Digestible nitrogen

Before the Machine Age, digestible nitrogen could not be created by the human hand it could only be recycled from the rot-... 

In Kjeldahl digestions, nitrogen is converted to ammonium ion, which is then distilled as ammonia and titrated. 

Temperature. Length of digestion. Nitrogen, in loo c c of Nitrogen not precipitable... 

TDN (total digestible nutrients) A term widely used in animal nutrition that indicates the energy value of feeds. TDN = % digestible protein + % digestible nitrogen-free extract (carbohydrates) -i- % digestible fiber + (% digestible fat x 2.25). 

Digestion. 20-25 mg. of the substance whose nitrogen content is to be estimated are weighed out in a stoppered weighing-tube and then transferred to the flask L that has been previously dried in an oven at izo C. With care, the substance may be transferred directly into the bulb of the flask without any adhering to the sides. If any material sticks on the way down, the flask should be tapped gently to cause the substance to fall to the bottom. 2 G. of the catalyst mixture (32 g. of potassium sulphate, 5 g. of mercury sulphate and ig. of selenium powder, well mixed) are added and 3 ml. of A.R. cone, sulphuric acid are measured out carefully and poured into the digestion... 

Acetamide has been used experimentally as a source of nonprotein nitrogen for sheep and dairy cattie (13). It does not appear to be toxic in amounts of about 2—3% of ration. Buffering the diet with dibasic acids serves to allow higher levels of intake because the ammonia Hberated in the digestive process is then scavenged. 

CeUulosic materials, such as farm wastes, can be upgraded for animal feed by simply bringing them into contact with ammonia (qv). The ceUulose sweUs and is made more digestible, and at the same time some ammonia nitrogen, which is a nutrient for mminants, is left behind. Supercritical ammonia improves susceptibiHty to enzymatic hydrolysis (17). 

A new concept is to use an on/oFf air supply cycle. During aeration, nitrates are produced. When the air is shut off, nitrates are reduced to nitrogen gas. This prevents acid buildup and removes nitrogen from the sludge. High power cost for aerobic digestion restricts the applica-bihty of this process. 

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