English

Abstract

The present study was conducted to evaluate the effects of graded levels of threonine (Thr) on growth performance and biochemical parameters in broiler chickens. For this purpose, one-day-old 150 broiler chicks were kept in pens at Poultry Farm of the University of Agriculture, Faisalabad for 5 weeks. Chicks were divided into three treatments including T1 (control group), T2 (CP 1% less and Thr 10% extra) and T3 (CP 2% less and Thr 20% extra). Iso-caloric diets were formulated according to two phases as a starter (1–21 days) and finisher (22–35 days). Treatments were replicated into 5 subgroups having 10 chicks in each. Data collected were analyzed by analysis of variance technique under CRD. Chicks fed diet contained CP 1% less and Thr 10% extra had lower (P < 0.05) feed intake, improved (P < 0.05) weight gain and FCR than those fed diet containing CP 2% less and Thr 20% extra. Dressing percentage was higher (P < 0.05) in chicks fed a control diet. However, higher (P < 0.05) breast yield and lower (P < 0.05) production cost per kg live weight were recorded in birds fed diet contained CP 1% less and Thr 10% extra than other groups. Different treatments had no effect (P > 0.05) on relative organ weight. Chicks fed diets having reduced CP and increased Thr had no effect (P > 0.05) on blood parameters and liver enzymes activity. Based on these findings, it can be concluded that lowering CP by 1% and increasing Thr by 10% resulted in better growth performance, breast yield and economics efficiency than lowering CP by 2% and increasing Thr by 20%. © 2022 Friends Science Publishers