The aim of this study was to testify if the growing broiler chick requires optimal level of lysine and/or methionine to be supplied continuously for 24 hrs. Three hundred one-day old Ross broiler chicks were equally distributed into 10 groups (G1 to G10), each of three equal replicates. The birds were fed four experimental diets (D1 to D4): D1 (optimal levels of lysine; 1.05% and methionine; 0.50%), D2 (suboptimal levels of lysine; 0.75% and methionine; 0.37%), D3 (suboptimal level of methionine; 0.37%), and D4 (suboptimal level of lysine; 0.75%). G1 (control) to G4 received D1 to D4; respectively continuously for 24 hrs. G5 to G7 received D1 interrupted (at three periods per day each of four hours) by discontinuous feeding of D2, D3 or D4; respectively. G8 to G10 were fed in a similar way to the last three groups except the discontinuous feeding of D2, D3 or D4 was at different time of feeding throughout the day. The effect of these treatments on body weight, body weight gain, feed consumption, feed efficiency, carcass parts and carcass composition was determined till 49 days of age.
The discontinuous feeding of suboptimal level of both lysine and methionine or lysine alone had a negative effect on body weight and gain, breast and liver weights, and feed efficiency; however, the discontinuous feeding of suboptimal level of methionine was less effective on the mentioned criteria.
The time of diurnal optimal feeding revealed an alleviating effect on body weight and breast weight in case of methionine; and on feed efficiency in case of lysine.
It could be concluded that the diurnal discontinuous feeding of suboptimal level of lysine was more deleterious than methionine. Moreover, the effect of time (throughout the day) of discontinuous feeding suboptimal level of lysine was more pronounced than methionine. Also, it could be concluded that diurnal continuous supply of lysine and methionine at optimal level is required for better broilers performance.