Effects of digestible lysine levels on growth performance, serum metabolites and carcass composition in barrows

Abstract

This study was conducted to investigate the effects of different levels of dietary lysineon growth performance, serum metabolites, and carcass composition in growing‐finishing barrows fed to achieve a body weight (BW) of about 70 kg from an initial weight of 40 kg. Forty‐eight barrows were randomly assigned to one of three dietary groups containing 0.59, 0.75 or 0.91% digestible lysine (DLys), respectively. Results showed that the ADG and G/F increased (P < 0.05) as the level of DLys increased. The dressing percentage of barrows in the 0.91% DLys treatment group was larger (P < 0.05) than that in the other two groups. Other chemical indexes of body composition, including protein, ash, lipid accretion rates, and estimated lean yields were also affected (P < 0.05) by the level of dietary DLys. Increases in of lysine intake elevated the concentrations of glucose and insulin (P > 0.05). The concentrations of serum urea nitrogen and T3 first decreased and then increased (P < 0.05), while T4 decreased (P < 0.05) with increasing levels of DLys. These findings suggest that barrows fed diets providing 14.21 MJ of DE/kg from over a period during which BW increases from 40 to 70 kg, show the maximum ADG and G/F when the concentration of DLys is 0.91%, which corresponds approximately to an intake of 18.4 g/day DLys and 0.63 g of DLys/MJ of DE, respectively.