Influence of different concentrations of metabolisable energy at constant ratio to dietary protein, lysine, methionine, calcium and phosphorus on the performance of White Leghorn layers in the tropics

Abstract

An experiment was conducted to study the effect of nutrient density on the performance (21–72 weeks of age) of White Leghorn layers reared in an open-sided poultry house in the tropics. Six diets with graded levels (9.62–11.72 MJ/kg) of metabolisable energy (ME) with an increment of 0.42 MJ were formulated. Concentrations of crude protein, lysine, methionine, calcium and non-phytate phosphorus were kept constant to ME in all diets (15.9, 0.73, 0.35, 3.19 and 0.31 g/MJ ME, respectively). At 21 weeks of age, a total of 5280 birds was distributed randomly in 4-bird colony cages and 22 such cages in a row constituted one replicate. Each diet was fed ad libitum to 10 replicates from 21 to 72 weeks of age and performance parameters were recorded at 28-day intervals (period, 1–13). Egg production (EP) increased (P < 0.05) with increasing dietary ME and maximum response in EP was observed when dietary ME levels ranged between 10.93 and 11.69 MJ/kg during the majority of periods, while in periods 6, 7 and 8 (summer, 28−37°C), maximum EP was observed at higher ME levels in diet (11.64–11.69 MJ/kg diet). Feed intake (P < 0.01) decreased, feed efficiency (P < 0.01), egg mass (P < 0.01) and weight gain (P < 0.05) improved quadratically with increase in dietary ME concentration. Maximum feed efficiency was observed at 11.36 MJ ME/kg diet during 21–72 weeks of age. Egg shell defects were not influenced (P > 0.05) by dietary nutrient density. Mortality reduced quadratically with increase in dietary ME concentration and mortality was minimum at 11.64 MJ ME/kg diet. Based on results from the experiment it was concluded that White Leghorn layers (21–72 weeks of age) require 11.36 MJ ME/kg diet for maximum egg production, feed efficiency and egg mass with better liveability. The calculated intake of metabolisable energy, crude protein, lysine, methionine, calcium and non-phytate phosphorus in layers fed 11.30 MJ ME/kg diet was 1.157 MJ, 18.42 g, 865 mg, 409 mg, 3.68 g and 358 mg per bird per day, respectively.