As long as natural dietary vitamin K sources (e.g., green leafy plants) are sufficiently high and bacterial synthesis in the intestinal tract remains functional, supplementary dietary vitamin K is not strictly necessary. However, good sources of vitamin K such as green leafy plants are not usually fed to poultry. An exception is alfalfa meal, which is sometimes included in small amounts in poultry diets. Therefore, a source of vitamin K needs to be added to the diets of poultry since they are not getting sufficient fresh greens or their dried equivalent and are not synthesizing sufficient amounts of this vitamin in their gastrointestinal tract.
Scott et al. (1982) reported that natural ingredients used in poultry diets some years ago probably contained sufficient vitamin K while present diets do not. The common feedstuffs used in past years, such as high levels of alfalfa meal, high-fat soybean and other oilseed meals and fish meals with some putrefication supplied ample vitamin K. Recent trends toward (1) eliminating levels of alfalfa for production of higher energy, higher efficiency diets; (2) solvent extraction of soybean and other oilseed meals; (3) improved processing of fish meals, resulting in lower menaquinone levels because of less putrefaction; and (4) use of vitamin K-inhibiting drugs in feed and drinking water have had a combined effect that makes supplementation of most present day poultry feeds a necessity.
Vitamin K antagonists will increase the vitamin K needs of livestock. In adjusting dietary vitamin K fortification levels, an appropriate margin of safety is needed to prevent deficiency and allow optimum performance in poultry. Vitamin K antagonists include the use of certain antibiotics and sulfa drugs. Mycotoxins, such as aflatoxin, are toxic substances produced by molds. Supplemental vitamin K may be helpful in correcting vitamin K deficiency in aflatoxicosis. Nelson and Norris (1961) showed that the inclusion of 0.1% sulfaquinoxaline increased the chick’s need for supplemental vitamin K by fourfold to sevenfold. By altering the intestinal microflora, an excellent source of vitamin K is lost.
The level of supplemental vitamin K should be adequate to meet the requirements under the wide variety of stress conditions encountered in practical poultry production. Squibb (1964) obtained increased prothrombin times, indicating a higher vitamin K requirement in chicks, during the early stages of Newcastle disease. Studies have shown an interrelationship between the severity of coccidiosis and vitamin K requirement and indicated that as much as 8 mg of vitamin K per kg (3.6 mg per lb) of diet was needed at times for maximum growth and feed efficiency. Scott et al. (1982) concluded that coccidiosis possibly produces a triple stress on the vitamin K requirement by (1) reducing feed intake and thereby the supply of vitamin K, (2) injuring the intestinal tract and reducing absorption of the vitamin and (3) treatment with sulfaquinoxaline or other anticoccidials that cause an increased requirement for vitamin K. Recovery of poultry from coccidiosis has been enhanced by high dietary levels of supplemental vitamin K.
Inadequate vitamin K under practical circumstances is most likely to occur during the starting period, and supplementation of the feed at this time is advantageous (NRC, 1994). Starting feeds seldom contain forage meals, and a poorly developed intestinal microflora together with the use of antimicrobials further reduces access to the vitamin.
Fleming et al. (1998) suggest that supplementation with extra vitamin K may be beneficial to bone strength at different ages in laying hens. Increasing dietary vitamin K (menadione) from 2 to 12 mg per kg (0.9 to 5.5 mg per lb) increased cancellous bone volume in the proximal tarsometalarus at 25 weeks. Studies are currently in progress to establish whether increasing the normal vitamin K supplement throughout the whole life of the hen has a beneficial effect on osteoporosis.
Vitamin K supplementation is needed if high dietary levels of other fat-soluble vitamins are fed (Abawi and Sullivan, 1989; Frank et al., 1997). Plasma clotting time is increased when vitamins A and E, in particular, are in excess.
Vitamin K1 is not currently available to the feed industry, as it is too expensive for this purpose; instead, water-soluble menadione (vitamin K3) salts are used to provide vitamin K activity in feeds. Because of instability, menadione is not used in feed as the pure vitamin but is formulated as an additional product with sodium bisulfite and derivatives thereof. Water-soluble derivatives of menadione include menadione sodium bisulfite (MSB), menadione sodium bisulfite complex (MSBC), and menadione dimethyl-pyrimidinol bisulfite (MPB) and the most recent compound introduced into the market, menadione nicotinamide bisulfite (MNB). The greatest menadione activity is 50% for MSB followed by 45.4% for MPB and 33% for MSBC (Schneider, 1986). Sometimes MSB is coated with gelatin to increase stability, resulting in a 25% menadione activity.
Stability of the naturally occurring sources of vitamin K is poor. However, stability of the water-soluble menadione salts is excellent in multivitamin premixes unless trace minerals are present (Frye, 1978). Basic pH conditions also accelerate the destruction of menadione salts; thus soluble or slightly soluble basic mineral substances should not be included in multivitamin premixes containing menadione. The MSB form is the most unstable formulation, followed by MSBC, MPB, and MSB-coated, and finally the most stable, MNB. A report by Huyghebaert (1991) determined the stability of different vitamin K formulations in a multivitamin, choline chloride and trace mineral premix at room temperature. At the end of four months, MSB retained 33%, MPB 57%, MSB-coated 62%, and MNB 83%.
Frye (1994) concludes that vitamin K in the form of MSB or MSBC is very sensitive to moisture and trace minerals, sensitive to light and gastric pH, and moderately sensitive to reduction and acid pH. Choline chloride is particularly destructive to vitamin K. Less water-soluble forms or coated K3 is recommended in premixes that contain large quantities of choline chloride and certain trace minerals and especially in all cases where plain MSB is used or when premixes are exported or stored for an extended period of time (Schneider, 1986).
