Digestive system of ruminants

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). 

Avoid overtaxing the fat-handling capabilities of digestion systems of the respective species, especially young animals and ruminants. 

Nonruminant Mammalian Systems. Fat digestion is described in greater detail in the following sections. The digestive systems of monogastric animals (swine, mink, and fish), a ruminant (bovine), a nonmminant herbivore (horse), and an avian (hen) are shown in Figure 2 (4). 

Figure 2. Digestive systems of representative animals. (1) Monogastrics with nonfunctional cecums swine (omnivore), mink (carnivore), and catfish (omnivore). (2) Nonruminant herbivore with functional cecum and colon horse. (3) Ruminant bovine. (4) Avian hen. Reprinted by permission from Ref. 4.

Ruminants. Treatment of ruminants with L-ascorbic acid has merit in unusual circumstances rather than any type of routine practice since these species synthesize their requirements in their normal life cycle pattern. The digestive system of the young calf or lamb functions similarly to that of monogastric animals for the early weeks of life until the ruminating process is initiated. 

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. 

Methane is formed in biological processes that occur in low-oxygen environments. Anaerobic bacteria, which flourish in swamps and landfills, near the roots of rice plants, and in the digestive systems of cows and other ruminant animals, produce methane FIQURE 18.14). It also leaks into the atmosphere during natural-gas extraction and transport. It is estimated that about two-thirds of present-day methane emissions, which are increasing by about 1% per year, are related to human activities. 

The digestive system of cows and other ruminant animals contain bacteria that break down cellulose and produce methane gas. Some large ruminants produce hundreds of liters of methane per day. The large increase in the world population of catde and sheep has given rise to a large increase in methane emissions from this source. 

Draw and compare the digestive systems of a ruminant, swine, equine, and poultry. Why is a horse capable of deriving energy from forages ... 

There are many modifications of this method, they may be to make the process more representative of the ruminant digestive system, or the desired residue may be just the plant cell walls. It is not always possible to say that one procedure is better than another, therefore the chosen procedure may be that which has been used by workers involved in animal nutrition over a number of years in a certain geographical area. The decision may be to use the usual procedure favoured by the referees for research papers in a particular journal. 

Toxins from plants may affect internal organs, such as the heart, kidney, liver, and stomach. Because of their very different digestive systems involving multiple stomachs, ruminant animals may react differently to these toxins than do monogastric animals. Some major plant toxins that affect internal organs are summarized in Table 19.1. 

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. 

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