellular mass production they were not chosen for this purpose, instead, various subspecies of yeast such as Candida, Rhodotorula were studied. These subspecies were generally grown up fast, having a highest cellular mass and giving a mixture of homogeneous fermentation liquor and collected easily by centrifugation.

Fat in lactation rations: review.

Recent research has demonstrated the effectiveness of added fat in diets to maintain milk production and fat percent. Much of the earlier work which indicated that fat affects digestion negatively may not be applicable because of great differences in the nature of diets and fats fed and especially in total feed intake. Nevertheless, much remains to be learned about interactions of fat, fiber, calcium, and rumen microorganisms if feeding of fat is to be maximized. The uniquely high acidity in the duodenum combined with detergent action of bile acids, lysolecithin, and fatty acids causes saturated fatty acids to be more digestible in ruminants than in nonruminants. Large quantities of added dietary fat increase concentrations in plasma of very low density lipoprotein triglyceride which increases their uptake by the mammary gland with inhibition of short chain fatty acid synthesis and consequent changes in milk fatty acid composition. In some cases, secretion of milk fat is increased. Current research and practice demonstrate that 3 to 5% fat may be added to diets for lactation to increase energy intake of high-producing cows and/or to reduce starch feeding, thereby increasing the ratio of forage to concentrate to prevent depression of milk fat.

Studies on the origin of milk fat. A further study of bovine serum lipoproteins and an estimation of their contribution to milk fat.

1. Tritium-labelled palmitic acid combined in olive-oil triglycerides was introduced into the rumen of a lactating cow and the specific radioactivity of the lipids of milk and of the lipoproteins of both jugular and mammary venous serum was measured. 2. As previously found in a similar experiment with [(3)H]stearic acid, the specific radioactivity of the triglyceride fraction of the dextran sulphate-precipitable lipoproteins reached a maximum earlier and greater than that of the milk fat. 3. This fraction was the only lipid separated that had a significant arteriovenous difference in concentration, and is therefore identified as the main circulating lipid precursor of milk fat. 4. Although the non-esterified fatty acids showed no arteriovenous difference in concentration, they showed a negative difference in specific radioactivity that could have occurred only at the expense of the triglycerides of the precipitable lipoproteins. 5. The mean specific radioactivity of the triglycerides immediately after removal from the blood is calculated and shown to be very close in value to that of the corresponding fraction in mammary venous serum. 6. By comparison of the mean specific radioactivities of milk fat and of this precursor, its contribution is calculated as 36%. 7. This value is discussed with reference to the concentration of C(16) and C(18) fatty acids in milk fat and it is concluded that substantial amounts of these acids must have been derived from a source other than preformed circulating lipids.

An investigation of serum lipoproteins and of their contribution to mild fat in the dairy cow.

1. Tritium-labelled olive-oil triglycerides were introduced into the rumens of lactating cows and the specific activities of the lipids of milk and plasma and of serum lipoproteins were measured. 2. On treatment of serum with dextran sulphate it was found that the lipid of the precipitated beta-lipoproteins consistently had a specific activity-time curve with a maximum comparable in value with, and occurring earlier than, that of the milk fat. 3. On fractionation of the lipids of these lipoproteins it was found that only the triglycerides and diglycerides had specific activity-time curves with maxima greater than that of milk fat, and on radioactivity data alone they are the only blood constituents studied that meet the requirements for being the precursor of milk fat. 4. From a consideration of abundances and the mean specific activities over the period of the experiment it is shown that the contribution of the diglycerides to the radioactivity in the milk fat must have been negligible and that only the triglycerides could have been responsible for all the radioactivity found in it. 5. Although no other fraction could alone have been responsible for all the radioactivity in the milk fat, at least one, the phospholipids, could have made some contribution. 6. It is calculated that 35-48% by weight of milk fat was derived from the beta-lipoprotein triglycerides, according to whether the phospholipids made an improbably large contribution or none at all.