In Animal Diets

Compounds in animal diets can exert their effects in the gastrointestinal tract or after absorption through the gut epithelial tissue into the bloodstream, or both. On some occasions the administered compounds may be applied topically (Table 1). 

Farmed animals tend to be subjected to compounds that can be classified more easily as drugs. In some cases, animals may encounter compounds in nature that have considerable limitations in inclusion in the diets of farmed animals. An example is the inclusion of zearalenone (Figure 1) and its derivatives in animal diets these have anabolic and oestrogenic properties " and are permitted to be used in some areas of the world but are prohibited from use in others, such as European Union countries. Thus this compound and its reduced isomers (zearalenols, zeranols) improve growth rates in animals but can cause reproductive problems, especially in pigs. Ralgro, which is a commercially prepared derivative of zearalenone, is used as an ear implant in beef cattle as a growth promoter in... 

The environmental effects of using drugs and additives in animal diets are... 

Precursors of phenylpropanoids are synthesized from two basic pathways the shikimic acid pathway and the malonic pathway (see Fig. 3.1). The shikimic acid pathway produces most plant phenolics, whereas the malonic pathway, which is an important source of phenolics in fungi and bacteria, is less significant in higher plants. The shikimate pathway converts simple carbohydrate precursors into the amino acids phenylalanine and tyrosine. The synthesis of an intermediate in this pathway, shikimic acid, is blocked by the broad-spectrum herbicide glyphosate (i.e., Roundup). Because animals do not possess this synthetic pathway, they have no way to synthesize the three aromatic amino acids (i.e., phenylalanine, tyrosine, and tryptophan), which are therefore essential nutrients in animal diets. 

Jensen et al. (1988) Pork cooked loin Static headspace HP7694 HS Sampler mg/kg DM 0.88 control 0.91 rapeseed + vitamin E in animal diet... 

Larick et al. (1992) Pork cooked loin Static headspace Perkin Elmer HS-6 Peak area" mV/sec x 1 O 11.55 with 6.10% linoleic acid in animal diet 7.81 with 1.76% linoleic acid in animal diet 4.76 with 6.10% linoleic acid in animal diet 3.16 with 1.76% linoleic acid in animal diet... 

The first difference is that in the product or formulation other compounds are present. If these compounds interfere unduly with the LC method or are present in much larger quantities than the compound of interest then some sample pre-treatment will be necessary. This has been dealt with in Chapter 8. However for a product or formulation this may be straightforward, frequently consisting only of selective dissolution followed by injection of supernatant or a filtration step. The choice of solvent for selective dissolution may be simple but for compounds in a complex formulation (such as a drug in animal diet) it might take some time to find suitable conditions to recover all the compound from the solid residue. 

Ullrey DE. 1992. Basis for regulation of selenium supplements in animal diets. J Anim Sci 70(12) 3922-3927. 

Cellulose Is an Indigestible polysaooharlde that provides structure for plants and fiber In animal diets. 

Cottonseed oil contains up to 0.5% of a pair of unique fatty acids malvalic (18 1) and sterculic (19 1). These acids are characterized by the presence of a cyclopropene group at or near the center of the fatty acid chain. Under appropriate conditions these give colored compounds and the development of a red color in the Halphen test (reaction with sulfur in carbon disulfide in the presence of amyl alcohol) is due to the cyclopropene acids and therefore characteristic of cottonseed oil (and other minor oils containing cyclopropene acids). This test for cottonseed oil was developed over a century ago in 1897. Inclusion of cyclopropenoid acids in animal diets causes undesirable physiological effects such as reduced egg production, poor hatching, and pink egg whites in chickens, and in rats, decreased growth and sexual development and... 

Sodium is not required by plants but can replace part of the K requirement of some plant species. The attraction of some animals to NaCl and the long history of NaCl as an important article of commerce suggest that soils in humid regions may provide inadequate Na+ and Cl- for animal diets. Humans ingest more NaCl than they require, because of taste preferences and because NaCl is used in food preservation, but a suggestion of insufficiency in animal diets remains. Of the essential elements, Na+, Cl-, I-, and F- are unique in that much of their supply to humans comes from additions to our diet rather than from natural foodstuffs. 

