Calcium-Containing Crystals in Alfalfa: Their Fate in Cattle

Open Access
Publisher Website
Google Scholar
Abstract
The fate of crystals in the parenchymatous sheaths around vascular bundles in alfalfa leaves was followed through the bovine digestive tract by scanning electron microscopy. The bundle and sheath pass from the rumen largely intact. Most crystals are released from the bundle sheath postruminally. In feces, some crystals appear partially eroded and others are intact. By energy-dispersive X-ray analysis Ca is the primary crystal cation. Intact crystals isolated from alfalfa leaves by low-temperature ashing and from bovine feces by washing and differential specific gravity were subjected to Raman microprobe analysis. Most crystals were calcium oxalate, a few were potassium oxalate and some contained both compounds. From 20-33% of Ca in alfalfa is in the form of oxalate and apparently unavailable to ruminants. Carbonate is probably in partially eroded crystals from feces. The poorer utilization by cattle of Ca from alfalfa than that from inorganic sources was studied.