Differential incorporation of precursor moieties into cerebral cortex and cerebellum glycerophospholipids during aging.

The incorporation of polar and non-polar moieties into cerebral cortex (CC) and cerebellum (CRBL) phospholipids of adult (3.5-month-old) and aged (21.5-month-old) rats was studied in a minced tissue suspension. The biosynthesis of acidic phospholipids through [3H]glycerol appears to be slightly increased with respect to that of zwitterionic or neutral lipids in CC of aged rats with respect to adult rats. On the contrary, the synthesis of phosphatidylcholine (PC) from [3H]choline was inhibited. However, the incorporation of [14C]serine into phosphatidylserine (PS) was higher in CC and CRBL in aged rats with respect to adult rats. The synthesis of phosphatidylethanolamine (PE) from PS was not modified during aging. Saturated ([3H]palmitic) and polyunsaturated ([3H]arachidonic) acids were incorporated successfully by adult and aged brain lipids. In addition [3H]palmitic, [3H]oleic and [3H]arachidonic acid were employed as glycerolipid precursors in brain homogenate from aged (28.5 month old) and adult (3.5 month old) rats. [3H]oleic acid incorporation into neutral lipids (NL) and [3H]arachidonic acid incorporation into PC, PE and phosphatidylinositol (PI) were increased in aged rats with respect to adult rats. Present results show the ability and avidity of aged brain tissue in vitro to incorporate unsaturated fatty acids when they are supplied exogenously. They also suggest a different handling of choline and serine by base exchange enzyme activities to synthesize PC and PS during aging.

The effect of using different levels of shrimp meal in broiler diets.

The objective of this study was to measure the effect of substituting different levels of shrimp meal (SM) for soybean meal (SBM) in broiler diets. In Experiment 1, 0, 10, 20, 30, and 40% of the crude protein contributed by the SBM in broiler diets was substituted by crude protein from SM. In Experiment 2, 0, 60, 80, and 100% of the crude protein contributed by SBM in broiler diets was replaced by crude protein from SM. Body weight, cumulative feed consumption, and feed conversion (feed:gain) were determined on a weekly basis for 49 d in Experiment 1 and 42 d in Experiment 2. Mortality was reported daily. Carcass weight and percentage yield were determined on a prechilled basis. In Experiment 1, no significant differences were found for body weight, feed consumption, feed conversion, mortality, carcass weight, or yield. In the second experiment, body weight was found to be significantly higher (P < 0.01) at 21, 28, 35, and 42 d of age in treatments in which SM was introduced at a 100% substitution for SBM. Growth responses to SM were also seen at lower levels of substitution at 21, 28, and 35 d. No significant differences were observed for feed consumption, feed conversion, mortality, or carcass yield for any of the treatments. Carcass weight increased significantly by 12.1% when SM was substituted 100% for SBM. Results of the present study show that the particular SM used in this study could partially or totally replace SBM in broiler diets without negatively affecting performance or carcass quality.

Age-associated changes in the content and fatty acid composition of brain glycerophospholipids.

The fatty acid composition of total lipids and individual phospholipids and the ratio of cholesterol-to-phospholipid content were studied in cerebral cortex, subcortical white matter, cerebellum and medulla oblongata/pons in 4-, 21.5- and 28-month-old rats. The cholesterol-to-phospholipid molar ratio in subcortical white matter, medulla oblongata/pons and cerebellum in 28-month-old rats was found to be 17, 17 and 16% higher, respectively, than in adult rats. These alterations in the molar ratio were produced as a result of a net increase in cholesterol content rather than by changes in the total phospholipid content. The content of alkenylacylglycerophosphoethanolamine (alkenylacyl GPE) increased in 28-month-old rats with respect to 4-month-old rats, following the order cerebral cortex > cerebellum > medulla oblongata/pons > subcortical white matter. The fatty acid composition of total lipids showed an increase in monounsaturated fatty acids (MUFA) and a decrease in polyunsaturated fatty acid (PUFA) content with increasing age in all regions studied, such changes being more marked in cerebellum, medulla oblongata/pons and subcortical white matter than in cerebral cortex. The proportion of 22:6(n-3) in cholineglycerophospholipids in the different brain regions of 28-month-old rats showed a slight decrease with respect to that in adult rats following the order cerebellum > medulla oblongata/pons > subcortical white matter, whereas that of 20:4(n-6) decreased only in cerebellum. Ethanolamineglycerophospholipid fatty acid composition was modified in 28-month-old rats through a marked increase in monounsaturated fatty acids (18:1(n-9) and 20:1(n-9) specifically) in all brain areas. The MUFA content of alkenylacyl GPE increased with increasing age in all the regions studied, in the order cerebral cortex > medulla oblongata/pons > subcortical white matter > cerebellum. An increase in the MUFA content of diacylglycerophosphoethanolamine was observed in medulla oblongata/pons and cerebellum of aged rats with respect to control rats. PUFA content of alkenylacyl GPE decreased mainly in medulla oblongata/pons, cerebral cortex and subcortical white matter of aged rats. The PUFA content of serineglycerophospholipids was the most affected by aging. Changes occurred mainly in the content of 22:6(n-3), 22:4(n-6) and 20:4(n-6) in cerebellum and of 22:6(n-3) and 22:4(n-6) in subcortical white matter. Changes in the inositolglycerophospholipid fatty acid content of 28-month-old rats were observed mainly in medulla oblongata/pons, which showed a decrease in PUFA (22:4(n-6) and 22:6(n-3)) content and an increase in MUFA (18:1 and 20:1).