NE for Growing/Finishing Beef Cattle California Net Energy System Lofgreen & Garrett, 1968 Net Energy for maintenance – NE m Net Energy for gain – NE g More useful than TDN Allows more accurate prediction of energy

NE for Growing/Finishing Beef Cattle NE m – ability of feed to meet energy reqmt for maintenance NE g – ability of feed to meet energy reqmt for gain Maintenance energy must be met first Then any additional energy can be used for gain

NE for Growing/Finishing Beef Cattle NE values of feeds + feed intake can be used to: Predict gain on particular diet Predict amount of feed required for particular gain (programmed feeding)

NE for Growing/Finishing Beef Cattle Two NE values for feeds Feed energy is used more efficiently for maintenance than for gain NE m values always higher than NE g

715 lb yearling steers (1,300 lb finished) From feed records, consuming 16 lb (7.26 kg) of diet which contains: 2.09 Mcal/kg NE m 1.42 Mcal/kg NE g 5 Example – NE System

NE m required per day is based only on body weight (Table 9) = 5.89 Mcal/day 6 Example – NE System

5.89 Mcal NE m /2.09 Mcal NE m /kg = 2.82 kg of diet needed for maintenance Total intake is 7.26 kg 7.26 kg – 2.82 kg = 4.44 kg remaining for gain 4.44 kg x 1.42 Mcal/kg NE g = 6.30 Mcal available for gain 7 Example – NE System requirement Energy in feed

6.30 Mcal available for gain From Table 9 – need 6.94 Mcal to gain 3.99 lb/day 8 Example – NE System

From Table 9 – need 6.94 Mcal to gain 3.99 lb/day Extrapolate: 3.99 lb/6.94 Mcal = x lb/6.30 Mcal x = 3.62 lb/day Predicted ADG 9 Example – NE System What we have available for gain

Feed efficiency Expressed 2 ways: lb feed/lb gain 16 lb/3.62 lb = 4.4 or lb gain/100 lb feed 3.62 lb/0.16 lb = Example – NE System