Protein from alternative forages
Increasing on-farm plant protein production addresses emerging consumer expectations. Producing more high-protein forage reduces reliance on imported protein sources. This reduces the carbon footprint of the feed and reduces the impact of fluctuations in the price of imported feeds, e.g., soya from South America.
- Demonstration plots of alternative forages were grown and harvested in a cool wet temperate climate in Scotland to support discussion with farmers and industry stakeholders.
- Plots were sown in early May and harvested in early August.
- Red clover, a red clover/grass mixture, lupin and a lupin/barley mixture, forage pea, a forage pea/barley mixture and crimson clover were grown in plots (3 m x 10 m) and compared with a perennial ryegrass/white clover mixture.
- Initial measurements of dry matter (DM) showed that the pea/barley mixture produced 8 t/ha, the lupin/barley mixture provided 7.3 t/ha, compared to the ryegrass/white clover at 3.8 t/ha.
- The red clover mixture had the highest crude protein content (17.7%) compared to the grass/white clover (16.9%) and pea (16.1%).
- Metabolisable energy (ME) level was highest for the pea and the grass white clover (10.5 MJ/kg DM) while the red clover (10.3 g/kg DM), crimson clover (10.2 MJ/kg DM) and lupin (10.2 MJ/kg DM) were very similar.
Sub-samples of the fresh cut material were compressed into 3 litre plastic air-tight containers and ensiled for 5 weeks. These were then analysed for feed quality.
- The silage analysis showed the pea, pea/barley and the lupin/barley mixtures gave the greater DM contents (g/kg).
- The crude protein content of the lupin (19.2%) and red clover mixture (19.6%) were most similar to the ryegrass/white clover (20.8%).
- The protein content of the crimson and red clover, at 18%, were close to the lupin (19.2%) and red clover mixture (19.6%).
- The ME content of the lupin provided just over 10 MJ of ME/kg DM compared to the grass and white clover that provided 11 MJ of ME/kg DM.
- The barley in pea/barley and the lupin/barley mixtures increased the metabolisable energy of the silages.
Key practice points
- Alternative forage crops can be grown successfully in a cool wet temperate climate.
- Forage yield, protein content and metabolisable energy levels can be maintained with most of the alternative crops.
- The grass/clover and clover swards are harvested several times through the growing season.
- The legumes fix nitrogen that is available to subsequent crops. This has been estimated to be 150 to 250 kg N/ha for red clover compared to 80 to 100 kg N/ha for white clover.