Applied research note: Validating energy systems for the formulation of laying hen diets

Practical diets used to feed laying hens can differ significantly, depending mainly on the energy systems ( ES ) and the relative cost of the feed ingredients used when formulating. The more accurate an ES is, the better it will predict performance. In earlier work, a predictive model was developed to evaluate the veracity of different ES for the formulation of layer diets. It was found that there was no advantage to using any particular ES. The work reported herein covers a trial conducted to validate the theoretical findings of the earlier model. Diets were formulated using Apparent Metabolizable Energy corrected for nitrogen retention ( AME n ) or Net Energy ( NE ), using different oil pricing structures. This effectively meant that the diets either contained oil or did not. Individually housed Hy-Line Brown Layers (aged 45 weeks) were used in a completely randomized factorial design (2 × 2 and 12 replicates per treatment) for eight weeks. No significant differences were found in feed intake, feed conversion ratio, body weight, or egg output. The calculated energy requirement per gram of egg output was significantly higher when NE was used in combination with oil, suggesting that the correction factor ascribed to lipid in NE determination may be generous. In conclusion, the AME and NE are equally effective at predicting egg production parameters and energy requirements, validating earlier theoretical work that AMEn is an adequate ES for diet formulation in laying hens.