December 30, 2020
Edwin Poots MLA, Agriculture, Environment and Rural Affairs Minister; John Henning, Senior Vice-Chair, AgriSearch; Harold Johnston; Peter Morrow, Vice-Chair, AgriSearch; Jason Rankin, General Manager, AgriSearch; Seamus McCaffrey, Chair, AgriSearch


Farmers interested in participating in AgriSearch’s new Beacon Farm Network are reminded that applications close on Monday 4th January at 12 Noon. AgriSearch aim to recruit beef, sheep and dairy farmers from a range of systems and land types (including upland…
December 18, 2020


On Tuesday 15th December, AgriSearch held an informational webinar for those interested in the recently announced Beacon Farm Network, attracting the interest of 65 farmers from across the province. In early 2020, AgriSearch commenced a strategy review,…
December 11, 2020

AgriSearch 2020 Christmas Newsletter

As 2020 draws to a close, we at AgriSearch have produced a Christmas Newsletter, featuring a round-up of our activities throughout the year. Like many others businesses during the COVID-19 pandemic, AgriSearch had to adapt to online platforms such as…
December 10, 2020


The successful EIT 'Focus on Farmers' Virtual Farm Walk and Discussion Series will come to a conclusion on Monday 14th December at 8pm with a with a “Christmas Special” webinar entitled “Productivity: the silver bullet to net zero carbon”. The main speaker on…


Concentrate feed levels have increased on Northern Ireland dairy farms, with concentrates now comprising 60-70% of the variable costs of milk production. However, CAFRE Benchmarking data has highlighted that concentrate use efficiency on dairy farms is hugely variable, while overfeeding of concentrates contributes to the Northern Ireland phosphorus (P) surplus. 

As concentrate feed levels have increased, concentrates are increasingly being offered to dairy cows on a ‘feed-to-yield’ basis, with feed levels in excess of 20 kg concentrate/cow/day not uncommon with higher yielding cows. However, AFBI research suggests that concentrate levels in excess of 13 - 14 kg concentrate/cow/day are associated with compromised milk quality, which can negate any economic benefit of these higher concentrate levels.  There is currently no ‘farm data’ to support this important finding, nor is there evidence of the impact of these feed levels on cow fertility and health.  It is expected that a number of factors will influence the performance and profitability of cows within feed-to-yield systems.

Thus the overall objective of this project is to examine the role of silage quality, concentrate composition, concentrate intake, feeding assumptions adopted, and cow genetics on the performance of individual cows within feed-to-yield systems, and in particular their effects on milk yield and milk composition (especially milk fat depression), and cow fertility/health, and ultimately provide improved advice on the management of feed-to-yield systems. This will include identifying how these factors contribute to overall economic performance at a herd level.

Farmer co-researchers involved in the "Feed-to-Yield" Study along with AFBI & AgriSearch staff

Lead Partner: AgriSearch

Research Partner: AFBI

Lead scientist: Dr Conrad Ferris

Co-Funding: DAERA Research Challenge Fund



Need / Problem

There has been a move to feed-to-yield concentrate allocation systems on many farms in an attempt to improve precision, and this has resulted in a significant increase in concentrate feed levels.  However, there is local research evidence that within these systems milk fat may be compromised with increasing concentrate feed level, especially with concentrate levels in excess of 13 –14 kg/cow/day.  However, this evidence was derived from a single research herd.  The impact of this observed reduction in milk fat content is that for individual cows, the margin over feed-and forage costs/cow was reduced at these high concentrate levels, especially at moderate and low milk prices.  While it is unknown if this is the case on commercial dairy farms, if it is, it may compromise the profitability of feed-to-yield systems, while contributing to the NI P surplus.  Thus a key objective of the current study is to examine the impact of feed-to-yield systems on cow performance and milk composition across a wide range of farm systems, thus providing information that is currently not available.  In addition, the impact of feed-to-yield systems on cow fertility and health is unknown, although it is hypothesised that this will lead to poorer fertility and health.  This project will clearly take us beyond current knowledge in this respect.  Also, through collection of data relating to feeding assumptions, silage quality, cow genetics, lactation number and concentrate composition, the project will allow us to identify some of the key drivers of both physical and financial performance within these systems.



