Document Type : Complete scientific research article
Authors
1
Assistant Professor, Department of Animal Science, Chaharmahal Bakhtiari Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Shahrekord, Iran
2
Assistant Professor, Department of Animal Science, Chaharmahal Bakhtiari Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Shahrekord, Iran,
3
Department of Animal Sciences, Faculty of Agriculture, Shahrekord University, Shahrekord, Iran
4
Research instructor, Department of Animal Science Research, Chaharmahal and Bakhtiari Agricultural and Natural Resources Research and Education Center, Agricultural Research Education and Extension Organization (AREEO), Shahrekord, Iran
5
Graduated master student, Department of animal science, Isfahan university of technology
6
Department of Animal Science, Faculty of Agriculture, University of Zanjan, Zanjan, Iran
7
Associate Professor, Animal Nutrition and Physiology Research Department, Animal Science Research Institute of Iran, Agricultural Research, Education and Extension Organization, Karaj, Iran
Abstract
Background and Objective: Corn silage is a major component of dairy cow diets, playing a crucial role in energy supply and overall animal productivity. Silage quality is influenced by various factors, including the silo structure and the methods used for covering and insulation. Selecting an appropriate covering method can reduce air infiltration, thereby minimizing dry matter (DM) loss and nutrient degradation. This study aimed to evaluate the effects of two covering methods—plastic sheet protected by green mesh (GS) and plastic sheet protected by tarpaulin (TS)—on the chemical quality, fermentation profile, and dry matter loss of corn silage stored in bunker and trench silos over a three-year period. Materials and Methods: A total of 12 silos (six bunker and six trench silos) were evaluated over three years (two silos per type annually from 2020 to 2022) at the Zagros Dairy and Meat Company farm in Shahr-e Kord, Iran. Two covering systems were tested. In the GS method, a plastic sheet was covered with a green mesh layer, while in the TS method; the plastic sheet was covered with a tarpaulin layer. Each silo was longitudinally divided to apply both covering systems. At silo filling, three mesh bags containing fresh chopped corn were buried at the center of the silage mass at 10-meter intervals (central samples; CeS) as positive controls. Additionally, 18 mesh bags (nine per covering method) were buried 40 cm below the top layer at three distances (100, 200, and 300 cm) from the sidewall (GS100, GS200, GS300 and TS100, TS200, TS300).
Results: In both silo types, the DM content at 300 cm from the sidewall was significantly higher in TS-covered silages than in GS-covered ones (P < 0.05). In trench silos, ash content at 100 cm from the sidewall was higher in GS than in TS (P = 0.01). In bunker silos, ash content was generally higher in GS-covered samples than in TS at all distances from the wall (P < 0.05). The DM loss at 100 cm from the sidewall was significantly greater in GS than TS (40.22% vs. 51.23%; P = 0.05). Silage pH was lower in TS compared to GS at 100 and 200 cm from the sidewall (P < 0.05). Ammonia concentration in CeS samples was similar to TS (0.20 vs. 0.19; P = 0.73), but significantly lower than in GS (0.20 vs. 0.28; P = 0.01). Lactic acid content was higher in TS than GS at 100 and 200 cm distances from the wall (P < 0.05). Covering type did not affect acetate, butyrate, propionate levels, or gas production parameters.Conclusion: The findings indicate that the tarpaulin covering system (TS) was more effective than the green mesh covering (GS) in reducing dry matter losses and improving the chemical quality of corn silage in both bunker and trench silos. Therefore, using TS as a covering method is recommended as a practical strategy to preserve the nutritional value and improve the storage quality of silage under similar conditions.
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