Development of Microbial Activity in the Alimentary Tract of Lambs

Two experiments were conducted to study the development of microbial fermentation in the various parts of the alimentary tract of lambs. The first experiment was concerned with the period from birth to 75 days of age. The second experiment was concerned with the development of fermentation activity between 56 and 150 days of age as it may be affected by diet. The effects of diet after 56 days of age on the anatomical development of the digestive tract were minor, but lambs fed in drylot had higher concentrations of VFA in their ingesta than lambs on pasture, and grew faster. The development of a functional rumen was preceded in the first 3 to 4 weeks of age by a period of significant hindgut fermentation. However, it was calculated that the VFA so produced made only a small contribution to the energy metabolism of the lamb (4.1% of the intake of D.E.). VFA production in the ruminoreticulum of these lambs was equivalent to only 2.4% of the D.E. intake.