On a global basis, in countries with developed dairy sectors, dairying tends to follow one of two diverse approaches, namely high concentrate input confinement type systems (North America, Northern Europe), or low input grass based systems (New Zealand, South America and Republic of Ireland). The former systems tend to operate in countries where milk price is high and concentrate feed ingredients are relatively inexpensive and plentiful, while the latter operate in countries where there is real potential to utilise grazed grass.  Northern Ireland has until recently tended to follow a middle course, making moderate use of concentrates and still maintaining a focus on forage in the diets of cows.  For this reason, the systems that we operate tend to be ‘less researched’ globally, with similar research tending to be confined to other Western European countries. AFBI is recognised as one of the leading Research centres within Europe for undertaking this type of research.


Outcomes of previous AFBI research programmes:

A three year research programme (11/1/13) has recently been completed at AFBI Hillsborough, and the proposed research programme has been developed to follow on from and compliment the previous research.  The objective of Strand 1 within 11/1/13 was to develop concentrate allocation strategies which optimise the economic return from concentrate and forage resources during the winter months, with three separate studies conducted:

The first of these studies involved a comparison of four diverse concentrate allocation strategies (Purcell et al., 2016), namely flat rate feeding through an out-of-parlour feeder, feed-to-yield feeding through an out-of-parlour feeder, the use of a basal diet containing some concentrates, with the remainder of the concentrates offered via an out-of parlour feeder, and finally a total mixed ration. In general, concentrate allocation strategy had little impact on cow performance. However, each of these systems were managed to achieve similar levels of concentrates in the diet, and in achieving this, true feed-to-yield strategies were not adopted. Nevertheless, the study clearly demonstrated that at a common concentrate input (across the study period), similar levels of cow performance were possible, albeit with a group of cows with a tight calving pattern.  The results of this study were largely in agreement with the outcomes of a number of previous AFBI studies, which compared feeding concentrates either separate to silage, or mixed with silage (as reviewed by Ferris et al., 1998). However, these previous studies involved much lower yielding dairy cows.

 A follow on study compared a true ‘feed-to-yield type system’, with a total mixed ration type system (Little et al., 2016).  While the treatments were again designed to have similar total concentrate intakes over the experimental period, the feed-to-yield system adopted true feed-to-yield principles.  In addition, the system adopted a ‘basal diet’ designed to meet the cow’s maintenance energy requirements, plus a certain level of cow performance, as is commonly practiced on local dairy farms.  Again, this study highlighted that feeding system had little impact on cow performance at a ‘herd’ level.  However, when data for individual cows were examined, the results demonstrated that there was a much greater range in concentrate intakes and performance with the feed-to-yield treatment.  In addition, this study also clearly demonstrated that when cows were offered concentrates on a feed to yield system, those offered higher concentrate levels had a reduced milk fat content, as expected, although this was not taken account of when allocating concentrates as concentrates were offered on a ‘yield’ basis.  However, surprisingly, these cows also had a wide range of energy balances over the course of the experiment, while in theory the treatment was designed to meet the energy requirements of each individual cow (Figure 1).  When the data was examined further, this could be attributed to the range of ‘assumptions’ adopted within a conventional feed-to-yield type system, including the assumption of a common maintenance requirement for each cow, the assumption of standard intake of basal diet for each cow and the assumption of standard milk composition.  All of these factors resulted in what was designed as a ‘precision feeding system’ being far from precise. 

Figure 1 Spread of energy balances with cows managed on a feed-to-yield type system (Little et al., 2016)


A third study (Purcell et al., 2015) within 11/1/13 examined the response of cows, managed within a feed-to-yield system, to increasing concentrate feed rates (0.35, 0.45 and 0.55 kg/litre of milk produced above that sustained by the basal diet).  This study provided the opportunity to examine the impact of feed-to-yield systems on forage intakes across a range of milk yields.  At a feed rate of 0.45 kg concentrate/kg milk, the feed rate most commonly used in practice, this study demonstrated that forage intakes tended to decrease slightly with increasing milk yield, and as such the assumption of a common milk yield being sustained by the basal diet irrespective of milk yield is not completely true (Figure 2).

