Studies on metabolism of broilers by using ¹⁴C‐labelled DL‐methionine and DL‐methionine hydroxy analogue Ca‐salt

Abstract

The metabolization of DL‐methionine and a hydroxy analogue form, DL‐MHA‐Ca, was studied by means of ¹⁴C‐labelled substances. For this purpose 60 male day‐old chicks were administered l‐¹⁴C‐labelled substances DL‐methionine and DL‐MHA‐Ca into the birds’ crop. In 20 birds the ¹⁴CO₂ activity excretion with the expired air was measured for a period of 24 hours post administration by means of radiorespirometry. The birds were killed 24, 48 and 72 hours post administration and the ¹⁴C‐activity determined in the following fractions: excrements, gastrointestinal contents, digestive tract, blood, kidney, liver and gallbladder, lung, heart, spleen, leg and breast muscles and the residual fraction.

Over the experimental period as a whole 17.0% of the administered does was recovered in the excrements of the l‐¹⁴C‐DL‐MHA‐Ca labelled birds and 4.4% in the l‐¹⁴C‐DL‐methionine treated birds.

The maximum ¹⁴CO₂ excretion in the expired air was reached after 1.5 hours, irrespective of whether 1‐¹⁴C‐DL‐methionine or l‐¹⁴C‐DL‐MHA‐Ca had been administered. Within 24 hours post administration, 15.8% of l‐¹⁴C‐DL‐methionine were excreted as ¹⁴CO₂ via the lungs, as against 11.4% following application of l‐¹⁴C‐DL‐MHA‐Ca.

While no significant differences between the groups were recorded for the ¹⁴C‐incorporation of the liver, the kidneys generally contained a higher ¹⁴C‐activity after the administration of l‐¹⁴C‐DL‐methionine than after l‐¹⁴C‐DL‐MHA‐Ca. The relative incorporated ¹⁴‐C‐activity was distributed in the following proportions: 25% in the leg and breast muscles, about 25% in the remaining organs and about 50% in the residual fraction. The ¹⁴C‐activity found in the protein of the leg and breast muscles was separated by thin layer chromatography and recovered exclusively in methionine. The ¹⁴C‐activity in the lipids of the leg and breast muscles accounted for only a very small proportion of the total incorporated ¹⁴C‐activity.

Irrespective of the adaptation diet, the rate of incorporation of ¹⁴C into the birds’ body was found to be higher after administration of ¹⁴C‐DL‐methionine than after l‐¹⁴C‐DL‐MHA‐Ca.

Key words:

• Chick
• Metabolization
• Catabolism
• Balance Studie
• Radio labelled DL‐methionine
• Radio labelled DL‐MHA‐Ca