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Last week’s dairy innovation event at AFBI Hillsborough highlighted how current research can be used to increase profitability at farm level across NI.
The key messages delivered from the numerous speakers mainly centred around the role that grass has to play on NI dairy farms.
Regardless of whether the farm operates a fully contained system, a low-cost grass-based system or a combination of both, there are significant financial gains to be made from increasing grass yields, sward quality and the feed-value of grass silage.
While this will not come as news to the majority of dairy farmers, it appears that the messages are not always taken on board.
Average dairy cow
According to AFBI chef executive Dr Sinclair Mayne, the average dairy cow in NI has increased yield from 5,500 litres to 7,200 litres per annum over the last 20 years.
With the average herd size also increasing, NI milk production has doubled during this period.
However, this upward trend in yield has been driven by purchased concentrate, as milk from forage has fallen from 3,200 to 2,500 litres per cow per year.
With volatility expected to remain a feature in global dairy markets, Mayne stressed that NI dairy farms need to focus on increasing the volume of milk produced from forage as a means to controlling production costs.
Dairy cows at Hillsborough are currently yielding 33 litres/day with approximately 21 litres coming from forage, indicating that in well managed systems, it is possible to get high levels of milk output from grazed grass.
Mayne also stated that dairy farmers need to look at embracing precision technology to improve management and efficiency inside the farm gate.
Future research will be geared towards the role of such technologies, as well as issues surrounding ammonia, greenhouse gas emissions and phosphate restrictions, all of which could have significant implications for local dairy farmers.
Soil fertility issues need to be addressed
Just over 40% of NI dairy farms have soils that are below the optimum pH level (pH 6.0 to 6.2) for grass growth. As soils become acidic, nutrients become locked up and unavailable for growth.
Applying lime is one of the best investments that can be made on farm.
For every £1 spent on lime, the value of increased grass production is worth anywhere from £5 to £8.
Increasing soils from pH 5.5 to pH 6.0 or better, will increase grass yields by as much as 2t of dry matter (DM) per hectare (approximately 10t of fresh grass per hectare).
Approximately 20% of dairy farms are deficient in potash (K), despite slurry being an excellent source of this nutrient.
Soils low in potash will see yields reduce by as much as 30% as the nutrient is crucial in the uptake of soil nitrogen by the plant.
Soils are also becoming deficient in sulphur which also impacts on yield. Every £5/ha of sulphur applied can increase grass growth by as much as £90/ha under ideal growing conditions.
Making the most from grass
The average NI dairy farm utilises 7.5t DM/ha. But with new grass varieties capable of producing 14t to 20t/ha under NI weather conditions, there is considerable scope for dairy farmers to increase this figure.
While soil type and farm location will influence grass production, according to Dr Debbie McConnell, there is potential on all dairy farms to grow 12t DM/ha and utilise at least 10t DM/ha.
Soil fertility will be a key factor in achieving such yields, with a greater requirement for higher levels of nitrogen to be applied to soils.
Fertiliser
NI dairy farms typically apply 140kg/ha of nitrogen annually, which is approximately 112 units of N/acre or the equivalent of four bags of CAN per acre. It is a level of N that is insufficient to grow 12t DM/ha.
However, research trials have shown that improving grass utilisation on dairy farms by 1t DM/ha can add profit of £334/ha/year (assuming a milk price of 28p/l).
In addition to this, analysis of fertiliser applications and grass growth on the GrassCheck farms working with AFBI has shown that every 1kg of nitrogen applied will yield 21kg of grass on a dry matter basis.
This means that every £1 of nitrogen fertiliser applied to grazing, will produce a return of £11.60 per cow.
Grazing residual
However, there is a balance between grazing management and cow prformance. Forcing cows to graze grass as tight as possible will reduce milk yield, although it will increase the profit per hectare of land farmed, due to an increase in stocking rates.
Cows grazing swards to a residual of 5.2cm had an average daily yield of 30.5 litres and supported a stocking rate of 7.8 cows/ha under trial work over a 142-day grazing period. Margin over feed and forage equated to £6,061/ha.
In contrast, swards grazed to a higher residual of 6.8cm produced higher daily yields averaging 33.2 litres/cow. However, stocking rates were lower at 5.6 cows/ha. Margin over feed and forage was £4,270/ha.
Supplementing cows at grass
According to Dr Steven Morrison, research has indicated that the most cost-effective concentrate feed rate in feed to yield systems is 0.45kg per litre of milk produced above maintenance plus values.
Cows in an AFBI study that were on a feed rate of 0.45kg yielded 19.8 litres/cow/day, whereas cows on 0.25kg yielded 17.3 litres/cow/day. In financial terms, the 0.45kg feed rate had a margin over feed cost of £3.96/cow/day and the 0.25kg feed rate delivered 31p less at £3.65/cow/day.
The other feed to yield rate under investigation in the study was 0.65kg. This rate delivered the highest milk yield of 20.4 litres/cow/day, but when the increased concentrate cost was factored in, it was not as cost-effective, as margin over feed cost stood at £3.82/cow/day.
Dr Morrison pointed out that higher concentrate rates also reduce grazed grass intakes which can make grass covers harder to manage. Higher post-grazing covers lower grass quality and reduce intakes in the next rotation. This will have an effect on subsequent milk yields, unless concentrate feeding is increased further.
Silage quality
Also, speaking at the open day, Dr Conrad Ferris told visitors that milk from forage is a key driver of profitability, regardless of the type of dairying system. He said that every additional 1,000 litres of milk produced from forage is worth around £10,800 in a 100-cow herd.
With many NI dairy farms operating year-round calving patterns, the role of silage in cow diets cannot be overlooked as it will help drive milk yield and cow fertility. However, Dr Ferris said that over the last 20 years, a period when more than 80,000-plus silage samples have been analysed by AFBI, silage quality has remained static for energy, protein and D-value.
He said that a key factor in silage quality is cutting date, with D-Value reducing by three units every week that silage harvesting is delayed once seed heads start to emerge. This equates to an average drop in milk yield of 1.3 litres/cow/day, which would require an extra 1.5kg/cow/day of concentrate feeding to offset.
While high-quality silage will reduce concentrate levels fed, it will also increase milk solids, especially butterfat. Ferris said that with high-quality silage, concentrate levels should be capped at 12kg to 14kg/day to avoid a negative effect on butterfat levels.
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