Ruminants vitamin requirements

Cobalt is essential for animal nutrition, but it has not been established as essential for plant growth. Ruminant animals require cobalt for the synthesis of vitamin Bi2 by their rumen microflora. This was established about 1935, but an essential role of cobalt in plants was not demonstrated until 1960 [33]. Cobalt has been found to be essential for the growth of legumes which rely on symbiotic nitrogen fixation. 

A completely independent study implicating the intestinal bacteria was that of Theiler and his associates (13) in ruminant animals. In the attempt to reproduce experimentally a South African paralytic disease known as lamzietke they fed cattle an experimental diet deficient in vitamin B and noted that evidences of deficiency failed to develop although pigeons on the same diet developed polyneuritis promptly. They assumed that either the vitamin requirement of cattle was extremely low or that it had been satisfied by bacterial synthesis in the intestinal tract the latter explanation seemed the more probable. 

The requirements of dairy cattle for B-vitamins, determined almost half a century ago, concluded that a ruminant animal does not require an exogenous supply of B-vitamins because its rumen microflora should synthesise enough of these compounds to avoid deficiency. Since then, dairy cows have greatly increased their average milk and milk component yields. More recent studies have shown that B-vitamin supply in dairy cows is increased by supplementation, although losses in the rumen are extensive (Santschi et al., 2005). Whilst there are few reports of B-vitamin supplementation affecting milk quality, supplemental biotin has been shown to directly improve milk yield (Majee et al., 2003). 

Amprolium (Fig. 5.7) is a vitamin IT analogue. It is a competitive antagonist of the thiamine transport mechanism. Amprolium has been used as a coccidi-ostat mainly in chickens, laying hens, turkeys, and ruminants. It is available as a soluble powder for addition to drinking water (60-240 mg/L) or as a premix, usually in combination with ethopabate and/or sulfaquinoxaline, for mixing with the feed (125-500 mg/kg feed). A withdrawal period of 3 days is required for chickens. 

The human body contains only about 1.5 mg of cobalt, almost all of it is in the form of cobalamin, vitamin B12. Ruminant animals, such as cattle and sheep, have a relatively high nutritional need for cobalt and in regions with a low soil cobalt content, such as Australia, cobalt deficiency in these animals is a serious problem. This need for cobalt largely reflects the high requirement of the microorganisms of the rumen (paunch) for vitamin B12. All bacteria require vitamin B12 but not all are able to synthesize it. For example, E. coli lacks one enzyme in the biosynthetic... 

Like all other animals, poultry require five components in their diet as a source of nutrients energy, protein, minerals, vitamins and water. A nutrient shortage or imbalance in relation to other nutrients will affect performance adversely. Poultry need a well-balanced and easily digested diet for optimal production of eggs and meat and are very sensitive to dietary quality because they grow quickly and make relatively little use of fibrous, bulky feeds such as lucerne hay or pasture, since they are non-ruminants (have a simple stomach compartment). 

Cobalt is a component of the vitamin B12 molecule but a deficiency of cobalt has not been demonstrated in poultry fed a diet adequate in vitamin B12. Therefore, supplementation with this element is not normally necessary. Diets containing no ingredients of animal origin (which contain vitamin B12) contain no vitamin B12. Therefore, poultry fed on all-plant diets may require dietary cobalt, unless the diet is supplemented with vitamin B12. In practice, many feed manufacturers use a cobalt-iodized salt for all species since cobalt is needed in ruminant diets. This avoids the need to stock separate salt types for ruminant and non-ruminant diets and the inclusion of cobalt provides some insurance in case the poultry diet is lacking sufficient vitamin B12. 

Ruminants require cobalt for the bacterial biosynthesis of vitamin B12 in the first stomach. Cobalt-deficient sheep or cattle show diminished feed intakes and weight loss. In cows, milk production declines and the fre-... 

Vitamin B12 is synthesized in large quantities by the intestinal flora, particularly in ruminants. The exact amount of vitamin B12 required by the normal human is not known. The absorption of vitamin B12 from the gastrointestinal tract is dependent on the presence of a gastric mucoprotein called intrinsic factor. Calcium ions seem to be necessary for the interaction of vitamin B12 with this intrinsic factor. Vitamin B12, which is absorbed only in the ileum, is stored in the liver. There are two transport proteins for vitamin Bj2 transcobalamin I and II, the latter being physiologically more important. Vitamin B12 plays an important role in the metabolism of functional groups with one carbon atom such as the methyl group... 

