Estimates of basal ileal endogenous losses of amino acids by regression analysis and determination of standardised ileal amino acid digestibilities from casein in newly weaned pigs

BACKGROUND: This study was carried out to estimate basal ileal endogenous crude protein (CP) and amino acid (AA) losses (IAAL_B) in newly weaned pigs by regression analysis from apparent ileal digestible and the corresponding total dietary contents of CP and AA in order to obtain standardised ileal digestibilities (SID) of CP and AA originating from casein. A total of fourteen 3‐week‐old barrows were fitted with simple T cannulas at the distal ileum and were fed six diets with two pigs per diet in 4 weekly repeated measurements. Corn starch‐based diets containing six graded levels of CP from casein with 90, 155, 220, 285, 350 and 415 g kg^?1 CP (as‐fed basis) were formulated. RESULTS: Linear relationships (P < 0.001) between apparent ileal digestible and total dietary contents of CP and AA (g kg^?1 dry matter intake (DMI)) exist for CP and all AA in the range of 90–220 g kg^?1 CP content in the diet. The IAAL_B extrapolated from the range of 90–220 g kg^?1 CP content are different from zero (P < 0.001 to P = 0.019) except for tryptophan (P = 0.220). Based on regression analysis in the range of 90–220 g kg^?1 CP, estimates of IAAL_B, expressed as g kg^?1 DMI, and SID of CP and AA in casein (in parentheses, %) were as follows: CP 9.3 (98.0); arginine 0.4 (98.9); histidine 0.2 (98.5); isoleucine 0.2 (98.1); leucine 0.5 (99.2); lysine 0.4 (99.0); methionine 0.1 (99.1); phenylalanine 0.4 (99.9); threonine 0.6 (97.8); tryptophan 0.1 (96.2); valine 0.4 (98.5). CONCLUSION: The IAAL_B and SID of CP and AA originating from casein in newly weaned pigs are in close agreement with values obtained in grower finisher pigs. Copyright © 2007 Society of Chemical Industry