Alternative Ruminant Feeds

Whilst the low food conversion efficiency of ruminants relative to monogastric production is frequently deemed a negative attribute, the ability of ruminants to produce high quality nutrition for humans; whilst themselves consuming a diet that is predominately inedible to humans is key to their value within the food-chain. Furthermore, if alternative forages, unsuitable for either human or monogastric consumption, are incorporated into ruminant rations alongside traditional grazing, the environmental impact of ruminant agriculture could decline drastically.

The caveat to this, however, is to ensure that the food by-products themselves are not part of an environmentally unsustainable model, a claim that could be made about the New Zealand dairy industry’s widespread adoption of palm kernel. With the widely publicised adverse environmental impacts of palm oil (including deforestation, biodiversity loss and GHG emissions) particularly in Indonesia and Malaysia, the Fonterra Co-operative Group introduced a voluntary Palm Kernel guideline in 2015. This recommended a maximum feeding of 3kgs/cow/day (NZ Herald, 2015).

Whilst Brewer’s grains, Trafford Gold (wheat moist feed) and sugar industry by-products are relatively commonly carbohydrate sources utilised in UK ruminant rations, Camelina sativa (an oilseed by product) is rare. This environmentally adaptable, low input crop capable of growing on less productive ground has a similar protein profile to soya, and offers the ability to increase the percentage of Omega 3 (trans-11 18:1 and cis-9, trans-11 18:2) fatty acids (the oft referred to ‘healthy fats’) in ruminant products, whilst also mitigating methane emissions 

Soya bean meal (Glycine max) has long been recognised as a nutrient dense feed source for ruminants, with the UK importing 3.1 million tonnes of soya bean equivalents in 2017. With only 5 % of soybean demand being produced in EU countries in 2017, this single product has been recognised as a significant factor in the loss of native South American forest, with the associated loss of biodiversity, carbon emissions and degradation of soils and water systems as already discussed. Whilst concerted efforts have been made via organisations such as the UK Roundtable on sustainable soya, to eliminate further deforestation as a consequence of soya production, a more secure sustainable future would be to grow crops within close proximity to where they will be consumed (thus reducing fossil fuel consumption due to transportation) which offer a comparable feed source to soya. This could include the cool season legume, peas (Pisum sativum L.); which provide a nutrient dense protein and carbohydrate source; faba beans (Vicia faba); which have a lower protein content but higher starch content when compared with soya, and have been cultivated in Europe for centuries and lupins (Lupinus sp.) which although varying with species, genotype and location, offer an energy and protein source to ruminants. The bitter taste of quinolizidine alkaloids within lupins greatly reduces their palatability to monogastrics, but ruminant’s do not seem to be perturbed by their presence.

Although currently cost prohibitive, microalgae offer an environmentally sustainable protein, carbohydrate, lipid, mineral and vitamin source to ruminants and Spirulina (Spirulina platensis) has been shown to increase microbial protein production whilst decreasing digesta retention time in the rumen.

A sustainable food future is likely to incorporate more alternative ruminant feeds to a greater or lesser extent. It is the role of  veterinary advisors to help encourage and enable their clients to understand the potential of these alternatives, and work towards a more carbon efficient ruminant feed chain.

Part 4 of the article series will be available next week; follow our social media channels, Twitter and LinkedIn, to ensure you don’t miss the release.