Crude protein levels in diets for laying hens

The aim of this study was to evaluate dietary crude protein (CP) levels for laying hens. 180 Hy-Line W-36 laying hens, with ages ranging from 27 to 43 weeks old, were distributed according to a randomized block design into three treatments with 10 replicates of six birds per cage. The dietary nutritional levels were adequate, except for CP. The treatments were 152, 172, and 182 g/kg. The following parameters were evaluated: feed intake (FI, g/day), egg production (EP, g/kg), egg weight (EW, g), egg mass (EM, g/day), feed conversion ratio (FCR, kg/kg and kg/dozen), yolk (g/kg of EW), eggshell (g/kg of EW), and albumen (g/kg of EW). Feed intake was not influenced by dietary CP levels (p>0.05). Egg weight, EM, FCR (kg/kg), and albumen were not influenced (p>0.05) by the treatments. Birds fed on diets with 172 g/kg CP showed an improvement (p<0.05) in EP of 2.35 % compared with the level of 152 g/kg CP. Increasing dietary CP levels showed better (p<0.05) FCR (kg/dozen) compared to the lowest CP level. Yolk and eggshell weight were influenced (p<0.05) by increasing dietary CP levels. The dietary CP levels of 172 and 182 g/kg increased yolk weight by 6.33 % and 10.1 % compared to the lowest CP level respectively. The eggshell weight showed an average improvement of 6.31 %, increasing the dietary CP levels. The CP level of 172 g/kg is recommended in diets for white-eggs laying hens from 27 to 43 weeks of age.