Amino acids ruminants

The nature of the diet sets the basic pattern of metabohsm. There is a need to process the products of digestion of dietary carbohydrate, lipid, and protein. These are mainly glucose, fatty acids and glycerol, and amino acids, respectively. In ruminants (and to a lesser extent in other herbivores), dietary cellulose is fermented by symbiotic microorganisms to short-chain fatty acids (acetic, propionic, butyric), and metabohsm in these animals is adapted to use these fatty acids as major substrates. All the products of digestion are metabohzed to a common product, acetyl-CoA, which is then oxidized by the citric acid cycle (Figure 15-1). 

Birds eat sufficient food to satisfy their energy intake, but this does not mean that they will eat enough protein, unless the protein proportion in the rotation is high. Protein quality is also important, the two most essential amino acids being lysine and methionine. The best quality protein for all poultry is white fishmeal (banned only for ruminants by the Soil Association). The best vegetable protein is soya bean which is low in methionine, but this can be made up by using sunflower meal in the ration. 

In the last few years additional members of the interferon family has been discovered. Amino acid sequence analysis of a protein called trophoblastin (which is found in many ruminants) revealed... 

Finally, the contents of the omasum, now a thick slurry of microorganisms, pass into the abomasum into which are secreted acid and proteinases to produce an environment corresponding to that of the human stomach. Some of the microflora passing from the rumen to the omasum die and are digested by the acid and the enzymes. This provides the ruminant not only with an additional energy source but with vitamins and essential amino acids that its own tissues caimot synthesise. 

In the last few years additional members of the IFN family has been discovered. Amino acid sequence analysis of a protein called trophoblastin—which is found in many ruminants — revealed that it was closely related to IFN-a. This result was surprising because, in sheep and several other ruminants, the primary function (and until recently the only known function) of trophoblastin is to sustain the corpus luteum during the early stages of pregnancy. The 172 amino acid protein is produced by the trophoblast (an outer layer of cells which surround the cells that constitute the early embryo) for several days immediately preceding implantation. In many ruminants, therefore, trophoblastin plays an essentially similar role to hCG in humans (Chapter 8). 

Like IFN-a, IFN-co genes have duplicated to high copy numbers in ruminants but not in humans [64], Unlike IFN-a, IFN-co protein is 172 amino-acid residues long and is capable of eliciting similar biological responses in vitro as compared to other type I IFNs [36],... 

About half of the NPN of milk is accounted for by urea. Orotic acid is a particular hallmark of the milks of ruminants milks of other species contain little if any of it (Larson and Hegarty 1977). The free amino acids constituting the a-amino N fraction in Table 1.6 include those that are also found in proteins, as well as ornithine, citrulline, and cx-amino butyric acid. Quantitative analyses of the mixture of free amino acids have been published (Deutsch and Samuelsson 1958 Armstrong and Yates 1963 Rassin et al. 1978). 

Evidence for consistent, positive metabolic effects of feeding antibiotics is fragmented and inconclusive. Direct measurement of increased uptake of nutrients, ie, in vivo amino acids, glucose, or volatile fatty acids in ruminants, have not been reported. 

Animal organisms generally require effective assistance of intestinal flora, as in ruminants, to assimilate inorganic nitrogen into body protein. This accounts for the human needs of a daily requirement of 70-80 grams of protein, However, over half of the protein-constituent amino adds can be derived from other amino acids by their own enzymic reactions. Thus, amino acids are classified as essential or nonessential. Amino acid requirements vary with the physiological state of the animal, age. and possibly with the nature of the intestinal flora. 

Urea is also used as feed supplement for ruminants, where it assists in the utilization of protein. Urea is one of the raw materials for urea—formaldehyde resins. Urea (with ammonia) pyrolyzes at high temperature and pressure to form melamine plastics (see also Cyanamides). Urea is used in the preparation of lysine, an amino acid widely used in poultry feed (see Amino acids Feeds and feed additives, petfoods). It also is used in some pesticides. 

Another problem for the UK farmer and feed manufacturer is a current ban on the use of fishmeal in feedmills that produce feed for ruminants (an industry-wide rather than an organic regulation). This means that organic feed manufacturers with only one mill (and who cannot now use pure amino acids) who produce ruminant and non-ruminant diets can no longer use fishmeal at all. The result is that those mills in particular have a very difficult task in producing organic poultry diets of the necessary nutritional standard. 

Synthesis of sulfur amino acids from inorganic sulfate by ruminants. Proc. Soc. Exptl. Biol. Med., 73, 391 (1950). With J. A. Stekol. 

For satisfying amino acid requirements of ruminants, experts developed a procedure, as a result of which the degradation of administered synthetic amino acids takes place in the small- and large intestines and not in the rumen. On the basis of microcapsule coating, the method of dimethionine coating was elaborated, and a plant with several tons of capacity has been established. Daily administration of only a few grams of protected methionine raised milk production by 1.2-1.51/day. 

One typical example of a controlled-release approach is the Smartamine system for ruminants developed and commercialized by Rhone-Poulenc Animal Nutrition. Smartamine products are rumen-protected amino-acids which are added to the feed of dairy cows in order to increase the protein content of the milk. 

Binding of the substrate urea to a nickel ion in urease is an integral part of the mechanism in the hydrolysis reaction (Nielsen 1984). Both ruminants and monogastric animals require urease for the decomposition of urea into ammonia, which is needed for the microbial synthesis of ammonia that, in turn, is necessary for amino acid and protein synthesis. This process also takes place in the appendix of monogastric animals and some species of ruminants (roe deer). 

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