by Maryam Hussain
Cattle animals are also called
ruminant animals because they are capable to consume and digest plant
materials and are classified as herbivores. Ruminants include cattle,
sheep, goats, deer, elk, and many other wild species.
The word ruminant came from the
property of such animals to ruminate i-e chew the cud. There are inherent major
modifications of the GI tract of ruminants relating to the stomach area, which
is divided into four compartments, and all of this help to process the
ingested food towards milk, meat, and energy. The symbiotic relationship
between microorganisms and host is developed to the highest degree in the GI
tract of ruminants because the rumen provides a favorable environment.
Cattle pick their meals by
smell and taste, then graze until the first chamber of the stomach, the
rumen, is full. Once the rumen is full of grass or hay, the cattle will
lie down in a comfortable spot and, mouthful by mouthful, burp it all back up
again. Because the cattle initially swallowed without chewing, the same now
brings those huge rear molars into play and takes the time to grind up the
grass into a slimy pulp before swallowing it again, this time into the second
stomach chamber, the reticulum.
Chewing the cud, as this
process is called, takes eight to ten hours each day and involves up to forty
thousand jaw movements. The cud present in the reticulum then moves
into the omasum and then next to the abomasum, the true stomach and then down
the intestines. What’s not absorbed comes out of the back end.
Although many cattle are grass-fed today, there are still those who are corn-fed or grain fed. The cattle are fattened on corn, soy, and other feed needs for several months before slaughter. The reason for this is that corn is higher in starch and high in energy, meaning less time is needed to fatten the beef, which results in an increased meat yield from dairy animals.
An animal’s body consists of a
few kinds of chemical compounds. About 55–60% of a ruminant body is water,
and 3–4% or so are minerals & inorganic components. The remaining 35–40%
consists of organic substances. These organic compounds are complex
compounds of carbon (C), hydrogen (H), and oxygen (O), sometimes together with
nitrogen (N), sulfur (, S) or other elements, which are in general found only
in living organisms.
Muscle tissue in cattle, which
is usually consumed as meat, consists of about 75% water and 20% protein. A
large part of the remaining 5% is fat with very small amounts of carbohydrates
(principally glycogen), free amino acids, dipeptides, and nucleotides.
Domestic cattle are kept by
humans to produce milk, meat, and Wool. Domestic ruminants provide 70% of
the total animal protein eaten and 10% of the natural fiber used by humans.
Proteins principally contain
carbon, hydrogen, oxygen, nitrogen, and sometimes Sulphur. Protein contains
22 different amino acids and ruminants may be unable to synthesize some of
these amino acids at a sufficient rate to meet their optimum requirements.
These are described as essential amino acids and must be absorbed from
digestion in the small intestine. The value of food as a potential source
of amino acids can be determined by analyzing for total nitrogen (N) and sulfur
(S) in the food. Cattle food contains Nitrogen in many forms other than amino
acids, which may be converted to amino acids by the rumen microbes. The term
crude protein (CP) is used to describe all forms of Ν present in the plant.
Sulfur (S) amino acids are an essential but small component of all proteins.
Milk production of cows can be
improved by increasing the quantity of amino acids absorbed from the small
intestine. The proteins that is responsible for a 68% increase in milk
production is by ewes from supplementation with urea hay containing 56 g
CP/kg DM. This increase in milk production was probably due to an improvement
in the total quantity of CP entering the small intestine.
An increase in the growth rate
and carcass composition of a cattle animal, eating a temperate pasture, has
been confirmed when the animal was fed with 182 g CP/kg DM. Additionally,
the cattle’s live weight was increased from 79 to 99 g/day, and empty-body gain
from 62 to 82 g/day. Carcass and whole-body protein content were reported to
increase from 10 g/kg and fat content was reduced by approximately 25 g/kg.
But it is important to note that
cattle food, with a relatively high CP content, is not the only factor to meet
the requirements of a young cattle animal like lamb (up to 25 kg live weight)
and that the protein: fat ratio in these animals can be manipulated by
changes in protein absorption.
The ruminants convert crude proteins of grass to fine proteins or amino acids and ammonia through a process that can be pictured by the following processes.
For reasons of human health
there is an interest in trying to increase the proportion of polyunsaturated
fatty acids to saturated fatty acids (the P:S ratio) in meat.
The microorganisms present
inside rumen of ruminants hydrogenate unsaturated fats in
the diet to saturated fats and this is one of the major reasons that causes the
hardness of carcass fat of cattle and sheep. However, about a tenth of the
ingested unsaturated fatty acids do seem to pass through the rumen unchanged
and feeding ruminants diets very rich in them can make the carcass fat softer,
although the effect is relatively small.
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