Energy lactation

Net Energy Lactation (NEL) is the energy value in forage or concentrate feedstuff directly available for milk production in dairy cows. 

Metabolisable energy (UK, MAFF 1975) Metabolisable energy (Sweden) Metabolisable energy (UK, ARC 1980) Net energy lactation (Netherlands)... 

The process of glycolysis converts some, but not all, of the metabolic energy of the glucose molecule into ATP. The free energy change for the conversion of glucose to two molecules of lactate (the anaerobic route shown in Figure 19.1) is -183.6 kj/mol ... 

Slime-Forming Bacteria. Several forms of bacteria produce a slimy capsule under certain environmental conditions. These organisms are heterotrophic, that is, they obtain their energy from organic sources such as sodium lactate. The reaction is... 

Figure 2. Force generation and energy metabolism in human quadriceps femoris muscle stimulated intermittently at 20 Hz, with 1.6 sec tetani with 1.6 sec rest periods between tetani. The upper panel shows force, ATP turnover rate, and pH the middle panel, the concentrations of PCr, P and lactate and the lower panel, ATP, ADP, IMP, H, and calculated H2PO4. From Hultman et al. (1990), with permission from Human Kinetics Publishers.

This is true of skeletal muscle, particularly the white fibers, where the rate of work output—and therefore the need for ATP formation—may exceed the rate at which oxygen can be taken up and utilized. Glycolysis in erythrocytes, even under aerobic conditions, always terminates in lactate, because the subsequent reactions of pymvate are mitochondrial, and erythrocytes lack mitochondria. Other tissues that normally derive much of their energy from glycolysis and produce lactate include brain, gastrointestinal tract, renal medulla, retina, and skin. The liver, kidneys, and heart usually take up... 

The main source of brain energy metabolism is the continuous availability of glucose from the blood. To some extent, energy can be derived from glycogen, stored in astrocytes. Neurons also use lactate as an energy source, even under normoxic conditions. During neuronal activation, lactate may even be the... 

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