Bioavailability of l-methionine relative to dl-methionine in Broiler chickens

Abstract

This study was aimed to estimate the relative bioavailability (RBA) of l-methionine (l-Met) to dl-methionine (dl-Met) in broiler chickens from 1 to 21 d of age. A total of 1664 one-day-old broiler chicks were randomly divided into 13 groups with 8 replicates per group. The basal diet contained 60% of the NRC requirement for Met. Birds in treatment groups were fed the basal diet supplemented with graded levels of dl- or l-Met, resulting in the dietary content of Met at 75%, 80%, 85%, 90%, 95% and 100% of the NRC requirement, respectively. Results showed that there were linear increases (p < .05) in average daily gain (ADG), average daily feed intake, feed efficiency (FE), eviscerated weight, breast muscle weight and leg muscle weight in response to the increasing supplementation of either dl- or l-Met, which also linearly reduced (p < .05) plasma uric acid and protein carbonyl contents. Compared with dl-Met, l-Met addition resulted in elevations (p < .05) in ADG and FE, along with leg muscle yield of birds. A lower (p < .05) content of urea nitrogen with a higher (p < .05) content of uric acid in plasma were observed in the birds supplemented with l-Met compared with dl-Met. Slope-ratio assay revealed that the RBA of l-Met to dl-Met for ADG and FE were 141.5% and 189.1%, respectively. And the respective values were calculated as 122.9% and 116.8% when based on eviscerated weight and breast muscle weight as the response criteria. However, the above RBA estimates except for FE did not differ from 100%. Collectively, supplemental l-Met had a higher bioavailability for FE of broilers relative to dl-Met during the first 3 weeks of life.

Highlights

• l-methionine addition has an advantage over dl-methionine for supporting the growth performance of broiler chickens in early age.

• The relative bioavailability of l-Met to dl-Met for feed efficiency of broiler chickens during the first 21 days post-hatch was calculated as 189.1% that differs from 100%.

Keywords:

• dl-methionine
• l-methionine
• relative bioavailability
• broiler

Disclosure statement

The authors (Xiaoli Dong and Chunyan Guo) may have interests in the submitted work.

Additional information

Funding

This study was financially supported by the China Agriculture Research System-Beijing Team for poultry Industry, the Agricultural Science and Technology Innovation Programme (ASTIP).