Calcium-Containing Crystals in Alfalfa: Their Fate in Cattle

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 calcium is the primary crystal cation. Intact cyrstals 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 to 33% of calcium in alfalfa is in the form of oxalate and apparently unavailable to ruminants. Carbonate is probably in partially eroded crystals from feces. Data presented account for the poorer utilization by cattle of calcium from alfalfa than that from inorganic sources.

Medicago truncatula Mutants Demonstrate the Role of Plant Calcium Oxalate Crystals as an Effective Defense against Chewing Insects

“…1B). Similar to the localization in M. sativa (Ward et al, 1979), the calcium oxalate crystals of M. truncatula are concentrated along these secondary veins and their prismatic shapes are clearly visible when viewed with a light microscope equipped with a cross-polarizing filter (Fig. 1C).…”

Localization of Germin Genes and Their Products in Developing Wheat Coleoptiles

“…2A and 2E). These cells were reported to be rich in calcium oxalate accumulation (Ward et al, 1979). The localization of an oxalic acid degrading enzyme in these cells is worth to pay attention.…”

Untitled

“…(Selangor, Malaysia) and it contained maize, wheat, wheat bran, rice bran, soybean meal, sesame meal, molasses, limestone, dicalcium phosphate, salt and feed additives. b The ME values of the feeds were calculated with the following equation (AFRC 1993): ME (MJ/kg DM) = 0.016 × digestible organic matter study, insoluble oxalate content in the feeds was not determined, because insoluble oxalate is not considered to have a harmful effect on the body's metabolism as it seems to pass through the digestive tract (Ward et al 1979), whereas soluble oxalate is likely to be absorbed in the intestine and cause chronic Ca deficiency (Blaney et al 1982). Certain plants have extremely high amounts of oxalate such as halogeton, wood sorrels and rhubarb leaves .…”