Comparison of Using Plastic or polyethylene Bags on the Qualitative and Quantitative Performance of Barley Silage

 Efficient forage preservation as silage requires minimizing losses during the ensiling, storage, and feed-out phases. The penetration of air into the silage is one of the important factors that stimulate aerobic bacteria, yeasts, and molds. This process severely impact silage quality and causes aerobic deterioration. Also, these conditions reduce the amount of dry matter and nutritional value of silage, and with the increase of pathogenic microorganisms and mycotoxins in silage, it will ultimately reduce the consumption of dry matter of silage in livestock. Polyethylene has been used for many years as a silage isolate and preservation. This study was to evaluate the chemical composition and microbial population of whole-crop barley silage preserved by different covers in laboratory conditions. 

Whole forage barley with dry matter of approximately 31% was harvested and cut into 30 to 50 mm long pieces. Then they were ensiled 1) in polyethylene laboratory tubes with screw lids with rubber rings, 2) in polyethylene bags and 3) in plastic bags, with an approximate weight of 10 kg in 4 repetitions, and kept in the closed environment of the laboratory for 60 days.

The results of the experiment showed the silages that were stored in polyethylene bags, compared to the silages that were ensiled in polyethylene tubes, the acidity index (3.79 vs. 3.53) and the yeast population (0.50 versus against 1.14 cfu/g of silage), were significantly increased (p=0.001), while in the silages that were ensiled in plastic bags, more changes occurred than in the silages that were ensiled in polyethylene tubes, and amount of dry matter (31.80% versus 31.24%; p=0.018), insoluble fibers in neutral detergent (61.89 percent of DM versus 59.8 percent of DM; p=0.014) and the mold population (1.95 versus 1.13 cfu/g of silage; p=0.046) also changed significantly. Aerobic stability in silages ensiled in polyethylene pipes was the highest (95 hours), while this index was significantly (P=0.001) less (62.5 hours) in silage covered with plastic bags than other silages. The recovery of dry matter after opening the ensiles and after 7 days of aerobic exposure also significantly (P=0.001) decreased rather than other silages (81.50 percent of DM versus 87.84 and 88.10 percent of DM).

According to the results of this experiment, the use of Polyethylene bags rather than plastic bags for ensiling small packages of forage can provide more favorable condition for the preservation of silage quality.