**3. Piscine vitamin K requirements**

The world growth in aquaculture has increased enormously over the last decade. From 2005 to 2013, the global worth of this industry has more than doubled to over 150 billion USD [76]. Any captive species will be dependent on being fed an appropriate diet for health in order to produce good quality product for an ever‐demanding consumer population.

Fish, like other animals, are not able to *de novo* synthesize vitamin K and have to obtain it from their diet. Vitamin K deficiency in fish results in several familiar health problems that are found in terrestrial animals, including increased blood coagulation time, reduced growth, anemia, hemorrhage, weak bones, and occurrence of spinal curvature, short tails and increased mortality, together with problems specifically related to fish, such as loss of fin tissue [77–79].

The role of vitamin K in salmonids began to be investigated in the 1960s [80, 81], and today, minimum requirements for vitamin K supplement in fish feed are largely based on the effect of vitamin K on blood coagulation. Although estimates of dietary vitamin K requirement differ a great deal among fish species, and the quantitative requirement of vitamin K for most fish is still largely unknown. In addition, dietary studies on fish entail problems that are not encoun‐ tered in terrestrial animals, such as vitamin leaching into their environment from supple‐ mented feed [82].

Studies on zebrafish and Japanese puffer fish have found genes for vitamin K‐dependent factors (VII, IX, X and prothrombin). Also, continuous exposure to warfarin causes spontane‐ ous bleeding in zebrafish [83–85]. In common carp, warfarin prolonged the prothrombin time and activated partial thromboplastin time, whereas supplementation of menadione prevented increase in prothrombin time. For the large yellow croaker, the blood coagulation time generally decreased with increasing dietary menadione levels [86].

Menadione can be alkylated enzymatically to menaquinone‐4 in tissues [87]. This conversion has been recorded in several fish species such as Atlantic salmon [88–90], Atlantic cod [91], cultured sardines [92], mummichog [93], ayu [94] and large yellow croaker [86].

The enzyme UBIAD1 that converts vitamin K1 into menaquinone‐4 has been the subject of an investigation in a zebrafish mutant (*reddishs587:reh*). The fish develop normally for 24–36 h, but by 48 h they present with cranial hemorrhage [95]. The UBIAD1 gene was found to be expressed as early as the single‐cell stage. With continued development, the *reh* zebrafish mutant presents with higher expression of UBIAD1 in the vasculature than cardiac tissues and gene expression decreases with time. Introduction of an antisense morpholino oligonucleotide targeted splice to knockdown wild‐type UBIAD1, or the administration of warfarin, produced similar vascular models to the reh mutant, with the warfarin challenge having notably less impact on cardiac tissue compared to the vascular effects. The defect in these fish could be salvage by the introduction of wild‐type zebrafish or human UBIAD1 mRNA, but not *reh* UBIAD1 mRNA. Similarly, the knockdown or warfarin‐treated larvae could be rescued by the administration of vitamin K1 or menaquinone‐4, vitamin K1 being used as the source of naphthoquinone for the UBIAD1 conversion to menaquinone‐4. The overall finding that the UBIAD1 gene and enzyme expression has an important role in vascular endothelial cell survival has implications across all tissues and in cancer.

relation to the administered dose; however, menaquinone‐4 administration did not show corresponding plasma level increases, the suggestion being that the horses in this study did not absorb this vitamer. Interestingly, administration of vitamin K3 did cause menaquinone‐4 plasma levels to rise, which may relate to UBIAD1 synthesis of menaquinone‐4 or intestinal flora.

Another consideration in equine health is for vitamin K3 administered parenterally; this form of intervention was been found to cause pronounced renal toxic effects [74, 75]. Reports of parenteral administration of vitamin K1 or K2 prophylaxis, or remedial coagulopathy,

The world growth in aquaculture has increased enormously over the last decade. From 2005 to 2013, the global worth of this industry has more than doubled to over 150 billion USD [76]. Any captive species will be dependent on being fed an appropriate diet for health in order to

Fish, like other animals, are not able to *de novo* synthesize vitamin K and have to obtain it from their diet. Vitamin K deficiency in fish results in several familiar health problems that are found in terrestrial animals, including increased blood coagulation time, reduced growth, anemia, hemorrhage, weak bones, and occurrence of spinal curvature, short tails and increased mortality, together with problems specifically related to fish, such as loss of fin tissue [77–79].

The role of vitamin K in salmonids began to be investigated in the 1960s [80, 81], and today, minimum requirements for vitamin K supplement in fish feed are largely based on the effect of vitamin K on blood coagulation. Although estimates of dietary vitamin K requirement differ a great deal among fish species, and the quantitative requirement of vitamin K for most fish is still largely unknown. In addition, dietary studies on fish entail problems that are not encoun‐ tered in terrestrial animals, such as vitamin leaching into their environment from supple‐

Studies on zebrafish and Japanese puffer fish have found genes for vitamin K‐dependent factors (VII, IX, X and prothrombin). Also, continuous exposure to warfarin causes spontane‐ ous bleeding in zebrafish [83–85]. In common carp, warfarin prolonged the prothrombin time and activated partial thromboplastin time, whereas supplementation of menadione prevented increase in prothrombin time. For the large yellow croaker, the blood coagulation time

Menadione can be alkylated enzymatically to menaquinone‐4 in tissues [87]. This conversion has been recorded in several fish species such as Atlantic salmon [88–90], Atlantic cod [91],

The enzyme UBIAD1 that converts vitamin K1 into menaquinone‐4 has been the subject of an investigation in a zebrafish mutant (*reddishs587:reh*). The fish develop normally for 24–36 h, but by 48 h they present with cranial hemorrhage [95]. The UBIAD1 gene was found to be

cultured sardines [92], mummichog [93], ayu [94] and large yellow croaker [86].

generally decreased with increasing dietary menadione levels [86].

produce good quality product for an ever‐demanding consumer population.

interventions were not obvious from screening the literature.

