Files
Abstract
Broiler chicken weight gain is a result of genetics and nutrition, with increased muscle mass attributed to accelerated embryonic myogenesis and post-hatch muscle growth. During the avian incubation period, in ovo injection may be used as a strategy to deliver exogenous supplements into growing embryos for improving skeletal muscle development and growth. Nicotinamide riboside (NR), a vitamin B3 analog, is a human performance supplement used to stimulate mitochondria biogenesis and elevate tissue NAD+ levels. Research showed injecting NR into the chick embryonic yolk sac increased breast muscle weight and muscle satellite cell numbers and proliferation rate. Therefore, our objective was to determine the effects of in ovo feeding of broilers with NR on breast muscle development and growth. Through NR dose study, we confirmed that 2.5 mM is the best dose of NR to improve high yield broiler breast muscle growth. Furthermore, our dose and location study proved yolk sac location of the broiler egg is an optimum for in ovo feeding of NR. This led to increased hatched chick breast muscle morphometrics, which coincided with an increase in muscle fiber density and tended to decrease fiber cross-sectional area (CSA). Increased Sirtuin1 and cyclin D mRNA expression of hatched chicks from eggs injected with 2.5 mM NR into yolk sac indicate a potential NR regulated Sirtuin1/cyclin D molecular mechanism mediating chicken muscle early development. At last, our broiler strain study also indicated NR supplemented in ovo has the potential to enhance hypertrophy of the PM muscle of commercial strain, Cobb 500 chicks through increasing PM thickness and PM muscle fiber CSA.INDEX WORDS: broiler, pectoralis major, muscle fiber, nicotinamide riboside, Cyclin D