不同日粮模式对奶山羊乳成分和乳腺中脂肪合成相关基因表达的影响研究

张航　敖长金　哈斯额尔敦　宋利文　张兴夫

摘 要：该研究两组不同粗饲料日粮在乳成分和乳腺中乳脂合成关键酶基因表达对泌乳奶山羊的影响。8只安装有阴外动脉（EPA）和腹部皮下乳静脉（SAV）血插管的经产泌乳奶山羊（体重=45.6±2.5千克，泌乳期=90±12天）进行2×2交叉试验。动物饲喂粗饲料不同但精粗比均为40：60的日粮。两组日粮分别是：（1）高质量粗饲料组（HCA）包含30%羊草，20%玉米青贮，10%苜蓿和40%精料（CP：10.6%，NDF：50.4%andME：2.24Mcal/kg）。（2）低质量粗饲料组（HCS）包含30%羊草，30%玉米秸秆和40%精料（CP：14.2%，NDF：39.7%and ME：2.39Mcal/kg）。每期21天。前18天为适应期，后三天为样品采集期。测定干物质采食量，乳产量和乳成分。EPA和SAV的血液及乳样采集用于测定脂肪酸组成。在每期的最后一天挤奶后进行乳腺活体采样分析乳脂合成相关基因ACACA，FASN，LPL，SCD的表达。HCA组乳产量低于HCS组（496.5vs.515.5 g/d），而乳脂和乳蛋白含量显著高于HCS组（分别是3.16%vs.2.96%；2.99%vs.2.89%）。乳脂肪酸组成只有C18：3两组间产生差异显著（0.27 vs.0.15 g/100 g），其余没有脂肪酸没有显著差异。与HCS组相比，HCA组的SAV血浆中组脂肪酸浓度更高（0.62 vs.0.44 mg/mL）。乳腺摄取和脂肪酸萃取率上没有显著差异。与HCS组相比，HCA组FASN，ACACA，LPL和SCD的基因表达分别提高了20，18，39和50%。数据结果显示高质量的粗饲料日粮会提高奶山羊乳脂肪和蛋白含量以及提高乳脂合成相关基因的表达。

关键词：泌乳奶山羊 乳腺 脂肪酸组成

Abstract：The current study determined the effects of two diets with different forage profiles on milk composition and the expression of key genes associated with fatty acid synthesis in the mammary gland of lactating dairy goats. Eight multiparous lactating goats （BW = 45.6 ± 2.5 kg， days in milk = 90 ± 12 d） fitted with external pudic artery （EPA） and subskin abdominal vein （SAV） intubations were assigned to two treatments in a crossover design. Animals were fed diets with different roughage profiles with the concentrate-roughage ratio in the treatments being 40：60. Diets were：（1） a high quality roughage treatment （HCA） containing 30% Chinese wildrye hay， 20% corn silage， 10% alfalfa and 40% concentrate （CP： 10.6%， NDF： 50.4% and ME： 2.24 Mcal/kg）.（2） a low quality roughage treatment （HCS） containing 30% Chinese wildrye hay， 30% corn stover and 40% concentrate （CP： 14.2%， NDF： 39.7% and ME： 2.39 Mcal/kg）， on dry matter （DM） basis. Each period lasted 21 d. The first 18 d served as an adaptation period， followed by a 3 d sample collection period. Dry matter intake （DMI） and milk yield and milk composition were measured. Milk and blood samples from EPA and SAV were collected for fatty acid （FA） analysis. Mammary gland biopsies were performed after milking on the last day of each period and the tissues were analyzed for mRNA expression of acetyl-coenzyme A carboxylase- α （ACACA）， fatty acid synthesis （FASN）， stearoyl CoA desaturase （SCD）， and lipoprotein lipase （LPL）. Milk yield was lower in HCA than HCS （496.5 vs. 515.5 g/d）. Milk fat content was significantly higher in HCA than in HCS （3.16% vs. 2.96%）.Milk protein content was higher in HCA than in HCS （2.99% vs. 2.89%）. Milk fatty acid composition had no significant changed between HCA and HCS except for C18：3 （0.27 vs. 0.15 g/100g）， which was significantly different. Compared with HCS， HCA had an increase in subskin abdominal vein （SAV） plasma concentration of total fatty acids （0.62 vs. 0.44 mg/mL）. No differences were found on the mammary uptake and extraction rate of specific fatty acids between the two treatments. Compared to HCS， in HCA goats， the expression of FASN， ACACA， LPL and SCD was increased by 20， 18， 39 and 50%， respectively. The data demonstrated that diets with high quality roughage can increase milk fat and protein content and the gene expression related to fatty acid synthesis in dairy goats.

Key Words：Dairy goat；Mammary gland；Fatty acid composition

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