The interrelations between vitamin E and selenium in cattle and sheep are undoubtedly as complex as they are in other species. It seems reasonable to state that vitamin E, in combatting the toxicity of unsaturated fat, acts as an antioxidant, for its effect can be duplicated by many other antioxidants and redox dyestuffs. Similarly it is indisputable that selenium is a dietar essential for ruminants and that its absence from their diet results in muscular disease. Both unsaturated fat excess and selenium deficiency must produce primary disturbances in the muscle cells. These disturbances need not be common to both, for muscle reacts similarly to a variety of biochemical insult. In the presence of selenium and the absence of unsaturated fat, vitamin E requirements of ruminants appear to be extremely small. The failure to produce reproductive disorders in ruminants by experimental vitamin E deficiency, and the failure to produce muscular disease on fat-free diets deficient in vitamin E but likely to have been adequate in selenium content is evidence of this contention. How vitamin E acts in preventing muscular disease due to selenium deficiency, however, is not known, and this aspect needs elucidation. 

Phosphorus has more known fimctions than any other mineral element in the animal body. The close association of phosphorus with calcium in bone has already been mentioned. In addition, phosphorus occms in phosphoproteins, nucleic acids and phosphohpids.The element plays a vital role in energy metabolism in the formation of sugar-phosphates and adenosine di- and triphosphates (see Chapter 9). The importance of vitamin D in calcimn and phosphorus metabolism has already been discussed in Chapter 5. The phosphorus content of the animal body is considerably less than that of calcimn content. Whereas 99 per cent of the calcium found in the body occurs in the bones and teeth, the proportion of the phosphorus in these structures is about 80-85 per cent of the total the remainder is in the soft tissues and fluids, where it serves the essential fimctions mentioned above. The control of phosphorus metabolism is different from that of calcium. If it is in an available form, phosphorus is absorbed well even when there is an excess over requirement. The excess is excreted via the kidney or the gut (via sahva). In monogastric animals, the kidney is the primary route of excretion. Plasma phosphorus diffuses into saliva and in ruminants the large amount of chewing during rumination results in saliva being the major input of phosphorus into the rumen rather than the food. 

Ruminants have a higher requirement for the element than non-ruminants because some of the element is wasted in microbial synthesis of organic compounds with no physiological activity in the host s tissues. Furthermore, vitamin B12 is poorly absorbed from the digestive tract of ruminants, the availability in some cases being as low as 0.03.The ruminant has an additional requirement for the vitamin because of its involvement in the metabolism of propionic acid (see p. 202), an important acid absorbed from the rumen. 

There is evidence that the intestinal microorganisms in non-ruminants also can synthesise vitamin B12, although in pigs and poultry this synthesis may be insufficient to meet their requirements. It is common practice to include in pig and poultry diets some animal protein food rich in vitamin B12 and/or a vitamin supplement, in preference to including a cobalt salt. 

Although an excess of cobalt can be toxic to animals, there is a wide margin of safety between the nutritional requirement and the toxic level. Cobalt toxicosis is extremely unlikely to occur under practical farming conditions. Unlike copper, cobalt is poorly retained by the body tissues and an excess of the element is soon excreted. The toxic level of cobalt for cattle is 1 mg cobalt/kg body weight daily. Sheep are less susceptible to cobalt toxicosis than cattle and have been shown to tolerate levels up to 3.5 mg/kg. Excessive cobalt supplementation of ruminant diets can lead to the production of analogues of vitamin B12 and a reduction in the quantity of the true vitamin. Cobalt compounds pose a risk to human health as they cause cancer if inhaled and they irritate the skin for this reason, their use has been restricted in the... 

Dietary intakes of the B vitamins are of no significance in ruminant animals because of ruminal synthesis. A physiological requirement, in addition to that needed for maintaining normal levels in milk, does exist for many of them owing to their involvement in the complicated enzyme systems responsible for the synthesis of milk. 

To convert 4- 5 toimes of fresh grass to 1 tonne of dried material requires about 300 1 of oil, and so although dried forages could be regarded as excellent feeds for ruminants, the high cost of preparing them restricts their use to speciality feeds for non-ruminants. In Britain, much of the dried forage is consumed by horses. Elsewhere, and especially in the USA, dried lucerne is used for poultry as a source of vitamins and also to provide xanthophyU as an egg-yolk colourant. 

Although vitamin synthesis will be discussed elsewhere, it should be noted that just as the bacteria of the ruminant and other herbivores synthesize vitamins in substantial amounts, so it is highly probable that in man vitamins K, B complex, and E are synthesized in amoimts which help to meet requirement. Indeed some evidence for this already exists. On the other hand, certain intestinal bacteria destroy vitamins, e.g., vitamin C and nicotinic acid. 

Synthesis of vitamins in the body may occur in the tissues themselves or through the agency of parasitic micro-organisms. In the case of vitamin C, animals which do not require it in their diet, such as the ruminants and rodents, appear to synthesize it in their tissues. With the B group, however, such synthesis as occurs is brought about largely by micro-organisms. A... 

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