不同生育期和乳酸菌添加剂对甜高粱青贮发酵品质和营养价值的影响

Effect of growth stage and Lactobacillus additive on the nutritional value of forage sorghum silage

为研究不同生育期和乳酸菌添加剂对甜高粱青贮发酵品质及营养价值的影响,本试验采用袋装青贮的方法,以大力士和牛魔王两个甜高粱品种的拔节期和抽穗期植株全株为原料,分别分为两个组,对照组(CK)不添加乳酸菌,试验组(LAB)添加5×10~6 cfu/g乳酸菌。青贮60 d后开封,对青贮进行感官评定和营养品质分析。试验结果表明:(1)大力士和牛魔王两种甜高粱抽穗期全株青贮后的粗蛋白质含量较拔节期分别降低了31.59%和58.87%(P<0.05),可溶性碳水化合物含量分别升高了274.84%、580.99%(P<0.05)。抽穗期植株青贮后的中性洗涤纤维含量较拔节期的显著升高(P<0.05),粗灰分含量显著降低(P<0.05),相对饲喂价值和体外消化率相应降低(P<0.05)。同时,与拔节期青贮相比,抽穗期甜高粱青贮pH显著降低(P<0.05),乳酸、总酸含量显著升高10%左右(P<0.05)。(2)乳酸菌添加剂对两个甜高粱品种的各时期植株青贮的粗灰分、中性洗涤纤维、酸性洗涤纤维、粗蛋白质和可溶性碳水化合物含量的影响不显著(P>0.05);添加乳酸菌显著降低了青贮饲料的pH(P<0.05);添加乳酸菌处理后,大力士甜高粱品种的拔节期和抽穗期以及牛魔王品种的拔节期植株,其乳酸含量均较不添加处理升高了10%以上(P<0.05),其总酸含量也显著升高(P<0.05)。由此可见,在实际生产中大力士和牛魔王这两种高粱青贮时,选用抽穗期植株并添加乳酸菌会有较高的成功率和较好的发酵品质。

This study evaluated the effects of growth stage and Laetobacillus additive on fermentation quality and nutritional value of forage sorghum. Two varieties of forage sorghum （Hunnigreen and Niumowang.） were selected for this experiment. Chopped Artichoke were ensiled in polybag for 60 d with application of Lactic acid bacteria at 5×10^6 cfu/g fresh weight at two different growth stages （jointing period and heading stage）. The results showed as follows： （1）Compared with sorghum silage in jointing period,the crude protein （CP） content of the sorghum silage of Hunnigreen and Niumowang at the heading stage were reduced by 31.59% and 58.87% ,and Water-soluble carbohydrates （WSC） content were increased by 274.84% and 580.99%,respectively （P 〈 0.05）;The Ash content of sorghum silage in heading stage was lower than that in jointing period （P 〈 0.05） ;The in vitro dry matter digestion （IVDMD） and relative feeding value was lower in heading stage than in jointing period due to the higher Neutral detergent fiber （NDF） concentration. The pH of sorghum silage in heading stage was lower than in jointing period due to tire higher total acid content. （2）No significant effects were observed on Ash,NDF,Acid detergent fiber （ADF）,WSC and CP contents with the addition of Lactobaeillus.The pH of silage was lower when adding Laetobacillus additive than controln group. The contents of lactic acid and total acids were more than 10% higher with Lactobaeillus additive in the two growth stages of Hunnigreen and in jointing period of Niumowang compared with control group.In conclusion, the quality of sorghum silage in heading stage with the addition of Laetobacillus was higher than other treatments,when Hunnigreen and Niumowang were selected as silage material.