Assessing the bioavailability of L-methionine and a methionine hydroxy analogue (MHA-Ca) compared to DL-methionine in rainbow trout (Oncorhynchus mykiss)

Abstract

Different synthetic forms of supplemental methionine (Met) are produced commercially by various manufacturers. Limited information exists on the bioavailability of these different forms in commercially relevant fish species. The objective of this study was to compare the relative bioavailability of L-methionine and a methionine hydroxy analogue calcium salt (MHA-Ca) to DL-methionine in a commercially relevant species, rainbow trout, using a linear slope-ratio assay. In addition, the ability of the rainbow trout to effectively convert the D-isomer of methionine into the biologically active L-isomer was studied by comparing the relative bioavailability of L-methionine to DL-methionine. Nine (9) diets were created from a methionine-deficient basal diet which was supplemented with graded equimolar levels of methionine (0.1%, 0.2%, 0.3% of diet by weight) from either DL-methionine, L-methionine and methionine hydroxy analogue calcium salt (MHA-Ca). Diets were fed in triplicate (IBW = 24.0 AE 0.6 g) for 12 weeks using a pair-feeding protocol. The basal diet was formulated to be deficient in both methionine (0.5%) and cysteine (0.3%), whereas meeting all other known nutritional requirements of rainbow trout. MHA-Ca was found to be less available (P < 0.05) than DL-methionine with relative bioavailability values of 69%, 60% and 73% based upon weight gain, growth rate (TGC) and retained nitrogen values respectively. No significant differences (P > 0.05) in bioavailability were found between DL-methionine and L-methionine.These findings lead to the conclusion that differences in bioavailability do exist between sources of synthetic methionine, additionally findings suggest that rainbow trout are able to effectively convert the D-isomer of methionine into the L-isomer without significantly affecting fish performance.

Growth Performance of Broilers as Influenced by Different Levels and Sources of Methionine Plus Cysteine

“…The quantity of methionine had no effect (p > 0.05) on the performance of broilers in the finisher period. This finding confirms the reports of earlier researchers [21,22] who observed that levels of methionine had no effect on feed intake, average daily gain, feed efficiency and FCR of broilers because DL-Met is readily converted into the L-isomer by the animal. Also, our finding that L-Met and DL-Met had no combined effect on feed intake, weight gain and FCR during the overall phase of broiler growth is supported by other researchers [33,35,36] who also observed that L-Met or DL-Met did not influence the feed intake, weight gain and overall FCR of broilers.…”

“…Therefore, the cystine deficiency results in the reduction in the recovery of breast meat and also decreases the extent of feathering. Our finding of no effects of the sources of methionine on the starter phase of broilers is supported by other researchers [22,31] who observed that L-Met and DL-Met did not affect growth performance due to conversion of DL-Met into L-Met. It seems that lower metabolization of D-amino acid due to the lower amount of D-amino acid oxidase in young broilers may reduce the utilization of higher amounts of DL-Met, which leads to metabolic stress and inhibition of body weight gain in the starter phase.…”

“…He observed no differences among L-Met, DL-Met and DL-HMTBA for weight gain and feed efficiency. No effect of methionine sources on overall growth of broiler has also been found by other researchers [21,22,31] who observed that L-Met and DL-Met had no effect on the overall phase of broilers.…”

“…The feed intake and FCR in the starter period remained unchanged by the combined effect of L-Met and DL-Met; this is supported by other researchers [21,22] who have also observed no significant difference in feed intake and FCR due to supplementation of L-Met and DL-Met because when the diet was supplemented with methionine alone, some methionine was converted to cysteine. The presence of small excess amounts of cysteine depressed the feed intake without a proportional reduction in weight gain because the presence of cysteine reduces the metabolic damage.…”

Black soldier fly larvae as a sustainable animal feed ingredient in Kenya

“…The crude protein, fat, starch, oil, acid detergent fiber, neutral detergent fiber, sugar and digestibility (NCGD) values were determined following standard laboratory procedures and energy values were calculated (Núñez-Sánchez et al, 2012;. Essential and non-essential amino acid contents of BSF larvae and experimental diets (Table 1) were analyzed by AMINOLab® (Evonik Industries, Hanau, Germany) using an amino acid analyzer (Biochrom 30 plus, Biochrom Ltd. Cambridge, UK) (Al Powell et al, 2017;. Feed samples were homogenously ground with an Ultra Centrifugal Mill RETSCH-ZM 200 to pass through a 0.5 mm sieve.…”