Variations of the Hydrocyanic Acid Content of Sudan Grass from a Single Lot of Seed 1

M ANY champions of the use of Sudan grass for feed have insisted that sorghum in Sudan grass, taken either as pasture or as hay, explained the loss of animals that ate the feed. Others have suggested thd presence of sorghum or of sorghum-Sudan grass hybrids. Crosses have been effected between a sorghum and Sudan grass in Australia (4)3. Such crosses are said to be easy to make and common when sorghum and Sudan grass flower near each other. Chemical analyses of the lel generation of such crosses and their parents indicate that the cyanide content of the hybrids may be much higher than that of either parent. In general, the cross sorghum X Sudan grass produces plants intermediate in size, appearance, and other characteristics. Moodie and Ramsey (4) claim that some of the hybrids they examined were higher in cyanogenetic glucosides than either parent, a condition which is genetically possible, but it seems improbable for many of the progeny of sorghum X Sudan grass crosses. No one has measured the individual variation of Sudan grass plants from the same planting with respect to seed used. Swanson (7) has shown that hydrocyanic acid content of Sudan grass may at times be fairly high in young plants, but that it disappears as the plant matures. Sirrine (6) claims to have been able select from samples of Sudan grass seed, individual seeds which would produce plants intermediate between sorghum and Sudan grass. All of the seeds she thought to be hybrids produced plants with intermediate characters, but many of the "normal," slender seeds also produced off-type plants, so that selection of hybrids on seed type alone would not separate all of the possible hybrids. If her ideas are correct, our information on Sudan grass seed types should be extended. It is contended by Martin (3) that hybrids may be easily detected in the field by size and nature of the plant. Hybrids tend to approach the sorghums in vegetative type, in appearance of the inflorescence, and in seed characters. The presence of harmful quantities of hydrocyanic (prussic) acid (HCN) has been generally assumed to be the cause of the poisoning of livestock by Sudan grass or sorghum. With sorghum, HCN has been occasionally proved to be the lethal agent. Many cases of death or illness from Sudan grass suggest the action of hydrocyanic acid because the deaths are sudden, and, where the animals are seen to die, death is violent or the animals collapse without a struggle and cease