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Growth and Development of the Ruminant Gastro-Intestinal Tract

Growth and Development of the Ruminant Gastro-Intestinal Tract. GI Tract development begins very early in gestation. Ruminant enters life as a simple stomached animal; forestomach (reticulorumen, omasum) is non-functioning at birth Only a few weeks are required for activation

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Growth and Development of the Ruminant Gastro-Intestinal Tract

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  1. Growth and Development of the Ruminant Gastro-Intestinal Tract • GI Tract development begins very early in gestation. • Ruminant enters life as a simple stomached animal; forestomach (reticulorumen, omasum) is non-functioning at birth • Only a few weeks are required for activation of the forestomach

  2. Growth and Development of the Ruminant Gastro-Intestinal Tract • Rumen papillae begin growth and development early in gestation. • The process begins as a capillary loop at about 3 months of gestation. • The capillary loop pushes up the lamina to create the papillae of the ruminal surface which is detectable by the 5th month of gestation.

  3. Growth and Development of the Ruminant Gastro-Intestinal Tract • Individual GI tract organs develop at different rates during gestation • Early in gestation the rumen, reticulum and omasum develop faster than the abomasum. • Later in gestation the abomasum develops rapidly, so that at birth the abomasum is equal in weight to the entire forestomach.

  4. Growth and Development of the Ruminant Gastro-Intestinal Tract At the Time of Birth • Rumen is small and flaccid, with a very thin wall. Is non-functioning at birth. • Reticulum is one-third the size of the rumen at birth. Also has a very thin wall. Is non-functioning at birth. • Omasum is a small bulbous structure on the abomasum. Is non- functioning at birth. • Abomasum is well developed and highly functional at birth. Comprises about 70% of stomach capacity at birth.

  5. Growth and Development of the Ruminant Gastro-Intestinal Tract • After birth, all digestive organs continue to grow, with the rumen, reticulum, omasum and small intestines growing at the greatest rates.

  6. Growth and Development of the Ruminant Gastro-Intestinal Tract • Under normal conditions, ruminants have access to vegetation from birth. Diet can have a large impact on development of the GI tract. • Three phases ruminant GI tract development • 0 to 3 weeks of age: non-ruminant phase • 3 to 8 weeks of age: transitional phase • 8 weeks onward: adult ruminant Figure is stomach of new born calf. Note size of abomasum relative to rumen.

  7. Growth and Development of the Ruminant Gastro-Intestinal Tract Effect of Diet on Gastro-Intestinal Tract Development

  8. Growth and Development of the Ruminant Gastro-Intestinal Tract • Given access to pasture, ruminants begin to graze in the first week or two of life. • By four weeks of age: • Rumen is 4 to 8 times its birth weight. • Still an elastic sac without thickness of walls. • By eight weeks of age: • Animal’s body weight has doubled. • Period of rapid rate of rumen development. • Animal is heavily dependant upon the products of rumen fermentation. • By 8 to 10 weeks of age, development of the reticulorumen with respect to body weight is complete

  9. Growth and Development of the Ruminant Gastro-Intestinal Tract • Tissues of the stomach consist of: • Outer layer of connective tissue (serous membrane). • Muscular tunic: aids in mixing digesta. • Rumen mucosa: inner surface of the mucosa is the epithelium. • Rumen epithelium serves in the absorption and metabolism of minerals and volatile fatty acids (VFA’s). Also protects the underlying rumen mucosa tissue. • Rumen papillae develop from the epithelium. Papillae increase the surface area for absorption of VFA’s.

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