Figure 2 Relationship between milk yield and silage intake from the basal diet at three different feed rates

However, when the data from all treatments were combined, the impact of increasing concentrate levels within a feed-to-yield type system on milk composition became clear (Figure 3), with milk fat decreasing with increasing concentrate level, and the effect particularly dramatic at levels above 13 - 14 kg/cow/day.  While a reduction in milk composition with higher yields has long been recognised and ‘accepted’ by the dairy sector, the implications of this on the financial performance of individual cows within the herd has never been examined. However, Figure 4 highlights that a reduction in milk composition can have a particularly dramatic effect on the value of each litre of milk produced, based on current milk pricing systems in NI, with the value of each litre of milk produced by cows offered lower concentrate levels being approximately 4 - 6 pence per litre higher than for those offered higher concentrate levels.  This study also provided an opportunity to examine the effects of increasing concentrate levels on margin-over-feed costs, and this was undertaken at three different milk prices, namely 18, 26 and 34 pence per litre (Figure 5).  At a milk price of 34 pence per litre, the additional margin-over-feed costs per cow was relatively small at concentrate levels in excess of 14 kg per cow per day.   At lower milk prices (18 and 26 pence per litre milk), margin per cow did not increase at concentrate levels above approximately 14 kg per cow/day.  Indeed, at a milk price of 18 pence per litre, margin per cow tended to decrease when concentrate level was increased beyond 14 kg/cow/day.  This levelling off (or reduction) in margin at higher concentrate levels is due to the decline in milk fat concentration at these levels, and the associated reduction in the value of each litre of milk produced.

Figure 3 Effect of concentrate intake on milk fat percentage


Figure 4 Effect of concentrate intake on financial payments for milk composition (bonuses or deductions; combined data for the three feed rates treatments)


Figure 5 Relationship between concentrate intake and margin-over-feed costs for each individual cow at three different milk prices










However, none of these studies were able to identify the impact of concentrate level on cow fertility and health due to inadequate numbers of animals involved.  This is important as it might be expected that cows offered high concentrate levels will be more susceptible to health issues, especially digestive upsets and lameness.  In addition, while there is published evidence of improved fertility performance with increasing energy status of cows, most of this data is not derived from studies involving concentrates being offered on a feed-to-yield basis. 

Precision feeding – previous research outside of AFBI:  A number of previous studies have examined ‘feed-to-yield’ and group feeding approaches, with most of this research conducted more than 20 years ago, and involving low yielding cows.  While studies have recognised the limitations of ‘precision approaches’ adopted in the past, few studies have sought to improve precision in these systems.  Exceptions include a number of early studies by Maltz et al. (1997) and Maltz (1997), who sought to develop feeding approaches that were driven primarily by cow live weight changes and milk yields.  These authors identified that these approaches offered potential to bring increased precision to dairy cow feeding, but this line of work received little further attention until revisited by Maltz et al. (2013).  In this study, the authors ‘fed cows to energy balance’, rather than milk yield (as in most previous studies, including those conducted under 11/1/13), and found milk yield to be significantly increased, and energy corrected milk yield/kg intake to be improved with cows offered diets according to energy requirements.  These authors also recognised that with increasing automation within dairy systems, there is more scope now to develop systems which bring increased precision to feeding systems, and that this is possible with minimum input from farmers, provided the correct software can be developed.



Work Plan

  1. To recruit 30 dairy farmer ‘co-researchers’ who meet the selection criteria for participating in the project.
  2. Collect the necessary data/information/samples over a 12 month period
  3. Determine individual cow concentrate intakes (based on feeding assumptions), and examine the effect of concentrate feed level on milk yield, milk composition and yield of milk solids.
  4. To examine how feeding assumptions adopted, silage quality, cow genetics, lactation number and concentrate composition influence the milk production and fertility/health responses at a cow and farm level, as appropriate.
  5. To undertake economic modelling of the data obtained
  6. Provide clear advice/information on key drivers of performance (physical and financial) within feed-to-yield systems, including recommendations for how these systems can be improved.
  7. Effective dissemination of research outcome




