Effects of dietary energy levels on Pectoralis major mixed muscle protein turnover and body composition in two broiler lines housed in different grow‐out environments

Abstract

This study determined the Pectoralis (P) major mixed muscle protein turnover (PT) in two meat broiler lines, Line A and Line B, during the finishing grow-out feeding period (21-42 days) as affected by the dietary metabolizable energy (ME) levels and ambient temperatures. Experimental finishing diets consisted of 80, 90, 100, 110 and 120% ME of recommended nutrient guidelines for energy level. Fractional synthesis rates (FSR) or fractional degradation rates (FDR) were measured in P. major at day 36 and 42. Protein and fat mass gain were measured, and respective energy retention efficiencies as protein and fat (EREp and EREf) were determined. Metabolic heat production (HP) was also reported. Experimental feeding studies were conducted in cool season (24 hr mean: 69.91˚F and 63.98% RH) and in hot season (24 hr mean: 77.55˚F and 86.04% RH). Results showed that FSR or FDR values were not affected by dietary ME levels at day 36, whereas reduced FSR (p < .05) were observed at day 42 fed diets with reduced ME levels (≤100% ME) which could have resulted from greater maintenance energy requirement of maturing broilers at that age. Broilers fed reduced ME diets (≤100% ME) maintained protein mass (equivalent to broilers fed ≥100%-120% ME) by reduced FDR and increased feed intake. Grow-out ambient temperature did not affect FSR or FDR values across ME levels. Line B retained higher protein mass, lower fat mass and greater HP compared to Line A. This was followed by higher feed intake in Line B. Further, Line B exhibited higher EREp and lower EREf across dietary ME levels. In summary, PT homeostasis and body composition changes in broiler lines studied seemed to be regulated by the birds' intent to normalize energy intake as per physiological need by controlling feed intake.

Vergelijk van voerprogramma’s met verschillende energie- en eiwitgehalten bij trager groeiende vleeskuikens

“…Onderzoek naar verstorende factoren zoals aminozuurgehalten (Delezie et al, 2010;Swennen et al, 2010;Classen, 2013;Maharjan et al, 2020a), energiegehalten (Dozier en Gehring, 2014;Maharjan et al, 2020b), en de fysieke kwaliteit van het voer zou verder kunnen bijdragen aan het begrip van wat de voeropname bij vleeskuikens drijft.…”

A novel dynamic proteomics approach for the measurement of broiler chicken protein fractional synthesis rate

“…Moreover, poultry meat is currently the biggest meat industry segment and global meat production is expected to reach 377 Mt by 2031 8 . Studies of chicken protein dynamics have been mostly limited to mixed muscle protein (MMP) turnover and mixed liver protein turnover to a lesser degree 9–23 . Notable exceptions to this trend are the work of Barnes et al 24 and Doherty et al 25 The Barnes et al study reported hemopexin fractional synthesis rate (FSR) during an immune challenge, in addition to mixed muscle and liver protein synthesis, being the first and only measurements of a chicken acute phase protein FSR, while the study of Doherty et al reported individual sarcoplasmic protein turnover rate.…”

“…Studies of chicken protein synthesis have been mostly limited to the use of radioactively labelled AAs first and AAs labelled with stable isotopes later, these AAs (predominantly Phe and Tyr) being administered intravenously or added to the chicken diet 9,11,12,15–17,27 . The method involving the intravenous administration of a flooding dose of 15 N‐Phe followed by the assessment of AA isotopic enrichment by gas chromatography with mass spectrometry (GC/MS) seems to have become the gold standard in the field with all studies of broiler protein synthesis in the last decade having adopted it 19–23,28,29 . These methods have been associated with several problems such as difficulties in assessing the true precursor enrichment at the site of synthesis (aminoacyl t‐RNAs), the necessity of confined conditions and the high cost of AA tracers 30 .…”

“…8 Studies of chicken protein dynamics have been mostly limited to mixed muscle protein (MMP) turnover and mixed liver protein turnover to a lesser degree. [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] Notable exceptions to this trend are the work of Barnes et al 24 and Doherty et al 25 The Barnes et al study reported hemopexin fractional synthesis rate (FSR) during an immune challenge, in addition to mixed muscle and liver protein synthesis, being the first and only measurements of a chicken acute phase protein FSR, while the study of Doherty et al reported individual sarcoplasmic protein turnover rate. Further investigation of broiler chicken individual protein synthesis rate could expand our current knowledge regarding broiler chicken growth and immune function, especially as protein and amino acid (AA) metabolism in chickens is intimately related with these metabolic events.…”

“…9,11,12,[15][16][17]27 The method involving the intravenous administration of a flooding dose of 15 N-Phe followed by the assessment of AA isotopic enrichment by gas chromatography with mass spectrometry (GC/MS) seems to have become the gold standard in the field with all studies of broiler protein synthesis in the last decade having adopted it. [19][20][21][22][23]28,29 These methods have been associated with several problems such as difficulties in assessing the true precursor enrichment at the site of synthesis (aminoacyl t-RNAs), the necessity of confined conditions and the high cost of AA tracers. 30 The use of deuterated water ( 2 H 2 O) as tracer eliminates most of these problems as it is a safe and inexpensive tracer that can be administered orally and equilibrates rapidly with body water (BW), labelling all AAs across different cellular compartments.…”