Ruminal Development and Distribution of Intraruminal Volatile Fatty Acids in Suckling Lambs

Abstract

Papillary lengths, widths and densities and percentages of the mucosa in the region of the anterior ventral sac of the rumen and the weights of total reticuloruminal tissue were determined in 19 creep-fed lambs ranging in age from 3 to 20 weeks. The total reticuloruminal tissue per unit of body weight increased to a maximum between 5 and 9 weeks of age, but measurements of papillae indicated a steady growth such that the linear dimension was essentially proportional to body weight. The maximum concentrations of volatile fatty acids were observed between 12 and 17 weeks. Acetic, propionic, butyric, isobutyric, valeric, and isovaleric acids were detected in the ruminal contents of all lambs with feed residues in the rumen. The C5 acids and butyric acid were not found in two lambs that received only milk. The proportion of acetate was negatively related to level of total volatile fatty acids and to age, body size, and stage of ruminal development. Displacement of acetate at higher concentrations of total volatile fatty acid was by both propionate and butyrate, but the displacement of acetate with growth and ruminal development was the result of a significant increase in the molar fraction of butyrate. Of the minor fatty acids, only isobutyrate showed a significant relationship (negative) to age. The simple product-moment, multiple, and partial correlations of acetate (negative) and of butyrate (positive) with ruminal characteristics were of such significance and magnitude to indicate that the pattern of intraruminal fermentation is associated with factors conditioning both total ruminal development and papillary growth in creep-fed suckling lambs.