Above 65 kg empty body weight (BW), protein deposition is greater in pigs fed essential amino acid (EAA)-restricted diets than standard diets. The aim of the study was to assess whether, compared to the current standard, the EAA supply could be markedly reduced in the finisher period to improve protein deposition efficiency. To this end, a growth performance study was performed with 48 Swiss Large White female and castrated male pigs that were assigned to three treatments: C, LPF or LPGF. The grower-finisher diets of treatment C were formulated using Swiss feeding recommendations. The grower-finisher diets in the LPGF treatment contained digestible EAA levels 20% lower than those in the C diets. Pigs in the LPGF group were offered in the grower and finisher period the standard and the low-EAA diets, respectively. From 20-110 kg BW, individual daily feed intake was monitored. The BW was determined weekly, and carcass composition at slaughter was determined by DXA. The data were analyzed with a linear mixed model using treatment, sex and the 2-way interaction as fixed effects and litter of origin as a random effect. The gain-to-CP- and NE-intake ratio was greater (P < 0.05) in females than in castrates of the C group but did not differ between sexes in the LPF and LPFG groups. The carcass protein deposition rate was 5% greater (P < 0.05) in LPGF than LPF or C pigs, and carcass protein deposition efficiency was 2.3 and 5.9%-points greater (P < 0.05) in LPGF than LPF or C pigs, respectively. In conclusion, the current data suggest that Swiss feeding recommendations for EAA supply in the finisher period could be reduced without negatively impacting the growth performance, thereby improving the efficiency of carcass protein deposition.
