Document Type : Research Paper
Authors
1 Department of Animal and Poultry Science, College of Agricultural Technology, University of Tehran,, Tehran, Iran
2 Department of Animal and Poultry Science,, College of Agricultural Technology (Aburaihan), University of Tehran, Tehran, Iran
3 Department of Animal and Poultry Science, College of Agricultural Technology, University of Tehran, Tehran, Iran,
Abstract
Objective: Forage harvesting at an appropriate stage of maturity is a key factor determining the productivity and nutritional quality of ensiled forages, improving silage fermentation, and reducing its loss. Likewise, forage intercropping strategies targeting the advantage of the additive characteristics of different plant species improve the quality of the forage product. This study was carried out to evaluate the effect of forage maturity at harvest and intercropping on ensiling characteristics, effluent production, and in vitro (laboratory) digestibility in three small-grain forages (barley, triticale and oat).
Method: In this study, whole plant barley was harvested at early heading and hard dough stage of growth; whole plant triticale was harvested at the tillering and soft dough stage, and the oats forage were harvested at the tillering and stem elongation stages. The intercropping treatments consisted of 53% barley, 33% triticale, and 14% oat, and were harvested at the above-mentioned stages. The experimental design was a 2×4 factorial arrangement in a completely randomized design with eight treatments and three replicates.
Results: The results showed that with the progress of growth stages, dry matter, organic matter, and crude protein yields increased in triticale, oat, and mixed-crop treatments. The highest dry matter (32.1%) was observed in the mixed crop in the second harvest stage, and the lowest (13.5%) was observed in the first stage in oats (p<0.001). The highest crude protein (19.3 %) was obtained from oats in the first harvest, and the lowest (10.8%) from barley in the second harvest stage (p<0.001). The lowest NDF content was observed in oats (49.5%) and the highest in barley (58.2%) (p<0.001). The interaction effect of forage type and harvest time on dry matter, crude protein, and ADF contents was significant, while other chemical components such as crude ash, lignin, acid-, and neutral-detergent insoluble nitrogen, crude fat, and water soluble carbohydrates (WSC) were similar in both harvest stages. Overall, harvesting at a later stage increased lignin and decreased crude protein, WSC, and NDF. Interestingly, the intercropping of oats with the other crops increased crude protein and improved digestibility in vitro, while decreasing silage NDF content. The silages of the second harvest crops had no effluent production. They also had an appropriate pH (close to 4.2) and an ammonia nitrogen level of less than 10% total nitrogen, demonstrating improved fermentation in silages with higher dry matter content.
Conclusions: The results suggested the second harvesting stage (hard dough in barley, soft dough in triticale, and stem elongation in oats) as the suitable times for harvesting small grain forages in the current study, whether ensiled as a sole forage or intercropped, because they increased the yield of organic matter, CP, energy, and digestible dry matter per hectare. Considering the greater yield performance of triticale compared to barley, it is suggested to incorporate triticale as the main crop in intercropping systems.
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