Increasing sward and animal performance with red clover
High artificial nitrogen costs have sparked a renewed interest in red clover silage. When grown in conjunction with a companion grass, these crops have the potential to provide a winter feed to livestock production systems from zero chemical nitrogen input.
Dr. Nicky Byrne, Research Officer in Teagasc Grange, joined a recent Let’s Talk Organics Webinar, where he discussed the agronomy and feeding value of red clover silage.
“Red clover is getting an awful lot of interest and it’s very just,” he explained, due to its ability to support increased levels of dry matter production and animal productivity.
Presenting work carried out in Teagasc Grange, which is examining the role red clover silage swards play in terms of the economic and environmental sustainability of dairy-beef systems, Dr. Byrne highlighted both the positives and negatives of red clover production.
“Red clover has massive potential to offer to every kind of system – organic systems of high and low intensity and conventional systems of high and low intensity. The pro of red clover is its massive ability to fix very high levels of biological nitrogen."
Along with the capacity to ‘fix’ >200kg of N/ha, yields in excess of 15t DM/ha are obtainable under zero nitrogen systems. The resulting silage produced from red clover also has the potential to provide additional levels of animal performance, derived from the extra intake potential associated from the feed.
However, red clover does have limitations, Dr. Byrne explained, noting that it is unsuitable for intensive grazing due to the risk of physical damage to the plant by grazing animals. Persistency can be an issue, with commercial farms observing a lifespan of 3-4 years, and the low dry matter nature of the crop can cause challenges when ensiling.
Swards in Teagasc Grange are managed under a multi-cut system, with three cuts taken throughout the year. The first cut is taken in mid-May, with the final harvest completed in September. An infrequent cutting policy is employed, with a space of 6-8 weeks left between cuts. This enables red clover to establish a full canopy, thus intercepting as much sun light as possible.
“If we allow enough time, we fully replenish those carbohydrate reserves and we are ready to cut the plant again. And that carbohydrate reserve that we have replenished will refuel our second and third cut and that’s really important to extend the lifespan of our red clover crops. We might think that it is ready to cut after a month, but we might be extra severe on the plant if we are going in a depleting it that little bit too frequently,” he commented.
Last year, red clover silage swards in Teagasc Grange yielded 19,247kg DM/ha, with 17,772kg DM/ha of this harvested as silage; the remainder was from grazing at the back end of the year to set up the sward for production in 2023. This level of performance was achieved from an organic nitrogen input of 54kg/ha, obtained from cattle slurry, 51kg/ha of phosphorous and 307kg/ha of potassium. No artificial or chemical nitrogen was used. When compared to a perennial ryegrass sward, managed under a two-cut system receiving 208kg/ha of chemical nitrogen, the yield benefit was 3,616kg DM/ha in favour of the red clover sward.
“If we do apply nitrogen,” Dr. Byrne said, “we will reduce the clover content and when we reduce our clover content, we reduce the overall amount of nitrogen that is going to be fixed by the plant itself. That can result in reduced dry matter production and reduced persistence of the red clover plant.”
Feeding value and animal performance
One of the big drivers of red clover is its ability to support higher levels of dry matter intake, Dr. Byrne explained. And although red clover silages often tend to test poorer in terms of dry matter digestibility – an indicator of grass silage quality – chemical and morphological differences between the red clover and grass plant mean that higher levels of animal intake are achieved.
Citing research work carried out at Hillsborough back in the 1980s, Dr. Byrne explained that dairy-beef weanlings achieved daily weight gains of 300g/head more when offered red clover silage when compared to grass silage, which occurred due to animals consuming 2kg/head/day of extra dry matter. Benefits were also witnessed in finishing animals from the same research centre. Despite a 12% lower DMD from the red clover silage in comparison to the grass silage, the dry matter intake of finishing steers increased by 1.7kg/day to support the same average daily gain as witnessed with the grass silage.
Research work is ongoing in Teagasc Grange to evaluate the performance of red clover silage in dairy-beef systems. Provisional results are positive with weanlings achieving higher daily gains on the back of increased dry matter intakes. Over the coming years, the research centre will also evaluate the role red clover silages can play in suckler beef production systems.
The full recoding of the webinar, where Dr. Byrne discusses the factors to consider when establishing red clover silage swards, is available below.