Adequate rumen papillae growth is indispensable to maximize the absorption of volatile fatty acids (VFA) in ruminants. In wild African ruminants for example, there is a change in papillae growth and epithelial intestinal growth between the dry and rainy seasons which results from the quality and abundance of the forage available.
Something similar happens when dry cows are fed low quality, highly fibrous forages that do not stimulate the production of VFA that are critical for papillae development. Similarly, in the pre-weaned ruminant, early development of these epithelial structures allows them to accelerate the transition to a ruminant with a functional rumen, thus reducing feed costs.
Recent research has demonstrated that high dietary fiber (NDF) to starch ratios negatively affect the expression of the gene regulating growth of papillae. The right ratio of volatile fatty acids in the diet then determines how much of those volatile fatty acids will be absorbed, and how much energy the cow will obtain from its feed!
Metabolic pathway of the butyrate synthesized in the rumen of lactating cows
Lipogenesis is the result of metabolic steps to synthesize of fatty acids and then triglycerides. The major locations in the body varies somewhat but it generally takes place in the intestinal mucosal cells, the liver, the adipose tissue and the mammary gland in lactating animals.