Effects of altitude and variety on nutrient levels and epiphytes of oats北大核心CSCD

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. © 2022 Editorial Office of Acta Prataculturae Sinica. All rights reserved.

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

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.