Volatile fatty acids maintenance

The surface of the mucosa is relatively smooth as there are no intestinal villi. Crypts of Lieberktlhn are present. Goblet cells account for more of the epithehal cells than in the small intestine. The mammalian large intestine is important for the maintenance of water and electrolyte balance. Its primary function is the reabsorption of water, sodium, chloride and volatile fatty acids it secretes potassium and bicarbonate. 

Wang J, Yue Z-B, Sheng G-P, Yu H-Q (2010) Kinetic analysis on the production of polyhydroxy-alkanoates from volatile fatty acids by Cupriavidus necator with a consideration of substrate inhibition, cell growth, maintenance, and product formation. Biochem Eng J 49 422-428 Wang Y, Yamada S, Asakawa N, Yamane T, Yoshie N, Inoue Y (2001) Comonomer compositional distribution and thermal and morphological characteristics of bacterial poly(3-hydroxybu-tyrate-co-3-hydroxyvalerate)s with high 3-hydroxyvalerate content. Biomacromolecules 2 1315-1323... 

However, there are disadvantages. The yield of biogas production varies due to the composition of food waste and retention time. Highest methane yields are found to be with excess of lipids and longest retention time while there are inhibitoiy effects likely to occur with excess of lipid and proteins due to the volatile fatty acid accumulation and ammonium nitrogen. Besides, there is extra attention and precaution for the leakage of CH4, extra cost of maintenance and air pollution control measures are needed. 

Table 11.5 also shows that, as one would expect, dietary fat is used for maintenance with high energetic efficiency. However, when protein is used to provide energy for maintenance, there is an appreciable heat increment of about 0.2, which is in part attributable to the energy required for urea synthesis (see Chapter 9). In ruminants, energy for maintenance is absorbed largely in the form of volatile fatty acids. Experiments in which the pure acids have been infused singly into the rumen of fasting sheep have shown that there are differences between them in the efficiency with which their energy is utilised (Table 11.5). But when the acids are combined into mixtures representing the extremes likely to be found in the rumen, the efficiency of utilisation is uniform and high. Nevertheless the efficiency is still less than that for...

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