Co-Innovation Center of Beef Cattle Science and Industry Technology, Yanbian University, Yanji, Jilin, P.R. China.
Department of Animal Science, Chungbuk National University, Cheongju, Chungbuk, Republic of Korea.
J Anim Sci. 2018 Jun 29;96(7):2698-2709. doi: 10.1093/jas/sky161.
We hypothesized that gene expression and fatty acid composition would differ among different muscle depots and over time on a grain-based finishing diet. Additionally, we hypothesized that the concentration of SFA would decrease and the concentration of MUFA would increase proportionately with increases in percent intramuscular lipid (%IML). Ten Yanbian Yellow cattle steers (approximately 8 mo of age) were fed a corn-based diet in which the proportion of corn in the ration was increased at 4-mo intervals. Muscle samples were taken by biopsy from the chuck (trapezius), loin (longissimus dorsi), and round (biceps femoris) muscles at 12, 16, 20, 24, and 28 mo of age. The %IML increased from 12 to 28 mo of age, especially between 24 and 28 mo of age, with loin > round > chuck (age × muscle interaction P < 0.001). The percentage (g/100 g total fatty acids) of oleic acid (18:1n-9), linoleic acid (18:2n-6), and α-linolenic acid (18:3n-3), and the MUFA:SFA ratio increased with age, whereas palmitic (16:0) and stearic acid (18:0) decreased with age in all muscles (age effect P < 0.001). The expression of sterol regulatory element binding protein (SREBP1), adipose tissue fatty acid- binding protein (FABP4), stearoyl-CoA desaturase (SCD), acetyl-CoA carboxylase (ACC1), and lipoprotein lipase (LPL) increased, whereas the expression of peroxisome proliferator-activated receptor gamma (PPARγ) and fatty acid synthase (FASN) decreased with age. Expression of PPARγ, FABP4, SREBP1, SCD, FASN, ACC1, and LPL was greater in the loin than in the chuck or round (age × muscle interaction P < 0.001), although the MUFA:SFA ratio was greater in the chuck than in the loin or round (muscle effect P < 0.001). In conclusion, adipogenic gene expression was greater in the loin than in the chuck or round muscles, consistent with the greater %IML of the loin. However, the greater SCD gene expression in the loin did not result in a greater amount of MUFA in the loin, relative to the chuck and round.
我们假设，在基于谷物的育肥日粮上，不同的肌肉部位和随时间的推移，基因表达和脂肪酸组成会有所不同。此外，我们还假设，随着肌肉内脂质（%IML）百分比的增加，饱和脂肪酸（SFA）的浓度会降低，而单不饱和脂肪酸（MUFA）的浓度会相应增加。10 头延边黄牛公牛（约 8 月龄）在以玉米为基础的日粮中饲养，日粮中玉米的比例每 4 个月增加一次。在 12、16、20、24 和 28 月龄时，通过活检从肩（斜方肌）、腰（最长肌）和臀（股二头肌）肌肉中采集肌肉样本。%IML 从 12 月龄增加到 28 月龄，尤其是在 24 月龄到 28 月龄之间，腰>臀>肩（年龄×肌肉互作 P < 0.001）。油酸（18:1n-9）、亚油酸（18:2n-6）和α-亚麻酸（18:3n-3）的百分比（每 100 克总脂肪酸中的克数）以及 MUFA:SFA 比值随年龄增长而增加，而棕榈酸（16:0）和硬脂酸（18:0）在所有肌肉中随年龄增长而减少（年龄效应 P < 0.001）。固醇调节元件结合蛋白（SREBP1）、脂肪组织脂肪酸结合蛋白（FABP4）、硬脂酰辅酶 A 去饱和酶（SCD）、乙酰辅酶 A 羧化酶（ACC1）和脂蛋白脂肪酶（LPL）的表达增加，而过氧化物酶体增殖物激活受体γ（PPARγ）和脂肪酸合酶（FASN）的表达随年龄增长而减少。PPARγ、FABP4、SREBP1、SCD、FASN、ACC1 和 LPL 的表达在腰比肩或臀高（年龄×肌肉互作 P < 0.001），尽管 MUFA:SFA 比值在肩比腰或臀高（肌肉效应 P < 0.001）。总之，与肩或臀相比，腰肌肉中的脂肪生成基因表达更高，这与腰肌肉中更大的%IML 一致。然而，腰肌肉中 SCD 基因表达的增加并没有导致腰肌肉中 MUFA 的含量相对于肩和臀增加。
