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Indicators of Feeding Value

Metabolisable energy (ME)(MJ/kg DM)

  • Metabolisable energy estimates the amount of energy silage will provide the ruminant for production as well as maintenance.

  • It is influenced more by the quality of grass at harvesting rather than efficiency of fermentation.

  • Good silage is expected to have a ME between 11 - 12 MJ/ kg DM.

Crude protein (CP) (% or g/kg DM)

  • In silages, CP is mainly in the form of degradable protein which will be used by rumen microbes.

  • High protein levels will indicate high level of nitrogen in the harvested grass, usually due to late fertiliser applications.

  • This will have negative effects on fermentation.

  • Good quality grass silage will have an average CP values ranging from 12 - 16%.

Neutral detergent fibre (NDF)(% or g/kg DM)

  • NDF measures the fibre or plant cell wall material in the silage.

  • Fibre in the silage influences the rate of digestion by the animal and thus the level of intake.

  • The higher the NDF, the lower the intake.

  • It is important to supply the animals with long fibre (more than 1 cm) in order to keep rumen functioning correctly.

  • There needs to be a balance between digestibility and sufficient fibre supply.

  • Good silage will have 45 - 50% NDF.

Potential intake

  • Most analysis will give a rough estimation of intake based on fermentation characteristics as well as feed value of sample.

Maize and fermented wholecrop silage

  • In general, maize and fermented wholecrop silage varies widely. Hence, it is important to analyse them before adding them to the cow's diet.

  • Good indicator for maize silage quality is starch content between 25 - 35%.

  • For fermented wholecrop, DM of 35 - 45% is important to have 15 - 25% starch.

  • If starch levels are too high for maize and fermented wholecrop, it is crucial to formulate the diets to prevent acidosis.

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