Effects of intramuscular fat on meat quality and its regulation mechanism in Tan sheep

Abstract

Intramuscular fat (IMF) contributes importantly to various aspects of meat quality, and genetic regulation is an effective pathway to improve IMF deposition in sheep. In this study, we systematically explored the effect of IMF content on meat quality in Tan sheep and investigated the regulatory mechanism of flavor precursors metabolism and IMF deposition. The results revealed that IMF significantly affected meat color, total muscle fiber numbers, and muscle fiber types in Tan sheep. Widely-targeted metabolomic analysis showed that amino acids were the main differential flavor precursors between lambs with different IMF content. Importantly, the comparison of fatty acid profiles revealed that saturated fatty acids and monounsaturated fatty acids are beneficial for IMF deposition. Furthermore, integrated analysis between metabolome and transcriptome indicated that MME is a key gene resulting in the reduction of amino acids in lambs with high IMF content; and the joint analysis between fatty acid profiles and transcript profiles showed that ADIPOQ, FABP4, PLIN1, PPARGC1A, SLC2A1 accelerated IMF deposition through positive regulation of saturated fatty acids and monounsaturated fatty acids metabolism. These results revealed key changes in meat quality affected by IMF content and the corresponding genetic mechanism, which may provide a new insight for understanding the IMF differential deposition and for improving meat quality in Tan sheep.

Characterization of meat quality traits, fatty acids and volatile compounds in Hu and Tan sheep

“…There was a much larger variation within breeds, in IMF content. Variation in IMF within breeds affects meat quality characteristics such as shear force, texture, and color coordinates ( 1 , 22 ). Consumer sensory evaluation shows that lamb overall palatability increases markedly at around 3% IMF and peaks at 4% IMF ( 7 ).…”

“…It has been shown in pork from high-fat Duroc pigs that the IMF content linearly related to the Warner-Bratzler shear force ( 29 ). Zhang et al concluded that the IMF content positively correlated with color coordinates, namely, lightness, redness, yellowness, and the IMF variation within Tan sheep was ascribed to the difference in meat color ( 22 ). Inconsistent with these findings, the IMF content did not correlate with shear force or color coordinates in the present study.…”

“…In a previous report, we showed that fatty acid content and the lipid species profile in IMF varied between individual Hu sheep and this variation would influence concentrations of odor-active volatile compounds such as 1-octen-3-ol, 2-pentylfuran, as well as ( E , E )-2,4-decadienal in lamb meat ( 17 ). Additionally, Zhang et al ( 22 ) found that the IMF variation existed within Tan sheep and were associated with changes in amnio acids and fatty acid profiles. However, studies investigating differences in volatile compound profiles between Hu and Tan sheep have not meaningfully addressed the normal variation in IMF within each breed.…”

Effects of Chinese Yam Polysaccharide on Intramuscular Fat and Fatty Acid Composition in Breast and Thigh Muscles of Broilers

“…IMF contributes a key factor to meat quality [ 38 ]. This process is regulated by lipid-forming transcription factors such as the C/EBPα and PPARγ .…”

Composition of Fatty Acids and Localization of SREBP1 and ELOVL2 Genes in Cauda Epididymides of Hu Sheep with Different Fertility

“…Crude fat content in cauda epididymis of one hundred twenty rams was measured with the Soxhlet method as previously described [ 14 ]. Fatty acid content in the freeze-dried epididymal tissue (0.2 g) were extracted using chloroform/methanol extraction methods referred to O’Fallon et al [ 15 ].…”