Except for much greater Cl accumulation in soils of arid regions, the soil chemistry of I and Br resembles that of Cl, except that I and Br are retained more strongly, especially by acid soils. The major input of I to soils appears to be atmospheric. Endemic iodine deficiency (goiter in humans) occurs in mountainous and continental areas isolated from the sea. Fortunately, supplementing NaCl with small amounts of I effectively supplies the I required in animal diets. Iodide and Br are both potentially toxic, but no natural cases have been reported. Bromide reactions in soils have been investigated as a tracer for die movement of water, nitrate, and soil solutions in soils. 

Molybdenum is one of the biologically active transition elements.1 It is believed to be a necessary trace element in animal diets, but function and minimum levels have not been established. It is well established that nitrogenfixing bacteria employ enzymes containing both Mo and Fe. Recently2 one such enzyme, or a part thereof, has been obtained in pure, crystalline form. One molecular unit appears to have a molecular weight in the range 270,000-300,000 Daltons and to contain two atoms of Mo and forty of Fe. This protein in association with another which contains only iron possesses the ability to catalyze the reduction of Nz and other substrates. Chemical and structural details are not yet known. 

Fisher, M.T. and Lee, J. (1982). Multi-element analysis by inductively-coupled plasma emission spectrometry in animal diets and faeces containing chromium marker. Anal. Chim. Acta 139, 333-339. 

Molybdenum (Mo) is an essential plant nutrient. It acts as a metallic cofactor in plant and animal enzymes. At high concentrations in forages, it can be toxic to ruminants by interfering with assimilation of copper (Cu). The range between toxicity and deficiency in animals is narrow, and therefore careful control of Mo in animal diets is essential. 

Sulfur is a constituent of the amino acids, methionine, cystine and cysteine, which are essential in proteins supplied in animal diets. Sulfur is also a constituent of the vitamins, thiamine and biotin, and of glutathione and coenzyme A. It plays an important role in the action of proteolytic enzymes and in oxidation—reduction processes. As a constituent of proteins it is present in cell protoplasm and is therefore of vital importance in cell metabolic processes. 

Adverse biological effects have been observed following the incorporation of sterculic acid in animal diets (Phelps etaL, 1965 Kircher, 1964). Pink coloration of eggs is caused when sterculic acid (25 mg/day) is fed to laying hens. The cyclopropenoid group is destroyed either by hydrogenation (Zarins et ai, 1982)... 

We may conclude that this enzyme provides a means of utilizing thymidine (which is not an intermediate in thymidylate synthesis de novo, but which may occur endogenously or in animal diets) its synthesis and activity are subject to controls, apparently because formation of the product, thymidylate, is a key step in the regulation of DNA synthesis. 

Tryptophan, phenylalanine, and tyrosine are biosynthesized through the common aromatic amino acid biosynthetic pathway (Figure 12.4). Tryptophan finds application in feed and pharmaceutical industries. Tryptophan in animal diets increases quality of pork, maximizes feed utilization, and reduces nitrogen excretion. The Chinese producer Ajinomoto holds 73% of the global production with a volume of 100 million dollars and Evonik 18%. ... 

This part provides details of the foods that are commonly given to animals, including their main nutrient content and factors that need to be taken into account when they are used in animal diets. 

The antinutrient properties of the proteinase inhibitor fractions have been ascribed primarily to the inhibitors of trypsin. However only limited data is available concerning the effects of inhibitors of chymotrypsin and elastase, and virtually nothing is known of the effects in animal diets of inhibitors with specificities toward the carboxypeptidase A and B. The major impediment to such research is the availability, for testing in animal diets, of inhibitors having these latter specificities. 

Trypsin inhibitors in animal diets are known to cause pancreatic hypertrophy and hyperplasia. We therefore monitored pancreas weight and enzymic contents in all of the above experiments. The pancreata were removed from the chicks at the termination of the experiments, weighed, and assayed for activities of trypsin, chymotrypsin and carboxypeptidases A and B, after activating their zymogens with either trypsin or enterokinase. 

The phenolic compounds are widely distributed in the plant kingdom. They vary considerably from plant to plant and may be present in small to very large amounts. Based on chemotaxonomic examination, at least 25 phenolics are of universal occurrence in animal diets derived from plants (Singleton and Kratzer, 1969). 

The increased interest in phytochemicals in animal diets has been spurred on by the reduction in and general market resistance to the use of in feed antibiotics, the removal of animal protein from diets, and thus the increased variety and inclusion levels of vegetable protein sources. Nevertheless, such effects may be the essential indicator of desirable properties, such as therapeutic potential, especially when the... 

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