Development and analysis of a rumen tissue sampling procedure.

A procedure for rumen tissue sampling was developed to determine treatment effects on rumen development and papillae growth in young calves and to improve repeatability in rumen tissue sampling techniques. Rumens were collected from 42 male Holstein calves from 4 separate experiments. Rumen sampling areas (n = 9) included the caudal dorsal blind sac, cranial dorsal sac, cranial ventral sac, and the caudal and ventral portions of the caudal ventral blind sac. Right and left sides of the rumen were sampled. Five 1-cm2 sections were removed from each area and measured for papillae length (n = 20/area), papillae width (n = 20/area), rumen wall thickness (n = 5/area), and number of papillae per cm2 (n = 5/area). Correlations between areas, samples, and measurements were obtained, and comparisons between experiments, areas, samples, and measurements were performed for all variables. In addition, power analyses were conducted for all variables to determine the efficacy of the procedure in detecting treatment differences. Results indicate that samples should be taken from the caudal and cranial sacs of the dorsal and ventral rumen to sufficiently represent papillae growth and development throughout the entire rumen. The procedure is capable of detecting treatment differences for papillae length and papillae width, has a decreased but acceptable capability of detecting treatment differences for rumen wall thickness, but appears limited in ability to detect treatment differences for papillae per square centimeter. In conclusion, rumen tissue sampling to determine extent of rumen development in calves can be performed in a nonbiased and repeatable manner utilizing a limited number of calves.