EVALUATION OF FULL-FAT SPAN RAPESEED AS AN ENERGY AND PROTEIN SOURCE FOR LAYING HENS

Abstract

Full-fat Span rapeseed (a low erucic acid variety), which had been steam-treated at 90 C for 30 min and then ground, was examined as a protein and energy source in rations of Single Comb White Leghorn laying hens during a laying period of 336 days. The levels of mortality and egg production were not significantly affected by the inclusion of 0, 5, 10 or 15% Span rapeseed in the ration; however, calculation of the simple regression between hen-day production and level of rapeseed used indicated a significant decrease in production with increasing levels of rapeseed in the ration. No mortality was attributed to ’haemorrhagic liver syndrome’ in the groups fed rations containing 0 and 5% rapeseed but the incidence of haemorrhagic liver syndrome was 3.1 and 4.2%, respectively, in birds fed rations containing 10 and 15% rapeseed. Egg quality, feed conversion and body weight were not affected by any of the dietary treatments. The sizes of the livers and hearts and their composition of dry matter, fat and protein were not significantly affected by dietary treatments. There was, however, a progressive and significant (P < 0.05) increase in the relative weights of the thyroids as the level of rapeseed in the ration was increased.