Net Energy of Successive Increments of Feed above Maintenance for Beef Cattle

Abstract

The net energy of successive increments (NE_p) of alfalfa hay and of a high concentrate ration has been determined with growing-fattening beef heifers. The first increment of alfalfa from maintenance to approximately one-half maximum gain had a NE_p for energy retention of 30.1 megcal. per 100 lb. while the second increment increasing consumption to full feeding had a NE_p of 25.1 megcal. per 100 lb. Corresponding values for the high concentrate ration were 54.8 and 59.9 megcal. per 100 lb. When NE_m+p (for maintenance and gain) was determined alfalfa hay fed for maintenance contained 55.2 megcal. of NE per 100 lb. and when fed for an intermediate rate of gain and at an ad libitum level the NE_m+p values were 47.4 and 39.7 megcal. per 100 lb., respectively. The high concentrate fed at maintenance, intermediate gain and ad libitum contained 82.0, 72.2 and 69.1 megcal. of NE_m+p per 100 lb. The NE_m+p value of alfalfa hay fed ad libitum was 72% the NE_m+p of the high concentrate ration at ad libitum intake was 84% of the NE_m. For maintenance, alfalfa had a relative NE_m value of 67% of that of the high concentrate while for gain alone (exclusive of maintenance) the value of alfalfa was only 49% that of the high concentrate. Copyright © 1963. American Society of Animal Science . Copyright 1963 by American Society of Animal Science