复合秸秆颗粒替代玉米青贮饲料对肉牛肌肉脂肪沉积和脂肪酸的影响

Effect of replacing corn silage with compound strawpellets on muscle fat deposition and fattyacids in beef cattle

摘要:

选择20头18月龄、体重相近的西门塔尔杂种公牛(西门塔尔牛♂×本地黄牛♀),随机分为4组,日粮营养水平一致,试验组1、2和3日粮粗饲料分别以复合秸秆颗粒(50%玉米秸秆+50%苜蓿干草)替代20%、50%和80%的全株玉米青贮,对照组粗饲料全部为全株玉米青贮饲料;育肥120 d屠宰后取背最长肌测定肌内脂肪(IMF)和脂肪酸含量,以研究日粮结构及粗饲料组成对肉牛肌肉脂肪沉积、脂肪酸含量的影响。结果表明:1)复合秸秆颗粒替代部分全株玉米青贮饲料,能显著提高肉牛肌肉中IMF含量(P＜0.05);2)添加不同比例复合秸秆颗粒后,肉牛的肌肉饱和脂肪酸(SFA)含量有下降趋势,但各组间无显著差异;硬脂酸(C18:0)和棕榈酸(C16:0)在各组肉牛中含量较高,分别为28.38%~32.18%和9.87%~11.48%;3)复合秸秆颗粒可提高肌肉不饱和脂肪酸(UFA)及单不饱和脂肪酸(MUFA)的含量及降低多不饱和脂肪酸(PUFA)、n-3 PUFAs含量,但各组间无显著差异;n-6 PUFAs相对含量为7.23%~10.17%,对照组显著高于试验组1和2(P＜0.05);4)粗饲料组成影响肉牛部分功能性UFA,其中试验组1的γ-亚麻酸(C18:3n6)显著低于对照组和试验组3(P＜0.05),而试验组2的花生四烯酸(C20:4n6)显著低于其他组(P＜0.05)。综上所述,复合秸秆颗粒替代不同比例全株玉米青贮饲料饲喂肉牛,能提高背最长肌IMF含量,不影响其脂肪酸组成和营养价值;复合秸秆颗粒可广泛应用于肉牛生产。

Abstract:

This experiment was carried out to investigate the effect of dietary composition on fat deposition and fatty acid content in muscle tissue of beef cattle.Twenty crossbred (Simmental ♂× Local Yellow Cattle ♀) bulls,average 18 months of age and similar body weight,were randomly divided into 4 treatments.The bulls from control were fed the diet with whole-plant corn silage,while the bulls from treatments 1,2 and 3 were fed the diet in which whole-plant corn silage were replaced by 20%,50% and 80% compound straw pellets (50% corn straw+50% alfalfa hay),respectively.The fatten trail was lasted for 120 days,then the bulls were slaughtered and the longissimus dorsi muscle were collected to measure the contents of intramuscular fat (IMF) and fatty acids.The results showed that: 1) The content of IMF was significantly increased when whole corn silage was partly replaced by compound straw pellets (P＜0.05);2) There was a tendency that the content of saturated fatty acid (SFA) decreased when the whole corn silage was replaced by compound straw pellets (P＞0.05).In all treatments,the percentages of stearic acid (C18:0) and palmitic acid (C16:0) were ranged from 28.38% to 32.18% and 9.87% to 11.48% in SFA respectively;3) There was a tendency that the compound straw pellets increased the contents of unsaturated fatty acid (UFA) and monounsaturated fatty acid (MUFA),and decreased the contents of polyunsaturated fatty acid (PUFA) and n-3 PUFAs,but no significant difference among treatments (P＞0.05).The relative content of n-6 PUFAs was ranged from 7.23% to 10.17% in all treatments,and it was significantly higher in the control group than treatment 1 and 2 (P＜0.05);4) The components of roughage affected the part of functional fatty acids in the longissimus dorsi muscle,and the content of gamma linolenic acid (C18:3n6) in treatment 1 was significantly lower than control and treatment 3 (P ＜ 0.05),while the content of arachidonic acid (C20:4n6) in treatment 2 was significantly lower than other groups (P＜0.05).In summary,the compound straw pellets could replace part of other roughage in diets and improve IMF content,and no negative effect on the contents of fatty acids in longissimus dorsi muscle.This indicates that the compound straw pellets can be widely used in beef cattle production.