Effect of Supplementation with Synthetic Lysine on the Performance of Finisher Broiler Chicks

The study was conducted to evaluate the effect of different levels of synthetic lysine (sLys) on dry matter intake (DMI), average daily weight gain (ADG), dry matter conversion ratio (DMCR), carcass characteris-tics and economics of production of finisher broiler chicks. As 240 day-old broiler chicks were randomly distributed to 12 pens of 20 chicks each and assigned to four treatment rations in a completely randomized design. Six broilers (3 males and 3 females) from each replication were starved for 16 hours and slaugh-tered to evaluate carcass characteristics. Control diet had a lysine content of 0.9 and 0.8% of the ration, which was 0.3 and 0.2% of the ration below the recommended level. The four rations were formulated by including sLys at levels of 0, 50, 100 and 150% of the deficient amount of lysine. No sLys in the ration (T1) and rations to which 50% (T2), 100% (T3) and 150% (T4) of the deficient amount of lysine being added as sLys. No significance difference (P > 0.05) was observed among treatments in total and daily DMI, meta-bolic energy (ME) and crude protein (CP) intakes and DMCR at all phases of the experiment. Final body weight (1665, 1672, 1707 and 1786 g (standard error of the means (SEM)=18.04)) and ADG during the entire period (33.0, 33.1, 33.9 and 35.5 g/day (SEM=0.36) for T1, T2, T3 and T4, respectively) was signifi-cantly higher (P < 0.05) for birds kept on T4 diets. No significant difference (P > 0.05) existed in mortality percentage among treatments. Dressed carcass weight (1407, 1426, 1461 and 1510 g (SEM=15.07)), breast weight (329, 334, 338 and 365 g (SEM=5.09)) and drumstick weight (134, 137, 135 and 150 g (SEM=2.3) for T1, T2, T3 and T4, respectively) were greater for T4 than other treatments. In conclusion, 12.5% extra addition of sLys above the level recommended by NRC to the commercial diets, as in T4, improved broiler performance and profitability.