Chick

Kitsopoulos T N, Chick C J, Zhao Y and Neumark D M 1991 Study of the low-lying electronic states of Sij and Si. using negative ion photodetachment techniques J. Chem. Phys. 95 1441... 

Most poultry production, and a growing percentage of swiae production, takes place ia iatensive, confinement operations. Much of the poultry production is carried out under a system of vertical iategration ia which a producer hatches the chicks, grows them ia the producer s faciUties or ia contract facihties, provides the feed, processes the animals, and markets the product. This system of vertically iategrated production is not as common ia the swiae iadustry. 

Requirements of poultry for vitamin D are expressed ia iatematioaal chick units (ICU) which are based on the activity of vitamin in chick bioassays. ... 

To convert kJ to kcal, divide by 4.184. ICU = international chick units. ... 

Vanadium. Vanadium is essential in rats and chicks (85,156). Estimated human intake is less than 4 mg/d. In animals, deficiency results in impaired growth, reproduction, and Hpid metaboHsm (157), and altered thyroid peroxidase activities (112). The levels of coen2yme A and coen2yme Q q in rats are reduced and monoamine oxidase activity is increased when rats are given excess vanadium (157). Vanadium may play a role in the regulation of (NaK)—ATPase, phosphoryl transferases, adenylate cyclase, and protein kinases (112). 

One vitamin E analogue, TROLOX, inhibits radiation-induced apoptosis in murine thymocytes (26). Chicks given vitamin E prior to exposure to a sublethal dose (2.25 Gy (225 rad)) of y-radiation demonstrate a more rapid recovery from damage to the thymus (100). 

In 1956 selenium was identified (123) as an essential micronutrient iu nutrition. In conjunction with vitamin E, selenium is effective iu the prevention of muscular dystrophy iu animals. Sodium selenite is adrninistered to prevent exudative diathesis iu chicks, a condition iu which fluid leaks out of the tissues white muscle disease iu sheep and infertility iu ewes (see Eeed ADDITIVES). Selenium lessens the iacidence of pneumonia iu lambs and of premature, weak, and stillborn calves controls hepatosis dietetica iu pigs and decreases muscular inflammation iu horses. White muscle disease, widespread iu sheep and cattle of the selenium-deficient areas of New Zealand and the United States, is insignificant iu high selenium soil areas. The supplementation of animal feeds with selenium was approved by the U.S. EDA iu 1974 (see Eeed additives). Much of selenium s metaboHc activity results from its involvement iu the selenoproteia enzyme, glutathione peroxidase. 

Bioassays procedures have been developed in species such as chicks which have been fed a niacin-deficient diet. Due to the fact that, for example, tryptophan is a biological precursor of niacin, niacin can be produced from other sources (55). As a result, the tryptophan content of the diet has to be monitored carefully for accurate results. 

Although riboflavin can be assayed more readily by chemical or microbiological methods than by animal methods, the latter are preferred for nutritional studies and as the basis of other techniques. Such assays depend upon a growth response the rat or chick is the preferred experimental animal. This method is particularly useful for assaying riboflavin derivatives, since the substituents frequently reduce or eliminate the biological activity. 

Parallel to the activities in the treatment of pernicious anemia were observations in the 1930s that most farm animals had a requirement for an unknown factor beyond the vitamins then known. The lack of this factor became apparent, eg, when chicks or pigs fed a diet with only vegetable protein evidenced slow growth rate and high mortahty. It became apparent that the requited factor, termed animal protein factor, was present in animal sources such as meat and tissue extracts, milk whey, and cow manure. Subsequent to its isolation, it was rapidly shown that vitamin B 2 is the same as animal protein factor. 

Bioassays are based on the growth response of vitamin-depleted rats or chicks to graded amounts of vitamin B 2 added in the diet. These assays are not specific for vitamin B 2 because factors, other than vitamin B 2 present in biological materials, produce a growth response. Because coen2yme primary form of natural vitamin 2 is light sensitive, assays should be carried out in subdued light. 

Irradiated ergosterol was found not to be as antirachitic in the chick as in the rat, whereas the chick could be protected by direct kradiation. The provitamin in cholesterol was shown not to be ergosterol. Rygh (14) in 1935 found that 1 rat unit of cod Hver oil was 100 times more potent in chicks than 1 rat unit of vitamin D2. Brockmann (15) in 1936, prepared the pure crystalline 3,5-dinitrobenzoate derivative of vitamin D obtained from tuna Hver oil... 

In 1949 the World Health Organization adopted the biological activity of 1 mg of an oil solution containing 0.025 p.g of crystalline D as the analytical standard for vitamin D. This standard was discontinued in 1972. USP uses crystalline cholecalciferol as a standard (80). Samples of reference standard may be purchased from U.S. Pharmacopeia Convention, Inc., Reference Standards Order Department, 12601, Twinbrook Parkway, Rockville, Maryland 20852. One international unit of vitamin D activity is that activity demonstrated by 0.025 ]1 of pure crystalline (7 -vitamin D. One gram of vitamin D3 is equivalent to 40 x 10 lU or USP units. The international chick unit (ICU) is identical to the USP unit. 

USP also issues vitamin D capsules for AO AC deterrnination in rats and an oil solution for the vitamin D AO AC deterrnination in chicks. Historically, the following units (shown with their approximate international unit equivalence) have been used but are currendy abandoned 1 clinical unit = 12-17 lU 1 biological unit = 0.125 lU 1 protection unit = 0.125 lU 1 Laquer unit = 0.14 lU 1 Poulson unit = 0.2 lU 1 Steenbach unit = 3 lU. The MRC, ICU, and Coward units all approximated the international unit and are also no longer in common use. 

The metabohtes of vitamin D are usually more toxic than the vitamin because the feedback mechanisms that regulate vitamin D concentrations are circumvented. 25-Hydroxycholecalciferol has a one-hundredfold increase in toxicity over vitamin D when fed to chicks (220) and 1 a,25-dihydroxy vitamin D is several times more toxic than the 25-hydroxy analogue. Vitamin D2 seems to have less toxicity than vitamin D, a circumstance which is beheved to be caused by the more efficient elimination of 25-hydroxy and the 1 a,25-dihydroxy vitamin D2 from the animals. Estimated safe upper dietary levels are given in Table 11. 

The classical method for the determination of vitamin K is based on the clotting time of a vitamin K-deficient chick. It is relatively easy to produce a hemorraghic state ia chicks (17). Vitamin K-deficient tats have also been used for this assay (18). Owiag to the development of modem chromatographic techniques, this method of analysis has been supplanted by other methodology. 

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