In vivo collagen and mixed muscle protein turnover in 2 meat-type broiler strains in relation to woody breast myopathy

Abstract

Two meat-type broiler strains, strain A and strain B, were reared in floor pens (25 birds/pen; 45 pens/strain) for pectoralis (P) major collagen and mixed muscle protein turnover ( PT ) study from 0–56 D using primary breeder nutrition and husbandry guidelines. Forty broilers (n = 10/strain for collagen PT; n = 10/strain for mixed muscle PT) were selected at each sampling age at day 21, 28, 35, 42, and 56 and infused with 1- 13 C proline ( Pro ) and 15 N-phenylalanine ( Phe ) which are used as amino acid tracers for collagen and mixed muscle PT measurements, respectively. Muscle and plasma samples were collected, and enrichments of 1- 13 C Pro and 15 N-Phe were determined using mass spectrometry. Fractional synthesis rate ( FSR ) and fractional degradation rate ( FDR ) were measured for collagen and mixed muscle using precursor-product principle. At day 42, after separating the sampled broilers as myopathy (woody breast [ WB ] score > 1) and nonmyopathy (WB = 0), plasma metabolites were screened for differential 3-methyhistidine ( 3-MH ) expression for both strains. Data were analyzed using one-way ANOVA using t test. Results showed that collagen and mixed muscle FSR and FDR in pectoralis major decreased ( P < 0.05) for both strains as the broilers aged. FSR for collagen and FDR for mixed muscle were higher for strain B than those for strain A ( P < 0.05). Total collagen was higher ( P < 0.05) for strain B. Differentially expressed 3-MH in plasma was higher ( P < 0.05) for myopathy-affected broilers indicating greater muscle degradation occurring in myopathy-affected broiler types for both strains. 3-MH Expression in plasma was higher for strain B than for strain A. The research findings showing an increased collagen content per unit muscle weight in pectoralis major in strain B (than in strain A) could be due to higher mixed muscle FDR and increased collagen FSR occurring during the grow-out period. The increased degradation of muscle fibers and probable replacement of muscle-specific protein with connective tissue, mainly collagen, was an evident pathophysiological phenomenon occurring in myopathy-affected broilers.

Woody breast myopathy broiler show age-dependent adaptive differential gene expression in Pectoralis major and altered in-vivo triglyceride kinetics in adipogenic tissues

“…Genes related to deubiquitinases such as ubiquitin-specific proteases are expressed higher with myopathy broiler at d 21 and d 42 (OTUD1 and SACS, respectively) that play role in steady state availability of monoubiquitin and regulation of substrate degradation at the proteasome ( Reyes-Turcu et al., 2009 ). Earlier studies also reported the higher mixed muscle degradation rates in myopathy broiler compared to non-myopathy ( Maharjan et al., 2020c ), the potential phenomenon responsible for leaving the space for connective tissue growth and lipid deposition when WB myopathy is concurrently occurring with white striping of muscle (Kuttappan et al., 2016; Vignale et al., 2017 ).…”

“…Studies on metabolic and physiological findings have showed the higher in-vivo muscle degradation rates occurred in myopathy broiler compared to non-myopathy ( Abasht et al., 2016 ; Maharjan et al., 2019 ; Maharjan et al., 2020c ). The higher degradation of mixed muscle proteins occurred in the P. major could be further complemented by significant higher expression of genes related to oxidative stress (BTG2, ZNF236, CXCR4, HMOX1) and hypertensive effects (ZNF236 and UTS2R) in the WB affected muscle as found in the present study.…”

“…Strain B, a high yielding broiler strain, reported in Maharjan et al., (2020c) was utilized in the present study for transcriptomic evaluations. The performance parameters (weight gain, FCR, yield), protein turnover, and collagen turnover of Strain B associated with this study can be retrieved from Maharjan et al., (2020c) . Furthermore, Strain B was reported to be myopathy vulnerable strain.…”

“…Tissue samples collected (antero-ventral region of P. major ) from the Maharjan et al. (2020c) were utilized for the RNA-Seq studies.…”

“…The etiopathology to the WB phenotype is unknown. Many studies have been conducted particularly over the past 5-year span to understand the associated pathophysiological processes in WB myopathy condition ( Velleman and Clark, 2015 ; Maharjan et al., 2019 , 2020a , b , c ; Kuttappan et al., 2017 ).Woody breast affected birds are phenotypically detected by palpation of the breast area (Kuttappan et al., 2016). The direct palpation of the breast muscle is a detection technique that is qualitative and can only be detected post manifestation of the myopathy condition.…”