Nitrogen undegradable

Permethylation of polysaccharides. Kuhn and Trischmann found that polysaccharides can be methylated very efficiently in DMSO with dimethyl sulfate and barium oxide and/or barium hydroxide. Srivastava et al. used the same method except for the substitution of sodium hydroxide as base. Sodium hydroxide pellets and dimethyl sulfate were added with stirring under nitrogen over 8 hrs. to a solution of undegraded stareh in dimethyl sulfoxide. After stirring for another 16 hrs. the mixture was heated to decompose the dimethyl sulfate, cooled, diluted, and neutralized, and the product was extracted with chloroform and precipitated from acetone with ether yield 91%, OCHa = 42.3%. Here the high solvent power of DMSO clearly contributes to the solvent effect. 

The chemical nature of crude protein in feedstuffs is the primary factor determining how rapidly it is degraded to ammonia or escapes microbial degradation. To compare feedstuffs, feed nitrogen can be divided into NPN, true protein, and unavailable fractions, which Pichard and van Soest (1977) labeled as the A, B, and C fractions, respectively (Fig. 18.3). The A fraction is rapidly attacked by rumen bacteria and converted to ammonia. Approximately 20% of the crude protein in SBM is in the A fraction and is degraded in the rumen at a rate of 300%/h (NRC, 1996). In contrast, a more undegradable protein source like distillers grains has 6% of the crude protein in the A fraction. 

The effects of technological processes were quantified only for the dry matter, the degradability parameters (for nitrogen, dry matter and starch) and the true intestinal digestibility of undegraded proteins. These values, and the PDI and the AADI values derived from them, are therefore different between the processed and the unprocessed feed material. 

Nitrogen fractions within the diet will vary in their susceptibility to breakdown, from immediately degraded to undegradable, and from 0 to 1 in the extent to which they are degraded in the rumen and digested when they reach the small intestine (see Table 13.8). 

AA = amino acids, ADIN = acid detergent insoluble nitrogen, DUP = digestible undegradable protein, ERDN = effective rumen degradable nitrogen, LCFA = long-chain fatty acids,... 

ME = metabolisable energy, MP = metabolisable protein, N = nitrogen, NF = nitrogen fraction, NFF = non-fermentable fraction, PFF = potentially fermentable fraction, UDN = undegradable nitrogen, VFA = volatile fatty acids, WSC = water-soluble carbohydrates. 

In order to determine the undegraded PVC content in the recycled material, about 0.2 g of the extruded mixtures were put in a glass tube, heated up to 280°C at a heating rate of about 5°C/min and held at this temperature for about 15 min under a slight flow of nitrogen. The evolved gases were absorbed in water and the resulting HCl titrated with NaOH. 

Figure 3.2 Chemiluminescence, measured in a nitrogen atmosphere of two different LDPE samples (a)Thermo-oxidlzed(100°C) A = LDPE B = LDPE + 7.7% starch C = LDPE + 15% MB and D = LDPE + 20% MB (see Reference 10). (b) Biodegraded (Pseudomonas aeruginosa). LDPE with and without Tween-80 biodegraded and undegraded, all samples pre-irradiated for 0,40 and 300 days before ageing.

Figure 3. Chemiluminescence measured in a nitrogen atmosphere of biodegraded (Pseudomonas aeruginosa). LDPE with and without Tween-80 biodegraded and undegraded, all samples pre-irradiatedfor 0, 40 and 300...

Noftsger, S. and N.R. St-Pierre, 2003. Supplementation of methionine and selection of highly digestible rumen undegradable protein to improve nitrogen efficiency for milk production. J. Dairy Sci. 86. 958-969. 

Krishnamoorthy, U., C. J. Sniffen, M.D. Stem and P. J. Van Soest, 1983. Evaluation of a mathematical model of mmen digestion and an in vitro simulation of mmen proteolysis to estimate the rumen-undegraded nitrogen content of feedstuff s. Brit. J. Nutr. 50, 555-568. 

Vanhatalo, A., P. Dakowski and P. Huhtanen, 1996. Effects of stage of growth and duration of rumen incubation time on intestinal digestibility of rumen-undegradable nitrogen of grass by mobile- bag method in cows. Acta Agric. Scand. 46, 1-10. 

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