Estimation of the metabolic rate by assessing carbon-13 turnover in broiler tissues using the stable isotope technique

Abstract

A B S T R A C TThe aim of this study was to estimate the metabolic rate of broiler tissues by assessing carbon turnover in different growth phases by using the stable isotope technique and by evaluating the natural changes in Carbon-13 ( 13 C) between C3 and C4 cycle plants. Six-hundred 1-day-old broiler chicks were divided into six groups and subjected to dietary changes containing different isotopic values at 7, 14, 21, 28, and 35 days of age. Birds of Group 1 received diets composed predominantly of C 3 cycle plants shortly after accommodation, while birds of other groups remained predominantly fed with C 4 diet. The diet of Group 2 was mainly replaced by C 3 diet on the 7th day of age. Group 3 started to receive C 3 diet on the 14th day of age, whereas the diet of Group 4 was replaced on the 21st, Group 5 on the 28th. In Group 6, the substitution occurred on the 35th day of age. Samples of the pectoral muscle, keel, tibia, legs muscle, intestinal mucosa, blood, plasma, and feathers were collected. Carbon isotope ratios were determined by mass-spectrometry of isotope ratios. To measure the speed of carbon substitution after a set interval (turnover), a time exponential function was employed and obtained by exponential equations of the first order calculated with Minitab ® 16 software. The carbon half-life varied from 1.78 to 8.20 days for the pectoral muscle, from 1.91 to 12.24 days for the keel, from 2.32 to 10.71 days for the tibia, from 1.87 to 9.43 days for the leg muscle, from 0.8 to 1.58 days for the intestinal mucosa, from 0.64 to 1.71 days for the plasma, from 2.61 to 11.07 days for blood, and from 1.84 to 28.41 days for the feathers during the total growth phase. With the exception of tibia and blood, all other tissues presented a high metabolic rate in the first week of the broilers' life. The metabolic rate of tissues is faster in younger animals, and the metabolism slows down as the broilers get older. The metabolic rates in the pectoral muscle, keel, tibia, and feathers decreased with age, whereas those of the plasma and intestinal mucosa were high in all evaluated periods; thus, these tissues can be used to study traceability of feed at all stages of the broilers' life.

Testing for effects of growth rate on isotope trophic discrimination factors and evaluating the performance of Bayesian stable isotope mixing models experimentally: A moment of truth?

“…Our results thus add to a growing body of evidence that differences in physiology among individuals have an important influence on TDFs, which we speculate is linked to increased routing of dietary protein to body tissues during rapid growth (i.e., anabolism). That we observed an inverse relationship between growth rate and Δ 13 C only in liver, a highly metabolically active tissue (relative to feathers), is consistent with this idea [63,64]. However, differences in the specific amino acid composition of livers and feather (i.e., keratin) may be an additional factor affecting differences in fractionation values between tissue types and the interaction with growth rate [65,66].…”

Threonine incorporation in tissues of growing broiler chickens using L‐[15N] threonine

“…It is known that plasma and liver present high metabolic activity (Pelícia et al, 2018). The plasma presented the highest L-[ 15 N] incorporation reduction, being 43% and 60% lower than the starter phase; however, its delivery increased with age.…”

“…It is known that different tissues may differ from each other considering their metabolic activity, nutrient demands, and dynamism or even with ageing (Pelícia et al, 2018). However, most of studies that evaluated threonine requirements were based on determining the threonine deposition in the feather-free body and feathers, or to the whole-body.…”