Standardized ileal digestibility of amino acids in four egg products and casein fed to weanling pigs

An experiment was conducted to test the hypothesis that a) the standardized ileal digestibility (SID) of amino acids (AA) in pasteurized egg products is sufficient for these ingredients to serve as a high-quality protein source in weanling pig diets; and b) the SID of AA in trypsin-inhibitor-free egg protein does not differ from that of casein, and is greater than the SID of AA in egg products containing residual trypsin inhibitor activity (TIA). Five diets that included raw egg powder (REP), dry-pasteurized egg powder (DPE), liquid pasteurized egg powder (LPE), trypsin inhibitor-free egg powder (TFE), or casein as the only source of AA were formulated. A nitrogen-free diet was also formulated to determine basal endogenous losses of crude protein (CP) and AA. Twelve weanling pigs (initial body weight: 11.99 ± 0.53 kg) with a T-cannula in the distal ileum were allotted to a replicated 6 × 6 Latin square design with six diets and six periods of 7 days. Ileal digesta samples were collected on days 6 and 7 of each period and were analyzed for CP and AA. Results indicated that no differences were observed in SID of CP or AA between REP and DPE or LPE, except that LPE had greater (P < 0.05) SID of Lys than REP. The SID of most AA was greater (P < 0.05) in TFE and casein compared with REP, DPE, and LPE, indicating that the residual TIA in REP, DPE, and LPE reduced AA digestibility. However, the SID of Lys, Cys, and Ser was not different between TFE and LPE. The SID of His, Lys, Asp, and Ser was less (P < 0.05) in TFE than in casein, whereas the SID of other AA and CP in TFE was not different from that in casein. In conclusion, all egg products had excellent SID of CP (> 82.0%) and AA (> 80.0%), but only when TIA were almost completely eliminated, as in TFE, were the SID of AA in egg protein not different from the SID of AA in casein. Overall, egg products can serve as effective sources of AA in diets for young pigs.