Abstract: The objective of this study was to investigate the difference in taste characteristics, umami substances and the expression of umami-related genes in Longissimus dorsi, Biceps femoris and Triceps brachii muscles from Sunit sheep subjected to two different feeding patterns (grazing and stall feeding). Sunit sheep were slaughtered at the age of 12 months for the collection of muscle samples. The results showed that the umami and saltiness of meat from grazed sheep were higher than those of stall-fed sheep, while the bitterness and astringency were lower than those of the latter. The contents of inosine monophosphate (IMP) and inosine (INO) as umami substances in meat from grazed sheep were significantly higher than in meat from stall-fed sheep (P < 0.05). The expression of adenosine monophosphate deaminase 1 (AMPD1) gene in Longissimus dorsi of grazed sheep were significantly higher than that in stall-fed sheep (P < 0.05), and there was also a significant increase in the expression of adenylosuccinate lyase (ADSL) and aminoimidazole carboxamide ribonucleotide transformylase (ATIC) gene in Biceps femoris (P < 0.05). For grazed sheep, a significant positive correlation was found between the expression of AMPD1 and ADSL (P < 0.01). Correlation analysis showed that IMP content was positively correlated with the expression of AMPD1 highly significantly (P < 0.01) in grazed sheep and with the expression of ATIC significantly (P < 0.05) in both grazed and stall-fed sheep. Finally, we concluded that when the expression of umami-related genes was increased, there was a concomitant increase in the content of umami substances.

Key words: feeding patterns, Sunit sheep, taste characteristics, umami substances, umami-related genes