Effects Of Packing Density And Aerobic Deterioration On The Quality Of Whole Plant Corn Silage

The effects of packing density and aerobic deterioration on the quality of whole plant corn silage were studied.In experiment 1,the effect of packing density on silage quality was observed.In experiment 2,the change of silage quality at different sampling depths after opening was observed.In experiment 3,the effect of aerobic exposure on silage quality was observed to evaluate the effect of aerobic deterioration on silage quality.The results were as follows:Experiment 1:effect of packing density on silage qualityWhole plant corn silage was treated with four packing densities of 800,750,700 and 650kg/cm~3.The results showed that the contents of ether extract,lactic acid,starch,neutral detergent fiber and crude protein of whole plant corn silage increased with packing density（P<0.05）.The dry matter content tended to increase with packing density（P<0.1）.At 24 h after opening,there was significant difference in silage temperature rise between high density（800 kg/cm~3）and low density（650 kg/cm~3）treatments（P<0.05）,but no significant difference between other groups,indicating that the density of 700 kg/cm~3or above can make silage have good aerobic stability after opening.After opening,the relative abundance of Fusarium and Gibberella in low density silage（650 kg/cm~3）increased with aerobic exposure time,and the silage temperature increased by more than two degrees,losing aerobic stability.The relative abundance of harmful mold was low at high pressure density（800 kg/cm~3）,and the silage still maintained aerobic stability.Experiment two:the effect of fetch depth on silage qualityAfter the silage was opened,samples were collected at 0,15,30 and 45 cm of silage.The results showed that the contents of dry matter,neutral detergent fiber and lactic acid of silage increased with the depth of silage（P<0.05）.There was no significant difference in the content of dry matter in silage at 800 kg/m~3,but at 700 kg/m~3,24 h of aerobic exposure,the content of dry matter at 0 cm was significantly lower than that at other sampling depths（P<0.05）.At 650 kg/m~3,at 12 h of aerobic exposure,the dry matter content at 0 cm depth was significantly lower than that at other sampling depths（P<0.05）,and at 24 h of aerobic exposure,the dry matter content at 45 cm depth was significantly higher than that at other sampling depths（P<0.05）.At 650 kg/m~3and 12 h of aerobic exposure,there were significant differences in starch content at different sampling depths（P<0.05）.The relative abundance of Gibberella at 45 cm depth was significantly higher than that at 0 cm depth,and the silage quality decreased.Experiment 3:effect of aerobic exposure on silage qualityThe silage was opened and samples were collected after 0,12 and 24 h aerobic exposure to detect the changes in nutrient composition and microbial flora of silage under aerobic exposure.The results showed that the contents of dry matter and neutral detergent fiber in silage decreased with the increase of aerobic exposure time（P<0.05）,and the content of lactic acid in silage increased with sampling depth（P=0.054）.Silage packing density did not affect the lactic acid content,but the lactic acid content of silage decreased with aerobic exposure time（P<0.05）.The results showed that lactic acid content was not affected by aerobic exposure（12 h）.In conclusion,with the increase of whole plant corn silage packing density,the nutrient content of silage also increases,and silage density up to 700 kg/m3 can maintain good quality.When the depth reached 45 cm,the silage was less affected by aerobic exposure.Aerobic exposure（24 h）decreased the lactic acid content in silage,decreased the abundance of lactic acid bacteria,and increased the abundance of mold;Aerobic exposure（12 h）had no significant effect on feeding value.The effect of aerobic exposure on the feeding value of whole corn silage needs further study.Aerobic exposure（24 h）significantly increased the relative abundance of Fusarium and Cladosporium.