海拔和品种对燕麦营养品质及表面附着微生物的影响

Effects of altitude and variety on nutrient levels and epiphytes of oats

燕麦是青藏高原及其周边地区主要的一年生饲草,鉴于秋季收获时雨水较多,燕麦更适宜制作青贮而非干草。但在这类地区海拔高度和品种对燕麦青贮前的产量、品质和表面附着微生物的影响尚不明确。为此,本试验用4个燕麦品种(陇燕3号、陇燕5号、白燕2号、坝莜3号)在湟中(2295 m)、天祝(2797 m)、山丹(2860 m)、合作(2957 m)、海晏(3052 m)、玛曲(3474 m)、玛沁(3765 m)和称多(4217 m)共8个不同海拔地区进行了田间试验,对燕麦灌浆期鲜草产量、干物质(DM)、水溶性碳水化合物(WSC)、粗蛋白(CP)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)和乳酸菌(LAB)、霉菌、酵母菌、好气性细菌等进行了测定和分析。结果表明:海拔、品种及二者互作对灌浆期鲜草产量、营养成分含量及附着微生物数量影响非常显著。鲜草产量、WSC、NDF含量及附着LAB数量随海拔上升总体呈增加趋势(P<0.05),在称多试验点比在湟中分别平均高出284.00%、15.49%、10.81%和11.60%;而DM、CP含量、酵母菌和霉菌数量随海拔上升明显下降(P<0.001),在称多比湟中分别降低了15.67%、36.27%、23.53%和7.75%。4个品种中,陇燕5号在称多试验点的鲜草产量、WSC和NDF含量最高,分别为75605 kg·hm^(-2)、201.4 g·kg^(-1)DM和604.2 g·kg^(-1)DM,其次为陇燕3号;白燕2号在湟中试验点CP含量(119.7 g·kg^(-1)DM)和霉菌数量(4.12 lg cfu·g^(-1)FM)最高,坝莜3号在玛沁和称多试验点的LAB和酵母菌数量最高。总体而言,陇燕3号和陇燕5号在海拔3000 m以上地区表现更优,3000 m以下地区4个品种均可用于青贮生产。

Oat crops are a major animal feed source in the Qinghai-Tibetan plateau and nearby areas.Typically,the crops are used for making silage rather than hay because of frequent rain at harvest in autumn.However,there is little data on how the yield,forage quality and levels of epiphytes that may affect silage quality of different oat varieties are affected by altitude.Therefore,four oat varieties(Longyan No.3,Longyan No.5,Baiyan No.2 and Bayou No.3)were planted in 8 localities forming an altitude gradient:Huangzhong(2295 m),Tianzhu(2797 m),Shandan(2860 m),Hezuo(2957 m),Haiyan(3052 m),Maqu(3474 m),Maqin(3765 m)and Chengduo(4217 m).Measurements included crop yield and dry matter(DM),water soluble carbohydrate(WSC),crude protein(CP),neutral detergent fiber(NDF)and acid detergent fiber(ADF)contents,and counts of lactic acid bacteria(LAB),molds,yeasts and aerobic bacteria.It was found that there were significant altitude and variety effects on fresh yield,nutritional quality and microbial epiphyte counts.With increase in altitude,fresh yield,WSC,NDF and LAB counts increased(P<0.05),as much as 284.00%,15.49%,10.81% and 11.60% increment were observed at Chengduo site than that at Huangzhong,respectively;meanwhile DM,CP and yeast and mold counts were reduced by 15.67%,36.27%,23.53% and 7.75% at Chengduo compared with Huangzhong site,respectively.Among the four tested varieties,Longyan No.5 had the highest fresh yield(75605 kg·ha^(−1)),WSC(201.4 g·kg^(-1) DM)and NDF(604.2 g·kg^(-1) DM)at the Chengduo site,followed by Longyan No.3.The highest CP(119.7 g·kg^(-1) DM)and mold counts(4.12 lg cfu·g^(-1) FM)were observed in Baiyan No.2 at the Huangzhong site.Bayou No.3 produced the highest LAB and yeast counts at Maqin and Chengduo sites.In general,Longyan No.3 and Longyan No.5 gave better performance at sites above 3000 m altitude;for sites below 3000 m,the four tested varieties were all found to be suitable for silage production.