Methionine-hydroxy analogue was found to be significantly less bioavailable compared to dl-methionine for protein deposition in growing pigs

Abstract

When methionine (Met) is limiting in swine diets, it is commonly supplemented by using anhydrous DL-methionine (DLM, 99% purity) or liquid DL-methionine-hydroxy analogue free acid (MHA-FA, 88% purity). The objective of this experiment was to test the null hypothesis that the bioavailability of DLM and MHA-FA were not different for growing pigs, using the indicator amino acid (AA) (phenylalanine, Phe) oxidation (IAAO) method in a slope-ratio assay. Six barrows (mean BW during study: 21.1 kg) received seven dietary treatments with all pigs receiving all diets in random order at an intake of 95 g/kg BW 0.75 . The basal diet (BD) contained analyzed content of 15.1% CP, 0.20% Met, 0.73% Phe and all other AA in excess of requirement. The BD was supplemented with three graded levels of DLM or MHA-FA on an equimolar basis. Dietary treatments only varied in Met content and included: (i) BD, (ii) BD 1 0.034% DLM, (iii) BD 1 0.054% DLM, (iv) BD 1 0.086% DLM, (v) BD 1 0.029% MHA-FA, (vi) BD 1 0.078% MHA-FA and (vii) BD 1 0.107% MHA-FA, as analyzed. Indicator AA oxidation was determined during 4 h studies, where pigs were fed half-hourly meals each equal to 1/32 of their daily feed allowance. Each meal was mixed with 258.7 kBq (s.e. 2.6) of L-[1-14 C]Phe with a prime of 3.5 times the half-hourly dose added to the first meal. The slope of the decrease in IAAO calculated by linear regression analysis was greater ( P 5 0.012) for DLM supplementation (9.87 6 1.450 per g, 1.488 6 0.215% per mmol) than for MHA-FA (6.48 6 0.89 per g, 1.107 6 0.152% per mmol). The ratio of slopes indicated a bioavailability of MHA-FA on a product basis, relative to DLM, of 65.7%. Bioavailability on an equimolar Met basis, calculated from the ratio of the slopes was 74.4% for MHA-FA, relative to DLM. In conclusion, these results indicate that the metabolic bioavailability of MHA-FA for growing pigs is appreciably lower than that of DLM on both an equimolar and a product basis.Keywords: bioavailability, indicator oxidation, methionine, methionine-hydroxy analogue, pig ImplicationsMethionine is an amino acid (AA) that is often included in swine diets and is commonly supplemented by using anhydrous DL-methionine (DLM, 99% purity) or liquid DL-methionine-hydroxy analogue free acid (liquid MHA-FA). There is an ongoing controversial discussion about the bioavailability of these two sources of methionine. Our data derived using the indicator AA oxidation (IAAO) method in a slope-ratio approach showed a bioavailability for MHA-FA of 74.4% on an equimolar basis or 65.7% on a product (wt/wt) basis, relative to DLM in growing pigs. These data can be used when considering supplementation of methionine as either MHA-FA or DLM.

Effects of dietary methionine supplementation on growth performance, intestinal morphology, antioxidant capacity and immune function in intra‐uterine growth‐retarded suckling piglets

“…In addition, circulating DAO activity is a useful indicator of intestinal permeability and mucosal injury (Li, Lu, Hu, Sun, & Yao, ). The present results found that L ‐Met had the potential to attenuate the increased activity of plasma DAO in the IUGR piglets, indicating that L ‐Met treatment is more effective in improving the morphological development of intestinal mucosa, which may be associated with the difference in relative bioavailability of the Met sources (Opapeju et al, ; Shoveller et al, ; Zimmermann et al, ).…”

“…Methionine (Met) is considered as the third‐limiting amino acid in the diets of pigs that must be supplied in adequate amounts to optimize performance (Brosnan, da Silva, & Brosnan, ; Gaines et al, ; Shoveller, Moehn, Rademacher, Htoo, & Ball, ). Methionine has the capacity to improve tissue development, promote antioxidant capacity and regulate immune function in animals (Liu, Zong, Zhang, & Cao, ).…”

“…Methionine (Met) is considered as the third-limiting amino acid in the diets of pigs that must be supplied in adequate amounts to optimize performance (Brosnan, da Silva, & Brosnan, 2007;Gaines et al, 2005;Shoveller, Moehn, Rademacher, Htoo, & Ball, 2010).…”

Bioavailability of arginine from Indian mustard protein concentrate and meal compared with that of a soy protein concentrate in rainbow trout (Oncorhynchys mykiss)

“…Linear models have been extensively used to determine bioavailability of individual amino acids or minerals in poultry (Major & Batterham ; Batterham, Lowe, Darnell & Major ; Adeola ; Parsons, Zhang & Araba ; Lumpkins & Batal ), pigs (Batterham, Andersen, Baigent & White ; Adeola , ; Fanimo, Susenbeth & Sudekum ; Mateo, Spallholz, Elder, Yoon & Kim ; Shoveller, Moehn, Rademacher, Htoo & Ball ; Petersen, Pedersen, Lindemann & Stein ), and recently, in fish (Zarate & Lovell ; El‐Haroun & Bureau ; Li, Burr, Wen, Goff, Murthy & Gatlin III 2009; Li, Wang, and Gatlin ;Poppi et al . ).…”

“…Linear models have been extensively used to determine bioavailability of individual amino acids or minerals in poultry (Major & Batterham 1981;Batterham, Lowe, Darnell & Major 1986; Adeola (Batterham, Andersen, Baigent & White 1990;Adeola 1996Adeola , 2009Fanimo, Susenbeth & Sudekum 2006;Mateo, Spallholz, Elder, Yoon & Kim 2007;Shoveller, Moehn, Rademacher, Htoo & Ball 2009;Petersen, Pedersen, Lindemann & Stein 2011), and recently, in fish (Zarate & Lovell 1997;El-Haroun & Bureau 2007;Li, Burr, Wen, Goff, Murthy & Gatlin III 2009;Li, Wang, and Gatlin 2008;Poppi et al 2011). The slope-ratio is usually determined by linear regression model (y = b1 + b2 9 S + b3 9 T, Sstandard and T-test diets) that needs pre-validation of three basic assumptions: linearity of the responses, common intercepts for all lines, and the equal basal level response to the common intercept (Finney 1951(Finney , 1964Batterham, Murison & Lewis 1979;Littel et al 1997).…”