Characteristics of the occurrence and some factors associated with reduced palatability of pearl millet.

During the prolonged drought conditions of 1978, cattle throughout the East Texas area abruptly refused to graze many fields of commercial pearl millet hybrids [Pennisetum americanum (L) K. Schum.]. This study was undertaken to characterize the occurrence of the lack of palatability, investigate some plant factors associated with reduced palatability, and verify that drought was involved in the development of the palatability problem. Forage was sampled from a pasture on an upland site where plants exhibited visual drought stress, and from a bottomland site where plants did not show drought stress symptoms. Analyses were conducted for total alkaloids and nitrate. Two management treatments, shredding and irrigation, were used in an effort to increase palatability of the drought stressed pearl millet. Total alkaloid concentration of non-drought stressed forage, which was readily consumed, ranged from 10 to 20 mg/kg throughout the August sampling period. Drought stressed forage, which was not consumed, had total alkaloid contents of 180 to 460 mg/kg. The total alkaloid concentration in the drought stressed plants was reduced to 20 mg/kg 4 days after a 1.8 cm rain. Re-growth forage from previously shredded areas in the drought stressed pasture was not consumed. Forage taken within the drought stressed pasture which was irrigated was readily consumed. The total alkaloid concentration of irrigated forage ranged from 10.0 to 16.7 mg/kg. Drought-stressed plants contained 3% nitrate and non-drought stressed plants contained 1% nitrate. Under extreme drought stress conditions, there appeared to be a negative relationship between both total alkaloids and % NO₃, and palatability and total consumption.