  1. Establishment of a successful research partnership between AgriSearch (representing primary milk producers in NI) and AFBI Scientists, to address an important issue which has been identified by these two organisations.
  2. A successfully completed research project which has been undertaken to highest standards.
  3. A robust data set which will be analysed to provide clear information to NI dairy farmers on improving management within feed-to-yield systems, and in particular:

    ·   the effect of concentrate feed level within feed-to-yield systems on milk yield, milk composition and the yield of milk solids

    ·   the effect of individual cow concentrate feed level on cow fertility and health

    ·   the impact of feeding assumptions adopted, silage quality, cow genetics, lactation number and concentrate composition on the milk production and fertility/health responses at a cow and farm level,

    ·   economic responses to concentrate feed level at an individual cow level under a range of milk prices, and using a number of milk payment schemes

    ·   economic impact of concentrate feed level on fertility and health traits

    ·   relationships between experimental data collected (feed rates, silage quality, cow performance) and whole farm profitability traits (based on benchmarking data)

  4. Effective and widespread dissemination of the findings of the study to Northern Ireland dairy farmers. This will be achieved through the joint activities of the AFBI-AgriSearch partnership which will target technology transfer to CAFRE advisors and local feed industry representatives, and directly to farmers through, the AgriSearch website, press releases, visits to Hillsborough, participation in farmer events and meetings, a farmer’s booklet and a final industry report.
  5. Through the dissemination strategies described above, an increased awareness amongst primary producers of the impact of concentrate feed levels within feed-to-yield systems on cow performance, milk composition, cow fertility and health, and the economic impact of decisions made within feed-to-yield systems. 
  6. Submission of a scientific paper describing the outcomes of the project to a high impact factor scientific journal (publication will likely take place outside of the projects lifetime).




A large part of the NI dairy sector has now adopted feed-to-yield concentrate allocation strategies as part of normal farming practice.  While these feeding systems are advocated as ‘precision feeding’, research conducted using the AFBI dairy herd has highlighted a number of concerns about aspects of feed-to-yield systems, especially in higher yielding herds.  In particular, the reduction in milk composition associated with increasing concentrate levels may actually reduce the profitability of individual cows.  In addition, there appears to be no information available on the impact of concentrate feed level within feed-to-yield systems on either fertility or health traits. Given the impact of the importance of these issues on long-term farm viability, it is prudent to investigate further.

This current research programme, while driven by the outcomes of previous research undertaken by AFBI and co-funded by AgriSearch, seeks to move beyond the ‘research farm environment’ and identify if the earlier findings hold true on commercial farms. Using a commercial farm platform will greatly increase the numbers of cows contributing data to the project, the genetic potential of the cow population, and the variability in feeding systems that will be examined. No published research to date appears to examine the responses to concentrate feeding across a large number of commercial dairy farms.

The proposed research does not ‘compete’ with any other technology, and does in fact seek to build on the finding of other recently completed research programmes undertaken at AFBI-Hillsborough. The outcomes could be used to direct and guide future developments within in-parlour and out-of-parlour feeding technologies.

Potential technological / scientific benefits / advances

Based on the outcomes of research conducted within a ‘research institute environment’, the assumption is made that milk composition will be compromised by the use of high concentrate feed levels within feed-to-yield systems. It is also hypothesised that fertility and health performance will be compromised at these higher concentrate levels. 

On this basis it is proposed that the physical and economic performance of dairy systems can be improved by modifying concentrate allocation strategies within these systems, and that the project will enhance the understanding of key drivers of efficiency within feed-to-yield systems.  Expected scientific benefits and advances are outlined below:

  • Clear understanding of the effect of concentrate feed level within feed-to-yield systems on milk yield, milk composition and the yield of milk solids
  • Clear understanding of the effect of individual cow concentrate feed level on cow fertility and health
  • Clear understanding of the impact of feeding assumptions adopted, silage quality, cow genetics, lactation number and concentrate composition on the milk production and fertility/health responses at a cow and farm level
  • Clear understanding of the economic responses to concentrate feed level at an individual cow level under a range of milk prices, and using a number of milk payment schemes
  • Quantification of the economic impact of concentrate feed level on fertility and health traits
  • Quantification of the relationships between experimental data collected (feed rates, silage quality, cow performance) and whole farm profitability traits (based on benchmarking data)
  • The knowledge/outcomes could be used by parlour and feeding system manufacturers to developed improved soft-ware systems that will take better account of individual animal performance.

