A trial was conducted to assess the requirement of digestible threonine concentration in the diets of WL layers. Pullets (390) were fed(25-44 weeks) with 13 test diets (6+6+1)containing protein at two levels i.e. 13.46 at 0.65% lysine and 15.56 at 0.60% lysine each with six graded concentrations of threonine (60, 63, 66, 69, 72,75) and a control with 17 % Protein , 0.70 % lysine and 66% of threonine. Each diet was fed adlibitum to five replicates of six birds. Hen day egg production (HDEP) did not varied with threonine concentration in diet in low crude protein group (LCP), where as a significant increase in HDEP was noticed in medium crude protein (MCP) group. Feed intake (FI) was significantly decreased in with increase in threonine in LCP group, but no variation was observed in FI in MCP group. Other production parameters like egg weight, egg mass , feed efficiency (g/g), mortality and body weight gain were not influenced (p>0.05) by the concentration of threonine in diet. Returns over the feed cost were highest at 63% threonine concentration at both the protein levels. It can be concluded that WL layers require approximately 63% of lysine as threonine in diet for optimum production.
Layer, Threonine, Production, Economics