**3. Piscine vitamin K requirements**

222 Vitamin K2 - Vital for Health and Wellbeing

mented feed [82].

Bone and spinal deformities are a major problem in commercial fish farming. Deformities are not only an economic problem for fish farms, but also raise ethical and welfare issues for the aquaculture industry. The importance of vitamin K in fish skeletal health has increased interest in vitamin K requirement for normal bone development in fish. There are a few studies that have dealt specifically with the effect of vitamin K deficiency on fish bone health [78, 88, 90, 96, 97]. Tissue‐specific gene expression of the vitamin K‐dependent proteins, such as osteo‐ calcin and matrix Gla protein (MGP), has been shown in the vertebrae of Atlantic salmon; however, dietary vitamin K was not found to regulate the expression of MGP [90, 98]. Inter‐ estingly, neither juvenile Atlantic salmon [90] or Atlantic salmon smolts [88] showed any sign of deformities on a diet lacking vitamin K supplementation.

Mummichog given feed that was not enriched with vitamin K grew thin, weak bones. Vitamin K deficiency induced bone structure abnormalities such as vertebral fusion and row irregu‐ larity, both in early development and during later growth [78, 96]. Furthermore, the offspring of vitamin K‐deprived fish had higher incidences of abnormal vertebral formation 5 days after hatching when compared to larvae from fish fed a vitamin K‐enriched diet [78]. In haddock, vitamin K appears to be necessary for bone mineralization [99]. However, vitamin K does not affect the number of osteoblast in haddock, while bone deformities coincided with an increased amount of osteoid and a decrease in bone mineral content. In the Senegalese sole given feed enriched with vitamin K, there was a notable improved larval growth performance and post‐ larval skeletal quality. Also, vitamin K modulated expression of protein involved in several biological processes including muscle contraction and development, cytoskeletal network, skin development, energy metabolism, protein chaperoning and folding, and bone develop‐ ment [97].

It now seems that vitamin K supply may be less than optimal for bone development, but sufficient to maintain normal growth and hemostasis [82, 87].

Fish feed is commonly enriched with vitamin K3 (menadione) in the form of water soluble salts, normally menadione sodium bisulphite (MSB) and menadione nicotinamide bisulphite (MNB) [82].

Using menadione in fish feed is, however, not without problems; too high a dosage, in particular MSB, has proven to cause reduced growth [91, 100]. Nevertheless, it remains one of the most common vitamin K supplements in fish feed.

reason for veterinary use of vitamin K clinically is as a rescue medication due to accidental rodenticide intoxication. As with the dog, the problem has probably been exacerbated by the increasing use of the more persistent anticoagulants used as rodenticides that have replaced

Vitamin K2 in Animal Health: An Overview http://dx.doi.org/10.5772/63901 225

Starting in the 1950s in South West UK, a breed of Rex cat was developed out of some accidental breeding with feral tom cats, which led to some reverse mating into their own genetic line with the intent to maintain the Rex breed. One of these lines of development led to the Devon Rex cat. In 1990, three Devon Rex cats were described with a vitamin K deficiency character [114], after exclusion of other factors such as accidental anticoagulant ingestion, liver disease, intestinal malabsorption problems and treatment with vitamin K to correct their deficiency. The nature of the defect in the Devon Rex was investigated in the Netherlands, and this cat was found to have a decreased ability to gamma‐carboxylate vitamin K‐dependent clotting factors due to a decrease binding of reduced vitamin K and the clotting factors to the carbox‐

With increasing age, cats also develop diseases that cause vitamin K deficiency coagulopathies, such as liver disease, inflammatory bowel disease and secondary malabsorption syndrome

It is possible to induce a vitamin K deficiency through diet, presumably as the cat is not particularly associated with coprophagic behavior. In an early study of queens and their kittens fed either a commercial tuna‐ or a salmon‐based fish diet, there was a notable increase in blood clotting times [119]. Where the information is available, current commercial cat diets provide

The cat is also prone to present clinically with chronic kidney disease (CKD) [120], and the reported prevalence is high, particularly in aged cats. It is interesting that the pathophysiology of feline CKD has been proposed to be sufficiently similar to human disease that the cat could provide a natural model to investigate human CKD [121]. In human CKD, there are several reports of an association with low vitamin K status [122] and a recent multi‐ethnic study demonstrated an inverse association between estimated glomerular filtration rate and a functional marker of vitamin K deficiency, namely de‐phospho‐undercarboxylated matrix Gla

Our pilot studies looking at circulating vitamin K in the healthy aged cats found that mena‐ quinone‐4 was the dominating form of vitamin K. This observation would suggest that the vitamin K3 in cat diet is converted through UBIAD1 to menaquinone‐4, although this has not been specifically demonstrated. There is a line of thought that vitamin K may also be provided to the cat through colonic bacterial supply. The absence of long‐chain menaquinones in our study suggest that this is unlikely and evidence supporting colonic absorption of fat‐soluble

Systemic inflammation is widely accepted as a dominant driver in the aetiology of CKD, and this is an active area of therapeutic interest [125]. The re‐emerging observation of direct anti‐ inflammatory activity for vitamins K1 and K2 and in particular their common 7‐carbon carboxylic acid catabolite [126–128] suggests that a low vitamin K status in CKD may also

vitamin K 'activity' in the form of vitamin K3, principally in the dry food products.

warfarin in order to overcome rodent warfarin resistance.

ylase enzyme [115].

[116–118].

protein [123].

vitamins K in general is limited [124].
