Abstract
The aim of this work was to ascertain the value of alterations in the energy concentration in layers' diets by the incorporation of high‐energy cereals and fat in diets composed of ingredients commonly used in the United Kingdom. Two similar experiments, employing 22 individually‐fed Light Sussex pullets on each diet, were carried out using cereal and cereal by‐products in four diets containing 1200, 1050, 1000 and 880 k cal. M.E./lb. Significant improvements in food conversion efficiency were found when low energy cereals were replaced by maize. Furthermore, the diet of lowest energy content led to a considerable reduction in the total energy intake of the pullets accompanied by a fall in production. There is evidence that the efficiency of utilisation of M.E. for egg production is not affected by the dietary level of M.E. over the range of energy concentration studied in these experiments. In two further experiments four groups of 48 Brown Leghorn x Light Sussex pullets were fed diets containing three levels of vegetable fat as groundnut oil to give dietary concentrations of 1170, 1240, 1270 and 1340 k cal. M.E./lb. The results show that fat addition had no significant effect on egg production or egg size.