Estimation by regression analysis of endogenous amino acid levels in digesta collected from the distal ileum of pigs

Abstract

An experiment was conducted to estimate by simple linear regression the levels of endogenous amino acids in digesta collected from the distal ileum in pigs. Six barrows, average initial BW 35 kg, were fitted with a simple T-cannula at the distal ileum and fed six diets according to a 6 x 6 Latin square design. Six cornstarch-based diets containing six levels of CP from soybean meal (4, 8, 12, 16, 20, and 24% CP, respectively) were formulated. Chromic oxide (.4%) was included as the digestibility marker. Each experimental period consisted of 8 d. Ileal digesta were collected, at 2-h intervals, for a total of 24 h during d 7 and 8. There were linear relationships (P < .001) between dietary contents of apparent ileal digestible and total amino acids, irrespective of the ranges in graded dietary levels of amino acids. Determined with the regression technique, the endogenous levels of the indispensable amino acids (grams/kilogram of DMI) were as follows: arginine, .64; histidine, .23; isoleucine, .46; leucine, .69; lysine, .47; methionine, .13; phenylalanine, .31; threonine, .69; and valine, .54. Differences in the ranges of graded dietary levels of amino acids resulted in large differences in the estimated amounts of endogenous amino acids in ileal digesta. Furthermore, it seems that the levels of endogenous amino acids, as grams/kilogram of DMI, were constant at different dietary levels of amino acids, whereas the contributions of endogenous amino acids, as percentages of their dietary contents, decreased curvilinearly with increasing dietary contents. Therefore, apparent ileal digestibilities of amino acids were quadratically related to their dietary contents until plateau digestibilities were reached, whereas the true ileal digestibilities of amino acids were independent of their respective dietary contents. Furthermore, true ileal amino acid digestibilities should be determined from their corresponding plateau apparent ileal digestibilities. In conclusion, the levels of endogenous amino acids in ileal digesta can be determined reliably from the linear relationships between dietary contents of apparent ileal digestible and total amino acids. An important methodological consideration in the determination of endogenous amino acids by regression analysis is to design an appropriate range of graded dietary levels of amino acids.

Ileal digestibility of protein and amino acids of feed peas with different trypsin inhibitor activity in pigs

“…These relative levels of digestibility were in agreement with values reported in apparent or standardised in different works (Leterme et al 1990;Fan et al 1994b;Grosjean et al 1998b). Absolute values of standardised digestibility in low TIA pea samples were higher than those reported by Rademacher et al (1999) partly because our estimates of endogenous output were lower than in other reports (Leterme et al 1990;Fan et al 1995) obtained with protein-free diets differing in composition from our proteinfree diet or obtained by regression. However, our low values for endogenous output were confirmed in a recent co-ordinated work (Sève et al 2000).…”

Avaliação da perda endógena de aminoácidos, em função de diferentes níveis de fibra para suínos

“…No tratamento 4, a metionina continuou apresentando o menor valor de perda endógena de aminoácidos (0,09 mg/g DIP consumida), entretanto a alanina demonstrou a maior perda endógena (0,82 mg/g DIP consumida). Essas diferenças entre o conteúdo de aminoácidos ileais endógenos, segundo Fan et al (1995), podem ser atribuídas, principalmente, às diferenças nas concentrações das várias secreções endógenas do trato digestivo.…”

Determination of standardized ileal crude protein and amino acid digestibilities in protein supplements for piglets

“…AmiPig, 2000;GfE, 2008;Rademacher et al, 2009). The SID of CP and AA are corrected for basal ileal endogenous CP and AA losses (IAAL B ), and are nearly independent of the CP and AA contents in the assay diets (Fan et al, 1995a;Eklund et al, 2008a and2008b). Thus, they represent the fundamental properties of the individual feed ingredients (Mosenthin and Rademacher, 2003), and they are more likely additive in mixed diets than apparent ileal digestibilities (AID) (Stein et al, 2005).…”

“…Presently, there are only few reports on SID of CP and AA, which were determined in protein supplements for piglets. The key issues for the calculation of SID of CP and AA are (i) the measurement of plateau AID and (ii) estimates of IAAL B (Fan et al, 1995a), which have recently been determined in piglets (Eklund, 2007;Eklund et al, 2008a).…”

“…If IAAL B are used at smaller dietary CP and AA levels to transform AID into SID, this correction may have a substantial impact on the determination of the SID, due to the fact that any possible inaccuracy in the estimation of IAAL B likely has a more pronounced effect on the determination of SID at smaller -E-mail: rhmosent@uni-hohenheim.de rather than at greater dietary CP and AA levels. Therefore, it has been generally accepted that SID should be determined from the AID measured at greater dietary CP and AA levels, ideally from the plateau AID (Fan et al, 1995a;Fan and Sauer, 1997;Eklund et al, 2008a).…”