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The period represented in this discussion is from 1 day of age until sexual maturity, which is approximately 18 to 20 weeks.

Pantothenic acid (PA) is an essential vitamin (vit B5) involved in numerous catabolic and synthetic cellular reactions1. This vitamin is a precursor of coenzyme A (CoA) which is required for the initial activation of free fatty acids to fatty acyl-CoA thioesters prior to their oxidation or esterification to complex lipids2,3.PA is also a structural element of acyl carrier protein which is an essential component of the fatty acid synthetase

Besides carbohydrates, proteins, and fats, there are many nutrients in the chicken’s diet that are necessary in smaller quantities to enable the bird to live, produce meat and eggs economically, and to reproduce efficiently. The list includes the vitamins, macro-and micro-minerals, and certain other additives.

Vitamins are a group of organic compounds which are essential in very small amounts for the normal functioning of the human body. They have widely varying chemical and physiological functions and are broadly distributed in natural food sources. Thirteen vitamins are recognized in human nutrition and these may be conveniently classified, according to their solubility, into two groups. The fat-soluble vitamins are represented by vitamins A, D, E and K; also included are the 50 or so carotenoids that possess varying degrees of vitamin A activity. The water-soluble vitamins comprise vitamin C and the members of the vitamin B group, namely thiamin (vitamin B1), riboflavin (vitamin B2), niacin, vitamin B6, pantothenic acid, biotin, folate and vitamin B12. This simple classification reflects to some extent the bioavailability of the vitamins, as the solubility affects their mode of intestinal absorption and their uptake by tissues. The solubility properties also have a direct bearing on the analytical methods employed in vitamin assays.

In the context of human and animal nutrition, vitamins are physiologically active substances. To assess the nutritional value of a food commodity or diet with respect to a particular vitamin it is necessary to determine the vitamin’s biological activity. Biological activity refers to the ability of a nutrient to fulfil a specific biological function or metabolic requirement. The only direct means of determining biological activity is a bioassay based on biological function. Such assays were the means by which the vitamins were originally recognized. They are still required today to measure the biopotency of new vitamin derivatives and food supplements, as well as validating new nonbiological assay methods.

Vitamins play an important role in intermediary metabolism as co-factors in numerous enzymatic reactions or in non-enzymatic physiological functions such as the visual process (vitamin A), as antioxidants (carotenoids, vitamins E, C, and riboflavin), in regulation of calcium metabolism (vitamin D) and in haematopoiesis (vitamin B12, folates and vitamin B6). Although research in the last few decades has in most cases been focused merely on deficiencies in order to establish requirements, development of diagnosis, etc., there is now a renewed interest in the role of vitamins in the maintenance of health. Recognition of the prominent role of some vitamins as antioxidants, in cell proliferation/differentiation, and in immune function has shed new light on the importance of these essential nutrients in the prevention of many chronic diseases, e.g. coronary heart disease, cancer and other immunorelated diseases (van den Berg et al., 1993).

The nutritional value of a food commodity or diet with respect to a particular vitamin is related to the quantity of the vitamin present and its bioavailability. Bioavailability has been defined in the experimental context as the biological vitamin activity or potency (expressed as the sum concentration of biologically available forms of the vitamin) divided by the total concentration of the vitamin as determined by microbiological or physicochemical assay (Gregory, 1988). The biological activity can be determined directly by means of an animal bioassay, but it would be more practicable to use an in vitro method of analysis preceded by an appropriate extraction procedure. In most cases, the extraction procedures do not adequately model mammalian digestion and absorption processes, and an in vitro assay can only replace an animal bioassay if a statistical correlation (r = >0.95) can be demonstrated between the results of the two methods for a particular food sample.