Energy requirements of ISA Brown and Hy-line brown layers

Abstract

ISA Brown and Hy-line Brown hens were fed 10 diets representing five metabolisable energy (ME) levels and two densities. ME ranged from 10.3 to 12.2 MJ/kg and density was either fixed or allowed to float. Daily energy intake increased as the energy concentration of the diet increased even though daily feed consumption decreased as the energy concentration of the diet increased. Clearly, the birds were not able to fully compensate to a constant energy intake as the energy level of the diet increased. This extra energy intake did not influence bird performance. Over the whole experimental period (18-66 weeks age), ISA birds laid heavier eggs (P<0.05), had lower feed intake (P<0.01) and the feed conversion was better although just outside the 5% level of significance (P=0.056). The ME intake of ISA birds was lower than Hy-line birds (P<0.01). Thus, overall the ISA Brown birds consumed less feed to produce the same number of heavier eggs, resulting in better feed conversion efficiency than Hy-line Brown birds. Changes in feed intake were attributed to dietary ME level. Diet density had significant (P<0.01) influence on energy intake but had no effect on feed intake. Birds on fixed density diets consumed 125 kJ/d more than birds on floating density diets.