The effect of dietary lysine level on the ileal digestibility of protein and amino acids in growing pigs

Abstract

A precondition to producing pork in a cost-effective and environment-friendly manner is to provide a balanced protein and amino acid supply for the animals with a special focus on optimal lysine supply. According to the literature, commercial pig breeds having different genetic potentials may show up to 30% differences in their performance, which also affects their amino acid requirements. It is justifiable therefore to conduct studies with the objective of determining the amino acid requirements of these pigs more accurately. were aimed at determining how the different lysine contents of the trial diets affect the ileal digestibility of protein and amino acids in growing pigs of high genetic potential. The trials, conducted in the 25−60 live weight interval, used 4 Hungahib-39 barrows per treatment in 2 replicates (8 pigs/treatment). The animals were fitted with a PVTC cannula. The initial live weight of the pigs was 34.9±5.3 kg. During the trial the effect of 6 corn−barley−soy based diets with different lysine contents – 7.6, 8.3, 9.4, 10.0, 10.7 and 11.5 g/kg diet − were studied. The trial data were subjected to variance analysis (SAS, 2004). Based on our results it can be concluded that when feeding the diet with 9.4 g lysine/kg of diet the ileal digestibility of protein and lysine improved significantly (P≤0.05) compared to the value determined when feeding the diet with the lowest lysine content (7.6 g/kg). Increasing the lysine content further, however, was not associated with the further improvement of lysine digestibility (P≥0.05). The digestibility of methionine increased significantly only at 10.0 g/kg (P≤0.05), and the further lysine dosages resulted in a further improvement (P≤0.05). Similar trends were found for threonine as well. Our data highlight the fact, that the different dietary lysine levels affect the ileal digestibility of dietary amino acids at different rates, which should be taken into account during feed formulation.