基于主成分分析和隶属函数法评价乳酸菌添加剂和收获时期对天然牧草青贮质量的影响

Effects of Lactic Acid Bacteria Additives and Harvest Periods on Quality of Natural Forage Silage Based on Principal Component Analysis and Membership Function Analysis

本试验探究了3种乳酸菌(LAB)添加剂和3个收获时期对天然牧草青贮质量的影响。试验分别在供试牧草中添加3种LAB添加剂,分别是中国农业大学饲草加工团队筛选出的植物乳杆菌(LP)和布氏乳杆菌(LB)以及商用LAB添加剂(SY),以未添加处理为对照(CK),于2021年7月12日(早期)、7月22日(中期)和8月1日(晚期)3个时期调制天然牧草青贮饲料,共计12个组,每组3个重复,发酵75 d后测定天然牧草青贮的发酵品质和营养品质。结果表明:LAB添加剂和收获时期对丁酸含量(P<0.01)、氨态氮/总氮(P<0.01)、干物质(P<0.05)和粗脂肪(P<0.05)含量具有显著的交互作用。与CK组相比,LAB组的pH、丁酸含量、氨态氮/总氮、中性洗涤纤维和酸性洗涤纤维含量显著降低(P<0.05),乳酸、乙酸和干物质含量显著增加(P<0.05)。随着收获时期的延后,天然牧草青贮饲料的粗蛋白质和半纤维素含量显著降低(P<0.05),酸性洗涤纤维和酸性洗涤木质素含量显著升高(P<0.05)。中期收获调制的青贮饲料的pH、丁酸含量、氨态氮/总氮和中性洗涤纤维含量显著高于早期收获和晚期收获(P<0.05)。根据主成分分析和隶属函数分析得出,早期收获时青贮饲料得分为LP组=SY组>LB组>CK组,中期收获时青贮饲料得分为LP组=LB组>SY组>CK组,晚期收获时青贮饲料得分为LB组>LP组=SY组>CK组。综上所述,收获时期会影响LAB添加剂对天然牧草青贮饲料质量的改善效果,早期和中期收获时添加LP的天然牧草青贮饲料质量较好,晚期收获时添加LB的天然牧草青贮饲料质量较好。

This experiment aimed at exploring the effects of three kinds of lactic acid bacteria(LAB)additives and three harvest periods on quality of natural forage silage.Three kinds of LAB addictive,Lactobacillus plan⁃tarum(LP)and L.buchneri(LB)cultivated by forage processing team of China Agricultural University and commercial LAB additive(SY),was inoculated to the natural forage silage,respectively,setting untreated as a control(CK).The natural forage silage was prepared on 12 July(early period),22 July(middle period)and 1 August(late period),2021.Thus there were 12 groups totally and each with 3 replicates.After 75 days of fermentation,fermentation quality and nutritional quality were tested.The results showed that the LAB addi⁃tive and harvest period had significant interaction on butyric acid content(P<0.01)and ammonia nitrogen/to⁃tal nitrogen(P<0.01),the contents of dry matter and ether extract(P<0.05).Compared with CK group,pH,contents of butyric acid,neutral detergent fiber and acid detergent fiber as well as ammonia nitrogen/total nitrogen in LAB groups were significantly reduced(P<0.05),while a significant increase of the contents of lactic acid,acetic acid and dry matter can be seen at the same time(P<0.05).As the harvest period passed,the contents of crude protein and hemi⁃cellulose in natural forage silage decreased evidently(P<0.05),while contents of acid detergent fiber and acid detergent lignin increased obviously(P<0.05).The pH,butyric acid content,ammonia nitrogen/total nitrogen and neutral detergent fiber content of silage in middle period were re⁃markably higher than those in early and late periods(P<0.05).According to principal component analysis and membership function analysis,the ranking of silage from early period was LP group=SY group>LB group>CK group,from middle period was LP group=LB group>SY group>CK group,and from late period was LB group>LP group=SY group>CK group.In conclusion,the harvest period can affect the improvement effects of LAB additives on the quality of natural forage silage.The addition effect of LP is better than other additives both in the early and middle periods,otherwise the addition effect of LB is best in the late period.