Bioavailability of liquid methionine hydroxy analogue-free acid relative to DL-methionine in broilers

Effects of supplemental methionine sources in finishing pig diets on growth performance, carcass characteristics, cutting yields, and meat quality

Supplemental methionine (Met) is widely used within the swine industry; however, data are limited regarding the effect of Met sources on carcass cutability and meat quality. The objective was to determine the effects of L-Met (LM, 99%), DL-Met (DLM, 99%), or calcium salt of DL-Met hydroxyl analog (MHA, 84%) in finishing pig diets on carcass characteristics and meat quality. At 9 weeks of age, pigs (N = 240) were allocated to 60 single-sex pens for a four-phase finishing trial that lasted 104 d. Pigs were fed a common grower diet until day 56 where pens were randomly allotted to one of the three experimental diets. For the remaining 7 wk of the finisher phase, pigs (BW = 79.9 ± 0.80 kg) were fed diets containing LM, DLM, or MHA, with the supplemental Met source providing 25% of standardized ileal digestible (SID) Met + cysteine (Cys) requirement based on 65% bioefficacy for MHA in comparison with LM or DLM. One pig per pen was slaughtered at the study conclusion (on day 104), and the left sides of carcasses were fabricated into subprimal cuts to determine carcass-cutting yields. Loin quality including proximate composition and shear force were measured. Hot carcass weight was not different (P = 0.34) between treatments (LM 104.5 kg; DLM 103.0 kg; MHA 101.5 kg), moreover, loin eye area was not different (P = 0.98) between treatments (LM 52.65 cm²; DLM 52.49 cm²; MHA 52.81 cm²). Boneless carcass-cutting yield was not different (P = 0.56) between treatments (LM 54.97 kg; DLM 54.82 kg; MHA 54.52 kg). Loin pH was not different (P = 0.24) between treatments (LM 5.45; DLM 5.48; MHA 5.45). However, drip loss tended to be reduced (P = 0.11) by the DLM treatment (5.58%) compared with LM (7.03%) and MHA (6.68%) treatments. Shear force was not different (P = 0.85) between treatments (LM 3.03 kg; DLM 3.06 kg; MHA 3.10 kg). However, cook loss tended to be reduced (P = 0.06) by the DLM treatment (16.20%) compared with LM (18.18%) and MHA (18.50%) treatments. These data suggest that only minimal differences in carcass cutability and meat quality can be attributed to Met source in finishing pig diets when using 65% bioefficacy for MHA relative to L-Met or DL-Met.

Assessing the nutritional equivalency of DL-methionine and L-methionine in broiler chickens: a meta-analytical study

The purpose of this study was to perform a meta-analysis comparing the biological efficiency of DL-methionine and L-methionine (DL-Met and L-Met) in broiler nutrition. This analysis was based on a dataset comprising experiment results published in peer-reviewed papers since 2007. All experiments investigated the response of broilers (aged 0-21 d) to different dietary concentrations of DL- and L-Met, achieved by supplementing crystalline Met. A graphical analysis was conducted on the database using ellipses coverage and nonparametric density techniques. Two methods of linear and nonlinear exponential meta-regression analysis were used to determine relative bioavailability based on average daily gain (ADG) and feed conversion ratio (FCR) responses to dietary Met sources. The analyses of ADG and FCR obtained from both linear and exponential models showed a relative difference between the tested methionine sources. The results showed that both ADG and FCR were improved in L-Met compared to DL-Met supplemented diets. Linear regression analysis revealed that DL-Met was 94.97% (for ADG) and 95.63% (for FCR) as efficacious as L-Met (P < 0.01). In contrast, the analysis of the fitted nonlinear exponential model showed that the biological efficiencies of DL-Met were 91.33% and 76.57% of the values for L-Met for ADG (P = 0.01) and FCR (P = 0.09), respectively. Based on the meta-analytical results, an equivalence of relative biological efficiency of DL-Met in comparison with L-Met for young broilers could not be confirmed.

