The relative effectiveness of 2-hydroxy-4-(methylthio) butanoic acid and DL-methionine in young swine.

Abstract

We compared the effectiveness of 2-hydroxy-4-(methylthio) butanoic acid (HMB) and DL-methionine (DLM) as sources of L-methionine activity in methionine-deficient primary cultures of pig liver cells and methionine-deficient early-weaned pigs. Viable hepatocytes were obtained from minced pig liver and maintained in a high density, differentiated, nonproliferation cell culture system. Culture medium was supplemented with HMB, DLM, or L-methionine, and cells were pulse-dosed with L-[14C(U)]leucine for 24 h to determine the level of protein synthesis. Leucine incorporation per milligram of protein indicated a six-to eightfold increase in protein synthesis (P < .01) with methionine levels between 5 and 10 microM, regardless of source of methionine activity. Two 24-pen replicate methionine dose titrations were conducted with 95 early-weaned commercial crossbred pigs. The pelleted corn, dried whey, and porcine plasma basal diet contained 1.5% lysine, .23% methionine, and .48% cystine and was supplemented with 0, .05, or .10% methionine activity as DLM or HMB for 21 d. There was a 134, 104, and 61% increase (P < .01) in cumulative ADG for each successive week on study with a 30 and 19% improvement in feed/gain (P < .01) after 7 and 14 d. Performance responses due to source of methionine activity did not differ and slope ratio potency determinations (gain vs intake of methionine source) of HMB vs DLM indicated a 119, 111, and 95% relative activity for cumulative weekly performance. These results support the hypothesis that HMB and DLM provide equimolar levels of methionine activity in swine.

Bioavailability of methionine hydroxy analog-calcium salt relative to dl-methionine to support nitrogen retention and growth in starter pigs

“…Zimmermann et al, 2005;Kim et al, 2006;Shoveller et al, 2010), whereas others suggested a similar RBV between DL-Met and MHA (e.g. Reifsnyder et al, 1984;Chung and Baker, 1992;Knight et al, 1998;Roemer and Abel, 1999). …”

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

“…There is wide disagreement over the bioavailability of MHA-FA compared to DLM. Some publications have proposed an equal bioavailability for MHA-FA compared to DLM (Reifsnyder et al, 1984;Knight et al, 1998;Rö mer and Abel, 1999;Gaines et al, 2005;Yi et al, 2006), whereas others have proposed a significantly lower bioavailability for MHA-FA, compared to DLM, on an equimolar or a product basis (Roth and Kirchgessner, 1986;Zimmermann et al, 2005;Kim et al, 2006;Dilger and Baker, 2008). In some of these experiments, Met was not showed to be limiting in all the diets or a diminishing incremental response to graded increases in Met intake was found.…”

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“…Estimates of the bioequivalence of HMTBa and DL-Met in pigs have ranged from 73 % on an equimolar basis (64 % on weight basis, 88 % HMTBa), when nitrogen retention was used as response criterion (Kim et al, 2006), to about 100 % (equimolar) in another study in which weight gain was assessed (Knight et al, 1998). In laying hens, HMTBa bioequivalence was found to be about 88 % on a molar basis (Liu et al, 2004).…”