As the proposed project will be undertaken on local farms, this will increase the likelihood that the outcomes from the project will be communicated to the wider farming community, and the associated benefits adopted.  Technology transfer will be embedded into the programme from its launch, with appropriate involvement from CAFRE. 

Benefits to Primary Production Sector in Northern Ireland

Dairy farming plays an important role within the rural economy of Northern Ireland, both in terms of those directly employed on dairy farms, the service and supply industry which supports the sector, and the processing sector. 

Concentrate feed levels have increased on Northern Ireland dairy farms, with concentrates now comprising 60-70% of the variable costs of milk production. The reasons for this are several, and reflect the increasing genetic merit of the local dairy herd, increasing herd size on most farms, and the high cost of land which means that ‘expansion’ in milk output is normally achieved through increased concentrate feeding. However, CAFRE Benchmarking data has highlighted that concentrate use efficiency on dairy farms is hugely variable, while concentrates contribute to the Northern Ireland phosphorus surplus.  CAFRE staff have estimated that the average dairy farm may be feeding an extra 0.3 - 0.5 t concentrate/cow/year above that which is required.

While it is impossible to obtain accurate data, a conservative estimate is that over 50% of farms now adopt a ‘feed-to-yield’ approach when feeding concentrates. However, as this practice tends to be most common on larger farms, it is likely that approximately 75% of cows in NI are offered concentrates using a feed-to-yield approach (65% of cows are in herds with more than 100 cows).  On this basis, it is calculated that the project will be relevant to approximately 206, 000 cows.  It is estimated that approximately 15 - 20% of these cows will be offered concentrate levels sufficiently high to compromise milk quality. However, the project has broader application to all herds where feed-to-yield systems are adopted in that it will seek to quantify the impact of concentrate levels within feeding system on fertility and health, and to identify key drivers of efficiency within production systems.  Thus potential benefits include: 

  • Reduction in concentrate feed levels to cows receiving more that 13 - 14 kg concentrate/day in early lactation.  Estimate of potential concentrate reduction with no negative impact on yield of milk solids is 3.0 kg/cow/day during the first 150 days of lactation: 206, 000 cows x 15% affected x 3 kg reduction x 150 days = annual saving of  13, 905 t concentrate.  It is likely that there would be an associated increase in forage intakes that would need to be considered.
  • This reduction in concentrate input would be associated with a 70 t reduction in P inputs onto farms (based on an average P content of 5 kg/t)
  • Any possible impact on fertility and health cannot be quantified as the impact of feed-to-yield systems on these parameters are simply unknown at this stage. Understanding these impacts, if they exist, is a key part of this study.
  • In addition the three very specific issues highlighted in the above bullet points, the project seeks to provide an improved understanding of the wider issues driving the efficiency of feed-to-yield type systems.  This improved understanding will also likely result in benefits, although these cannot be quantified at this time.
  • Thus the proposed project has potential to have very significant benefits for the primary production sector and to play a major role in directing the industry to improvements in production efficiency.  In doing so, the project will have a very significant function in terms of driving competitiveness of the Northern Ireland dairy industry.

Sustainable Development and Environmental Benefits

Developing an improved understanding off feed-to-yield concentrate feeding systems, and the adoption of enhanced concentrate allocation strategies, has a number of sustainability and environmental benefits:

Reducing concentrate feed levels on local farms, without loss of performance, resulting in an economic saving.

Reduction in phosphorus excretion associated with dairy systems.  With regards P, the calculation in 7c suggests that if adopted, the project could result in a 70 t reduction in P inputs onto NI dairy farms, a significant reduction.  If fertility and health benefits could also be achieved, this would reduce the number of ‘non-productive’ animals on the farm, with a further reduction in the P surplus.

Similarly, any potential improvement in health and fertility would have a positive impact on GHG emissions. It is widely acknowledged that one of the key strategies by which GHG emissions can be reduced from dairy systems involves improving production efficiency and cow survival.