Harvest date can effect haylage hygienic quality
Wrapped forages for horses are commonly harvested in a relatively late botanical growth stage. Plant maturity influences not only the nutritional content but also the composition of the microflora living on the crop which can influence the conservation of the feed. This study that was performed in Sweden has examined how late harvest date affects the hygienic quality of the forage. The microbial and chemical composition in haylage during conservation and storage was compared between three first harvests from the same lay (mainly timothy and meadow fescue). The three harvests were taken in May (ear emergence of approximately 50% of the timothy), June (timothy seeds present in the ears and firmly attached) and August (timothy stems dry and wilted, no seeds left in the ears).
The harvest date was shown to have an impact on the hygienic quality of haylage, but to a limited extent. The later the harvest resulted in higher numbers of yeast, but lower numbers of Enterobacteria in the haylages (Tabell 1). The harvest date had no effect on number of clostridial spores. At the latest harvest the highest number of mould species was found before the grass was conserved, but after conservation there was no difference.
The harvest date had only a small impact on the haylage conservation. The wanted lactic acid bacteria were in highest numbers in the latest harvest, but the lactic acid concentration was generally low. The latest harvest in August had the lowest pH and the lowest concentration of ethanol. Since haylage has a high DM concentration and is not ensiled to a larger extent the differences were small and these variables are difficult to use as quality measurements.
In conclusion it is recommended to harvest within reasonable time, under Swedish conditions not later than beginning of July, to prevent negative effects on the hygienic quality of the forage.
Sara Muhonen, AgrD
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