New statistical approach shows that hydroxy-methionine is noninferior to DL-Methionine in 35-day-old broiler chickens

The efficacy of a new molecule is assessed in the pharmaceutical industry through noninferiority tests to establish that it is not unacceptably less efficient than the reference. This method was proposed to compare DL-Methionine (DL-Met) as reference and DL-Hydroxy-Methionine (OH-Met) as alternative, in broiler chickens. The research hypothesized that OH-Met is inferior to DL-Met. Noninferiority margins were determined using 7 datasets comparing broiler growth response between a sulfur amino acid deficient and adequate diet from 0 to 35 d. The datasets were selected from the literature and internal records of the company. The noninferiority margins were then fixed as the largest loss of effect (inferiority) acceptable when OH-Met is compared to DL-Met. Three corn/soybean meal-based experimental treatments were offered to 4,200 chicks (35 replicates of 40 birds). Birds received from 0 to 35 d 1) a negative control diet deficient in Met and Cys; the negative control treatment supplemented on equimolar basis with 2) DL-Met or 3) OH-Met in amounts allowing to reach Aviagen Met+Cys recommendations. The three treatments were adequate in all other nutrients. Growth performance, which was analysed with one-way ANOVA, showed no significant difference between DL-Met and OH-Met. The supplemented treatments improved (P < 0.0001) the performance parameters compared to the negative control. The lower limits of the confidence intervals of the difference between means for the feed intake [-1.34; 1.41], body weight [-57.3; 9.8] and daily growth [-1.64; 0.28], did not exceed the noninferiority margins. This demonstrates that OH-Met was non-inferior to DL-Met.

Safety and efficacy of hydroxy analogue of methionine and its calcium salt (ADRY+®) for all animal species

The European Commission asked EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) to deliver a scientific opinion on the safety and efficacy of ADRY+®. ADRY+® consists of hydroxy analogue of methionine (HMTBa) and its calcium salt (HMTBa-Ca), both precursors of l-methionine. HMTBa and HMTBa-Ca are currently authorised for use as a nutritional additives, under the functional group 'amino acids, their salts and analogues'. ADRY+® is produced by chemical synthesis and it is intended to be used in feed for all animal species and categories. The FEEDAP Panel concluded that ADRY+® is safe for the target animals. The use of the additive in animal nutrition is not expected to result in an accumulation of HMTBa or its metabolites in edible tissues and animal products. Therefore, its use does not raise safety concerns for the consumer. ADRY+® is irritant to eyes and not irritant to the skin. The FEEDAP Panel cannot conclude on the skin sensitisation potential of this additive. The exposure of the users to the additive by inhalation is expected to be low. The use of this product as a feed additive does not represent a risk to the environment. ADRY+® is an effective source of methionine for protein synthesis in non-ruminant animals and fish, although HMTBa may show a lower bioefficacy than dl-methionine. In ruminants, HMTBa is more slowly degraded in the rumen than dl-methionine.

Comparison of methionine sources around requirement levels using a methionine efficacy method in 0 to 28 day old broilers

The addition of methionine in the poultry feed industry is still facing the relative efficacy dilemma between DL-methionine (DLM) and hydroxy-methionine (HMTBA). The aim of this study was to compare the effect of dietary DLM and HMTBA on broiler performance at different levels of total sulfur amino acids (TSAA). The treatments consisted of a basal diet without methionine addition, and 4 increasing methionine doses for both sources resulting in TSAA/Lysine ratios from 0.62 to 0.73 in the starter phase and 0.59 to 0.82 in the grower phase. The comparison of product performance was performed by three-way ANOVA analysis and by methionine efficacy calculation as an alternative method of comparison. Growth results obtained during the starter phase with the different methionine supplementations did not show significant growth responses to TSAA levels, indicating a lower methionine requirement in the starter phase than currently assumed. However, a significant methionine dose effect was obtained for the period 10 to 28 day of age and for the entire growth period of 0 to 28 day of age. Excepting a significant gender effect, the statistical analysis did not allow for the discrimination of methionine sources, and no interaction between source and dose level was observed up to 28 days of age. A significant interaction between source and dose level was observed for methionine efficacy for the grower phase, and the total growth period showed better HMTBA efficacy at higher TSAA value. The exponential model fitted to each methionine source for body weight response depending on methionine intake or for feed conversion ratio (FCR) depending on methionine doses did not allow the methionine sources to be distinguished. Altogether, these results conclude that methionine sources lead to similar performances response when compared at TSAA values around the broiler requirement level. These results also showed that at TSAA values above requirement, HMTBA had a better methionine efficacy value than DLM, caused by the different properties of that molecule, whereas below the TSAA requirement levels, the opposite was observed in females.