Sandra Hoedtke

Comparative evaluation of laboratory‐scale silages using standard glass jar silages or vacuum‐packed model silages

BACKGROUND The objective of this study was to compare the fermentation variables of laboratory-scale silages made in glass preserving jars (GLASS) and vacuum-packed plastic bags (Rostock model silages, ROMOS). Silages were prepared from perennial ryegrass (fresh and wilted, 151 g kg(-1) and 286 g kg(-1) dry matter (DM), respectively) and remoistened coarsely ground rye grain (650 g kg(-1) DM) either with or without the addition of a lactic acid bacteria inoculant (3×10(5) colony forming units (cfu) g(-1) , LAB). Quintuplicate silos were opened on days 2, 4, 8, 49 and 90. RESULTS Silage pH (P=0.073), acetic acid content (P=0.608) and ethanol content (P=0.223) were not influenced by the ensiling method. The contents of DM (P<0.001) and propionic acid (P=0.008) were affected by the ensiling method, but mean differences were only marginal. In ROMOS the concentration of lactic acid was increased (P=0.007) whereas butyric acid was produced less (P=0.001) when compared to GLASS. This suggested slightly better ensiling conditions for ROMOS. CONCLUSIONS ROMOS represents a reasonable alternative to glass jar silages and opens the possibility for further investigations, e.g. studying the impact of packing density as well as the quantitative and qualitative analysis of fermentation gases.

Effect of ensiling treatment on secondary compounds and amino acid profile of tropical forage legumes, and implications for their pig feeding potential

BACKGROUND Smallholders in the tropics depend on local protein supplements to balance pig diets. Thus, various tropical forage legumes are a potential feeding option. Ensiling allows converting forages into a ready-to-feed-out choice, but the lactic acid fermentation may influence various (anti)nutritional components. The purpose of this study was to evaluate the effects of sucrose (SU) and a tropical Lactobacillus plantarum strain (LAB) as ensiling treatments (control, SU, LAB, LAB + SU) on the potential nutrient availability of 10 forage legume species. RESULTS Ensiling commonly reduced antinutritional compounds such as tannins (by 49-84%) and trypsin inhibitory activity (by 74-78%), as well as oxalic acid (by 51-100%). An improved potential absorbability of protein and minerals for pigs is thus inferred. There was no major loss in total amino acids. In general, the species effect was stronger than the treatment effect. A clear effect of the treatments SU, LAB and LAB + SU over all 10 forage species was only observed for oxalic acid, single amino acids and trypsin inhibitory activity. CONCLUSION Ensiling is a viable option to enhance nutrient utilization of tropical forages for pigs. Species-specific treatment of forage legumes is recommended.