Studies on Energy Levels in Poultry Rations

UNTIL recently, chickens were considered to have a limited tolerance for fat. Henderson and Irwin (1940) reported that chicks tolerated as much as 10% added soybean oil in their ration without deleterious effects during the first eight weeks of life, but the higher levels caused a growth depression and increased rate of feather shedding. Yacowitz (1953) reported that 2½ to 5% cotton seed oil, soybean oil, or lard improved growth and feed conversion of growing chicks. However, 10 to 15% cotton seed oil resulted in growth depression and poor feathering. Biely and March (1954) found that the addition of fat to a 19% protein ration depressed growth and feed conversion in New Hampshire chicks but did not adversely affect growth and feed conversion when added to rations containing 24 to 28% protein. Recent studies in this laboratory have shown that growth rate, feed consumption, body composition, and feather condition in . . .