Ruminants intestinal synthesis

Numerous workers (72, 74, 75) have reported that the rat can thrive well on a black tongue producing diet. Balance studies (76) showed that rats excreted as much as 40 y of nicotinic acid in excess of the intake. The fecal output alone was three times the intake, a strong evidence for intestinal synthesis which has been shown to occur in the cecum (77). It has also bpen claimed to take place in the tissue of the rat (78). Ruminants (79) also thrive well for a long period on a ration deficient in nicotinic acid with no ill effects. In sheep the excretion of nicotinic acid (80, 81) remains substantial despite a deficient intake and the nicotinic acid level in the blood (81) is comparable in value to that of animals fed a stock ration. A study of the rumen of the calf (51, 52) showed clearly that nicotinic acid is synthesized to a considerable extent. Similar results were obtained in the cow (76). 

For animal feed, biotin is also of high importance. [110] Whereas ruminants have normally a sufficient supply of biotin provided by their fodder and by the amounts of biotin synthesised in the gastrointestinal tract, deficiencies occur more often in pigs, especially in piglets. Poultry tends to underutilise the biotin in their feed, and their enteral biotin synthesis is poor. Turkeys have an especially high demand for biotin. The use of sulfonamides and other antibiotics in animal husbandry affects the intestinal flora and may necessitate biotin-fortified feed (Tab. 7.4). 

CLA Synthesis in Ruminant Microbial Ecosystem 7 leading to accumulation of stearic acid within the intestinal contents. 

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. 

As investigations have revealed the mechanisms of rumen digestion, attempts have been made to alter the patterns of digestion in ways that should improve the nutrition of ruminants. The primary approach has been to modify the microbial population in order to suppress undesirable processes (e.g. methane production see Section 8.4 and Chapter 11) or stimulate desirable processes (e.g. microbial protein synthesis). A secondary approach has been to protect nutrients from rumen fermentation in order that they should be digested in the small intestine. Changing the bacterial... 

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. 

When considering sources of niacin, it should be noted that niacin can be, and is, synthesized by the intestinal flora. However, the amount produced is only of minor importance in the human. By contrast, as with thiamin and riboflavin, ruminants (cattle, sheep, etc.) have no dietary requirements for niacin because of bacterial synthesis in the rumen. 

To optimize milk protein production, requirements must be accurately determined and matched with dietary supply. Through microbial digestion in the reticulo-rumen, ruminants have a capacity to utilize forages that are indigestible in non-ruminants. Dietary proteins are degraded in the rumen and used in microbial protein synthesis, which modifies dietary supply of protein both quantitatively and qualitatively making predictions of the amount and profile of amino acids (AA) absorbed from the small intestine difficult. 

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. 

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