Improving feed efficiency is a viable route to reducing emissions from ruminants and supporting the sustainability of livestock production. Forage plays an important part here; its unique ‘upcycling’ role allows for the use of resources that would not be consumed otherwise, thus reducing the competition for other energy sources, such as corn, wheat and barley.
Global Services Manager
AB Vista
Ruminant producers face a complex balancing act of meeting the global demand for animal protein products in a sustainable and profitable way. Over the next 25 years, around two times the amount of milk and meat that is currently produced will be necessary to meet human requirements. With this comes the challenge of reducing the environmental impact of livestock production.
Livestock production is considered to generate significant amounts of greenhouse gases, particularly carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O); 40% of carbon emissions associated with livestock are due to enteric methane emissions, with ruminants the main contributors.
As the carbon pledge for net zero by 2050 gets stronger, the scrutiny on ruminant production is intensified. While the industry is encouraged to develop solutions to lower enteric methane emissions, improved feed efficiency and overall dietary manipulation present a sustainable method of mitigation.
A good place to start is by making the best use of forage. The selection, utilisation and supplementation of forages allows ruminants to transform non-human edible energy sources (which would otherwise not be consumed) into energy, which can, in turn, produce products for human consumption, such as meat and dairy.
DETERMINING FORAGE QUALITY
Forage is critical to promote rumen function and health in cattle; plant cell wall digestibility is often lower than 50%. With a proper characterisation and valorisation of the nutrients and digestible energy contained in forage, improvements can be made to forage utilisation efficiency and ration formulation, which contributes to better feed efficiency and cost.
Portable near infrared (NIR) instruments are now used on farms to determine forage quality – with NIR analysis enabling nutritionists to quickly and accurately adjust formulation. As an example, AB Vista compared the quality of grass silage from the UK in 2021 and 2022. Figure 1 shows the lower metabolisable energy (ME) content as a percentage of dry matter (DM) and Figure 2 shows neutral detergent fibre (NDF) content as a percentage of DM – which were promptly noticed upon harvest with the NIR. This coincided with a dry season in 2022, which negatively impacted the ME content of grass silage, while the NDF level was higher as compared to 2021.
EXTRACTING MORE ENERGY
A crude fermentation extract from Trichoderma reesei (VistaPre-T, AB Vista) can be used in total mixed rations to get more energy from forage by forming pits and roughening the fibre surface, hence speeding up the microbial attachment and colonisation, assuring reduced lag time, and greater fibre digestion. A study demonstrated an increase in NDF and acid detergent fibre (ADF) digestibility in an in vitro rumen fermentation model. This was associated with a faster attachment and colonisation of fibre-degrading microbes in the rumen, then resulting in a greater utilisation of both the hemicellulose and cellulose.
METHODS TO EVALUATE RATION QUALITY
Fecal starch analysis is a method used to evaluate total tract starch digestibility (TTSD). When fecal starch content is lower than 3%, the value is associated with good TTSD. Portable NIR can now be used to measure the fecal starch content in fresh feces, on farms. This enables a quick evaluation of the quality of the ration, and formulation adjustment.
Beyond starch, fecal NDF level can be used to evaluate the efficiency of energy utilisation. As an example, fresh fecal samples were collected in eight groups of cows from four different dairy farms in the UK. The NIR predictions indicated an optimal fecal starch level below 3% in all groups of cows, whereas fecal NDF levels were high relative to dietary NDF. After VistaPre-T application, the NIR predictions indicated an 8% average reduction in fecal NDF, which demonstrated the efficiency of VistaPre-T in increasing fibre utilisation.
FORMULATION STRATEGIES
VistaPre-T can be easily formulated into the total ration to save cost. In dairy diets, it can generate approximately 10 MJ of additional energy (coming from 0.8 MJ energy uplift per kg of forage DM, given a cow consumes 12.5kg of forage DM per day on average). This extra energy is equivalent to 300g of protected fat per cow/day.
Figure 4. Average milk yield increase with VistaPre-T per lactation stage.
A study was performed in the UK involving 147 Holstein-Friesian dairy cows. After assigning the energy uplift value to VistaPre-T, the least-cost reformulation allowed a reduction in the ground maize, molasses and protected fat usage, while adding more grass silage. In addition to a 9% increase in milk yield with no effect on milk composition, VistaPre-T usage resulted in a 15% reduction in the carbon footprint of fat and protein corrected milk.
VistaPre-T can also be applied on the top of the ration to enable extra energy supply and improved performance. In a separate study, 350 milking cows maintained as one group were fed a maize and grass silage-based ration, with VistaPre-T applied on the top of the ration. The average milk yield (kg/cow/day) in the pre-trial period and after feeding VistaPre-T was recorded and indicated increased milk yield in every stage of lactation.
CONCLUSION
Improving feed efficiency is a viable route to reducing emissions from ruminants and supporting the sustainability of livestock production. Forage plays an important part here; its unique “upcycling” role allows for the use of resources that would not be consumed otherwise, thus reducing the competition for other energy sources, such as corn, wheat and barley. Additional supplementation, such as VistaPre-T, should be considered to enable greater fibre utilisation and increase home-grown forage usage – boosting efficiency and reducing emissions, for more environmentally friendly and profitable production.
About Virginie Blanvillain Rivera
Born and raised in France, Virginie Blanvillain Rivera lives in Quebec, Canada. She developed an international experience in the animal feed industry by working in research and development, technology transfer, nutrition and quality assurance. Over the past years, she has been actively involved in the development and implementation of innovative tools and services for nutritionists, producers, integrators and feed mills. She provides training and technical support to the AB Vista network worldwide, while leading the development and continuous improvement of NIR, carbon emissions and lab services.
