How a Goat Digests Feed
Written by Administrator-GL   
Wednesday, 04 March 2009
Ruminant Digestion

* A few animals with ruminant digestive systems are sheep, cattle, goats, deer and giraffes.
* Ruminant animals have four complex stomach structures.
* The four stomachs are called the rumen, reticulum, omasum and abomasum.
* Herbivores are usually ruminant animals.

Parts of Ruminant System

* Mouth- teeth and lips hold food and chew it, saliva moistens food.
* Esophagus-food travels to stomach.
* Four Compartments:
* 1st-Rumen
* 2nd-Reticulum
* 3rd-Omasum
* 4th-Abomasum

1st Compartment: Rumen

* Large fermentation vat, where bacteria and protozoa thrive to break down roughages. (which is where probiotics come into play)
* Rumen is lined with papillae to increase surface area and absorption

* Contains microorganisms that digest cellulose and can synthesize amino acids as well as B-complex vitamins.

Rumen Sizes in Cattle and Sheep Cow- 40 Gallons
Sheep/Goats(Adult) - 5 Gallons

2nd Compartment- Reticulum

* Reticulum has a lining with small compartments similar to a honeycomb. Hence its nickname the “honeycomb.”
* Interacts with the rumen in initiating mixing activity and provides additional storage for fermentation.
* Capacity:
* Cow: 2 Gallons
* Sheep/Goats(Adult) : 2 Quarts

3rd Compartment: Omasum

* Omasum has many folds, often referred to as manyplies.
* Aids in the grinding action of the food
* Capacity:
* Cow: 4 gallons
* Sheep/Goats(Adult) : 1 quart

4th Compartment: Abomasum


* Abomasum: The true stomach
* Corresponds with the stomach of monogastric animals.
* Majority of Digestion takes place.
* Capacity:
* Cow 4 Gallons, Sheep/Goats (Adult) 3 quarts

Small Intestine

* Functions in splitting food molecules and in nutrient absorption.
* Capacity of Ruminant Animals:
* Cow: 15 Gallons or 130 feet
* Sheep/Goats (Adult): 2 Gallons or 80 feet

Large Intestine

* Functions in absorbing water and forms indigestible wastes into solids.
* Last chance for minor nutrient absorption.
* Capacity of Ruminant Animals
* Cow: 10 gallons
* Sheep/Goats (Adult): 6 quarts

Review of Ruminant Digestive Systems

* Animals that have ruminant digestive systems eat forage rapidly and later regurgitate the feed, known as the cud.
* The regurgitated food is chewed thoroughly, swallowed and then more feed is regurgitated. This process is continued until all the feed is masticated.

How the Ruminant System Works

* Once the feed has arrived in the rumen, it is mixed with microorganisms, such as bacteria, protozoa and certain fungi. (Again, where the probiotics come into play) They assist the ruminant animal in utilizing cellulose, and in synthesizing protein from non-protein nitrogen and certain vitamins.

* Then the feed arrives in the Reticulum that is commonly referred to as the “honeycomb”. Its major function is to work with the rumen in mixing and grinding the feed.
* Also functions in screening foreign objects from the digestive system.

* Then the feed arrives in the omasum, or the third compartment referred to as “manyplies.” The omasum assists in removing 60 to 70 percent of the water before the feed enters the abomasum.

* Once the feed has arrived in the abomasum, or the “true stomach,” digestive juices, which contain enzymes, break down proteins, and add moisture to the feed as it enters the small intestine.

Small & Large Intestine in Review

* From the abomasum, the feed enters the small intestine where nutrients are absorbed in the blood system.
* From the small intestine, the food passes into the large intestine where the water is removed and the feed is prepared for excretion.

How Probiotics work in the ruminant:

Ruminant animals, including cattle, sheep and goats, depend on microbial degradation of their feed rather than on direct enzyme degradation, as in nonruminants. The animal then absorbs volatile fatty acids from the rumen for glucose formation in the liver, and the protein digested in the gastric stomach (the abomasum) is largely microbial. In a normally functioning ruminant, little or none of the sugars and proteins originally present in the feed are directly incorporated in the animal: they are first processed by bacterial fermentation in the rumen.

At birth, the calf's gut is sterile and the rumen is undeveloped. Milk bypasses the rudimentary rumen, entering the abomasum directly (Quigley, 2000). The rumen develops in response to dry feed intake (Haenlein, 1998). The microbial fermentation in the rumen becomes fully active only after rumen development is complete, and increasing feed intake in early life accelerates this development (Wallace and Newbold, 1995).

Probiotic additives have been shown to be of benefit at all stages of life in the ruminant. The available literature on probiotic use in cattle, and in farm animals in general, is vast, and the short timescale of this review allows little more than an overview of the tremendous amount of work that has been done on the subject. The few papers cited here represent, quite literally, the tip of an enormous iceberg.

In addition:
Probiotics and the Rumen

The role that Probiotics will play in the calf and dairy cow are discussed in a detailed literature review by Dr Kevin Hillman. In summary, the benefits for the dairy cow can be outlined as follows:

Healthy Rumen Function = Optimum Productivity

* Assist in stabilising the rumen during ration changes (such as the transition period)
* Reduce weight loss at start of lactation
* Increase lactic acid metabolism
* Reduce risk of SARA and Clinical Acidosis and rumen dysfunction
* Increase levels of total VFA's
* Increase cellulytic bacteria to utilise high starch rations
* Improve FCR - increase utilisation of Dry Matter and fermentation of Organic Matter
* Important in aiding the establishment of the microflora in order to develop the rumen papillae during the transition period
* Maintain feed intake
* Increase milk yield (maintained butterfat and protein levels)
Additional benefits: Probiotics have also been shown to have:

* Anti-pathogenic and anti-diarrhoea properties
* Immunomodulatory function
* Binding capability of mycotoxins within the gut.

Rumen Function and Probiotics

Last Updated ( Wednesday, 04 March 2009 )