Cattle digestive system

Cobalt is one of twenty-seven known elements essential to humans (28) (see Mineral NUTRIENTS). It is an integral part of the cyanocobalamin [68-19-9] molecule, ie, vitamin B 2> only documented biochemically active cobalt component in humans (29,30) (see Vitamins, VITAMIN Vitamin B 2 is not synthesized by animals or higher plants, rather the primary source is bacterial flora in the digestive system of sheep and cattle (8). Except for humans, nonmminants do not appear to requite cobalt. Humans have between 2 and 5 mg of vitamin B22, and deficiency results in the development of pernicious anemia. The wasting disease in sheep and cattle is known as bush sickness in New Zealand, salt sickness in Florida, pine sickness in Scotland, and coast disease in AustraUa. These are essentially the same symptomatically, and are caused by cobalt deficiency. Symptoms include initial lack of appetite followed by scaliness of skin, lack of coordination, loss of flesh, pale mucous membranes, and retarded growth. The total laboratory synthesis of vitamin B 2 was completed in 65—70 steps over a period of eleven years (31). The complex stmcture was reported by Dorothy Crowfoot-Hodgkin in 1961 (32) for which she was awarded a Nobel prize in 1964. 

The >3(1 — 4) linkage is particularly stable with respect to hydrolysis. Cellulose cannot be digested by mammals, but some insects (notably termites and wood-eating cockroaches), protozoans and fungi possess celluloses, enzymes that can hydrolyze the /3(1—>4) linkages. Ruminants, such as sheep and cattle, can digest cellulose because of the protozoans that live symbiotically in their digestive system. 

CelluiO >e molecules tend to be straight chains, and the fibers which result from collections of cellulose molecules have the strength to form the supporting structures of plants. Even though human digestion carmot break down cellulose for use as a food, animals such as cattle and termites rely on the energy content of cellulose. They have protozoa and bacteria with the necessary enzymes in their digestive systems. Cellulose in the human diet is needed for fibre. 

Cellulose, the structural biopolymer found in plants, contains the 1,4-linkage of glucose units. Our digestive systems are incapable of breaking the 8-1,4-linkage, so we cannot utilize cellulose as a source of stored glucose. Some animals such as termites and cattle are able to digest cellulose. 

The organisms that form methane live in anaerobic (oxygen-lacking) conditions. Those significant for global methane are found in the digestive systems of ruminants (cattle, sheep, etc.) and termites and in organic carbon-rich aquatic systems (shallow freshwater sediments and rice paddies). 

Ruminants include those animals that we normally think of as cud-chewing, or ruminating animals common examples include cattle, sheep, and goats. The most unusual feature of these animals involves their digestive system, and in particular their multi-compartmented stomach. They are commonly referred to as having four stomachs. The true stomach, that part comparable to the stomach of man, is preceded by 3 other compartments. These are, in order, the rumen, reticulum, omasum, and abomasum. 

A Figure 18.12 Ruminant animals such as cows and sheep produce methane in their digestive systems. In Australia sheep and cattle produce about 14% of the country s total greenhouse emissions. 

Methane is another greenhouse gas that is 21 times more potent than carbon dioxide. This fact is particularly significant for countries with lots of animals, because methane is produced by methanogenic archae that five in the animals rumen. For example, sheep and cattle produce about 14% of Australia s total greenhouse emissions. To reduce this level, Australia has initiated a program to vaccinate sheep and cattle to lower the number of archae present in their digestive systems. It is hoped that this effort will reduce by 20% the amount of methane emitted by these animals. 

Bacterial methane formation in the digestive system of cattle has gained attention in connection with the resulting global warming gas emission because 10 tons of CH4 are released annually in this way and methane is a much more potent greenhouse gas than C02. Methanogens reduce... 

The biogas plant of BIMA-system realized on basis of the test results fulfils the projected parameters, it is suitable for producing biogas by digesting litterless cattle slurry. A basic precondition of the profitable operation is the total utilization of the... 

Although forests are obvious as sources of gas, it is the microorganisms that are especially important in generating atmospheric trace gases. Methane, which we have already discussed, is generated by reactions in anaerobic systems. Damp soils, as found in marshes or rice paddies, are important micro-biologically dominated environments, as are the digestive tracts of ruminants such as cattle. 

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