Abstract: The objective of this study was to determine the effects of dietary supplementation with Allium mongolicum Regel and its extract on the deposition and distribution of 4-alkyl branched-chain fatty acids in adipose tissues of lambs. Sixty 3-month-old small-tailed Han rams (averagely weighing (23.67 ± 3.43) kg) were selected and randomly divided into four groups in a randomized block design, each containing five animals in triplicates. Four feeding treatments were used: 1) a basal diet without any supplementation as the control group, 2) basal diet supplemented with Allicum mongolicum Regel powder at 10 g/d for each sheep as the AMR group, 3) basal diet supplemented with Allicum mongolicum Regel water extract at 3.4 g/d for each sheep as the AWE group, and 4) basal diet supplemented with Allicum mongolicum Regel ethanol extract at 2.8 g/d for each sheep as the AFE group. The experiment lasted for 75 days, including a 15-day preliminary feeding period for adaptation and a 60-day experimental feeding period. At the end of the experiment, perirenal, dorsal subcutaneous, tail, and greater omental adipose tissue samples were collected to determine the contents of 4-alkyl branched-chain fatty acids. The results demonstrated that compared with the control group, dietary supplementation with Allicum mongolicum Regel and its extracts significantly decreased the concentrations of 4-methyloctanoic acid (MOA) in perirenal, dorsal subcutaneous and greater omental adipose tissues (P < 0.000 1), as well as the concentrations of 4-ethyloctanoic acid (EOA) in perirenal and dorsal subcutaneous adipose tissues (P < 0.000 1), and reduced EOA concentrations in greater omental adipose tissue (P = 0.062 0). In addition, dietary supplementation with Allicum mongolicum Regel and its extracts significantly decreased the concentrations of 4-methylnonanoic acid (MNA) in perirenal adipose tissue (P = 0.044 0), and lowered MNA concentrations in greater omental adipose tissue (P = 0.066 0). The deposition of the three 4-alkyl branched-chain fatty acids in various adipose tissues showed a decreasing order as follows: tail > dorsal subcutaneous > greater omental > perirenal. The concentration of MOA in dorsal subcutaneous adipose tissue was significantly correlated with EOA concentration ([ρ] = 0.610, P = 0.001). The concentration of MOA in perirenal adipose tissue was significantly correlated with EOA concentration ([ρ] = 0.700, P = 0.001) and MNA concentration ([ρ] = 0.660, P = 0.001), and the correlation between EOA and MNA is weak ([ρ] = 0.570, P = 0.004). Therefore, Allicum mongolicum Regel and its extracts could reduce the deposition of 4-alkyl branched-chain fatty acids in dorsal subcutaneous, greater omental and perirenal adipose tissues thereby having the potential to improve lamb fat flavor.

Key words: Allium mongolicum Regel; extracts; adipose tissues; 4-alkyl branched-chain fatty acids; characteristic flavor