張航　敖長金　哈斯額爾敦　宋利文　張興夫

摘 要：該研究兩組不同粗飼料日糧在乳成分和乳腺中乳脂合成關(guān)鍵酶基因表達(dá)對泌乳奶山羊的影響。8只安裝有陰外動脈（EPA）和腹部皮下乳靜脈（SAV）血插管的經(jīng)產(chǎn)泌乳奶山羊（體重=45.6±2.5千克，泌乳期=90±12天）進(jìn)行2×2交叉試驗。動物飼喂粗飼料不同但精粗比均為40：60的日糧。兩組日糧分別是：（1）高質(zhì)量粗飼料組（HCA）包含30%羊草，20%玉米青貯，10%苜蓿和40%精料（CP：10.6%，NDF：50.4%andME：2.24Mcal/kg）。（2）低質(zhì)量粗飼料組（HCS）包含30%羊草，30%玉米秸稈和40%精料（CP：14.2%，NDF：39.7%and ME：2.39Mcal/kg）。每期21天。前18天為適應(yīng)期，后三天為樣品采集期。測定干物質(zhì)采食量，乳產(chǎn)量和乳成分。EPA和SAV的血液及乳樣采集用于測定脂肪酸組成。在每期的最后一天擠奶后進(jìn)行乳腺活體采樣分析乳脂合成相關(guān)基因ACACA，F(xiàn)ASN，LPL，SCD的表達(dá)。HCA組乳產(chǎn)量低于HCS組（496.5vs.515.5 g/d），而乳脂和乳蛋白含量顯著高于HCS組（分別是3.16%vs.2.96%；2.99%vs.2.89%）。乳脂肪酸組成只有C18：3兩組間產(chǎn)生差異顯著（0.27 vs.0.15 g/100 g），其余沒有脂肪酸沒有顯著差異。與HCS組相比，HCA組的SAV血漿中組脂肪酸濃度更高（0.62 vs.0.44 mg/mL）。乳腺攝取和脂肪酸萃取率上沒有顯著差異。與HCS組相比，HCA組FASN，ACACA，LPL和SCD的基因表達(dá)分別提高了20，18，39和50%。數(shù)據(jù)結(jié)果顯示高質(zhì)量的粗飼料日糧會提高奶山羊乳脂肪和蛋白含量以及提高乳脂合成相關(guān)基因的表達(dá)。

關(guān)鍵詞：泌乳奶山羊 乳腺 脂肪酸組成

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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