Investigations on ensilability of pea seeds (Pisum sativum) harvested before maturation

Autor: OTT, E.M.; GEFROM, A.
In:

Proceedings of the 12th International Symposium on Forage Conservation, Brno, Czech Republic, 2-5. April 2006

Seite: 189Jahr: 2006

Einordung:
Institut: Professur Ernährungsphysiologie und Tierernährung

Abstract:


INTRODUCTION
Patchy maturation in field peas grown for seed production is a known problem resulting in high post harvest costs for technical drying of the seeds. Developing a method for preserving peas harvested before maturation by lactic acid fermentation would have several advantages:
- supplying a low cost feed high in protein from local sources
- initiation of harvest independent on moisture content of pea seeds
- early clearing of pea fields for following crops
- reducing harvesting losses from cracked pods
- saving costs for technical drying of the material
Thus, the aim of the investigation was to verify ensilability of pea seeds harvested at approximately 65 % dry matter content.

MATERIAL AND METHODS
Bruised seeds of pea (Pisum sativum, variety “Lisa”) harvested with an experimental harvester at approximately 65 % dry matter (DM) were used for an ensiling study. Six hundred grams of this material were filled in plastic bags (3 per treatment) either pure, with molasses addition (2% of fresh matter [FM]) or inoculated with lactic acid bacteria (LAB; commercial product containing Lactobacillus plantarum, inoculation with 3x105 cfu/g FM) alone or in combination with molasses. Air was evacuated and bags were sealed using a vacuum sealer. Bags were stored at 20°C for 5, 15, 50 and 90 days. After incubation silage extracts were prepared (50 g silage in 200 ml aqua dest., stored for 15 h at 5°C) and pH-values were measured. Fermentation parameters in the silage extracts as mentioned in table 2 were determined by HPLC and GC. A T-test (Duncan) was performed to compare the results.
Nutrient contents in the harvested material were analysed according to the Weende feed analysis.

RESULTS AND DISCUSSION
The nutrient content of the harvested material is shown in table 1. Regarding the high content of crude protein in peas in comparison with the low content of easily fermentable carbohydrates known from the literature (Bastianelli et al., 1998) ensilability was expected to be low. However, organoleptic evaluation of the resulting silages revealed good quality in all variants tested. This could be approved by analytical determination of the fermentation parameters: The pH was below the DM-dependent critical value in all silages. Butyric acid did not occur in any of the samples and contents of acetic and propionic acid as well as ethanol were low.
Regarding the additives molasses had no effect on fermentation except for slightly increasing the amount of lactic and acetic acid produced. On the contrary, addition of lactic acid bacteria resulted in a faster and deeper decrease of pH, significantly higher amounts of lactic acid and reduced fermentation losses. Providing molasses in combination with LAB had no further positive impact on fermentation quality suggesting that enough fermentable carbohydrates are supplied by the pea seeds.

CONCLUSIONS
1. Preliminary results prove good ensilability of pea seeds harvested at approximately 65 % DM without and with addition of silage additives.
2. Addition of lactic acid bacteria accelerates pH-decrease and improves fermentation parameters of resulting silages.
3. As addition of molasses has no effect on silage quality, providing additional sources of easily fermentable carbohydrates is not necessary for the preparation of pea seed silage.
The preliminary results suggest ensiling as a suitable method for conserving pea seeds harvested with a moisture content not adequate for dry storage.

SUMMARY
Patchy maturation in peas results in high post harvest costs for technical drying of the seeds. In order to verify possibilities of preserving peas with high moisture content by lactic acid fermentation, model silages from pea seeds harvested at 65 % DM content were prepared without and with addition of molasses and/or lactic acid bacteria and incubated for 5 to 90 days at 20°C. Organoleptic evaluation showed good quality of all silages, even in the variants prepared without silage additives. Addition of lactic acid bacteria improved fermentation. Molasses addition had no effect on silage quality. Thus, ensiling seems to be a suitable method for conservation of pea seeds harvested before maturation.

REFERENCES
Bastianelli, D.; Grosjean, F.; Peyronnet, C.; Duparque, M. and Regnier, J.M. (1998): Feeding value of pea (Pisum sativum, L). 1. Chemical composition of different categories of pea. Animal Science 67 (3), 609-619

Table 1: Nutrient contents of pea seeds harvested before maturation
...

Table 2: Fermentation parameters of silages from pea seeds depending on additives and time of storage (means: n=3, ± s)
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The project is funded by BMELV (Bundesanstalt für Landwirtschaft und Ernährung, BLE).

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