Impact of different amino acid levels in diets of fattening boars on growth and slaughter performance as well as on meat and fat quality

A total of 426 hybrid boars of two different sire-lines (320 Pietrain and 106 Duroc) were allocated on three locations and fed with three diets, only differing in the content of prececal digestible (pcd) amino acids (AA) in a two phase feeding experiment (growing phase [GP] 13.4 MJ ME/kg, finishing phase [FP] 13.0 MJ ME/kg). Growth rate, slaughter performance as well as meat and fat quality were examined. The lysin content in the control group (CG100) was 1.01% pcd lysine (GP) and 0.78 pcd lysine (FP), respectively. In verum groups (VG115 and VG130) lysin was supplemented and the content of pcd lysine was 1.18% and 0.91% (VG115), and 1.34% and 1.04% (VG130), respectively, whereas the ratio of first limiting AA remained unchanged. During the entire experimental period growth performance of Pietrain sired boars was not affected. Daily weight gain (DWG) during the experimental period was 961 g/d (CG100), 966 g/d (VG115) and 958 g/d (VG130), respectively. Feed conversion ratio (feed to weight gain, FCR) amounted to 2.33 (CG100), 2.30 (VG115), and 2.32 (VG130) kg/kg, respectively. Lean meat content (LMC) was 59.7 (CG100), 60.0 (VG115), and 60.0% (VG130), respectively. Growth performance of Duroc sired boars was reduced in VG115 and VG130 (1133 g/d vs. 1123 g/d) compared to control (1189 g/d, p = 0.002). Daily feed intake (DFI) was increased in CG100 (2.48 kg/d, p = 0.008) compared to VG115 (2.36 kg/d) and VG130 (2.32 kg/d). LMC of Duroc sired boars was 57.7 (CG100), 58.6 (VG115) and 58.4% (VG130), respectively. However, neither the content of odour-active substances nor the number of carcasses with boar taint was affected by an increased content of AA. From the results it can be speculated that a supplementation of AA above the actual German recommendations (GfE, 2006; DLG, 2010) has no beneficial effect on growth- or slaughter performance of fattening boars.