Calf Rumen Images

Rumen Comparisons: 4 Weeks of Age

The calf fed grain in addition to hay and milk has a larger stomach, and greater rumen development. Note the healthy, dark coloration and visible rumen papillae.

4 weeks of age
Diet: milk, grain, hay
The calf fed grain in addition to hay and milk has a larger stomach, and greater rumen development. Note the healthy, dark coloration and visible rumen papillae.

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4 weeks of age
Diet: milk, hay

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Rumen Comparisons: 6 Weeks of Age

The rumen of the calf fed milk only is considerably smaller than the calf fed milk and grain. In addition, the grain-fed calf has much darker coloration and greater papillae development than the milk only calf. The grain-fed calf has a healthy, properly developing rumen.

6 weeks of age
Diet: milk only
The rumen of the calf fed milk only is considerably smaller than that of the calf fed milk and grain.

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6 weeks of age
Diet: milk and grain
The grain-fed calf has much darker coloration and greater papillae development than the milk only calf. The grain-fed calf has a healthy, properly developing rumen.

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More Rumen Comparisons: 6 Weeks of Age

Developing a healthy rumen is important to ease the transition from a pre-ruminant to a ruminant animal. These pictures show how the rumen develops over time when dairy calves are fed various combinations of milk, grain, and hay. As you compare the pictures in this section, keep in mind that a healthy rumen has a dark coloration, which is caused by increased tissue mass and large blood vessels (vascularization). The papillae in a healthy rumen are numerous and visible without magnification. Differences in the number and size of papillae and the color of the rumen wall can be seen easily in these three calves.

6 weeks of age

Diet: milk only

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6 weeks of age
Diet: milk and grain

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6 weeks of age
Diet: milk and hay

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Esophagus Images

The esophageal groove is formed by muscular folds of the reticulum, which you can easily see in these photos. When the esophageal groove forms, liquids bypass the rumen and pass into the omasum and on to the abomasum where most digestion occurs. The formation of the esophageal groove is controlled by neural stimulation from suckling and milk proteins. This means milk, colostrum, and milk replacer bypass the rumen, while water enters it. The esophageal groove forms whether calves drink from a nipple bottle or an open bucket. Feeding milk for an extended time usually results in development of the calf, but limited rumen development because the esophageal groove keeps liquid feeds out of the rumen.

6 weeks of age
Diet: milk and grain

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6 weeks of age
Diet: milk only
Feeding milk for an extended time usually results in development of the calf, but limited rumen development because the esophageal groove keeps liquid feeds out of the rumen.

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Rumen Comparisons: 8 Weeks of Age

Both of these calves exhibit dark coloration of the rumen and reticulum, but if you examine the rumen it is apparent that the calf fed hay has much less papillae development. The rumen wall is thin and papillae are short and sparse. In this case, the calf ate a large amount of hay and less grain than the calf on the left. The bulky fiber in hay filled the calf's small stomach and limited grain intake.

8 weeks of age
Diet: milk and grain

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8 weeks of age
Diet: milk, grain, and hay
This calf has much less papillae development. The rumen wall is thin and papillae are short and sparse.

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Rumen Comparisons: 12 Weeks of Age

Both of these rumens are very large, but when it comes to rumen development size isn't everything! Look at the dramatic difference in the number and length of papillae between these two calves. Also, note the healthy, dark coloration of the calf fed grain. The calf fed milk and hay has stunted rumen development, with light color and very little papillae growth.

12 weeks of age
Diet: milk, hay and grain
Note the healthy, dark coloration of the calf fed grain.

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12 weeks of age
Diet: milk and hay
The calf fed milk and hay has stunted rumen development, with light color and very little papillae growth.

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The Importance of Grain in Developing the Rumen

The importance of grain in developing the rumen should be obvious from the follwoing two photos. The rumen of the calf at 4 weeks of age is more developed than the 12-week-old calf that received no grain.

4 weeks of age
Diet: milk and grain
The rumen of the calf at 4 weeks of age is more developed than the 12-week-old calf that received no grain.

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12 weeks of age
Diet: milk and hay

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Continued grain feeding through 6 or 8 weeks leads to further papillae growth and development. Since grain intake is strongly related to rumen development and since we normally cannot see the inside of calves' rumens, grain intake can be used as an indirect estimator of rumen development and a criterion for weaning. If calves are healthy and eat 1.5 to 2 pounds of grain per day for three consecutive days, they can be weaned any time after 4 weeks of age.

Age 6 weeks
Diet: milk and grain

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Age 8 weeks
Diet: milk and grain

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Omasum Images

The pictures below show the omasum of a calf at 6 weeks of age. You can clearly see the "many plies" of this stomach compartment. In the omasum water is squeezed out of the digesta and some nutrients are absorbed.

Intact omasum at 6 weeks

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Interior of the Omasum
Here the omasum has been cut open, and you can see how many folds of tissue are packed into this small stomach compartment.

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Omasum walls
In this image, note the thin the walls of the omasum.

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